// Copyright (c) 2015-2019 Michael Popoloski
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security;

namespace SharpBgfx {
    /// <summary>
    /// Provides an interface for programs to respond to callbacks from the bgfx library.
    /// </summary>
    public interface ICallbackHandler {
        /// <summary>
        /// Called when an error occurs in the library.
        /// </summary>
        /// <param name="fileName">The name of the source file in which the message originated.</param>
        /// <param name="line">The line number in which the message originated.</param>
        /// <param name="errorType">The type of error that occurred.</param>
        /// <param name="message">Message string detailing what went wrong.</param>
        /// <remarks>
        /// If the error type is not <see cref="ErrorType.DebugCheck"/>, bgfx is in an
        /// unrecoverable state and the application should terminate.
        ///
        /// This method can be called from any thread.
        /// </remarks>
        void ReportError (string fileName, int line, ErrorType errorType, string message);

        /// <summary>
        /// Called to print debug messages.
        /// </summary>
        /// <param name="fileName">The name of the source file in which the message originated.</param>
        /// <param name="line">The line number in which the message originated.</param>
        /// <param name="format">The message format string.</param>
        /// <param name="args">A pointer to format arguments.</param>
        /// <remarks>This method can be called from any thread.</remarks>
        void ReportDebug (string fileName, int line, string format, IntPtr args);

        /// <summary>
        /// Called when a profiling region is entered.
        /// </summary>
        /// <param name="name">The name of the region.</param>
        /// <param name="color">The color of the region.</param>
        /// <param name="filePath">The path of the source file containing the region.</param>
        /// <param name="line">The line number on which the region was started.</param>
        void ProfilerBegin (string name, int color, string filePath, int line);

        /// <summary>
        /// Called when a profiling region is ended.
        /// </summary>
        void ProfilerEnd ();

        /// <summary>
        /// Queries the size of a cache item.
        /// </summary>
        /// <param name="id">The cache entry ID.</param>
        /// <returns>The size of the cache item, or 0 if the item is not found.</returns>
        int GetCachedSize (long id);

        /// <summary>
        /// Retrieves an entry from the cache.
        /// </summary>
        /// <param name="id">The cache entry ID.</param>
        /// <param name="data">A pointer that should be filled with data from the cache.</param>
        /// <param name="size">The size of the memory block pointed to be <paramref name="data"/>.</param>
        /// <returns><c>true</c> if the item is found in the cache; otherwise, <c>false</c>.</returns>
        bool GetCacheEntry (long id, IntPtr data, int size);

        /// <summary>
        /// Saves an entry in the cache.
        /// </summary>
        /// <param name="id">The cache entry ID.</param>
        /// <param name="data">A pointer to the data to save in the cache.</param>
        /// <param name="size">The size of the memory block pointed to be <paramref name="data"/>.</param>
        void SetCacheEntry (long id, IntPtr data, int size);

        /// <summary>
        /// Save a captured screenshot.
        /// </summary>
        /// <param name="path">The path at which to save the image.</param>
        /// <param name="width">The width of the image.</param>
        /// <param name="height">The height of the image.</param>
        /// <param name="pitch">The number of bytes between lines in the image.</param>
        /// <param name="data">A pointer to the image data to save.</param>
        /// <param name="size">The size of the image memory.</param>
        /// <param name="flipVertical"><c>true</c> if the image origin is bottom left instead of top left; otherwise, <c>false</c>.</param>
        void SaveScreenShot (string path, int width, int height, int pitch, IntPtr data, int size, bool flipVertical);

        /// <summary>
        /// Notifies that a frame capture has begun.
        /// </summary>
        /// <param name="width">The width of the capture surface.</param>
        /// <param name="height">The height of the capture surface.</param>
        /// <param name="pitch">The number of bytes between lines in the captured frames.</param>
        /// <param name="format">The format of captured frames.</param>
        /// <param name="flipVertical"><c>true</c> if the image origin is bottom left instead of top left; otherwise, <c>false</c>.</param>
        void CaptureStarted (int width, int height, int pitch, TextureFormat format, bool flipVertical);

        /// <summary>
        /// Notifies that a frame capture has finished.
        /// </summary>
        void CaptureFinished ();

        /// <summary>
        /// Notifies that a frame has been captured.
        /// </summary>
        /// <param name="data">A pointer to the frame data.</param>
        /// <param name="size">The size of the frame data.</param>
        void CaptureFrame (IntPtr data, int size);
    }

    /// <summary>
    /// Managed interface to the bgfx graphics library.
    /// </summary>
    public unsafe static class Bgfx {
        /// <summary>
        /// Attempts to allocate both a transient vertex buffer and index buffer.
        /// </summary>
        /// <param name="vertexCount">The number of vertices to allocate.</param>
        /// <param name="layout">The layout of each vertex.</param>
        /// <param name="indexCount">The number of indices to allocate.</param>
        /// <param name="vertexBuffer">Returns the allocated transient vertex buffer.</param>
        /// <param name="indexBuffer">Returns the allocated transient index buffer.</param>
        /// <returns><c>true</c> if both space requirements are satisfied and the buffers were allocated.</returns>
        public static bool AllocateTransientBuffers (int vertexCount, VertexLayout layout, int indexCount, out TransientVertexBuffer vertexBuffer, out TransientIndexBuffer indexBuffer) {
            return NativeMethods.bgfx_alloc_transient_buffers(out vertexBuffer, ref layout.data, (ushort)vertexCount, out indexBuffer, (ushort)indexCount);
        }

        /// <summary>
        /// Packs a vector into vertex stream format.
        /// </summary>
        /// <param name="input">The four element vector to pack.</param>
        /// <param name="inputNormalized"><c>true</c> if the input vector is normalized.</param>
        /// <param name="attribute">The attribute usage of the vector data.</param>
        /// <param name="layout">The layout of the vertex stream.</param>
        /// <param name="data">The pointer to the vertex data stream.</param>
        /// <param name="index">The index of the vertex within the stream.</param>
        public static void VertexPack (float* input, bool inputNormalized, VertexAttributeUsage attribute, VertexLayout layout, IntPtr data, int index = 0) {
            NativeMethods.bgfx_vertex_pack(input, inputNormalized, attribute, ref layout.data, data, index);
        }

        /// <summary>
        /// Unpack a vector from a vertex stream.
        /// </summary>
        /// <param name="output">A pointer to four floats that will receive the unpacked vector.</param>
        /// <param name="attribute">The usage of the vertex attribute.</param>
        /// <param name="layout">The layout of the vertex stream.</param>
        /// <param name="data">A pointer to the vertex data stream.</param>
        /// <param name="index">The index of the vertex within the stream.</param>
        public static void VertexUnpack (float* output, VertexAttributeUsage attribute, VertexLayout layout, IntPtr data, int index = 0) {
            NativeMethods.bgfx_vertex_unpack(output, attribute, ref layout.data, data, index);
        }

        /// <summary>
        /// Converts a stream of vertex data from one format to another.
        /// </summary>
        /// <param name="destinationLayout">The destination format.</param>
        /// <param name="destinationData">A pointer to the output location.</param>
        /// <param name="sourceLayout">The source format.</param>
        /// <param name="sourceData">A pointer to the source vertex data to convert.</param>
        /// <param name="count">The number of vertices to convert.</param>
        public static void VertexConvert (VertexLayout destinationLayout, IntPtr destinationData, VertexLayout sourceLayout, IntPtr sourceData, int count = 1) {
            NativeMethods.bgfx_vertex_convert(ref destinationLayout.data, destinationData, ref sourceLayout.data, sourceData, count);
        }

        /// <summary>
        /// Welds vertices that are close together.
        /// </summary>
        /// <param name="layout">The layout of the vertex stream.</param>
        /// <param name="data">A pointer to the vertex data stream.</param>
        /// <param name="count">The number of vertices in the stream.</param>
        /// <param name="remappingTable">An output remapping table from the original vertices to the welded ones.</param>
        /// <param name="epsilon">The tolerance for welding vertex positions.</param>
        /// <returns>
        /// The number of unique vertices after welding.
        /// </returns>
        public static int WeldVertices (VertexLayout layout, IntPtr data, int count, out int[] remappingTable, float epsilon = 0.001f) {
            var output = stackalloc ushort[count];
            var result = NativeMethods.bgfx_weld_vertices(output, ref layout.data, data, (ushort)count, epsilon);

            remappingTable = new int[count];
            for (int i = 0; i < count; i++)
                remappingTable[i] = output[i];

            return result;
        }

        /// <summary>
        /// Swizzles an RGBA8 image to BGRA8.
        /// </summary>
        /// <param name="destination">The destination image data.</param>
        /// <param name="width">The width of the image.</param>
        /// <param name="height">The height of the image.</param>
        /// <param name="pitch">The pitch of the image (in bytes).</param>
        /// <param name="source">The source image data.</param>
        /// <remarks>
        /// This method can operate in-place on the image (i.e. src == dst).
        /// </remarks>
        public static void ImageSwizzleBgra8(IntPtr destination, int width, int height, int pitch, IntPtr source) {
            NativeMethods.bgfx_image_swizzle_bgra8(destination, width, height, pitch, source);
        }

        /// <summary>
        /// Downsamples an RGBA8 image with a 2x2 pixel average filter.
        /// </summary>
        /// <param name="destination">The destination image data.</param>
        /// <param name="width">The width of the image.</param>
        /// <param name="height">The height of the image.</param>
        /// <param name="pitch">The pitch of the image (in bytes).</param>
        /// <param name="source">The source image data.</param>
        /// <remarks>
        /// This method can operate in-place on the image (i.e. src == dst).
        /// </remarks>
        public static void ImageRgba8Downsample2x2 (IntPtr destination, int width, int height, int pitch, IntPtr source) {
            NativeMethods.bgfx_image_rgba8_downsample_2x2(destination, width, height, pitch, source);
        }

        /// <summary>
        /// Sets platform-specific data pointers to hook into low-level library functionality.
        /// </summary>
        /// <param name="platformData">A collection of platform-specific data pointers.</param>
        public static void SetPlatformData (PlatformData platformData) {
            NativeMethods.bgfx_set_platform_data(ref platformData);
        }

        /// <summary>
        /// Sets the handle of the main rendering window.
        /// </summary>
        /// <param name="windowHandle">The handle of the native OS window.</param>
        public static void SetWindowHandle (IntPtr windowHandle) {
            var data = new PlatformData { WindowHandle = windowHandle };
            NativeMethods.bgfx_set_platform_data(ref data);
        }

        /// <summary>
        /// Gets access to underlying API internals for interop scenarios.
        /// </summary>
        /// <returns>A structure containing API context information.</returns>
        public static InternalData GetInternalData () {
            unsafe { return *NativeMethods.bgfx_get_internal_data(); }
        }

        /// <summary>
        /// Manually renders a frame. Use this to control the Bgfx render loop.
        /// </summary>
        /// <param name="timeoutMs">
        /// The amount of time to wait, in milliseconds, for the next frame to be rendered.
        /// If the timeout is exceeded, the call
        /// returns.
        /// </param>
        /// <returns>The result of the render call.</returns>
        /// <remarks>
        /// Use this function if you don't want Bgfx to create and maintain a
        /// separate render thread. Call this once before <see cref="Bgfx.Init(RendererBackend, Adapter, ICallbackHandler)"/>
        /// to avoid having the thread created internally.
        /// </remarks>
        public static RenderFrameResult ManuallyRenderFrame (int timeoutMs = -1) {
            return NativeMethods.bgfx_render_frame(timeoutMs);
        }

        /// <summary>
        /// Gets the currently active rendering backend API.
        /// </summary>
        /// <returns>The currently active rendering backend.</returns>
        public static RendererBackend GetCurrentBackend () {
            return NativeMethods.bgfx_get_renderer_type();
        }

        /// <summary>
        /// Closes the library and releases all resources.
        /// </summary>
        public static void Shutdown () {
            NativeMethods.bgfx_shutdown();
            CallbackShim.FreeShim();
        }

        /// <summary>
        /// Gets the capabilities of the rendering device.
        /// </summary>
        /// <returns>Information about the capabilities of the device.</returns>
        public static Capabilities GetCaps () {
            return new Capabilities(NativeMethods.bgfx_get_caps());
        }

        /// <summary>
        /// Gets frame performance statistics.
        /// </summary>
        /// <returns>Information about frame performance.</returns>
        public static PerfStats GetStats () {
            return new PerfStats(NativeMethods.bgfx_get_stats());
        }


        /// <summary>
        /// Resets graphics settings and surfaces.
        /// </summary>
        /// <param name="width">The width of the main window.</param>
        /// <param name="height">The height of the main window.</param>
        /// <param name="flags">Flags used to configure rendering output.</param>
        public static void Reset (int width, int height, ResetFlags flags = ResetFlags.None) {
            Reset(width, height, flags, (TextureFormat)TextureFormatCount);
        }

        /// <summary>
        /// Resets graphics settings and surfaces.
        /// </summary>
        /// <param name="width">The width of the main window.</param>
        /// <param name="height">The height of the main window.</param>
        /// <param name="flags">Flags used to configure rendering output.</param>
        /// <param name="format">The format of the backbuffer.</param>
        public static void Reset (int width, int height, ResetFlags flags, TextureFormat format) {
            NativeMethods.bgfx_reset(width, height, flags, format);
        }

        /// <summary>
        /// Advances to the next frame.
        /// </summary>
        /// <param name="capture">If <c>true</c> the frame is captured for debugging.</param>
        /// <returns>The current frame number.</returns>
        /// <remarks>
        /// When using a multithreaded renderer, this call
        /// just swaps internal buffers, kicks render thread, and returns. In a
        /// singlethreaded renderer this call does frame rendering.
        /// </remarks>
        public static int Frame (bool capture = false) {
            return NativeMethods.bgfx_frame(capture);
        }

        /// <summary>
        /// Initializes the graphics library on the specified adapter.
        /// </summary>
        /// <param name="settings">Settings that control initialization, or <c>null</c> to use sane defaults.</param>
        /// <returns><c>true</c> if initialization succeeds; otherwise, <c>false</c>.</returns>
        public static bool Init (InitSettings settings = null) {
            InitSettings.Native native;
            NativeMethods.bgfx_init_ctor(&native);

            settings = settings ?? new InitSettings();
            native.Backend = settings.Backend;
            native.VendorId = (ushort)settings.Adapter.Vendor;
            native.DeviceId = (ushort)settings.Adapter.DeviceId;
            native.Debug = (byte)(settings.Debug ? 1 : 0);
            native.Profiling = (byte)(settings.Profiling ? 1 : 0);
            native.Resolution.Format = settings.Format;
            native.Resolution.Width = (uint)settings.Width;
            native.Resolution.Height = (uint)settings.Height;
            native.Resolution.Flags = (uint)settings.ResetFlags;
            native.Resolution.NumBackBuffers = (byte)settings.BackBufferCount;
            native.Resolution.MaxFrameLatency = (byte)settings.MaxFrameLatency;
            native.Callbacks = CallbackShim.CreateShim(settings.CallbackHandler ?? new DefaultCallbackHandler());
            native.PlatformData = settings.PlatformData;

            return NativeMethods.bgfx_init(&native);
        }

        /// <summary>
        /// Gets the set of supported rendering backends.
        /// </summary>
        /// <returns></returns>
        public static RendererBackend[] GetSupportedBackends () {
            var types = new RendererBackend[(int)RendererBackend.Default];
            var count = NativeMethods.bgfx_get_supported_renderers((byte)types.Length, types);

            return types.Take(count).ToArray();
        }

        /// <summary>
        /// Gets the friendly name of a specific rendering backend.
        /// </summary>
        /// <param name="backend">The backend for which to retrieve a name.</param>
        /// <returns>The friendly name of the specified backend.</returns>
        public static string GetBackendName (RendererBackend backend) {
            return Marshal.PtrToStringAnsi(new IntPtr(NativeMethods.bgfx_get_renderer_name(backend)));
        }

        /// <summary>
        /// Enables debugging features.
        /// </summary>
        /// <param name="features">The set of debug features to enable.</param>
        public static void SetDebugFeatures (DebugFeatures features) {
            NativeMethods.bgfx_set_debug(features);
        }

        /// <summary>
        /// Sets a marker that can be used for debugging purposes.
        /// </summary>
        /// <param name="marker">The user-defined name of the marker.</param>
        public static void SetDebugMarker (string marker) {
            NativeMethods.bgfx_set_marker(marker);
        }

        /// <summary>
        /// Clears the debug text buffer.
        /// </summary>
        /// <param name="color">The color with which to clear the background.</param>
        /// <param name="smallText"><c>true</c> to use a small font for debug output; <c>false</c> to use normal sized text.</param>
        public static void DebugTextClear (DebugColor color = DebugColor.Black, bool smallText = false) {
            var attr = (byte)((byte)color << 4);
            NativeMethods.bgfx_dbg_text_clear(attr, smallText);
        }

        /// <summary>
        /// Writes debug text to the screen.
        /// </summary>
        /// <param name="x">The X position, in cells.</param>
        /// <param name="y">The Y position, in cells.</param>
        /// <param name="foreColor">The foreground color of the text.</param>
        /// <param name="backColor">The background color of the text.</param>
        /// <param name="format">The format of the message.</param>
        /// <param name="args">The arguments with which to format the message.</param>
        public static void DebugTextWrite (int x, int y, DebugColor foreColor, DebugColor backColor, string format, params object[] args) {
            DebugTextWrite(x, y, foreColor, backColor, string.Format(CultureInfo.CurrentCulture, format, args));
        }

        /// <summary>
        /// Writes debug text to the screen.
        /// </summary>
        /// <param name="x">The X position, in cells.</param>
        /// <param name="y">The Y position, in cells.</param>
        /// <param name="foreColor">The foreground color of the text.</param>
        /// <param name="backColor">The background color of the text.</param>
        /// <param name="message">The message to write.</param>
        public static void DebugTextWrite (int x, int y, DebugColor foreColor, DebugColor backColor, string message) {
            var attr = (byte)(((byte)backColor << 4) | (byte)foreColor);
            NativeMethods.bgfx_dbg_text_printf((ushort)x, (ushort)y, attr, "%s", message);
        }

        /// <summary>
        /// Writes debug text to the screen.
        /// </summary>
        /// <param name="x">The X position, in cells.</param>
        /// <param name="y">The Y position, in cells.</param>
        /// <param name="foreColor">The foreground color of the text.</param>
        /// <param name="backColor">The background color of the text.</param>
        /// <param name="message">The message to write.</param>
        public static void DebugTextWrite (int x, int y, DebugColor foreColor, DebugColor backColor, IntPtr message) {
            var attr = (byte)(((byte)backColor << 4) | (byte)foreColor);
            var format = stackalloc byte[3];
            format[0] = (byte)'%';
            format[1] = (byte)'s';
            format[2] = 0;
            NativeMethods.bgfx_dbg_text_printf((ushort)x, (ushort)y, attr, format, message);
        }

        /// <summary>
        /// Draws data directly into the debug text buffer.
        /// </summary>
        /// <param name="x">The X position, in cells.</param>
        /// <param name="y">The Y position, in cells.</param>
        /// <param name="width">The width of the image to draw.</param>
        /// <param name="height">The height of the image to draw.</param>
        /// <param name="data">The image data bytes.</param>
        /// <param name="pitch">The pitch of each line in the image data.</param>
        public static void DebugTextImage (int x, int y, int width, int height, IntPtr data, int pitch) {
            NativeMethods.bgfx_dbg_text_image((ushort)x, (ushort)y, (ushort)width, (ushort)height, data, (ushort)pitch);
        }

        /// <summary>
        /// Draws data directly into the debug text buffer.
        /// </summary>
        /// <param name="x">The X position, in cells.</param>
        /// <param name="y">The Y position, in cells.</param>
        /// <param name="width">The width of the image to draw.</param>
        /// <param name="height">The height of the image to draw.</param>
        /// <param name="data">The image data bytes.</param>
        /// <param name="pitch">The pitch of each line in the image data.</param>
        public static void DebugTextImage (int x, int y, int width, int height, byte[] data, int pitch) {
            fixed (byte* ptr = data)
                NativeMethods.bgfx_dbg_text_image((ushort)x, (ushort)y, (ushort)width, (ushort)height, new IntPtr(ptr), (ushort)pitch);
        }

        /// <summary>
        /// Sets the name of a rendering view, for debugging purposes.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="name">The name of the view.</param>
        public static void SetViewName (ushort id, string name) {
            NativeMethods.bgfx_set_view_name(id, name);
        }

        /// <summary>
        /// Sets the viewport for the given rendering view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="x">The X coordinate of the viewport.</param>
        /// <param name="y">The Y coordinate of the viewport.</param>
        /// <param name="width">The width of the viewport, in pixels.</param>
        /// <param name="height">The height of the viewport, in pixels.</param>
        public static void SetViewRect (ushort id, int x, int y, int width, int height) {
            NativeMethods.bgfx_set_view_rect(id, (ushort)x, (ushort)y, (ushort)width, (ushort)height);
        }

        /// <summary>
        /// Sets the viewport for the given rendering view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="x">The X coordinate of the viewport.</param>
        /// <param name="y">The Y coordinate of the viewport.</param>
        /// <param name="ratio">The ratio with which to automatically size the viewport.</param>
        public static void SetViewRect (ushort id, int x, int y, BackbufferRatio ratio) {
            NativeMethods.bgfx_set_view_rect_auto(id, (ushort)x, (ushort)y, ratio);
        }

        /// <summary>
        /// Sets the scissor rectangle for a specific view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="x">The X coordinate of the scissor rectangle.</param>
        /// <param name="y">The Y coordinate of the scissor rectangle.</param>
        /// <param name="width">The width of the scissor rectangle.</param>
        /// <param name="height">The height of the scissor rectangle.</param>
        /// <remarks>
        /// Set all values to zero to disable the scissor test.
        /// </remarks>
        public static void SetViewScissor (ushort id, int x, int y, int width, int height) {
            NativeMethods.bgfx_set_view_scissor(id, (ushort)x, (ushort)y, (ushort)width, (ushort)height);
        }

        /// <summary>
        /// Sets view clear flags.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="targets">The target surfaces that should be cleared.</param>
        /// <param name="colorRgba">The clear color.</param>
        /// <param name="depth">The value to fill the depth buffer.</param>
        /// <param name="stencil">The value to fill the stencil buffer.</param>
        public static void SetViewClear (ushort id, ClearTargets targets, int colorRgba, float depth = 1.0f, byte stencil = 0) {
            NativeMethods.bgfx_set_view_clear(id, targets, colorRgba, depth, stencil);
        }

        /// <summary>
        /// Sets view clear flags for multiple render targets.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="targets">The target surfaces that should be cleared.</param>
        /// <param name="depth">The value to fill the depth buffer.</param>
        /// <param name="stencil">The value to fill the stencil buffer.</param>
        /// <param name="rt0">The color palette index for render target 0.</param>
        /// <param name="rt1">The color palette index for render target 1.</param>
        /// <param name="rt2">The color palette index for render target 2.</param>
        /// <param name="rt3">The color palette index for render target 3.</param>
        /// <param name="rt4">The color palette index for render target 4.</param>
        /// <param name="rt5">The color palette index for render target 5.</param>
        /// <param name="rt6">The color palette index for render target 6.</param>
        /// <param name="rt7">The color palette index for render target 7.</param>
        public static void SetViewClear (
            ushort id,
            ClearTargets targets,
            float depth,
            byte stencil,
            byte rt0 = byte.MaxValue,
            byte rt1 = byte.MaxValue,
            byte rt2 = byte.MaxValue,
            byte rt3 = byte.MaxValue,
            byte rt4 = byte.MaxValue,
            byte rt5 = byte.MaxValue,
            byte rt6 = byte.MaxValue,
            byte rt7 = byte.MaxValue
        ) {
            NativeMethods.bgfx_set_view_clear_mrt(
                id,
                targets,
                depth,
                stencil,
                rt0,
                rt1,
                rt2,
                rt3,
                rt4,
                rt5,
                rt6,
                rt7
            );
        }

        /// <summary>
        /// Sets an entry in the color palette.
        /// </summary>
        /// <param name="index">The index of the palette entry to set.</param>
        /// <param name="color">The color to set.</param>
        /// <remarks>
        /// The clear color palette is used with SetViewClear for clearing multiple render targets
        /// to different color values.
        /// </remarks>
        public static void SetPaletteColor (byte index, float* color) {
            NativeMethods.bgfx_set_palette_color(index, color);
        }

        /// <summary>
        /// Sets the sorting mode to use for the given view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="mode">The sorting mode to use.</param>
        public static void SetViewMode (ushort id, ViewMode mode) {
            NativeMethods.bgfx_set_view_mode(id, mode);
        }

        /// <summary>
        /// Sets the view and projection transforms for the given rendering view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="view">The 4x4 view transform matrix.</param>
        /// <param name="projection">The 4x4 projection transform matrix.</param>
        public static void SetViewTransform (ushort id, float* view, float* projection) {
            NativeMethods.bgfx_set_view_transform(id, view, projection);
        }

        /// <summary>
        /// Sets the frame buffer used by a particular view.
        /// </summary>
        /// <param name="id">The index of the view.</param>
        /// <param name="frameBuffer">The frame buffer to set.</param>
        public static void SetViewFrameBuffer (ushort id, FrameBuffer frameBuffer) {
            NativeMethods.bgfx_set_view_frame_buffer(id, frameBuffer.handle);
        }

        /// <summary>
        /// Sets the model transform to use for drawing primitives.
        /// </summary>
        /// <param name="matrix">A pointer to one or more matrices to set.</param>
        /// <param name="count">The number of matrices in the array.</param>
        /// <returns>An index into the matrix cache to allow reusing the matrix in other calls.</returns>
        public static int SetTransform (float* matrix, int count = 1) {
            return NativeMethods.bgfx_set_transform(matrix, (ushort)count);
        }

        /// <summary>
        /// Sets a model transform from the cache.
        /// </summary>
        /// <param name="cacheIndex">The index of the cached matrix.</param>
        /// <param name="count">The number of matrices to set from the cache.</param>
        public static void SetTransform (int cacheIndex, int count = 1) {
            NativeMethods.bgfx_set_transform_cached(cacheIndex, (ushort)count);
        }

        /// <summary>
        /// Sets the scissor rectangle to use for clipping primitives.
        /// </summary>
        /// <param name="x">The X coordinate of the scissor rectangle.</param>
        /// <param name="y">The Y coordinate of the scissor rectangle.</param>
        /// <param name="width">The width of the rectangle.</param>
        /// <param name="height">The height of the rectangle.</param>
        /// <returns>
        /// An index into the scissor cache to allow reusing the rectangle in other calls.
        /// </returns>
        public static int SetScissor (int x, int y, int width, int height) {
            return NativeMethods.bgfx_set_scissor((ushort)x, (ushort)y, (ushort)width, (ushort)height);
        }

        /// <summary>
        /// Sets a scissor rectangle from the cache.
        /// </summary>
        /// <param name="cacheIndex">The index of the cached scissor rectangle, or -1 to unset.</param>
        public static void SetScissor (int cacheIndex = -1) {
            NativeMethods.bgfx_set_scissor_cached((ushort)cacheIndex);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public static void SetIndexBuffer (IndexBuffer indexBuffer) {
            NativeMethods.bgfx_set_index_buffer(indexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public static void SetIndexBuffer (IndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_set_index_buffer(indexBuffer.handle, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public static void SetVertexBuffer (int stream, VertexBuffer vertexBuffer) {
            NativeMethods.bgfx_set_vertex_buffer((byte)stream, vertexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public static void SetVertexBuffer (int stream, VertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_set_vertex_buffer((byte)stream, vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public static void SetIndexBuffer (DynamicIndexBuffer indexBuffer) {
            NativeMethods.bgfx_set_dynamic_index_buffer(indexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public static void SetIndexBuffer (DynamicIndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_set_dynamic_index_buffer(indexBuffer.handle, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public static void SetVertexBuffer (int stream, DynamicVertexBuffer vertexBuffer) {
            NativeMethods.bgfx_set_dynamic_vertex_buffer((byte)stream, vertexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="startVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public static void SetVertexBuffer (int stream, DynamicVertexBuffer vertexBuffer, int startVertex, int count) {
            NativeMethods.bgfx_set_dynamic_vertex_buffer((byte)stream, vertexBuffer.handle, startVertex, count);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public static void SetIndexBuffer (TransientIndexBuffer indexBuffer) {
            NativeMethods.bgfx_set_transient_index_buffer(ref indexBuffer, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public static void SetIndexBuffer (TransientIndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_set_transient_index_buffer(ref indexBuffer, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public static void SetVertexBuffer (int stream, TransientVertexBuffer vertexBuffer) {
            NativeMethods.bgfx_set_transient_vertex_buffer((byte)stream, ref vertexBuffer, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public static void SetVertexBuffer (int stream, TransientVertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_set_transient_vertex_buffer((byte)stream, ref vertexBuffer, firstVertex, count);
        }

        /// <summary>
        /// Sets the number of auto-generated vertices for use with gl_VertexID.
        /// </summary>
        /// <param name="count">The number of auto-generated vertices.</param>
        public static void SetVertexCount(int count) {
            NativeMethods.bgfx_set_vertex_count(count);
        }

        /// <summary>
        /// Sets the number of auto-generated indices for use with gl_InstanceID.
        /// </summary>
        /// <param name="count">The number of auto-generated instances.</param>
        public static void SetInstanceCount (int count) {
            NativeMethods.bgfx_set_instance_count(count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="instanceData">The instance data.</param>
        /// <param name="start">The starting offset in the buffer.</param>
        /// <param name="count">The number of entries to pull from the buffer.</param>
        public static void SetInstanceDataBuffer (ref InstanceDataBuffer instanceData, int start = 0, int count = -1) {
            NativeMethods.bgfx_set_instance_data_buffer(ref instanceData.data, (uint)start, (uint)count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="vertexBuffer">The vertex buffer containing instance data.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public static void SetInstanceDataBuffer (VertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_set_instance_data_from_vertex_buffer(vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="vertexBuffer">The vertex buffer containing instance data.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public static void SetInstanceDataBuffer (DynamicVertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_set_instance_data_from_dynamic_vertex_buffer(vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public static void SetUniform (Uniform uniform, float value, int arraySize = 1) {
            NativeMethods.bgfx_set_uniform(uniform.handle, &value, (ushort)arraySize);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public static void SetUniform (Uniform uniform, void* value, int arraySize = 1) {
            NativeMethods.bgfx_set_uniform(uniform.handle, value, (ushort)arraySize);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public static void SetUniform (Uniform uniform, IntPtr value, int arraySize = 1) {
            NativeMethods.bgfx_set_uniform(uniform.handle, value.ToPointer(), (ushort)arraySize);
        }

        /// <summary>
        /// Sets a texture to use for drawing primitives.
        /// </summary>
        /// <param name="textureUnit">The texture unit to set.</param>
        /// <param name="sampler">The sampler uniform.</param>
        /// <param name="texture">The texture to set.</param>
        public static void SetTexture (byte textureUnit, Uniform sampler, Texture texture) {
            NativeMethods.bgfx_set_texture(textureUnit, sampler.handle, texture.handle, uint.MaxValue);
        }

        /// <summary>
        /// Sets a texture to use for drawing primitives.
        /// </summary>
        /// <param name="textureUnit">The texture unit to set.</param>
        /// <param name="sampler">The sampler uniform.</param>
        /// <param name="texture">The texture to set.</param>
        /// <param name="flags">Sampling flags that override the default flags in the texture itself.</param>
        public static void SetTexture (byte textureUnit, Uniform sampler, Texture texture, TextureFlags flags) {
            NativeMethods.bgfx_set_texture(textureUnit, sampler.handle, texture.handle, (uint)flags);
        }

        /// <summary>
        /// Sets a texture mip as a compute image.
        /// </summary>
        /// <param name="stage">The buffer stage to set.</param>
        /// <param name="texture">The texture to set.</param>
        /// <param name="mip">The index of the mip level within the texture to set.</param>
        /// <param name="format">The format of the buffer data.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeImage (byte stage, Texture texture, byte mip, ComputeBufferAccess access, TextureFormat format = TextureFormat.Unknown) {
            NativeMethods.bgfx_set_image(stage, texture.handle, mip, format, access);
        }

        /// <summary>
        /// Sets an index buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeBuffer (byte stage, IndexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_set_compute_index_buffer(stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a verterx buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeBuffer (byte stage, VertexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_set_compute_vertex_buffer(stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a dynamic index buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeBuffer (byte stage, DynamicIndexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_set_compute_dynamic_index_buffer(stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a dynamic vertex buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeBuffer (byte stage, DynamicVertexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_set_compute_dynamic_vertex_buffer(stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets an indirect buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public static void SetComputeBuffer (byte stage, IndirectBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_set_compute_indirect_buffer(stage, buffer.handle, access);
        }

        /// <summary>
        /// Marks a view as "touched", ensuring that its background is cleared even if nothing is rendered.
        /// </summary>
        /// <param name="id">The index of the view to touch.</param>
        /// <returns>The number of draw calls.</returns>
        public static int Touch (ushort id) {
            return NativeMethods.bgfx_touch(id);
        }

        /// <summary>
        /// Resets all view settings to default.
        /// </summary>
        /// <param name="id">The index of the view to reset.</param>
        public static void ResetView (ushort id) {
            NativeMethods.bgfx_reset_view(id);
        }

        /// <summary>
        /// Submits the current batch of primitives for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public static int Submit (ushort id, Program program, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_submit(id, program.handle, depth, preserveState);
        }

        /// <summary>
        /// Submits the current batch of primitives for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="query">An occlusion query to use as a predicate during rendering.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public static int Submit (ushort id, Program program, OcclusionQuery query, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_submit_occlusion_query(id, program.handle, query.handle, depth, preserveState);
        }

        /// <summary>
        /// Submits an indirect batch of drawing commands to be used for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="indirectBuffer">The buffer containing drawing commands.</param>
        /// <param name="startIndex">The index of the first command to process.</param>
        /// <param name="count">The number of commands to process from the buffer.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public static int Submit (ushort id, Program program, IndirectBuffer indirectBuffer, int startIndex = 0, int count = 1, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_submit_indirect(id, program.handle, indirectBuffer.handle, (ushort)startIndex, (ushort)count, depth, preserveState);
        }

        /// <summary>
        /// Discards all previously set state for the draw call.
        /// </summary>
        public static void Discard () {
            NativeMethods.bgfx_discard();
        }

        /// <summary>
        /// Dispatches a compute job.
        /// </summary>
        /// <param name="id">The index of the view to dispatch.</param>
        /// <param name="program">The shader program to use.</param>
        /// <param name="xCount">The size of the job in the first dimension.</param>
        /// <param name="yCount">The size of the job in the second dimension.</param>
        /// <param name="zCount">The size of the job in the third dimension.</param>
        public static void Dispatch (ushort id, Program program, int xCount = 1, int yCount = 1, int zCount = 1) {
            NativeMethods.bgfx_dispatch(id, program.handle, (uint)xCount, (uint)yCount, (uint)zCount);
        }

        /// <summary>
        /// Dispatches an indirect compute job.
        /// </summary>
        /// <param name="id">The index of the view to dispatch.</param>
        /// <param name="program">The shader program to use.</param>
        /// <param name="indirectBuffer">The buffer containing drawing commands.</param>
        /// <param name="startIndex">The index of the first command to process.</param>
        /// <param name="count">The number of commands to process from the buffer.</param>
        public static void Dispatch (ushort id, Program program, IndirectBuffer indirectBuffer, int startIndex = 0, int count = 1) {
            NativeMethods.bgfx_dispatch_indirect(id, program.handle, indirectBuffer.handle, (ushort)startIndex, (ushort)count);
        }

        /// <summary>
        /// Requests that a screenshot be saved. The ScreenshotTaken event will be fired to save the result.
        /// </summary>
        /// <param name="filePath">The file path that will be passed to the callback event.</param>
        public static void RequestScreenShot(string filePath) {
            NativeMethods.bgfx_request_screen_shot(ushort.MaxValue, filePath);
        }

        /// <summary>
        /// Requests that a screenshot be saved. The ScreenshotTaken event will be fired to save the result.
        /// </summary>
        /// <param name="frameBuffer">The frame buffer to save.</param>
        /// <param name="filePath">The file path that will be passed to the callback event.</param>
        public static void RequestScreenShot (FrameBuffer frameBuffer, string filePath) {
            NativeMethods.bgfx_request_screen_shot(frameBuffer.handle, filePath);
        }

        /// <summary>
        /// Set rendering states used to draw primitives.
        /// </summary>
        /// <param name="state">The set of states to set.</param>
        public static void SetRenderState (RenderState state) {
            NativeMethods.bgfx_set_state((ulong)state, 0);
        }

        /// <summary>
        /// Set rendering states used to draw primitives.
        /// </summary>
        /// <param name="state">The set of states to set.</param>
        /// <param name="colorRgba">The color used for "factor" blending modes.</param>
        public static void SetRenderState (RenderState state, int colorRgba) {
            NativeMethods.bgfx_set_state((ulong)state, colorRgba);
        }

        /// <summary>
        /// Sets stencil test state.
        /// </summary>
        /// <param name="frontFace">The stencil state to use for front faces.</param>
        public static void SetStencil (StencilFlags frontFace) {
            SetStencil(frontFace, StencilFlags.None);
        }

        /// <summary>
        /// Sets stencil test state.
        /// </summary>
        /// <param name="frontFace">The stencil state to use for front faces.</param>
        /// <param name="backFace">The stencil state to use for back faces.</param>
        public static void SetStencil (StencilFlags frontFace, StencilFlags backFace) {
            NativeMethods.bgfx_set_stencil((uint)frontFace, (uint)backFace);
        }

        /// <summary>
        /// Begins submission of commands via an encoder on this thread.
        /// </summary>
        /// <returns>An encoder instance that can be used to submit commands.</returns>
        public static Encoder Begin () {
            return new Encoder(NativeMethods.bgfx_begin());
        }

        static readonly int TextureFormatCount = Enum.GetValues(typeof(TextureFormat)).Length;

        class DefaultCallbackHandler : ICallbackHandler {
            public void ProfilerBegin (string name, int color, string filePath, int line) {}
            public void ProfilerEnd () {}
            public void CaptureStarted(int width, int height, int pitch, TextureFormat format, bool flipVertical) {}
            public void CaptureFrame(IntPtr data, int size) {}
            public void CaptureFinished() {}
            public int GetCachedSize(long id) { return 0; }
            public bool GetCacheEntry(long id, IntPtr data, int size) { return false; }
            public void SetCacheEntry(long id, IntPtr data, int size) {}
            public void SaveScreenShot(string path, int width, int height, int pitch, IntPtr data, int size, bool flipVertical) {}

            public void ReportDebug(string fileName, int line, string format, IntPtr args) {
                sbyte* buffer = stackalloc sbyte[1024];
                NativeMethods.bgfx_vsnprintf(buffer, new IntPtr(1024), format, args);
                Debug.Write(Marshal.PtrToStringAnsi(new IntPtr(buffer)));
            }

            public void ReportError(string fileName, int line, ErrorType errorType, string message) {
                if (errorType == ErrorType.DebugCheck)
                    Debug.Write(message);
                else {
                    Debug.Write(string.Format("{0}: {1}", errorType, message));
                    Debugger.Break();
                    Environment.Exit(1);
                }
            }
        }
    }

    /// <summary>
    /// Contains various settings used to initialize the library.
    /// </summary>
    public class InitSettings {
        /// <summary>
        /// The backend API to use for rendering.
        /// </summary>
        public RendererBackend Backend { get; set; }

        /// <summary>
        /// The adapter on which to create the device.
        /// </summary>
        public Adapter Adapter { get; set; }

        /// <summary>
        /// Enable debugging with the device.
        /// </summary>
        public bool Debug { get; set; }

        /// <summary>
        /// Enable profling with the device.
        /// </summary>
        public bool Profiling { get; set; }

        /// <summary>
        /// The initial texture format of the screen.
        /// </summary>
        public TextureFormat Format { get; set; }

        /// <summary>
        /// The initial width of the screen.
        /// </summary>
        public int Width { get; set; }

        /// <summary>
        /// The initial height of the screen.
        /// </summary>
        public int Height { get; set; }

        /// <summary>
        /// Various flags that control creation of the device.
        /// </summary>
        public ResetFlags ResetFlags { get; set; }

        /// <summary>
        /// The number of backbuffers to create.
        /// </summary>
        public int BackBufferCount { get; set; }

        /// <summary>
        /// The maximum allowed frame latency, or zero if you don't care.
        /// </summary>
        public int MaxFrameLatency { get; set; }

        /// <summary>
        /// A set of handlers for various library callbacks.
        /// </summary>
        public ICallbackHandler CallbackHandler { get; set; }

        /// <summary>
        /// Optional platform-specific initialization data.
        /// </summary>
        public PlatformData PlatformData { get; set; }

        /// <summary>
        /// Initializes a new intance of the <see cref="InitSettings"/> class.
        /// </summary>
        unsafe public InitSettings () {
            Native native;
            NativeMethods.bgfx_init_ctor(&native);

            Backend = native.Backend;
            Adapter = new Adapter((Vendor)native.VendorId, native.DeviceId);
            Debug = native.Debug != 0;
            Profiling = native.Profiling != 0;
            Format = native.Resolution.Format;
            Width = (int)native.Resolution.Width;
            Height = (int)native.Resolution.Height;
            ResetFlags = (ResetFlags)native.Resolution.Flags;
            BackBufferCount = native.Resolution.NumBackBuffers;
            MaxFrameLatency = native.Resolution.MaxFrameLatency;
            PlatformData = native.PlatformData;
        }

        /// <summary>
        /// Initializes a new intance of the <see cref="InitSettings"/> class.
        /// </summary>
        /// <param name="width">The initial width of the screen.</param>
        /// <param name="height">The initial height of the screen.</param>
        /// <param name="resetFlags">Various flags that control creation of the device.</param>
        public InitSettings (int width, int height, ResetFlags resetFlags = ResetFlags.None)
            : this() {

            Width = width;
            Height = height;
            ResetFlags = resetFlags;
        }

        internal struct ResolutionNative {
            public TextureFormat Format;
            public uint Width;
            public uint Height;
            public uint Flags;
            public byte NumBackBuffers;
            public byte MaxFrameLatency;
        }

        internal struct InitLimits {
            public ushort MaxEncoders;
            public uint TransientVbSize;
            public uint TransientIbSize;
        }

        internal struct Native {
            public RendererBackend Backend;
            public ushort VendorId;
            public ushort DeviceId;
            public byte Debug;
            public byte Profiling;
            public PlatformData PlatformData;
            public ResolutionNative Resolution;
            public InitLimits Limits;
            public IntPtr Callbacks;
            public IntPtr Allocator;
        }
    }

    /// <summary>
    /// Represents a loaded texture.
    /// </summary>
    public unsafe sealed class Texture : IDisposable, IEquatable<Texture> {
        internal readonly ushort handle;

        /// <summary>
        /// The width of the texture.
        /// </summary>
        public int Width { get; private set; }

        /// <summary>
        /// The height of the texture.
        /// </summary>
        public int Height { get; private set; }

        /// <summary>
        /// The depth of the texture, if 3D.
        /// </summary>
        public int Depth { get; private set; }

        /// <summary>
        /// Indicates whether the texture is a cubemap.
        /// </summary>
        public bool IsCubeMap { get; private set; }

        /// <summary>
        /// The number of texture array layers (for 2D or cube textures).
        /// </summary>
        public int ArrayLayers { get; private set; }

        /// <summary>
        /// The number of mip levels in the texture.
        /// </summary>
        public int MipLevels { get; private set; }

        /// <summary>
        /// The number of bits per pixel.
        /// </summary>
        public int BitsPerPixel { get; private set; }

        /// <summary>
        /// The size of the entire texture, in bytes.
        /// </summary>
        public int SizeInBytes { get; private set; }

        /// <summary>
        /// The format of the image data.
        /// </summary>
        public TextureFormat Format { get; private set; }

        internal Texture (ushort handle, ref TextureInfo info) {
            this.handle = handle;

            Width = info.Width;
            Height = info.Height;
            Depth = info.Depth;
            ArrayLayers = info.Layers;
            MipLevels = info.MipCount;
            BitsPerPixel = info.BitsPerPixel;
            SizeInBytes = info.StorageSize;
            Format = info.Format;
            IsCubeMap = info.IsCubeMap;
        }

        /// <summary>
        /// Creates a new texture from a file loaded in memory.
        /// </summary>
        /// <param name="memory">The content of the file.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <param name="skipMips">A number of top level mips to skip when parsing texture data.</param>
        /// <returns>The newly created texture.</returns>
        /// <remarks>
        /// This function supports textures in the following container formats:
        /// - DDS
        /// - KTX
        /// - PVR
        /// </remarks>
        public static Texture FromFile (MemoryBlock memory, TextureFlags flags = TextureFlags.None, int skipMips = 0) {
            TextureInfo info;
            var handle = NativeMethods.bgfx_create_texture(memory.ptr, flags, (byte)skipMips, out info);

            return new Texture(handle, ref info);
        }

        /// <summary>
        /// Creates a new 2D texture.
        /// </summary>
        /// <param name="width">The width of the texture.</param>
        /// <param name="height">The height of the texture.</param>
        /// <param name="hasMips">Indicates that texture contains full mip-map chain.</param>
        /// <param name="arrayLayers">Number of layers in texture array. Must be 1 if Texture2DArray caps flag not set.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <param name="memory">If not <c>null</c>, contains the texture's image data.</param>
        /// <returns>
        /// The newly created texture handle.
        /// </returns>
        public static Texture Create2D (int width, int height, bool hasMips, int arrayLayers, TextureFormat format, TextureFlags flags = TextureFlags.None, MemoryBlock? memory = null) {
            var info = new TextureInfo();
            NativeMethods.bgfx_calc_texture_size(ref info, (ushort)width, (ushort)height, 1, false, hasMips, (ushort)arrayLayers, format);

            var handle = NativeMethods.bgfx_create_texture_2d(info.Width, info.Height, hasMips, (ushort)arrayLayers, format, flags, memory == null ? null : memory.Value.ptr);
            return new Texture(handle, ref info);
        }

        /// <summary>
        /// Creates a new 2D texture that scales with backbuffer size.
        /// </summary>
        /// <param name="ratio">The amount to scale when the backbuffer resizes.</param>
        /// <param name="hasMips">Indicates that texture contains full mip-map chain.</param>
        /// <param name="arrayLayers">Number of layers in texture array. Must be 1 if Texture2DArray caps flag not set.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <returns>
        /// The newly created texture handle.
        /// </returns>
        public static Texture Create2D (BackbufferRatio ratio, bool hasMips, int arrayLayers, TextureFormat format, TextureFlags flags = TextureFlags.None) {
            var info = new TextureInfo {
                Format = format,
                Layers = (ushort)arrayLayers
            };

            var handle = NativeMethods.bgfx_create_texture_2d_scaled(ratio, hasMips, (ushort)arrayLayers, format, flags);
            return new Texture(handle, ref info);
        }

        /// <summary>
        /// Creates a new 3D texture.
        /// </summary>
        /// <param name="width">The width of the texture.</param>
        /// <param name="height">The height of the texture.</param>
        /// <param name="depth">The depth of the texture.</param>
        /// <param name="hasMips">Indicates that texture contains full mip-map chain.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <param name="memory">If not <c>null</c>, contains the texture's image data.</param>
        /// <returns>The newly created texture handle.</returns>
        public static Texture Create3D (int width, int height, int depth, bool hasMips, TextureFormat format, TextureFlags flags = TextureFlags.None, MemoryBlock? memory = null) {
            var info = new TextureInfo();
            NativeMethods.bgfx_calc_texture_size(ref info, (ushort)width, (ushort)height, (ushort)depth, false, hasMips, 1, format);

            var handle = NativeMethods.bgfx_create_texture_3d(info.Width, info.Height, info.Depth, hasMips, format, flags, memory == null ? null : memory.Value.ptr);
            return new Texture(handle, ref info);
        }

        /// <summary>
        /// Creates a new cube texture.
        /// </summary>
        /// <param name="size">The size of each cube face.</param>
        /// <param name="hasMips">Indicates that texture contains full mip-map chain.</param>
        /// <param name="arrayLayers">Number of layers in texture array. Must be 1 if Texture2DArray caps flag not set.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <param name="memory">If not <c>null</c>, contains the texture's image data.</param>
        /// <returns>
        /// The newly created texture handle.
        /// </returns>
        public static Texture CreateCube (int size, bool hasMips, int arrayLayers, TextureFormat format, TextureFlags flags = TextureFlags.None, MemoryBlock? memory = null) {
            var info = new TextureInfo();
            NativeMethods.bgfx_calc_texture_size(ref info, (ushort)size, (ushort)size, 1, true, hasMips, (ushort)arrayLayers, format);

            var handle = NativeMethods.bgfx_create_texture_cube(info.Width, hasMips, (ushort)arrayLayers, format, flags, memory == null ? null : memory.Value.ptr);
            return new Texture(handle, ref info);
        }

        /// <summary>
        /// Checks whether a texture with the given parameters would be considered valid.
        /// </summary>
        /// <param name="depth">The depth of the texture.</param>
        /// <param name="isCube"><c>true</c> if the texture contains a cubemap.</param>
        /// <param name="arrayLayers">Number of layers in texture array.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <returns></returns>
        public static bool IsValid (int depth, bool isCube, int arrayLayers, TextureFormat format, TextureFlags flags = TextureFlags.None) {
            return NativeMethods.bgfx_is_texture_valid((ushort)depth, isCube, (ushort)arrayLayers, format, flags);
        }

        /// <summary>
        /// Releases the texture.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_texture(handle);
        }

        /// <summary>
        /// Sets the name of the texture, for debug display purposes.
        /// </summary>
        /// <param name="name">The name of the texture.</param>
        public void SetName(string name) {
            NativeMethods.bgfx_set_texture_name(handle, name, int.MaxValue);
        }

        /// <summary>
        /// Updates the data in a 2D texture.
        /// </summary>
        /// <param name="arrayLayer">The layer in a texture array to update.</param>
        /// <param name="mipLevel">The mip level.</param>
        /// <param name="x">The X coordinate of the rectangle to update.</param>
        /// <param name="y">The Y coordinate of the rectangle to update.</param>
        /// <param name="width">The width of the rectangle to update.</param>
        /// <param name="height">The height of the rectangle to update.</param>
        /// <param name="memory">The new image data.</param>
        /// <param name="pitch">The pitch of the image data.</param>
        public void Update2D (int arrayLayer, int mipLevel, int x, int y, int width, int height, MemoryBlock memory, int pitch) {
            NativeMethods.bgfx_update_texture_2d(handle, (ushort)arrayLayer, (byte)mipLevel, (ushort)x, (ushort)y, (ushort)width, (ushort)height, memory.ptr, (ushort)pitch);
        }

        /// <summary>
        /// Updates the data in a 3D texture.
        /// </summary>
        /// <param name="mipLevel">The mip level.</param>
        /// <param name="x">The X coordinate of the volume to update.</param>
        /// <param name="y">The Y coordinate of the volume to update.</param>
        /// <param name="z">The Z coordinate of the volume to update.</param>
        /// <param name="width">The width of the volume to update.</param>
        /// <param name="height">The height of the volume to update.</param>
        /// <param name="depth">The depth of the volume to update.</param>
        /// <param name="memory">The new image data.</param>
        public void Update3D (int mipLevel, int x, int y, int z, int width, int height, int depth, MemoryBlock memory) {
            NativeMethods.bgfx_update_texture_3d(handle, (byte)mipLevel, (ushort)x, (ushort)y, (ushort)z, (ushort)width, (ushort)height, (ushort)depth, memory.ptr);
        }

        /// <summary>
        /// Updates the data in a cube texture.
        /// </summary>
        /// <param name="face">The cube map face to update.</param>
        /// <param name="arrayLayer">The layer in a texture array to update.</param>
        /// <param name="mipLevel">The mip level.</param>
        /// <param name="x">The X coordinate of the rectangle to update.</param>
        /// <param name="y">The Y coordinate of the rectangle to update.</param>
        /// <param name="width">The width of the rectangle to update.</param>
        /// <param name="height">The height of the rectangle to update.</param>
        /// <param name="memory">The new image data.</param>
        /// <param name="pitch">The pitch of the image data.</param>
        public void UpdateCube (CubeMapFace face, int arrayLayer, int mipLevel, int x, int y, int width, int height, MemoryBlock memory, int pitch) {
            NativeMethods.bgfx_update_texture_cube(handle, (ushort)arrayLayer, face, (byte)mipLevel, (ushort)x, (ushort)y, (ushort)width, (ushort)height, memory.ptr, (ushort)pitch);
        }

        /// <summary>
        /// Blits the contents of the texture to another texture.
        /// </summary>
        /// <param name="viewId">The view in which the blit will be ordered.</param>
        /// <param name="dest">The destination texture.</param>
        /// <param name="destX">The destination X position.</param>
        /// <param name="destY">The destination Y position.</param>
        /// <param name="sourceX">The source X position.</param>
        /// <param name="sourceY">The source Y position.</param>
        /// <param name="width">The width of the region to blit.</param>
        /// <param name="height">The height of the region to blit.</param>
        /// <remarks>The destination texture must be created with the <see cref="TextureFlags.BlitDestination"/> flag.</remarks>
        public void BlitTo (ushort viewId, Texture dest, int destX, int destY, int sourceX = 0, int sourceY = 0,
                            int width = ushort.MaxValue, int height = ushort.MaxValue) {
            BlitTo(viewId, dest, 0, destX, destY, 0, 0, sourceX, sourceY, 0, width, height, 0);
        }

        /// <summary>
        /// Blits the contents of the texture to another texture.
        /// </summary>
        /// <param name="viewId">The view in which the blit will be ordered.</param>
        /// <param name="dest">The destination texture.</param>
        /// <param name="destMip">The destination mip level.</param>
        /// <param name="destX">The destination X position.</param>
        /// <param name="destY">The destination Y position.</param>
        /// <param name="destZ">The destination Z position.</param>
        /// <param name="sourceMip">The source mip level.</param>
        /// <param name="sourceX">The source X position.</param>
        /// <param name="sourceY">The source Y position.</param>
        /// <param name="sourceZ">The source Z position.</param>
        /// <param name="width">The width of the region to blit.</param>
        /// <param name="height">The height of the region to blit.</param>
        /// <param name="depth">The depth of the region to blit.</param>
        /// <remarks>The destination texture must be created with the <see cref="TextureFlags.BlitDestination"/> flag.</remarks>
        public void BlitTo (ushort viewId, Texture dest, int destMip, int destX, int destY, int destZ,
                            int sourceMip = 0, int sourceX = 0, int sourceY = 0, int sourceZ = 0,
                            int width = ushort.MaxValue, int height = ushort.MaxValue, int depth = ushort.MaxValue) {
            NativeMethods.bgfx_blit(viewId, dest.handle, (byte)destMip, (ushort)destX, (ushort)destY, (ushort)destZ,
                handle, (byte)sourceMip, (ushort)sourceX, (ushort)sourceY, (ushort)sourceZ, (ushort)width, (ushort)height, (ushort)depth);
        }

        /// <summary>
        /// Blits the contents of the texture to another texture.
        /// </summary>
        /// <param name="encoder">The encoder used for threaded command submission.</param>
        /// <param name="viewId">The view in which the blit will be ordered.</param>
        /// <param name="dest">The destination texture.</param>
        /// <param name="destX">The destination X position.</param>
        /// <param name="destY">The destination Y position.</param>
        /// <param name="sourceX">The source X position.</param>
        /// <param name="sourceY">The source Y position.</param>
        /// <param name="width">The width of the region to blit.</param>
        /// <param name="height">The height of the region to blit.</param>
        /// <remarks>The destination texture must be created with the <see cref="TextureFlags.BlitDestination"/> flag.</remarks>
        public void BlitTo (Encoder encoder, ushort viewId, Texture dest, int destX, int destY, int sourceX = 0, int sourceY = 0,
                            int width = ushort.MaxValue, int height = ushort.MaxValue) {
            BlitTo(encoder, viewId, dest, 0, destX, destY, 0, 0, sourceX, sourceY, 0, width, height, 0);
        }

        /// <summary>
        /// Blits the contents of the texture to another texture.
        /// </summary>
        /// <param name="encoder">The encoder used for threaded command submission.</param>
        /// <param name="viewId">The view in which the blit will be ordered.</param>
        /// <param name="dest">The destination texture.</param>
        /// <param name="destMip">The destination mip level.</param>
        /// <param name="destX">The destination X position.</param>
        /// <param name="destY">The destination Y position.</param>
        /// <param name="destZ">The destination Z position.</param>
        /// <param name="sourceMip">The source mip level.</param>
        /// <param name="sourceX">The source X position.</param>
        /// <param name="sourceY">The source Y position.</param>
        /// <param name="sourceZ">The source Z position.</param>
        /// <param name="width">The width of the region to blit.</param>
        /// <param name="height">The height of the region to blit.</param>
        /// <param name="depth">The depth of the region to blit.</param>
        /// <remarks>The destination texture must be created with the <see cref="TextureFlags.BlitDestination"/> flag.</remarks>
        public void BlitTo (Encoder encoder, ushort viewId, Texture dest, int destMip, int destX, int destY, int destZ,
                            int sourceMip = 0, int sourceX = 0, int sourceY = 0, int sourceZ = 0,
                            int width = ushort.MaxValue, int height = ushort.MaxValue, int depth = ushort.MaxValue) {
            NativeMethods.bgfx_encoder_blit(encoder.ptr, viewId, dest.handle, (byte)destMip, (ushort)destX, (ushort)destY, (ushort)destZ,
                handle, (byte)sourceMip, (ushort)sourceX, (ushort)sourceY, (ushort)sourceZ, (ushort)width, (ushort)height, (ushort)depth);
        }

        /// <summary>
        /// Reads the contents of the texture and stores them in memory pointed to by <paramref name="data"/>.
        /// </summary>
        /// <param name="data">The destination for the read image data.</param>
        /// <param name="mip">The mip level to read.</param>
        /// <returns>The frame number on which the result will be available.</returns>
        /// <remarks>The texture must have been created with the <see cref="TextureFlags.ReadBack"/> flag.</remarks>
        public int Read (IntPtr data, int mip) {
            return (int)NativeMethods.bgfx_read_texture(handle, data, (byte)mip);
        }

        /// <summary>
        /// Override internal texture with externally created texture.
        /// </summary>
        /// <param name="ptr">The native API texture pointer.</param>
        /// <returns>
        /// Native API pointer to the texture. If result is <see cref="IntPtr.Zero"/>, the texture is not yet
        /// created from the main thread.
        /// </returns>
        public IntPtr OverrideInternal (IntPtr ptr) {
            return NativeMethods.bgfx_override_internal_texture_ptr(handle, ptr);
        }

        /// <summary>
        /// Override internal texture by creating a new 2D texture.
        /// </summary>
        /// <param name="width">The width of the texture.</param>
        /// <param name="height">The height of the texture.</param>
        /// <param name="mipCount">The number of mip levels.</param>
        /// <param name="format">The format of the texture data.</param>
        /// <param name="flags">Flags that control texture behavior.</param>
        /// <returns>
        /// Native API pointer to the texture. If result is <see cref="IntPtr.Zero"/>, the texture is not yet
        /// created from the main thread.
        /// </returns>
        public IntPtr OverrideInternal (int width, int height, int mipCount, TextureFormat format, TextureFlags flags = TextureFlags.None) {
            Width = width;
            Height = height;
            MipLevels = mipCount;
            Format = format;
            return NativeMethods.bgfx_override_internal_texture(handle, (ushort)width, (ushort)height, (byte)mipCount, format, flags);
        }

        /// <summary>
        /// Returns a direct pointer to the texture memory.
        /// </summary>
        /// <returns>
        /// A pointer to the texture's memory. If result is <see cref="IntPtr.Zero"/> direct access is
        /// not supported. If the result is -1, the texture is pending creation.
        /// </returns>
        public IntPtr GetDirectAccess () {
            return NativeMethods.bgfx_get_direct_access_ptr(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (Texture other) {
            if (ReferenceEquals(other, null))
                return false;

            if (ReferenceEquals(other, this))
                return true;

            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            return Equals(obj as Texture);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator == (Texture left, Texture right) {
            if (ReferenceEquals(left, null))
                return ReferenceEquals(right, null);

            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator != (Texture left, Texture right) {
            return !(left == right);
        }

        internal struct TextureInfo {
            public TextureFormat Format;
            public int StorageSize;
            public ushort Width;
            public ushort Height;
            public ushort Depth;
            public ushort Layers;
            public byte MipCount;
            public byte BitsPerPixel;
            public bool IsCubeMap;
        }
    }

    /// <summary>
    /// Describes the layout of data in a vertex stream.
    /// </summary>
    public sealed class VertexLayout {
        internal Data data;

        /// <summary>
        /// The stride of a single vertex using this layout.
        /// </summary>
        public int Stride {
            get { return data.Stride; }
        }

        /// <summary>
        /// Starts a stream of vertex attribute additions to the layout.
        /// </summary>
        /// <param name="backend">The rendering backend with which to associate the attributes.</param>
        /// <returns>This instance, for use in a fluent API.</returns>
        public VertexLayout Begin (RendererBackend backend = RendererBackend.Noop) {
            NativeMethods.bgfx_vertex_decl_begin(ref data, backend);
            return this;
        }

        /// <summary>
        /// Starts a stream of vertex attribute additions to the layout.
        /// </summary>
        /// <param name="attribute">The kind of attribute to add.</param>
        /// <param name="count">The number of elements in the attribute (1, 2, 3, or 4).</param>
        /// <param name="type">The type of data described by the attribute.</param>
        /// <param name="normalized">if set to <c>true</c>, values will be normalized from a 0-255 range to 0.0 - 0.1 in the shader.</param>
        /// <param name="asInt">if set to <c>true</c>, the attribute is packaged as an integer in the shader.</param>
        /// <returns>
        /// This instance, for use in a fluent API.
        /// </returns>
        public VertexLayout Add (VertexAttributeUsage attribute, int count, VertexAttributeType type, bool normalized = false, bool asInt = false) {
            NativeMethods.bgfx_vertex_decl_add(ref data, attribute, (byte)count, type, normalized, asInt);
            return this;
        }

        /// <summary>
        /// Skips the specified number of bytes in the vertex stream.
        /// </summary>
        /// <param name="count">The number of bytes to skip.</param>
        /// <returns>This instance, for use in a fluent API.</returns>
        public VertexLayout Skip (int count) {
            NativeMethods.bgfx_vertex_decl_skip(ref data, (byte)count);
            return this;
        }

        /// <summary>
        /// Marks the end of the vertex stream.
        /// </summary>
        /// <returns>This instance, for use in a fluent API.</returns>
        public VertexLayout End () {
            NativeMethods.bgfx_vertex_decl_end(ref data);
            return this;
        }

        /// <summary>
        /// Gets the byte offset of a particular attribute in the layout.
        /// </summary>
        /// <param name="attribute">The attribute for which to get the offset.</param>
        /// <returns>The offset of the attribute, in bytes.</returns>
        public unsafe int GetOffset (VertexAttributeUsage attribute) {
            fixed (Data* ptr = &data)
                return ptr->Offset[(int)attribute];
        }

        /// <summary>
        /// Determines whether the layout contains the given attribute.
        /// </summary>
        /// <param name="attribute">The attribute to check/</param>
        /// <returns><c>true</c> if the layout contains the attribute; otherwise, <c>false</c>.</returns>
        public unsafe bool HasAttribute (VertexAttributeUsage attribute) {
            fixed (Data* ptr = &data)
                return ptr->Attributes[(int)attribute] != ushort.MaxValue;
        }

        internal unsafe struct Data {
            const int MaxAttribCount = 18;

            public uint Hash;
            public ushort Stride;
            public fixed ushort Offset[MaxAttribCount];
            public fixed ushort Attributes[MaxAttribCount];
        }
    }

    /// <summary>
    /// Contains details about an installed graphics adapter.
    /// </summary>
    public struct Adapter {
        /// <summary>
        /// Represents the default adapter for the system.
        /// </summary>
        public static readonly Adapter Default = new Adapter(Vendor.None, 0);

        /// <summary>
        /// The IHV that published the adapter.
        /// </summary>
        public readonly Vendor Vendor;

        /// <summary>
        /// A vendor-specific identifier for the adapter type.
        /// </summary>
        public readonly int DeviceId;

        /// <summary>
        /// Initializes a new instance of the <see cref="Adapter"/> struct.
        /// </summary>
        /// <param name="vendor">The vendor.</param>
        /// <param name="deviceId">The device ID.</param>
        public Adapter (Vendor vendor, int deviceId) {
            Vendor = vendor;
            DeviceId = deviceId;
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Vendor: {0}, Device: {0}", Vendor, DeviceId);
        }
    }

    /// <summary>
    /// Represents a framebuffer attachment.
    /// </summary>
    public struct Attachment {
        /// <summary>
        /// Access control for using the attachment.
        /// </summary>
        public ComputeBufferAccess Access;

        /// <summary>
        /// The attachment texture handle.
        /// </summary>
        public Texture Texture;

        /// <summary>
        /// The texture mip level.
        /// </summary>
        public int Mip;

        /// <summary>
        /// Cube map face or depth layer/slice.
        /// </summary>
        public int Layer;

        /// <summary>
        /// Additional flags for framebuffer resolve.
        /// </summary>
        public ResolveFlags Resolve;
    }

    /// <summary>
    /// Contains information about the capabilities of the rendering device.
    /// </summary>
    public unsafe struct Capabilities {
        Caps* data;

        /// <summary>
        /// The currently active rendering backend API.
        /// </summary>
        public RendererBackend Backend {
            get { return data->Backend; }
        }

        /// <summary>
        /// A set of extended features supported by the device.
        /// </summary>
        public DeviceFeatures SupportedFeatures {
            get { return data->Supported; }
        }

        /// <summary>
        /// The maximum number of draw calls in a single frame.
        /// </summary>
        public int MaxDrawCalls {
            get { return (int)data->MaxDrawCalls; }
        }

        /// <summary>
        /// The maximum number of texture blits in a single frame.
        /// </summary>
        public int MaxBlits {
            get { return (int)data->MaxBlits; }
        }

        /// <summary>
        /// The maximum size of a texture, in pixels.
        /// </summary>
        public int MaxTextureSize {
            get { return (int)data->MaxTextureSize; }
        }

        /// <summary>
        /// The maximum layers in a texture.
        /// </summary>
        public int MaxTextureLayers {
            get { return (int)data->MaxTextureLayers; }
        }

        /// <summary>
        /// The maximum number of render views supported.
        /// </summary>
        public int MaxViews {
            get { return (int)data->MaxViews; }
        }

        /// <summary>
        /// The maximum number of frame buffers that can be allocated.
        /// </summary>
        public int MaxFramebuffers {
            get { return (int)data->MaxFramebuffers; }
        }

        /// <summary>
        /// The maximum number of attachments to a single framebuffer.
        /// </summary>
        public int MaxFramebufferAttachments {
            get { return (int)data->MaxFramebufferAttachements; }
        }

        /// <summary>
        /// The maximum number of programs that can be allocated.
        /// </summary>
        public int MaxPrograms {
            get { return (int)data->MaxPrograms; }
        }

        /// <summary>
        /// The maximum number of shaders that can be allocated.
        /// </summary>
        public int MaxShaders {
            get { return (int)data->MaxShaders; }
        }

        /// <summary>
        /// The maximum number of textures that can be allocated.
        /// </summary>
        public int MaxTextures {
            get { return (int)data->MaxTextures; }
        }

        /// <summary>
        /// The maximum number of texture samplers that can be allocated.
        /// </summary>
        public int MaxTextureSamplers {
            get { return (int)data->MaxTextureSamplers; }
        }

        /// <summary>
        /// The maximum number of compute bindings that can be allocated.
        /// </summary>
        public int MaxComputeBindings {
            get { return (int)data->MaxComputeBindings; }
        }

        /// <summary>
        /// The maximum number of vertex declarations that can be allocated.
        /// </summary>
        public int MaxVertexDecls {
            get { return (int)data->MaxVertexDecls; }
        }

        /// <summary>
        /// The maximum number of vertex streams that can be used.
        /// </summary>
        public int MaxVertexStreams {
            get { return (int)data->MaxVertexStreams; }
        }

        /// <summary>
        /// The maximum number of index buffers that can be allocated.
        /// </summary>
        public int MaxIndexBuffers {
            get { return (int)data->MaxIndexBuffers; }
        }

        /// <summary>
        /// The maximum number of vertex buffers that can be allocated.
        /// </summary>
        public int MaxVertexBuffers {
            get { return (int)data->MaxVertexBuffers; }
        }

        /// <summary>
        /// The maximum number of dynamic index buffers that can be allocated.
        /// </summary>
        public int MaxDynamicIndexBuffers {
            get { return (int)data->MaxDynamicIndexBuffers; }
        }

        /// <summary>
        /// The maximum number of dynamic vertex buffers that can be allocated.
        /// </summary>
        public int MaxDynamicVertexBuffers {
            get { return (int)data->MaxDynamicVertexBuffers; }
        }

        /// <summary>
        /// The maximum number of uniforms that can be used.
        /// </summary>
        public int MaxUniforms {
            get { return (int)data->MaxUniforms; }
        }

        /// <summary>
        /// The maximum number of occlusion queries that can be used.
        /// </summary>
        public int MaxOcclusionQueries {
            get { return (int)data->MaxOcclusionQueries; }
        }

        /// <summary>
        /// The maximum number of encoder threads.
        /// </summary>
        public int MaxEncoders {
            get { return (int)data->MaxEncoders; }
        }

        /// <summary>
        /// The amount of transient vertex buffer space reserved.
        /// </summary>
        public int TransientVertexBufferSize {
            get { return (int)data->TransientVbSize; }
        }

        /// <summary>
        /// The amount of transient index buffer space reserved.
        /// </summary>
        public int TransientIndexBufferSize {
            get { return (int)data->TransientIbSize; }
        }

        /// <summary>
        /// Indicates whether depth coordinates in NDC range from -1 to 1 (true) or 0 to 1 (false).
        /// </summary>
        public bool HomogeneousDepth {
            get { return data->HomogeneousDepth != 0; }
        }

        /// <summary>
        /// Indicates whether the coordinate system origin is at the bottom left or top left.
        /// </summary>
        public bool OriginBottomLeft {
            get { return data->OriginBottomLeft != 0; }
        }

        /// <summary>
        /// Details about the currently active graphics adapter.
        /// </summary>
        public Adapter CurrentAdapter {
            get { return new Adapter((Vendor)data->VendorId, data->DeviceId); }
        }

        /// <summary>
        /// A list of all graphics adapters installed on the system.
        /// </summary>
        public AdapterCollection Adapters {
            get { return new AdapterCollection(data->GPUs, data->GPUCount); }
        }

        static Capabilities() {
            Debug.Assert(Caps.TextureFormatCount == Enum.GetValues(typeof(TextureFormat)).Length);
        }

        internal Capabilities (Caps* data) {
            this.data = data;
        }

        /// <summary>
        /// Checks device support for a specific texture format.
        /// </summary>
        /// <param name="format">The format to check.</param>
        /// <returns>The level of support for the given format.</returns>
        public TextureFormatSupport CheckTextureSupport (TextureFormat format) {
            return (TextureFormatSupport)data->Formats[(int)format];
        }

        /// <summary>
        /// Provides access to a collection of adapters.
        /// </summary>
        public unsafe struct AdapterCollection : IReadOnlyList<Adapter> {
            ushort* data;
            int count;

            /// <summary>
            /// Accesses the element at the specified index.
            /// </summary>
            /// <param name="index">The index of the element to retrieve.</param>
            /// <returns>The element at the given index.</returns>
            public Adapter this[int index] {
                get { return new Adapter((Vendor)data[index * 2], data[index * 2 + 1]); }
            }

            /// <summary>
            /// The number of elements in the collection.
            /// </summary>
            public int Count {
                get { return count; }
            }

            internal AdapterCollection (ushort* data, int count) {
                this.data = data;
                this.count = count;
            }

            /// <summary>
            /// Gets an enumerator for the collection.
            /// </summary>
            /// <returns>A collection enumerator.</returns>
            public Enumerator GetEnumerator () {
                return new Enumerator(this);
            }

            IEnumerator<Adapter> IEnumerable<Adapter>.GetEnumerator () {
                return GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator () {
                return GetEnumerator();
            }

            /// <summary>
            /// Implements an enumerator for an AdapterCollection.
            /// </summary>
            public struct Enumerator : IEnumerator<Adapter> {
                AdapterCollection collection;
                int index;

                /// <summary>
                /// The current enumerated item.
                /// </summary>
                public Adapter Current {
                    get { return collection[index]; }
                }

                object IEnumerator.Current {
                    get { return Current; }
                }

                internal Enumerator (AdapterCollection collection) {
                    this.collection = collection;
                    index = -1;
                }

                /// <summary>
                /// Advances to the next item in the sequence.
                /// </summary>
                /// <returns><c>true</c> if there are more items in the collection; otherwise, <c>false</c>.</returns>
                public bool MoveNext () {
                    var newIndex = index + 1;
                    if (newIndex >= collection.Count)
                        return false;

                    index = newIndex;
                    return true;
                }

                /// <summary>
                /// Empty; does nothing.
                /// </summary>
                public void Dispose () {
                }

                /// <summary>
                /// Not implemented.
                /// </summary>
                public void Reset () {
                    throw new NotImplementedException();
                }
            }
        }

#pragma warning disable 649
        internal unsafe struct Caps {
            public const int TextureFormatCount = 85;

            public RendererBackend Backend;
            public DeviceFeatures Supported;
            public ushort VendorId;
            public ushort DeviceId;
            public byte HomogeneousDepth;
            public byte OriginBottomLeft;
            public byte GPUCount;

            public fixed ushort GPUs[8];

            public uint MaxDrawCalls;
            public uint MaxBlits;
            public uint MaxTextureSize;
            public uint MaxTextureLayers;
            public uint MaxViews;
            public uint MaxFramebuffers;
            public uint MaxFramebufferAttachements;
            public uint MaxPrograms;
            public uint MaxShaders;
            public uint MaxTextures;
            public uint MaxTextureSamplers;
            public uint MaxComputeBindings;
            public uint MaxVertexDecls;
            public uint MaxVertexStreams;
            public uint MaxIndexBuffers;
            public uint MaxVertexBuffers;
            public uint MaxDynamicIndexBuffers;
            public uint MaxDynamicVertexBuffers;
            public uint MaxUniforms;
            public uint MaxOcclusionQueries;
            public uint MaxEncoders;
            public uint TransientVbSize;
            public uint TransientIbSize;

            public fixed ushort Formats[TextureFormatCount];
        }
#pragma warning restore 649
    }

    /// <summary>
    /// Represents a dynamically updateable index buffer.
    /// </summary>
    public unsafe struct DynamicIndexBuffer : IDisposable, IEquatable<DynamicIndexBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly DynamicIndexBuffer Invalid = new DynamicIndexBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="DynamicIndexBuffer"/> struct.
        /// </summary>
        /// <param name="indexCount">The number of indices that can fit in the buffer.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public DynamicIndexBuffer (int indexCount, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_dynamic_index_buffer(indexCount, flags);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DynamicIndexBuffer"/> struct.
        /// </summary>
        /// <param name="memory">The initial index data with which to populate the buffer.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public DynamicIndexBuffer (MemoryBlock memory, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_dynamic_index_buffer_mem(memory.ptr, flags);
        }

        /// <summary>
        /// Updates the data in the buffer.
        /// </summary>
        /// <param name="startIndex">Index of the first index to update.</param>
        /// <param name="memory">The new index data with which to fill the buffer.</param>
        public void Update (int startIndex, MemoryBlock memory) {
            NativeMethods.bgfx_update_dynamic_index_buffer(handle, startIndex, memory.ptr);
        }

        /// <summary>
        /// Releases the index buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_dynamic_index_buffer(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (DynamicIndexBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as DynamicIndexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(DynamicIndexBuffer left, DynamicIndexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(DynamicIndexBuffer left, DynamicIndexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Represents a dynamically updateable vertex buffer.
    /// </summary>
    public unsafe struct DynamicVertexBuffer : IDisposable, IEquatable<DynamicVertexBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly DynamicVertexBuffer Invalid = new DynamicVertexBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="DynamicVertexBuffer"/> struct.
        /// </summary>
        /// <param name="vertexCount">The number of vertices that fit in the buffer.</param>
        /// <param name="layout">The layout of the vertex data.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public DynamicVertexBuffer (int vertexCount, VertexLayout layout, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_dynamic_vertex_buffer(vertexCount, ref layout.data, flags);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DynamicVertexBuffer"/> struct.
        /// </summary>
        /// <param name="memory">The initial vertex data with which to populate the buffer.</param>
        /// <param name="layout">The layout of the vertex data.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public DynamicVertexBuffer (MemoryBlock memory, VertexLayout layout, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_dynamic_vertex_buffer_mem(memory.ptr, ref layout.data, flags);
        }

        /// <summary>
        /// Updates the data in the buffer.
        /// </summary>
        /// <param name="startVertex">Index of the first vertex to update.</param>
        /// <param name="memory">The new vertex data with which to fill the buffer.</param>
        public void Update (int startVertex, MemoryBlock memory) {
            NativeMethods.bgfx_update_dynamic_vertex_buffer(handle, startVertex, memory.ptr);
        }

        /// <summary>
        /// Releases the vertex buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_dynamic_vertex_buffer(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (DynamicVertexBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as DynamicVertexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(DynamicVertexBuffer left, DynamicVertexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(DynamicVertexBuffer left, DynamicVertexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// An interface for encoding a list of commands from multiple threads.
    /// Dispose of the encoder to finish submitting calls from the current thread.
    /// </summary>
    public unsafe struct Encoder : IDisposable, IEquatable<Encoder> {
        internal readonly IntPtr ptr;

        internal Encoder (IntPtr ptr) {
            this.ptr = ptr;
        }

        /// <summary>
        /// Sets a marker that can be used for debugging purposes.
        /// </summary>
        /// <param name="marker">The user-defined name of the marker.</param>
        public void SetDebugMarker (string marker) {
            NativeMethods.bgfx_encoder_set_marker(ptr, marker);
        }

        /// <summary>
        /// Set rendering states used to draw primitives.
        /// </summary>
        /// <param name="state">The set of states to set.</param>
        public void SetRenderState (RenderState state) {
            NativeMethods.bgfx_encoder_set_state(ptr, (ulong)state, 0);
        }

        /// <summary>
        /// Set rendering states used to draw primitives.
        /// </summary>
        /// <param name="state">The set of states to set.</param>
        /// <param name="colorRgba">The color used for "factor" blending modes.</param>
        public void SetRenderState (RenderState state, int colorRgba) {
            NativeMethods.bgfx_encoder_set_state(ptr, (ulong)state, colorRgba);
        }

        /// <summary>
        /// Sets stencil test state.
        /// </summary>
        /// <param name="frontFace">The stencil state to use for front faces.</param>
        public void SetStencil (StencilFlags frontFace) {
            SetStencil(frontFace, StencilFlags.None);
        }

        /// <summary>
        /// Sets stencil test state.
        /// </summary>
        /// <param name="frontFace">The stencil state to use for front faces.</param>
        /// <param name="backFace">The stencil state to use for back faces.</param>
        public void SetStencil (StencilFlags frontFace, StencilFlags backFace) {
            NativeMethods.bgfx_encoder_set_stencil(ptr, (uint)frontFace, (uint)backFace);
        }

        /// <summary>
        /// Sets the scissor rectangle to use for clipping primitives.
        /// </summary>
        /// <param name="x">The X coordinate of the scissor rectangle.</param>
        /// <param name="y">The Y coordinate of the scissor rectangle.</param>
        /// <param name="width">The width of the rectangle.</param>
        /// <param name="height">The height of the rectangle.</param>
        /// <returns>
        /// An index into the scissor cache to allow reusing the rectangle in other calls.
        /// </returns>
        public int SetScissor (int x, int y, int width, int height) {
            return NativeMethods.bgfx_encoder_set_scissor(ptr, (ushort)x, (ushort)y, (ushort)width, (ushort)height);
        }

        /// <summary>
        /// Sets a scissor rectangle from the cache.
        /// </summary>
        /// <param name="cacheIndex">The index of the cached scissor rectangle, or -1 to unset.</param>
        public void SetScissor (int cacheIndex = -1) {
            NativeMethods.bgfx_encoder_set_scissor_cached(ptr, (ushort)cacheIndex);
        }

        /// <summary>
        /// Sets the model transform to use for drawing primitives.
        /// </summary>
        /// <param name="matrix">A pointer to one or more matrices to set.</param>
        /// <param name="count">The number of matrices in the array.</param>
        /// <returns>An index into the matrix cache to allow reusing the matrix in other calls.</returns>
        public int SetTransform (float* matrix, int count = 1) {
            return NativeMethods.bgfx_encoder_set_transform(ptr, matrix, (ushort)count);
        }

        /// <summary>
        /// Sets a model transform from the cache.
        /// </summary>
        /// <param name="cacheIndex">The index of the cached matrix.</param>
        /// <param name="count">The number of matrices to set from the cache.</param>
        public void SetTransform (int cacheIndex, int count = 1) {
            NativeMethods.bgfx_encoder_set_transform_cached(ptr, cacheIndex, (ushort)count);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public void SetUniform (Uniform uniform, float value, int arraySize = 1) {
            NativeMethods.bgfx_encoder_set_uniform(ptr, uniform.handle, &value, (ushort)arraySize);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public void SetUniform (Uniform uniform, void* value, int arraySize = 1) {
            NativeMethods.bgfx_encoder_set_uniform(ptr, uniform.handle, value, (ushort)arraySize);
        }

        /// <summary>
        /// Sets the value of a uniform parameter.
        /// </summary>
        /// <param name="uniform">The uniform to set.</param>
        /// <param name="value">A pointer to the uniform's data.</param>
        /// <param name="arraySize">The size of the data array, if the uniform is an array.</param>
        public void SetUniform (Uniform uniform, IntPtr value, int arraySize = 1) {
            NativeMethods.bgfx_encoder_set_uniform(ptr, uniform.handle, value.ToPointer(), (ushort)arraySize);
        }

        /// <summary>
        /// Sets a texture to use for drawing primitives.
        /// </summary>
        /// <param name="textureUnit">The texture unit to set.</param>
        /// <param name="sampler">The sampler uniform.</param>
        /// <param name="texture">The texture to set.</param>
        public void SetTexture (byte textureUnit, Uniform sampler, Texture texture) {
            NativeMethods.bgfx_encoder_set_texture(ptr, textureUnit, sampler.handle, texture.handle, uint.MaxValue);
        }

        /// <summary>
        /// Sets a texture to use for drawing primitives.
        /// </summary>
        /// <param name="textureUnit">The texture unit to set.</param>
        /// <param name="sampler">The sampler uniform.</param>
        /// <param name="texture">The texture to set.</param>
        /// <param name="flags">Sampling flags that override the default flags in the texture itself.</param>
        public void SetTexture (byte textureUnit, Uniform sampler, Texture texture, TextureFlags flags) {
            NativeMethods.bgfx_encoder_set_texture(ptr, textureUnit, sampler.handle, texture.handle, (uint)flags);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public void SetIndexBuffer (IndexBuffer indexBuffer) {
            NativeMethods.bgfx_encoder_set_index_buffer(ptr, indexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public void SetIndexBuffer (IndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_encoder_set_index_buffer(ptr, indexBuffer.handle, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public void SetVertexBuffer (int stream, VertexBuffer vertexBuffer) {
            NativeMethods.bgfx_encoder_set_vertex_buffer(ptr, (byte)stream, vertexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public void SetVertexBuffer (int stream, VertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_encoder_set_vertex_buffer(ptr, (byte)stream, vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public void SetIndexBuffer (DynamicIndexBuffer indexBuffer) {
            NativeMethods.bgfx_encoder_set_dynamic_index_buffer(ptr, indexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public void SetIndexBuffer (DynamicIndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_encoder_set_dynamic_index_buffer(ptr, indexBuffer.handle, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public void SetVertexBuffer (int stream, DynamicVertexBuffer vertexBuffer) {
            NativeMethods.bgfx_encoder_set_dynamic_vertex_buffer(ptr, (byte)stream, vertexBuffer.handle, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="startVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public void SetVertexBuffer (int stream, DynamicVertexBuffer vertexBuffer, int startVertex, int count) {
            NativeMethods.bgfx_encoder_set_dynamic_vertex_buffer(ptr, (byte)stream, vertexBuffer.handle, startVertex, count);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        public void SetIndexBuffer (TransientIndexBuffer indexBuffer) {
            NativeMethods.bgfx_encoder_set_transient_index_buffer(ptr, ref indexBuffer, 0, -1);
        }

        /// <summary>
        /// Sets the index buffer to use for drawing primitives.
        /// </summary>
        /// <param name="indexBuffer">The index buffer to set.</param>
        /// <param name="firstIndex">The first index in the buffer to use.</param>
        /// <param name="count">The number of indices to pull from the buffer.</param>
        public void SetIndexBuffer (TransientIndexBuffer indexBuffer, int firstIndex, int count) {
            NativeMethods.bgfx_encoder_set_transient_index_buffer(ptr, ref indexBuffer, firstIndex, count);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        public void SetVertexBuffer (int stream, TransientVertexBuffer vertexBuffer) {
            NativeMethods.bgfx_encoder_set_transient_vertex_buffer(ptr, (byte)stream, ref vertexBuffer, 0, -1);
        }

        /// <summary>
        /// Sets the vertex buffer to use for drawing primitives.
        /// </summary>
        /// <param name="stream">The index of the vertex stream to set.</param>
        /// <param name="vertexBuffer">The vertex buffer to set.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public void SetVertexBuffer (int stream, TransientVertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_encoder_set_transient_vertex_buffer(ptr, (byte)stream, ref vertexBuffer, firstVertex, count);
        }

        /// <summary>
        /// Sets the number of auto-generated vertices for use with gl_VertexID.
        /// </summary>
        /// <param name="count">The number of auto-generated vertices.</param>
        public void SetVertexCount (int count) {
            NativeMethods.bgfx_encoder_set_vertex_count(ptr, count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="instanceData">The instance data.</param>
        /// <param name="start">The starting offset in the buffer.</param>
        /// <param name="count">The number of entries to pull from the buffer.</param>
        public void SetInstanceDataBuffer (ref InstanceDataBuffer instanceData, int start = 0, int count = -1) {
            NativeMethods.bgfx_encoder_set_instance_data_buffer(ptr, ref instanceData.data, (uint)start, (uint)count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="vertexBuffer">The vertex buffer containing instance data.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public void SetInstanceDataBuffer (VertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_encoder_set_instance_data_from_vertex_buffer(ptr, vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Sets instance data to use for drawing primitives.
        /// </summary>
        /// <param name="vertexBuffer">The vertex buffer containing instance data.</param>
        /// <param name="firstVertex">The index of the first vertex to use.</param>
        /// <param name="count">The number of vertices to pull from the buffer.</param>
        public void SetInstanceDataBuffer (DynamicVertexBuffer vertexBuffer, int firstVertex, int count) {
            NativeMethods.bgfx_encoder_set_instance_data_from_dynamic_vertex_buffer(ptr, vertexBuffer.handle, firstVertex, count);
        }

        /// <summary>
        /// Marks a view as "touched", ensuring that its background is cleared even if nothing is rendered.
        /// </summary>
        /// <param name="id">The index of the view to touch.</param>
        /// <returns>The number of draw calls.</returns>
        public int Touch (ushort id) {
            return NativeMethods.bgfx_encoder_touch(ptr, id);
        }

        /// <summary>
        /// Submits the current batch of primitives for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public int Submit (ushort id, Program program, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_encoder_submit(ptr, id, program.handle, depth, preserveState);
        }

        /// <summary>
        /// Submits the current batch of primitives for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="query">An occlusion query to use as a predicate during rendering.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public int Submit (ushort id, Program program, OcclusionQuery query, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_encoder_submit_occlusion_query(ptr, id, program.handle, query.handle, depth, preserveState);
        }

        /// <summary>
        /// Submits an indirect batch of drawing commands to be used for rendering.
        /// </summary>
        /// <param name="id">The index of the view to submit.</param>
        /// <param name="program">The program with which to render.</param>
        /// <param name="indirectBuffer">The buffer containing drawing commands.</param>
        /// <param name="startIndex">The index of the first command to process.</param>
        /// <param name="count">The number of commands to process from the buffer.</param>
        /// <param name="depth">A depth value to use for sorting the batch.</param>
        /// <param name="preserveState"><c>true</c> to preserve internal draw state after the call.</param>
        /// <returns>The number of draw calls.</returns>
        public int Submit (ushort id, Program program, IndirectBuffer indirectBuffer, int startIndex = 0, int count = 1, int depth = 0, bool preserveState = false) {
            return NativeMethods.bgfx_encoder_submit_indirect(ptr, id, program.handle, indirectBuffer.handle, (ushort)startIndex, (ushort)count, depth, preserveState);
        }

        /// <summary>
        /// Sets a texture mip as a compute image.
        /// </summary>
        /// <param name="stage">The buffer stage to set.</param>
        /// <param name="texture">The texture to set.</param>
        /// <param name="mip">The index of the mip level within the texture to set.</param>
        /// <param name="format">The format of the buffer data.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeImage (byte stage, Texture texture, byte mip, ComputeBufferAccess access, TextureFormat format = TextureFormat.Unknown) {
            NativeMethods.bgfx_encoder_set_image(ptr, stage, texture.handle, mip, format, access);
        }

        /// <summary>
        /// Sets an index buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeBuffer (byte stage, IndexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_encoder_set_compute_index_buffer(ptr, stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a verterx buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeBuffer (byte stage, VertexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_encoder_set_compute_vertex_buffer(ptr, stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a dynamic index buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeBuffer (byte stage, DynamicIndexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_encoder_set_compute_dynamic_index_buffer(ptr, stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets a dynamic vertex buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeBuffer (byte stage, DynamicVertexBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_encoder_set_compute_dynamic_vertex_buffer(ptr, stage, buffer.handle, access);
        }

        /// <summary>
        /// Sets an indirect buffer as a compute resource.
        /// </summary>
        /// <param name="stage">The resource stage to set.</param>
        /// <param name="buffer">The buffer to set.</param>
        /// <param name="access">Access control flags.</param>
        public void SetComputeBuffer (byte stage, IndirectBuffer buffer, ComputeBufferAccess access) {
            NativeMethods.bgfx_encoder_set_compute_indirect_buffer(ptr, stage, buffer.handle, access);
        }

        /// <summary>
        /// Dispatches a compute job.
        /// </summary>
        /// <param name="id">The index of the view to dispatch.</param>
        /// <param name="program">The shader program to use.</param>
        /// <param name="xCount">The size of the job in the first dimension.</param>
        /// <param name="yCount">The size of the job in the second dimension.</param>
        /// <param name="zCount">The size of the job in the third dimension.</param>
        public void Dispatch (ushort id, Program program, int xCount = 1, int yCount = 1, int zCount = 1) {
            NativeMethods.bgfx_encoder_dispatch(ptr, id, program.handle, (uint)xCount, (uint)yCount, (uint)zCount);
        }

        /// <summary>
        /// Dispatches an indirect compute job.
        /// </summary>
        /// <param name="id">The index of the view to dispatch.</param>
        /// <param name="program">The shader program to use.</param>
        /// <param name="indirectBuffer">The buffer containing drawing commands.</param>
        /// <param name="startIndex">The index of the first command to process.</param>
        /// <param name="count">The number of commands to process from the buffer.</param>
        public void Dispatch (ushort id, Program program, IndirectBuffer indirectBuffer, int startIndex = 0, int count = 1) {
            NativeMethods.bgfx_encoder_dispatch_indirect(ptr, id, program.handle, indirectBuffer.handle, (ushort)startIndex, (ushort)count);
        }

        /// <summary>
        /// Discards all previously set state for the draw call.
        /// </summary>
        public void Discard () {
            NativeMethods.bgfx_encoder_discard(ptr);
        }

        /// <summary>
        /// Finishes submission of commands from this encoder.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_end(ptr);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (Encoder other) {
            return ptr == other.ptr;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as Encoder?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return ptr.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return ptr.ToString();
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator == (Encoder left, Encoder right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator != (Encoder left, Encoder right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// An aggregated frame buffer, with one or more attached texture surfaces.
    /// </summary>
    public unsafe struct FrameBuffer : IDisposable, IEquatable<FrameBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly FrameBuffer Invalid = new FrameBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="FrameBuffer"/> struct.
        /// </summary>
        /// <param name="width">The width of the render target.</param>
        /// <param name="height">The height of the render target.</param>
        /// <param name="format">The format of the new surface.</param>
        /// <param name="flags">Texture sampling flags.</param>
        public FrameBuffer (int width, int height, TextureFormat format, TextureFlags flags = TextureFlags.ClampU | TextureFlags.ClampV) {
            handle = NativeMethods.bgfx_create_frame_buffer((ushort)width, (ushort)height, format, flags);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FrameBuffer"/> struct.
        /// </summary>
        /// <param name="ratio">The amount to scale when the backbuffer resizes.</param>
        /// <param name="format">The format of the new surface.</param>
        /// <param name="flags">Texture sampling flags.</param>
        public FrameBuffer (BackbufferRatio ratio, TextureFormat format, TextureFlags flags = TextureFlags.ClampU | TextureFlags.ClampV) {
            handle = NativeMethods.bgfx_create_frame_buffer_scaled(ratio, format, flags);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FrameBuffer"/> struct.
        /// </summary>
        /// <param name="attachments">A set of attachments from which to build the frame buffer.</param>
        /// <param name="destroyTextures">if set to <c>true</c>, attached textures will be destroyed when the frame buffer is destroyed.</param>
        public FrameBuffer (Attachment[] attachments, bool destroyTextures = false) {
            var count = (byte)attachments.Length;
            var native = stackalloc NativeAttachment[count];
            for (int i = 0; i < count; i++) {
                var attachment = attachments[i];
                native[i] = new NativeAttachment {
                    access = attachment.Access,
                    handle = attachment.Texture.handle,
                    mip = (ushort)attachment.Mip,
                    layer = (ushort)attachment.Layer,
                    resolve = attachment.Resolve
                };
            }

            handle = NativeMethods.bgfx_create_frame_buffer_from_attachment(count, native, destroyTextures);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FrameBuffer"/> struct.
        /// </summary>
        /// <param name="textures">A set of textures from which to build the frame buffer.</param>
        /// <param name="destroyTextures">if set to <c>true</c>, attached textures will be destroyed when the frame buffer is destroyed.</param>
        public FrameBuffer (Texture[] textures, bool destroyTextures = false) {
            var count = (byte)textures.Length;
            var native = stackalloc ushort[count];
            for (int i = 0; i < count; i++)
                native[i] = textures[i].handle;

            handle = NativeMethods.bgfx_create_frame_buffer_from_handles(count, native, destroyTextures);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FrameBuffer"/> struct.
        /// </summary>
        /// <param name="windowHandle">The OS window handle to which the frame buffer is attached.</param>
        /// <param name="width">The width of the render target.</param>
        /// <param name="height">The height of the render target.</param>
        /// <param name="depthFormat">A desired format for a depth buffer, if applicable.</param>
        public FrameBuffer (IntPtr windowHandle, int width, int height, TextureFormat depthFormat = TextureFormat.UnknownDepth) {
            handle = NativeMethods.bgfx_create_frame_buffer_from_nwh(windowHandle, (ushort)width, (ushort)height, depthFormat);
        }

        /// <summary>
        /// Sets the name of the frame buffer, for debug display purposes.
        /// </summary>
        /// <param name="name">The name of the texture.</param>
        public void SetName(string name) {
            NativeMethods.bgfx_set_frame_buffer_name(handle, name, int.MaxValue);
        }

        /// <summary>
        /// Releases the frame buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_frame_buffer(handle);
        }

        /// <summary>
        /// Gets the texture associated with a particular framebuffer attachment.
        /// </summary>
        /// <param name="attachment">The attachment index.</param>
        /// <returns>The texture associated with the attachment.</returns>
        public Texture GetTexture (int attachment = 0) {
            var info = new Texture.TextureInfo();
            return new Texture(NativeMethods.bgfx_get_texture(handle, (byte)attachment), ref info);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (FrameBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as FrameBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(FrameBuffer left, FrameBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(FrameBuffer left, FrameBuffer right) {
            return !left.Equals(right);
        }

        internal struct NativeAttachment {
            public ComputeBufferAccess access;
            public ushort handle;
            public ushort mip;
            public ushort layer;
            public ResolveFlags resolve;
        }
    }

    /// <summary>
    /// Represents a static index buffer.
    /// </summary>
    public unsafe struct IndexBuffer : IDisposable, IEquatable<IndexBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly IndexBuffer Invalid = new IndexBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="IndexBuffer"/> struct.
        /// </summary>
        /// <param name="memory">The 16-bit index data used to populate the buffer.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public IndexBuffer (MemoryBlock memory, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_index_buffer(memory.ptr, flags);
        }

        /// <summary>
        /// Sets the name of the index buffer, for debug display purposes.
        /// </summary>
        /// <param name="name">The name of the texture.</param>
        public void SetName(string name) {
            NativeMethods.bgfx_set_index_buffer_name(handle, name, int.MaxValue);
        }

        /// <summary>
        /// Releases the index buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_index_buffer(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (IndexBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as IndexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(IndexBuffer left, IndexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(IndexBuffer left, IndexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Represents a buffer that can contain indirect drawing commands created and processed entirely on the GPU.
    /// </summary>
    public unsafe struct IndirectBuffer : IDisposable, IEquatable<IndirectBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly IndirectBuffer Invalid = new IndirectBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="IndirectBuffer"/> struct.
        /// </summary>
        /// <param name="size">The number of commands that can fit in the buffer.</param>
        public IndirectBuffer (int size) {
            handle = NativeMethods.bgfx_create_indirect_buffer(size);
        }

        /// <summary>
        /// Releases the index buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_indirect_buffer(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (IndirectBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as IndirectBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(IndirectBuffer left, IndirectBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(IndirectBuffer left, IndirectBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Maintains a data buffer that contains instancing data.
    /// </summary>
    public unsafe struct InstanceDataBuffer : IEquatable<InstanceDataBuffer> {
        internal NativeStruct data;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly InstanceDataBuffer Invalid = new InstanceDataBuffer();

        /// <summary>
        /// A pointer that can be filled with instance data.
        /// </summary>
        public IntPtr Data { get { return data.data; } }

        /// <summary>
        /// The size of the data buffer.
        /// </summary>
        public int Size { get { return data.size; } }

        /// <summary>
        /// Initializes a new instance of the <see cref="InstanceDataBuffer" /> struct.
        /// </summary>
        /// <param name="count">The number of elements in the buffer.</param>
        /// <param name="stride">The stride of each element.</param>
        public InstanceDataBuffer (int count, int stride) {
            NativeMethods.bgfx_alloc_instance_data_buffer(out data, count, (ushort)stride);
        }

        /// <summary>
        /// Gets the available space that can be used to allocate an instance buffer.
        /// </summary>
        /// <param name="count">The number of elements required.</param>
        /// <param name="stride">The stride of each element.</param>
        /// <returns>The number of available elements.</returns>
        public static int GetAvailableSpace (int count, int stride) {
            return NativeMethods.bgfx_get_avail_instance_data_buffer(count, (ushort)stride);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (InstanceDataBuffer other) {
            return data.data == other.data.data &&
                   data.offset == other.data.offset &&
                   data.size == other.data.size;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as InstanceDataBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return (data.data.GetHashCode() ^ data.offset) >> 13 ^ data.size;
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Size: {0}", Size);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(InstanceDataBuffer left, InstanceDataBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(InstanceDataBuffer left, InstanceDataBuffer right) {
            return !left.Equals(right);
        }

#pragma warning disable 649
        internal struct NativeStruct {
            public IntPtr data;
            public int size;
            public int offset;
            public ushort stride;
            public ushort num;
            public ushort handle;
        }
#pragma warning restore 649
    }

    /// <summary>
    /// Exposes internal API data for interop scenarios.
    /// </summary>
    public struct InternalData {
        /// <summary>
        /// Pointer to internal Bgfx capabilities structure. Use <see cref="Bgfx.GetCaps"/> instead.
        /// </summary>
        public IntPtr Caps;

        /// <summary>
        /// The underlying API's device context (OpenGL, Direct3D, etc).
        /// </summary>
        public IntPtr Context;
    }

    /// <summary>
    /// Represents a block of memory managed by the graphics API.
    /// </summary>
    public unsafe struct MemoryBlock : IEquatable<MemoryBlock> {
        internal readonly DataPtr* ptr;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly MemoryBlock Invalid = new MemoryBlock();

        /// <summary>
        /// The pointer to the raw data.
        /// </summary>
        public IntPtr Data {
            get { return ptr == null ? IntPtr.Zero : ptr->Data; }
        }

        /// <summary>
        /// The size of the block, in bytes.
        /// </summary>
        public int Size {
            get { return ptr == null ? 0 : ptr->Size; }
        }

        MemoryBlock (DataPtr* ptr) {
            this.ptr = ptr;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="MemoryBlock"/> struct.
        /// </summary>
        /// <param name="size">The size of the block, in bytes.</param>
        public MemoryBlock (int size) {
            ptr = NativeMethods.bgfx_alloc(size);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="MemoryBlock"/> struct.
        /// </summary>
        /// <param name="data">A pointer to the initial data to copy into the new block.</param>
        /// <param name="size">The size of the block, in bytes.</param>
        public MemoryBlock (IntPtr data, int size) {
            ptr = NativeMethods.bgfx_copy(data, size);
        }

        /// <summary>
        /// Copies a managed array into a native graphics memory block.
        /// </summary>
        /// <typeparam name="T">The type of data in the array.</typeparam>
        /// <param name="data">The array to copy.</param>
        /// <returns>The native memory block containing the copied data.</returns>
        public static MemoryBlock FromArray<T>(T[] data) where T : struct {
            if (data == null || data.Length == 0)
                throw new ArgumentNullException("data");

            var gcHandle = GCHandle.Alloc(data, GCHandleType.Pinned);
            var block = new MemoryBlock(gcHandle.AddrOfPinnedObject(), Marshal.SizeOf<T>() * data.Length);

            gcHandle.Free();
            return block;
        }

        /// <summary>
        /// Creates a reference to the given data.
        /// </summary>
        /// <typeparam name="T">The type of data in the array.</typeparam>
        /// <param name="data">The array to reference.</param>
        /// <returns>The native memory block referring to the data.</returns>
        /// <remarks>
        /// The array must not be modified for at least 2 rendered frames.
        /// </remarks>
        public static MemoryBlock MakeRef<T>(T[] data) where T : struct {
            if (data == null || data.Length == 0)
                throw new ArgumentNullException("data");

            var gcHandle = GCHandle.Alloc(data, GCHandleType.Pinned);
            return MakeRef(gcHandle.AddrOfPinnedObject(), Marshal.SizeOf<T>() * data.Length, GCHandle.ToIntPtr(gcHandle), ReleaseHandleCallback);
        }

        /// <summary>
        /// Makes a reference to the given memory block.
        /// </summary>
        /// <param name="data">A pointer to the memory.</param>
        /// <param name="size">The size of the memory block.</param>
        /// <param name="userData">Arbitrary user data passed to the release callback.</param>
        /// <param name="callback">A function that will be called when the data is ready to be released.</param>
        /// <returns>A new memory block referring to the given data.</returns>
        /// <remarks>
        /// The memory referred to by the returned memory block must not be modified
        /// or released until the callback fires.
        /// </remarks>
        public static MemoryBlock MakeRef (IntPtr data, int size, IntPtr userData, ReleaseCallback callback) {
            return new MemoryBlock(NativeMethods.bgfx_make_ref_release(data, size, Marshal.GetFunctionPointerForDelegate(callback), userData));
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (MemoryBlock other) {
            return ptr == other.ptr;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as MemoryBlock?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return new IntPtr(ptr).GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Size: {0}", Size);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(MemoryBlock left, MemoryBlock right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(MemoryBlock left, MemoryBlock right) {
            return !left.Equals(right);
        }

#pragma warning disable 649
        internal struct DataPtr {
            public IntPtr Data;
            public int Size;
        }
#pragma warning restore 649

        static ReleaseCallback ReleaseHandleCallback = ReleaseHandle;
        static void ReleaseHandle (IntPtr userData) {
            var handle = GCHandle.FromIntPtr(userData);
            handle.Free();
        }
    }

    /// <summary>
    /// Represents an occlusion query.
    /// </summary>
    public unsafe struct OcclusionQuery : IDisposable, IEquatable<OcclusionQuery> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly OcclusionQuery Invalid = new OcclusionQuery();

        /// <summary>
        /// Gets the result of the query.
        /// </summary>
        public OcclusionQueryResult Result {
            get { return NativeMethods.bgfx_get_result(handle, null); }
        }

        /// <summary>
        /// Gets the number of pixels that passed the test. Only valid
        /// if <see cref="Result"/> is also valid.
        /// </summary>
        public int PassingPixels {
            get {
                int pixels = 0;
                NativeMethods.bgfx_get_result(handle, &pixels);
                return pixels;
            }
        }

        OcclusionQuery (ushort handle) {
            this.handle = handle;
        }

        /// <summary>
        /// Creates a new query.
        /// </summary>
        /// <returns>The new occlusion query.</returns>
        public static OcclusionQuery Create() {
            return new OcclusionQuery(NativeMethods.bgfx_create_occlusion_query());
        }

        /// <summary>
        /// Releases the query.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_occlusion_query(handle);
        }

        /// <summary>
        /// Sets the condition for which the query should check.
        /// </summary>
        /// <param name="visible"><c>true</c> for visible; <c>false</c> for invisible.</param>
        public void SetCondition (bool visible) {
            NativeMethods.bgfx_set_condition(handle, visible);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (OcclusionQuery other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as OcclusionQuery?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator == (OcclusionQuery left, OcclusionQuery right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator != (OcclusionQuery left, OcclusionQuery right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Contains various performance metrics tracked by the library.
    /// </summary>
    public unsafe struct PerfStats {
        Stats* data;

        /// <summary>
        /// CPU time between two <see cref="Bgfx.Frame"/> calls.
        /// </summary>
        public long CpuTimeFrame {
            get { return data->CpuTimeFrame; }
        }

        /// <summary>
        /// CPU frame start time.
        /// </summary>
        public long CpuTimeStart {
            get { return data->CpuTimeBegin; }
        }

        /// <summary>
        /// CPU frame end time.
        /// </summary>
        public long CpuTimeEnd {
            get { return data->CpuTimeEnd; }
        }

        /// <summary>
        /// CPU timer frequency.
        /// </summary>
        public long CpuTimerFrequency {
            get { return data->CpuTimerFrequency; }
        }

        /// <summary>
        /// Elapsed CPU time.
        /// </summary>
        public TimeSpan CpuElapsed {
            get { return TimeSpan.FromSeconds((double)(CpuTimeEnd - CpuTimeStart) / CpuTimerFrequency); }
        }

        /// <summary>
        /// GPU frame start time.
        /// </summary>
        public long GpuTimeStart {
            get { return data->GpuTimeBegin; }
        }

        /// <summary>
        /// GPU frame end time.
        /// </summary>
        public long GpuTimeEnd {
            get { return data->GpuTimeEnd; }
        }

        /// <summary>
        /// GPU timer frequency.
        /// </summary>
        public long GpuTimerFrequency {
            get { return data->GpuTimerFrequency; }
        }

        /// <summary>
        /// Elapsed GPU time.
        /// </summary>
        public TimeSpan GpuElapsed {
            get { return TimeSpan.FromSeconds((double)(GpuTimeEnd - GpuTimeStart) / GpuTimerFrequency); }
        }

        /// <summary>
        /// Time spent waiting for the render thread.
        /// </summary>
        public long WaitingForRender {
            get { return data->WaitRender; }
        }

        /// <summary>
        /// Time spent waiting for the submit thread.
        /// </summary>
        public long WaitingForSubmit {
            get { return data->WaitSubmit; }
        }

        /// <summary>
        /// The number of draw calls submitted.
        /// </summary>
        public int DrawCallsSubmitted {
            get { return data->NumDraw; }
        }

        /// <summary>
        /// The number of compute calls submitted.
        /// </summary>
        public int ComputeCallsSubmitted {
            get { return data->NumCompute; }
        }

        /// <summary>
        /// The number of blit calls submitted.
        /// </summary>
        public int BlitCallsSubmitted {
            get { return data->NumBlit; }
        }

        /// <summary>
        /// Maximum observed GPU driver latency.
        /// </summary>
        public int MaxGpuLatency {
            get { return data->MaxGpuLatency; }
        }

        /// <summary>
        /// Number of allocated dynamic index buffers.
        /// </summary>
        public int DynamicIndexBufferCount {
            get { return data->NumDynamicIndexBuffers; }
        }

        /// <summary>
        /// Number of allocated dynamic vertex buffers.
        /// </summary>
        public int DynamicVertexBufferCount {
            get { return data->NumDynamicVertexBuffers; }
        }

        /// <summary>
        /// Number of allocated frame buffers.
        /// </summary>
        public int FrameBufferCount {
            get { return data->NumFrameBuffers; }
        }

        /// <summary>
        /// Number of allocated index buffers.
        /// </summary>
        public int IndexBufferCount {
            get { return data->NumIndexBuffers; }
        }

        /// <summary>
        /// Number of allocated occlusion queries.
        /// </summary>
        public int OcclusionQueryCount {
            get { return data->NumOcclusionQueries; }
        }

        /// <summary>
        /// Number of allocated shader programs.
        /// </summary>
        public int ProgramCount {
            get { return data->NumPrograms; }
        }

        /// <summary>
        /// Number of allocated shaders.
        /// </summary>
        public int ShaderCount {
            get { return data->NumShaders; }
        }

        /// <summary>
        /// Number of allocated textures.
        /// </summary>
        public int TextureCount {
            get { return data->NumTextures; }
        }

        /// <summary>
        /// Number of allocated uniforms.
        /// </summary>
        public int UniformCount {
            get { return data->NumUniforms; }
        }

        /// <summary>
        /// Number of allocated vertex buffers.
        /// </summary>
        public int VertexBufferCount {
            get { return data->NumVertexBuffers; }
        }

        /// <summary>
        /// Number of allocated vertex declarations.
        /// </summary>
        public int VertexDeclarationCount {
            get { return data->NumVertexDecls; }
        }

        /// <summary>
        /// The amount of memory used by textures.
        /// </summary>
        public long TextureMemoryUsed {
            get { return data->TextureMemoryUsed; }
        }

        /// <summary>
        /// The amount of memory used by render targets.
        /// </summary>
        public long RenderTargetMemoryUsed {
            get { return data->RtMemoryUsed; }
        }

        /// <summary>
        /// The number of transient vertex buffers used.
        /// </summary>
        public int TransientVertexBuffersUsed {
            get { return data->TransientVbUsed; }
        }

        /// <summary>
        /// The number of transient index buffers used.
        /// </summary>
        public int TransientIndexBuffersUsed {
            get { return data->TransientIbUsed; }
        }

        /// <summary>
        /// Maximum available GPU memory.
        /// </summary>
        public long MaxGpuMemory {
            get { return data->GpuMemoryMax; }
        }

        /// <summary>
        /// The amount of GPU memory currently in use.
        /// </summary>
        public long GpuMemoryUsed {
            get { return data->GpuMemoryUsed; }
        }

        /// <summary>
        /// The width of the back buffer.
        /// </summary>
        public int BackbufferWidth {
            get { return data->Width; }
        }

        /// <summary>
        /// The height of the back buffer.
        /// </summary>
        public int BackbufferHeight {
            get { return data->Height; }
        }

        /// <summary>
        /// The width of the debug text buffer.
        /// </summary>
        public int TextBufferWidth {
            get { return data->TextWidth; }
        }

        /// <summary>
        /// The height of the debug text buffer.
        /// </summary>
        public int TextBufferHeight {
            get { return data->TextHeight; }
        }

        /// <summary>
        /// Gets a collection of statistics for each rendering view.
        /// </summary>
        public ViewStatsCollection Views {
            get { return new ViewStatsCollection(data->ViewStats, data->NumViews); }
        }

        static PerfStats() {
            Debug.Assert(Stats.NumTopologies == Enum.GetValues(typeof(Topology)).Length);
        }

        internal PerfStats (Stats* data) {
            this.data = data;
        }

        /// <summary>
        /// Gets the number of primitives rendered with the given topology.
        /// </summary>
        /// <param name="topology">The topology whose primitive count should be returned.</param>
        /// <returns>The number of primitives rendered.</returns>
        public int GetPrimitiveCount(Topology topology) {
            return (int)data->NumPrims[(int)topology];
        }

        /// <summary>
        /// Contains perf metrics for a single rendering view.
        /// </summary>
        public struct ViewStats {
            ViewStatsNative* data;

            /// <summary>
            /// The name of the view.
            /// </summary>
            public string Name {
                get { return new string(data->Name); }
            }

            /// <summary>
            /// The amount of CPU time elapsed during processing of this view.
            /// </summary>
            public long CpuTimeElapsed {
                get { return (long)data->CpuTimeElapsed; }
            }

            /// <summary>
            /// The amount of GPU time elapsed during processing of this view.
            /// </summary>
            public long GpuTimeElapsed {
                get { return (long)data->GpuTimeElapsed; }
            }

            internal ViewStats(ViewStatsNative* data) {
                this.data = data;
            }
        }

        /// <summary>
        /// Provides access to a collection of view statistics.
        /// </summary>
        public struct ViewStatsCollection : IReadOnlyList<ViewStats> {
            ViewStatsNative* data;
            int count;

            /// <summary>
            /// Accesses the element at the specified index.
            /// </summary>
            /// <param name="index">The index of the element to retrieve.</param>
            /// <returns>The element at the given index.</returns>
            public ViewStats this[int index] {
                get { return new ViewStats(data + index); }
            }

            /// <summary>
            /// The number of elements in the collection.
            /// </summary>
            public int Count {
                get { return count; }
            }

            internal ViewStatsCollection(ViewStatsNative* data, int count) {
                this.data = data;
                this.count = count;
            }

            /// <summary>
            /// Gets an enumerator for the collection.
            /// </summary>
            /// <returns>A collection enumerator.</returns>
            public Enumerator GetEnumerator() {
                return new Enumerator(this);
            }

            IEnumerator<ViewStats> IEnumerable<ViewStats>.GetEnumerator() {
                return GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator() {
                return GetEnumerator();
            }

            /// <summary>
            /// Implements an enumerator for a ViewStatsCollection.
            /// </summary>
            public struct Enumerator : IEnumerator<ViewStats> {
                ViewStatsCollection collection;
                int index;

                /// <summary>
                /// The current enumerated item.
                /// </summary>
                public ViewStats Current {
                    get { return collection[index]; }
                }

                object IEnumerator.Current {
                    get { return Current; }
                }

                internal Enumerator(ViewStatsCollection collection) {
                    this.collection = collection;
                    index = -1;
                }

                /// <summary>
                /// Advances to the next item in the sequence.
                /// </summary>
                /// <returns><c>true</c> if there are more items in the collection; otherwise, <c>false</c>.</returns>
                public bool MoveNext() {
                    var newIndex = index + 1;
                    if (newIndex >= collection.Count)
                        return false;

                    index = newIndex;
                    return true;
                }

                /// <summary>
                /// Empty; does nothing.
                /// </summary>
                public void Dispose() {
                }

                /// <summary>
                /// Not implemented.
                /// </summary>
                public void Reset() {
                    throw new NotImplementedException();
                }
            }
        }

        /// <summary>
        /// Contains perf metrics for a single encoder instance.
        /// </summary>
        public struct EncoderStats {
            EncoderStatsNative* data;

            /// <summary>
            /// CPU frame start time.
            /// </summary>
            public long CpuTimeStart {
                get { return data->CpuTimeBegin; }
            }

            /// <summary>
            /// CPU frame end time.
            /// </summary>
            public long CpuTimeEnd {
                get { return data->CpuTimeEnd; }
            }

            internal EncoderStats (EncoderStatsNative* data) {
                this.data = data;
            }
        }

        /// <summary>
        /// Provides access to a collection of encoder statistics.
        /// </summary>
        public struct EncoderStatsCollection : IReadOnlyList<EncoderStats> {
            EncoderStatsNative* data;
            int count;

            /// <summary>
            /// Accesses the element at the specified index.
            /// </summary>
            /// <param name="index">The index of the element to retrieve.</param>
            /// <returns>The element at the given index.</returns>
            public EncoderStats this[int index] {
                get { return new EncoderStats(data + index); }
            }

            /// <summary>
            /// The number of elements in the collection.
            /// </summary>
            public int Count {
                get { return count; }
            }

            internal EncoderStatsCollection (EncoderStatsNative* data, int count) {
                this.data = data;
                this.count = count;
            }

            /// <summary>
            /// Gets an enumerator for the collection.
            /// </summary>
            /// <returns>A collection enumerator.</returns>
            public Enumerator GetEnumerator () {
                return new Enumerator(this);
            }

            IEnumerator<EncoderStats> IEnumerable<EncoderStats>.GetEnumerator () {
                return GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator () {
                return GetEnumerator();
            }

            /// <summary>
            /// Implements an enumerator for an EncoderStatsCollection.
            /// </summary>
            public struct Enumerator : IEnumerator<EncoderStats> {
                EncoderStatsCollection collection;
                int index;

                /// <summary>
                /// The current enumerated item.
                /// </summary>
                public EncoderStats Current {
                    get { return collection[index]; }
                }

                object IEnumerator.Current {
                    get { return Current; }
                }

                internal Enumerator (EncoderStatsCollection collection) {
                    this.collection = collection;
                    index = -1;
                }

                /// <summary>
                /// Advances to the next item in the sequence.
                /// </summary>
                /// <returns><c>true</c> if there are more items in the collection; otherwise, <c>false</c>.</returns>
                public bool MoveNext () {
                    var newIndex = index + 1;
                    if (newIndex >= collection.Count)
                        return false;

                    index = newIndex;
                    return true;
                }

                /// <summary>
                /// Empty; does nothing.
                /// </summary>
                public void Dispose () {
                }

                /// <summary>
                /// Not implemented.
                /// </summary>
                public void Reset () {
                    throw new NotImplementedException();
                }
            }
        }

#pragma warning disable 649
        internal struct ViewStatsNative {
            public fixed char Name[256];
            public ushort View;
            public ulong CpuTimeElapsed;
            public ulong GpuTimeElapsed;
        }

        internal struct EncoderStatsNative {
            public long CpuTimeBegin;
            public long CpuTimeEnd;
        }

        internal struct Stats {
            public const int NumTopologies = 5;

            public long CpuTimeFrame;
            public long CpuTimeBegin;
            public long CpuTimeEnd;
            public long CpuTimerFrequency;
            public long GpuTimeBegin;
            public long GpuTimeEnd;
            public long GpuTimerFrequency;
            public long WaitRender;
            public long WaitSubmit;
            public int NumDraw;
            public int NumCompute;
            public int NumBlit;
            public int MaxGpuLatency;
            public ushort NumDynamicIndexBuffers;
            public ushort NumDynamicVertexBuffers;
            public ushort NumFrameBuffers;
            public ushort NumIndexBuffers;
            public ushort NumOcclusionQueries;
            public ushort NumPrograms;
            public ushort NumShaders;
            public ushort NumTextures;
            public ushort NumUniforms;
            public ushort NumVertexBuffers;
            public ushort NumVertexDecls;
            public long TextureMemoryUsed;
            public long RtMemoryUsed;
            public int TransientVbUsed;
            public int TransientIbUsed;
            public fixed uint NumPrims[NumTopologies];
            public long GpuMemoryMax;
            public long GpuMemoryUsed;
            public ushort Width;
            public ushort Height;
            public ushort TextWidth;
            public ushort TextHeight;
            public ushort NumViews;
            public ViewStatsNative* ViewStats;
            public byte NumEncoders;
            public EncoderStatsNative* EncoderStats;
        }
#pragma warning restore 649
    }

    /// <summary>
    /// Contains platform-specific data used to hook into the bgfx library.
    /// </summary>
    public struct PlatformData {
        /// <summary>
        /// EGL native display type.
        /// </summary>
        public IntPtr DisplayType;

        /// <summary>
        /// Platform window handle.
        /// </summary>
        public IntPtr WindowHandle;

        /// <summary>
        /// Device context to use instead of letting the library create its own.
        /// </summary>
        public IntPtr Context;

        /// <summary>
        /// Backbuffer pointer to use instead of letting the library create its own.
        /// </summary>
        public IntPtr Backbuffer;

        /// <summary>
        /// Depth-stencil pointer to use instead of letting the library create its own.
        /// </summary>
        public IntPtr BackbufferDepthStencil;
    }

    /// <summary>
    /// Represents a compiled and linked shader program.
    /// </summary>
    public struct Program : IDisposable, IEquatable<Program> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly Program Invalid = new Program();

        /// <summary>
        /// Initializes a new instance of the <see cref="Program"/> struct.
        /// </summary>
        /// <param name="vertexShader">The vertex shader.</param>
        /// <param name="fragmentShader">The fragment shader.</param>
        /// <param name="destroyShaders">if set to <c>true</c>, the shaders will be released after creating the program.</param>
        public Program (Shader vertexShader, Shader fragmentShader, bool destroyShaders = false) {
            handle = NativeMethods.bgfx_create_program(vertexShader.handle, fragmentShader.handle, destroyShaders);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Program"/> struct.
        /// </summary>
        /// <param name="computeShader">The compute shader.</param>
        /// <param name="destroyShaders">if set to <c>true</c>, the compute shader will be released after creating the program.</param>
        public Program (Shader computeShader, bool destroyShaders = false) {
            handle = NativeMethods.bgfx_create_compute_program(computeShader.handle, destroyShaders);
        }

        /// <summary>
        /// Releases the program.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_program(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (Program other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as Program?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(Program left, Program right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(Program left, Program right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Specifies state information used to configure rendering operations.
    /// </summary>
    public struct RenderState : IEquatable<RenderState> {
        const int AlphaRefShift = 40;
        const int PointSizeShift = 52;
        const ulong AlphaRefMask = 0x0000ff0000000000;
        const ulong PointSizeMask = 0x0ff0000000000000;

        readonly ulong value;

        /// <summary>
        /// No state bits set.
        /// </summary>
        public static readonly RenderState None = 0;

        /// <summary>
        /// Enable writing the Red color channel to the framebuffer.
        /// </summary>
        public static readonly RenderState WriteR = 0x0000000000000001;

        /// <summary>
        /// Enable writing the Green color channel to the framebuffer.
        /// </summary>
        public static readonly RenderState WriteG = 0x0000000000000002;

        /// <summary>
        /// Enable writing the Blue color channel to the framebuffer.
        /// </summary>
        public static readonly RenderState WriteB = 0x0000000000000004;

        /// <summary>
        /// Enable writing alpha data to the framebuffer.
        /// </summary>
        public static readonly RenderState WriteA = 0x0000000000000008;

        /// <summary>
        /// Enable writing to the depth buffer.
        /// </summary>
        public static readonly RenderState WriteZ = 0x0000004000000000;

        /// <summary>
        /// Enable writing all three color channels to the framebuffer.
        /// </summary>
        public static readonly RenderState WriteRGB = WriteR | WriteG | WriteB;

        /// <summary>
        /// Use a "less than" comparison to pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestLess = 0x0000000000000010;

        /// <summary>
        /// Use a "less than or equal to" comparison to pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestLessEqual = 0x0000000000000020;

        /// <summary>
        /// Pass the depth test if both values are equal.
        /// </summary>
        public static readonly RenderState DepthTestEqual = 0x0000000000000030;

        /// <summary>
        /// Use a "greater than or equal to" comparison to pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestGreaterEqual = 0x0000000000000040;

        /// <summary>
        /// Use a "greater than" comparison to pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestGreater = 0x0000000000000050;

        /// <summary>
        /// Pass the depth test if both values are not equal.
        /// </summary>
        public static readonly RenderState DepthTestNotEqual = 0x0000000000000060;

        /// <summary>
        /// Never pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestNever = 0x0000000000000070;

        /// <summary>
        /// Always pass the depth test.
        /// </summary>
        public static readonly RenderState DepthTestAlways = 0x0000000000000080;

        /// <summary>
        /// Use a value of 0 as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendZero = 0x0000000000001000;

        /// <summary>
        /// Use a value of 1 as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendOne = 0x0000000000002000;

        /// <summary>
        /// Use the source pixel color as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendSourceColor = 0x0000000000003000;

        /// <summary>
        /// Use one minus the source pixel color as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendInverseSourceColor = 0x0000000000004000;

        /// <summary>
        /// Use the source pixel alpha as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendSourceAlpha = 0x0000000000005000;

        /// <summary>
        /// Use one minus the source pixel alpha as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendInverseSourceAlpha = 0x0000000000006000;

        /// <summary>
        /// Use the destination pixel alpha as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendDestinationAlpha = 0x0000000000007000;

        /// <summary>
        /// Use one minus the destination pixel alpha as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendInverseDestinationAlpha = 0x0000000000008000;

        /// <summary>
        /// Use the destination pixel color as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendDestinationColor = 0x0000000000009000;

        /// <summary>
        /// Use one minus the destination pixel color as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendInverseDestinationColor = 0x000000000000a000;

        /// <summary>
        /// Use the source pixel alpha (saturated) as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendSourceAlphaSaturate = 0x000000000000b000;

        /// <summary>
        /// Use an application supplied blending factor as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendFactor = 0x000000000000c000;

        /// <summary>
        /// Use one minus an application supplied blending factor as an input to a blend equation.
        /// </summary>
        public static readonly RenderState BlendInverseFactor = 0x000000000000d000;

        /// <summary>
        /// Blend equation: A + B
        /// </summary>
        public static readonly RenderState BlendEquationAdd = 0x0000000000000000;

        /// <summary>
        /// Blend equation: B - A
        /// </summary>
        public static readonly RenderState BlendEquationSub = 0x0000000010000000;

        /// <summary>
        /// Blend equation: A - B
        /// </summary>
        public static readonly RenderState BlendEquationReverseSub = 0x0000000020000000;

        /// <summary>
        /// Blend equation: min(a, b)
        /// </summary>
        public static readonly RenderState BlendEquationMin = 0x0000000030000000;

        /// <summary>
        /// Blend equation: max(a, b)
        /// </summary>
        public static readonly RenderState BlendEquationMax = 0x0000000040000000;

        /// <summary>
        /// Enable independent blending of simultaenous render targets.
        /// </summary>
        public static readonly RenderState BlendIndependent = 0x0000000400000000;

        /// <summary>
        /// Enable alpha to coverage blending.
        /// </summary>
        public static readonly RenderState BlendAlphaToCoverage = 0x0000000800000000;

        /// <summary>
        /// Don't perform culling of back faces.
        /// </summary>
        public static readonly RenderState NoCulling = 0x0000000000000000;

        /// <summary>
        /// Perform culling of clockwise faces.
        /// </summary>
        public static readonly RenderState CullClockwise = 0x0000001000000000;

        /// <summary>
        /// Perform culling of counter-clockwise faces.
        /// </summary>
        public static readonly RenderState CullCounterclockwise = 0x0000002000000000;

        /// <summary>
        /// Primitive topology: triangle list.
        /// </summary>
        public static readonly RenderState PrimitiveTriangles = 0x0000000000000000;

        /// <summary>
        /// Primitive topology: triangle strip.
        /// </summary>
        public static readonly RenderState PrimitiveTriangleStrip = 0x0001000000000000;

        /// <summary>
        /// Primitive topology: line list.
        /// </summary>
        public static readonly RenderState PrimitiveLines = 0x0002000000000000;

        /// <summary>
        /// Primitive topology: line strip.
        /// </summary>
        public static readonly RenderState PrimitiveLineStrip = 0x0003000000000000;

        /// <summary>
        /// Primitive topology: point list.
        /// </summary>
        public static readonly RenderState PrimitivePoints = 0x0004000000000000;

        /// <summary>
        /// Enable multisampling.
        /// </summary>
        public static readonly RenderState Multisampling = 0x1000000000000000;

        /// <summary>
        /// Enable line antialiasing.
        /// </summary>
        public static readonly RenderState LineAA = 0x2000000000000000;

        /// <summary>
        /// Enable conservative rasterization.
        /// </summary>
        public static readonly RenderState ConservativeRasterization = 0x4000000000000000;

        /// <summary>
        /// Provides a set of sane defaults.
        /// </summary>
        public static readonly RenderState Default =
            WriteRGB |
            WriteA |
            WriteZ |
            DepthTestLess |
            CullClockwise |
            Multisampling;

        /// <summary>
        /// Predefined blend effect: additive blending.
        /// </summary>
        public static readonly RenderState BlendAdd = BlendFunction(BlendOne, BlendOne);

        /// <summary>
        /// Predefined blend effect: alpha blending.
        /// </summary>
        public static readonly RenderState BlendAlpha = BlendFunction(BlendSourceAlpha, BlendInverseSourceAlpha);

        /// <summary>
        /// Predefined blend effect: "darken" blending.
        /// </summary>
        public static readonly RenderState BlendDarken = BlendFunction(BlendOne, BlendOne) | BlendEquation(BlendEquationMin);

        /// <summary>
        /// Predefined blend effect: "lighten" blending.
        /// </summary>
        public static readonly RenderState BlendLighten = BlendFunction(BlendOne, BlendOne) | BlendEquation(BlendEquationMax);

        /// <summary>
        /// Predefined blend effect: multiplicative blending.
        /// </summary>
        public static readonly RenderState BlendMultiply = BlendFunction(BlendDestinationColor, BlendZero);

        /// <summary>
        /// Predefined blend effect: normal blending based on alpha.
        /// </summary>
        public static readonly RenderState BlendNormal = BlendFunction(BlendOne, BlendInverseSourceAlpha);

        /// <summary>
        /// Predefined blend effect: "screen" blending.
        /// </summary>
        public static readonly RenderState BlendScreen = BlendFunction(BlendOne, BlendInverseSourceColor);

        /// <summary>
        /// Predefined blend effect: "linear burn" blending.
        /// </summary>
        public static readonly RenderState BlendLinearBurn = BlendFunction(BlendDestinationColor, BlendInverseDestinationColor) | BlendEquation(BlendEquationSub);

        /// <summary>
        /// Initializes a new instance of the <see cref="RenderState"/> struct.
        /// </summary>
        /// <param name="value">The integer value of the state.</param>
        public RenderState (long value) {
            this.value = (ulong)value;
        }

        /// <summary>
        /// Encodes an alpha reference value in a render state.
        /// </summary>
        /// <param name="alpha">The alpha reference value.</param>
        /// <returns>The encoded render state.</returns>
        public static RenderState AlphaRef (byte alpha) {
            return (((ulong)alpha) << AlphaRefShift) & AlphaRefMask;
        }

        /// <summary>
        /// Encodes a point size value in a render state.
        /// </summary>
        /// <param name="size">The point size.</param>
        /// <returns>The encoded render state.</returns>
        public static RenderState PointSize (byte size) {
            return (((ulong)size) << PointSizeShift) & PointSizeMask;
        }

        /// <summary>
        /// Builds a render state for a blend function.
        /// </summary>
        /// <param name="source">The source blend operation.</param>
        /// <param name="destination">The destination blend operation.</param>
        /// <returns>The render state for the blend function.</returns>
        public static RenderState BlendFunction (RenderState source, RenderState destination) {
            return BlendFunction(source, destination, source, destination);
        }

        /// <summary>
        /// Builds a render state for a blend function.
        /// </summary>
        /// <param name="sourceColor">The source color blend operation.</param>
        /// <param name="destinationColor">The destination color blend operation.</param>
        /// <param name="sourceAlpha">The source alpha blend operation.</param>
        /// <param name="destinationAlpha">The destination alpha blend operation.</param>
        /// <returns>
        /// The render state for the blend function.
        /// </returns>
        public static RenderState BlendFunction (RenderState sourceColor, RenderState destinationColor, RenderState sourceAlpha, RenderState destinationAlpha) {
            return (sourceColor | (destinationColor << 4)) | ((sourceAlpha | (destinationAlpha << 4)) << 8);
        }

        /// <summary>
        /// Builds a render state for a blend equation.
        /// </summary>
        /// <param name="equation">The equation.</param>
        /// <returns>
        /// The render state for the blend equation.
        /// </returns>
        public static RenderState BlendEquation (RenderState equation) {
            return BlendEquation(equation, equation);
        }

        /// <summary>
        /// Builds a render state for a blend equation.
        /// </summary>
        /// <param name="sourceEquation">The source equation.</param>
        /// <param name="alphaEquation">The alpha equation.</param>
        /// <returns>
        /// The render state for the blend equation.
        /// </returns>
        public static RenderState BlendEquation (RenderState sourceEquation, RenderState alphaEquation) {
            return sourceEquation | (alphaEquation << 3);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return value.GetHashCode();
        }

        /// <summary>
        /// Determines whether the specific value is equal to this instance.
        /// </summary>
        /// <param name="other">The value to compare with this instance.</param>
        /// <returns><c>true</c> if the value is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (RenderState other) {
            return value == other.value;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var state = obj as RenderState?;
            if (state == null)
                return false;

            return Equals(state);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(RenderState left, RenderState right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(RenderState left, RenderState right) {
            return !left.Equals(right);
        }

        /// <summary>
        /// Performs an implicit conversion from ulong.
        /// </summary>
        /// <param name="value">The value to convert.</param>
        public static implicit operator RenderState (ulong value) {
            return new RenderState((long)value);
        }

        /// <summary>
        /// Performs an explicit conversion to ulong.
        /// </summary>
        /// <param name="state">The value to convert.</param>
        public static explicit operator ulong (RenderState state) {
            return state.value;
        }

        /// <summary>
        /// Implements the bitwise-or operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static RenderState operator |(RenderState left, RenderState right) {
            return left.value | right.value;
        }

        /// <summary>
        /// Implements the bitwise-and operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static RenderState operator &(RenderState left, RenderState right) {
            return left.value & right.value;
        }

        /// <summary>
        /// Implements the bitwise-complement operator.
        /// </summary>
        /// <param name="state">The operand.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static RenderState operator ~(RenderState state) {
            return ~state.value;
        }

        /// <summary>
        /// Implements the left shift operator.
        /// </summary>
        /// <param name="state">The value to shift.</param>
        /// <param name="amount">The amount to shift.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static RenderState operator <<(RenderState state, int amount) {
            return state.value << amount;
        }

        /// <summary>
        /// Implements the right shift operator.
        /// </summary>
        /// <param name="state">The value to shift.</param>
        /// <param name="amount">The amount to shift.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static RenderState operator >>(RenderState state, int amount) {
            return state.value >> amount;
        }
    }

    /// <summary>
    /// Represents a single compiled shader component.
    /// </summary>
    public unsafe struct Shader : IDisposable, IEquatable<Shader> {
        Uniform[] uniforms;
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly Shader Invalid = new Shader();

        /// <summary>
        /// The set of uniforms exposed by the shader.
        /// </summary>
        public IReadOnlyList<Uniform> Uniforms {
            get {
                if (uniforms == null) {
                    var count = NativeMethods.bgfx_get_shader_uniforms(handle, null, 0);
                    uniforms = new Uniform[count];
                    NativeMethods.bgfx_get_shader_uniforms(handle, uniforms, count);
                }

                return uniforms;
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Shader"/> struct.
        /// </summary>
        /// <param name="memory">The compiled shader memory.</param>
        public Shader (MemoryBlock memory) {
            handle = NativeMethods.bgfx_create_shader(memory.ptr);
            uniforms = null;
        }

        /// <summary>
        /// Releases the shader.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_shader(handle);
        }

        /// <summary>
        /// Sets the name of the shader, for debug display purposes.
        /// </summary>
        /// <param name="name">The name of the shader.</param>
        public void SetName(string name) {
            NativeMethods.bgfx_set_shader_name(handle, name, int.MaxValue);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (Shader other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as Shader?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(Shader left, Shader right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(Shader left, Shader right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Specifies state information used to configure rendering operations.
    /// </summary>
    public struct StencilFlags : IEquatable<StencilFlags> {
        const int ReadMaskShift = 8;
        const uint RefMask = 0x000000ff;
        const uint ReadMaskMask = 0x0000ff00;

        readonly uint value;

        /// <summary>
        /// No state bits set.
        /// </summary>
        public static readonly StencilFlags None = 0;

        /// <summary>
        /// Perform a "less than" stencil test.
        /// </summary>
        public static readonly StencilFlags TestLess = 0x00010000;

        /// <summary>
        /// Perform a "less than or equal" stencil test.
        /// </summary>
        public static readonly StencilFlags TestLessEqual = 0x00020000;

        /// <summary>
        /// Perform an equality stencil test.
        /// </summary>
        public static readonly StencilFlags TestEqual = 0x00030000;

        /// <summary>
        /// Perform a "greater than or equal" stencil test.
        /// </summary>
        public static readonly StencilFlags TestGreaterEqual = 0x00040000;

        /// <summary>
        /// Perform a "greater than" stencil test.
        /// </summary>
        public static readonly StencilFlags TestGreater = 0x00050000;

        /// <summary>
        /// Perform an inequality stencil test.
        /// </summary>
        public static readonly StencilFlags TestNotEqual = 0x00060000;

        /// <summary>
        /// Never pass the stencil test.
        /// </summary>
        public static readonly StencilFlags TestNever = 0x00070000;

        /// <summary>
        /// Always pass the stencil test.
        /// </summary>
        public static readonly StencilFlags TestAlways = 0x00080000;

        /// <summary>
        /// On failing the stencil test, zero out the stencil value.
        /// </summary>
        public static readonly StencilFlags FailSZero = 0x00000000;

        /// <summary>
        /// On failing the stencil test, keep the old stencil value.
        /// </summary>
        public static readonly StencilFlags FailSKeep = 0x00100000;

        /// <summary>
        /// On failing the stencil test, replace the stencil value.
        /// </summary>
        public static readonly StencilFlags FailSReplace = 0x00200000;

        /// <summary>
        /// On failing the stencil test, increment the stencil value.
        /// </summary>
        public static readonly StencilFlags FailSIncrement = 0x00300000;

        /// <summary>
        /// On failing the stencil test, increment the stencil value (with saturation).
        /// </summary>
        public static readonly StencilFlags FailSIncrementSaturate = 0x00400000;

        /// <summary>
        /// On failing the stencil test, decrement the stencil value.
        /// </summary>
        public static readonly StencilFlags FailSDecrement = 0x00500000;

        /// <summary>
        /// On failing the stencil test, decrement the stencil value (with saturation).
        /// </summary>
        public static readonly StencilFlags FailSDecrementSaturate = 0x00600000;

        /// <summary>
        /// On failing the stencil test, invert the stencil value.
        /// </summary>
        public static readonly StencilFlags FailSInvert = 0x00700000;

        /// <summary>
        /// On failing the stencil test, zero out the depth value.
        /// </summary>
        public static readonly StencilFlags FailZZero = 0x00000000;

        /// <summary>
        /// On failing the stencil test, keep the depth value.
        /// </summary>
        public static readonly StencilFlags FailZKeep = 0x01000000;

        /// <summary>
        /// On failing the stencil test, replace the depth value.
        /// </summary>
        public static readonly StencilFlags FailZReplace = 0x02000000;

        /// <summary>
        /// On failing the stencil test, increment the depth value.
        /// </summary>
        public static readonly StencilFlags FailZIncrement = 0x03000000;

        /// <summary>
        /// On failing the stencil test, increment the depth value (with saturation).
        /// </summary>
        public static readonly StencilFlags FailZIncrementSaturate = 0x04000000;

        /// <summary>
        /// On failing the stencil test, decrement the depth value.
        /// </summary>
        public static readonly StencilFlags FailZDecrement = 0x05000000;

        /// <summary>
        /// On failing the stencil test, decrement the depth value (with saturation).
        /// </summary>
        public static readonly StencilFlags FailZDecrementSaturate = 0x06000000;

        /// <summary>
        /// On failing the stencil test, invert the depth value.
        /// </summary>
        public static readonly StencilFlags FailZInvert = 0x07000000;

        /// <summary>
        /// On passing the stencil test, zero out the depth value.
        /// </summary>
        public static readonly StencilFlags PassZZero = 0x00000000;

        /// <summary>
        /// On passing the stencil test, keep the old depth value.
        /// </summary>
        public static readonly StencilFlags PassZKeep = 0x10000000;

        /// <summary>
        /// On passing the stencil test, replace the depth value.
        /// </summary>
        public static readonly StencilFlags PassZReplace = 0x20000000;

        /// <summary>
        /// On passing the stencil test, increment the depth value.
        /// </summary>
        public static readonly StencilFlags PassZIncrement = 0x30000000;

        /// <summary>
        /// On passing the stencil test, increment the depth value (with saturation).
        /// </summary>
        public static readonly StencilFlags PassZIncrementSaturate = 0x40000000;

        /// <summary>
        /// On passing the stencil test, decrement the depth value.
        /// </summary>
        public static readonly StencilFlags PassZDecrement = 0x50000000;

        /// <summary>
        /// On passing the stencil test, decrement the depth value (with saturation).
        /// </summary>
        public static readonly StencilFlags PassZDecrementSaturate = 0x60000000;

        /// <summary>
        /// On passing the stencil test, invert the depth value.
        /// </summary>
        public static readonly StencilFlags PassZInvert = 0x70000000;

        /// <summary>
        /// Initializes a new instance of the <see cref="StencilFlags"/> struct.
        /// </summary>
        /// <param name="value">The integer value of the state.</param>
        public StencilFlags (int value) {
            this.value = (uint)value;
        }

        /// <summary>
        /// Encodes a reference value in a stencil state.
        /// </summary>
        /// <param name="reference">The stencil reference value.</param>
        /// <returns>The encoded stencil state.</returns>
        public static StencilFlags ReferenceValue (byte reference) {
            return reference & RefMask;
        }

        /// <summary>
        /// Encodes a read mask in a stencil state.
        /// </summary>
        /// <param name="mask">The mask.</param>
        /// <returns>
        /// The encoded stencil state.
        /// </returns>
        public static StencilFlags ReadMask (byte mask) {
            return (((uint)mask) << ReadMaskShift) & ReadMaskMask;
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return value.GetHashCode();
        }

        /// <summary>
        /// Determines whether the specific value is equal to this instance.
        /// </summary>
        /// <param name="other">The value to compare with this instance.</param>
        /// <returns><c>true</c> if the value is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (StencilFlags other) {
            return value == other.value;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var state = obj as StencilFlags?;
            if (state == null)
                return false;

            return Equals(state);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(StencilFlags left, StencilFlags right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(StencilFlags left, StencilFlags right) {
            return !left.Equals(right);
        }

        /// <summary>
        /// Performs an implicit conversion from uint.
        /// </summary>
        /// <param name="value">The value to convert.</param>
        public static implicit operator StencilFlags (uint value) {
            return new StencilFlags((int)value);
        }

        /// <summary>
        /// Performs an explicit conversion to uint.
        /// </summary>
        /// <param name="state">The value to convert.</param>
        public static explicit operator uint (StencilFlags state) {
            return state.value;
        }

        /// <summary>
        /// Implements the bitwise-or operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static StencilFlags operator |(StencilFlags left, StencilFlags right) {
            return left.value | right.value;
        }

        /// <summary>
        /// Implements the bitwise-and operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static StencilFlags operator &(StencilFlags left, StencilFlags right) {
            return left.value & right.value;
        }

        /// <summary>
        /// Implements the bitwise-complement operator.
        /// </summary>
        /// <param name="state">The operand.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static StencilFlags operator ~(StencilFlags state) {
            return ~state.value;
        }

        /// <summary>
        /// Implements the left shift operator.
        /// </summary>
        /// <param name="state">The value to shift.</param>
        /// <param name="amount">The amount to shift.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static StencilFlags operator <<(StencilFlags state, int amount) {
            return state.value << amount;
        }

        /// <summary>
        /// Implements the right shift operator.
        /// </summary>
        /// <param name="state">The value to shift.</param>
        /// <param name="amount">The amount to shift.</param>
        /// <returns>
        /// The result of the operator.
        /// </returns>
        public static StencilFlags operator >>(StencilFlags state, int amount) {
            return state.value >> amount;
        }
    }

    /// <summary>
    /// Maintains a transient index buffer.
    /// </summary>
    /// <remarks>
    /// The contents of the buffer are valid for the current frame only.
    /// You must call SetVertexBuffer with the buffer or a leak could occur.
    /// </remarks>
    public unsafe struct TransientIndexBuffer : IEquatable<TransientIndexBuffer> {
        readonly IntPtr data;
        int size;
        int startIndex;
        readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly TransientIndexBuffer Invalid = new TransientIndexBuffer();

        /// <summary>
        /// A pointer that can be filled with index data.
        /// </summary>
        public IntPtr Data { get { return data; } }

        /// <summary>
        /// The size of the buffer.
        /// </summary>
        public int Count { get { return size; } }

        /// <summary>
        /// Initializes a new instance of the <see cref="TransientIndexBuffer"/> struct.
        /// </summary>
        /// <param name="indexCount">The number of 16-bit indices that fit in the buffer.</param>
        public TransientIndexBuffer (int indexCount) {
            NativeMethods.bgfx_alloc_transient_index_buffer(out this, indexCount);
        }

        /// <summary>
        /// Gets the available space in the global transient index buffer.
        /// </summary>
        /// <param name="count">The number of 16-bit indices required.</param>
        /// <returns>The number of available indices.</returns>
        public static int GetAvailableSpace (int count) {
            return NativeMethods.bgfx_get_avail_transient_index_buffer(count);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (TransientIndexBuffer other) {
            return handle == other.handle && data == other.data;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as TransientIndexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode() >> 13 ^ data.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Count: {0}", Count);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(TransientIndexBuffer left, TransientIndexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(TransientIndexBuffer left, TransientIndexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Maintains a transient vertex buffer.
    /// </summary>
    /// <remarks>
    /// The contents of the buffer are valid for the current frame only.
    /// You must call SetVertexBuffer with the buffer or a leak could occur.
    /// </remarks>
    public unsafe struct TransientVertexBuffer : IEquatable<TransientVertexBuffer> {
        readonly IntPtr data;
        int size;
        int startVertex;
        ushort stride;
        readonly ushort handle;
        ushort decl;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly TransientVertexBuffer Invalid = new TransientVertexBuffer();

        /// <summary>
        /// A pointer that can be filled with vertex data.
        /// </summary>
        public IntPtr Data { get { return data; } }

        /// <summary>
        /// The size of the buffer.
        /// </summary>
        public int Count { get { return size; } }

        /// <summary>
        /// Initializes a new instance of the <see cref="TransientVertexBuffer"/> struct.
        /// </summary>
        /// <param name="vertexCount">The number of vertices that fit in the buffer.</param>
        /// <param name="layout">The layout of the vertex data.</param>
        public TransientVertexBuffer (int vertexCount, VertexLayout layout) {
            NativeMethods.bgfx_alloc_transient_vertex_buffer(out this, vertexCount, ref layout.data);
        }

        /// <summary>
        /// Gets the available space in the global transient vertex buffer.
        /// </summary>
        /// <param name="count">The number of vertices required.</param>
        /// <param name="layout">The layout of each vertex.</param>
        /// <returns>The number of available vertices.</returns>
        public static int GetAvailableSpace (int count, VertexLayout layout) {
            return NativeMethods.bgfx_get_avail_transient_vertex_buffer(count, ref layout.data);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (TransientVertexBuffer other) {
            return handle == other.handle && data == other.data;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as TransientVertexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode() >> 13 ^ data.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(TransientVertexBuffer left, TransientVertexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(TransientVertexBuffer left, TransientVertexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Represents a shader uniform.
    /// </summary>
    public unsafe struct Uniform : IDisposable, IEquatable<Uniform> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly Uniform Invalid = new Uniform();

        /// <summary>
        /// The name of the uniform.
        /// </summary>
        public string Name {
            get {
                Info info;
                NativeMethods.bgfx_get_uniform_info(handle, out info);
                return Marshal.PtrToStringAnsi(new IntPtr(info.name));
            }
        }

        /// <summary>
        /// The type of the data represented by the uniform.
        /// </summary>
        public UniformType Type {
            get {
                Info info;
                NativeMethods.bgfx_get_uniform_info(handle, out info);
                return info.type;
            }
        }

        /// <summary>
        /// Size of the array, if the uniform is an array type.
        /// </summary>
        public int ArraySize {
            get {
                Info info;
                NativeMethods.bgfx_get_uniform_info(handle, out info);
                return info.arraySize;
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Uniform"/> struct.
        /// </summary>
        /// <param name="name">The name of the uniform.</param>
        /// <param name="type">The type of data represented by the uniform.</param>
        /// <param name="arraySize">Size of the array, if the uniform is an array type.</param>
        /// <remarks>
        /// Predefined uniform names:
        /// u_viewRect vec4(x, y, width, height) - view rectangle for current view.
        /// u_viewTexel vec4 (1.0/width, 1.0/height, undef, undef) - inverse width and height
        /// u_view mat4 - view matrix
        /// u_invView mat4 - inverted view matrix
        /// u_proj mat4 - projection matrix
        /// u_invProj mat4 - inverted projection matrix
        /// u_viewProj mat4 - concatenated view projection matrix
        /// u_invViewProj mat4 - concatenated inverted view projection matrix
        /// u_model mat4[BGFX_CONFIG_MAX_BONES] - array of model matrices.
        /// u_modelView mat4 - concatenated model view matrix, only first model matrix from array is used.
        /// u_modelViewProj mat4 - concatenated model view projection matrix.
        /// u_alphaRef float - alpha reference value for alpha test.
        /// </remarks>
        public Uniform (string name, UniformType type, int arraySize = 1) {
            handle = NativeMethods.bgfx_create_uniform(name, type, (ushort)arraySize);
        }

        /// <summary>
        /// Releases the uniform.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_uniform(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (Uniform other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as Uniform?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(Uniform left, Uniform right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(Uniform left, Uniform right) {
            return !left.Equals(right);
        }

        internal struct Info {
            public fixed sbyte name[256];
            public UniformType type;
            public ushort arraySize;
        }
    }

    /// <summary>
    /// Represents a static vertex buffer.
    /// </summary>
    public unsafe struct VertexBuffer : IDisposable, IEquatable<VertexBuffer> {
        internal readonly ushort handle;

        /// <summary>
        /// Represents an invalid handle.
        /// </summary>
        public static readonly VertexBuffer Invalid = new VertexBuffer();

        /// <summary>
        /// Initializes a new instance of the <see cref="VertexBuffer"/> struct.
        /// </summary>
        /// <param name="memory">The vertex data with which to populate the buffer.</param>
        /// <param name="layout">The layout of the vertex data.</param>
        /// <param name="flags">Flags used to control buffer behavior.</param>
        public VertexBuffer (MemoryBlock memory, VertexLayout layout, BufferFlags flags = BufferFlags.None) {
            handle = NativeMethods.bgfx_create_vertex_buffer(memory.ptr, ref layout.data, flags);
        }

        /// <summary>
        /// Sets the name of the vertex buffer, for debug display purposes.
        /// </summary>
        /// <param name="name">The name of the texture.</param>
        public void SetName(string name) {
            NativeMethods.bgfx_set_vertex_buffer_name(handle, name, int.MaxValue);
        }

        /// <summary>
        /// Releases the vertex buffer.
        /// </summary>
        public void Dispose () {
            NativeMethods.bgfx_destroy_vertex_buffer(handle);
        }

        /// <summary>
        /// Determines whether the specified object is equal to this instance.
        /// </summary>
        /// <param name="other">The object to compare with this instance.</param>
        /// <returns><c>true</c> if the specified object is equal to this instance; otherwise, <c>false</c>.</returns>
        public bool Equals (VertexBuffer other) {
            return handle == other.handle;
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals (object obj) {
            var other = obj as VertexBuffer?;
            if (other == null)
                return false;

            return Equals(other);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>
        /// A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.
        /// </returns>
        public override int GetHashCode () {
            return handle.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString () {
            return string.Format("Handle: {0}", handle);
        }

        /// <summary>
        /// Implements the equality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator ==(VertexBuffer left, VertexBuffer right) {
            return left.Equals(right);
        }

        /// <summary>
        /// Implements the inequality operator.
        /// </summary>
        /// <param name="left">The left side of the operator.</param>
        /// <param name="right">The right side of the operator.</param>
        /// <returns>
        /// <c>true</c> if the two objects are not equal; otherwise, <c>false</c>.
        /// </returns>
        public static bool operator !=(VertexBuffer left, VertexBuffer right) {
            return !left.Equals(right);
        }
    }

    /// <summary>
    /// Specifies scaling relative to the size of the backbuffer.
    /// </summary>
    public enum BackbufferRatio {
        /// <summary>
        /// Surface is equal to the backbuffer size.
        /// </summary>
        Equal,

        /// <summary>
        /// Surface is half the backbuffer size.
        /// </summary>
        Half,

        /// <summary>
        /// Surface is a quater of the backbuffer size.
        /// </summary>
        Quater,

        /// <summary>
        /// Surface is an eighth of the backbuffer size.
        /// </summary>
        Eighth,

        /// <summary>
        /// Surface is a sixteenth of the backbuffer size.
        /// </summary>
        Sixteenth,

        /// <summary>
        /// Surface is double the backbuffer size.
        /// </summary>
        Double
    }

    /// <summary>
    /// Specifies various flags that control vertex and index buffer behavior.
    /// </summary>
    [Flags]
    public enum BufferFlags : short {
        /// <summary>
        /// No flags specified.
        /// </summary>
        None,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 8x1.
        /// </summary>
        ComputeFormat8x1 = 0x1,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 8x2.
        /// </summary>
        ComputeFormat8x2 = 0x2,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 8x4.
        /// </summary>
        ComputeFormat8x4 = 0x3,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 16x1.
        /// </summary>
        ComputeFormat16x1 = 0x4,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 16x2.
        /// </summary>
        ComputeFormat16x2 = 0x5,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 16x4.
        /// </summary>
        ComputeFormat16x4 = 0x6,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 32x1.
        /// </summary>
        ComputeFormat32x1 = 0x7,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 32x2.
        /// </summary>
        ComputeFormat32x2 = 0x8,

        /// <summary>
        /// Specifies the format of data in a compute buffer as being 32x4.
        /// </summary>
        ComputeFormat32x4 = 0x9,

        /// <summary>
        /// Specifies the type of data in a compute buffer as being unsigned integers.
        /// </summary>
        ComputeTypeInt = 0x10,

        /// <summary>
        /// Specifies the type of data in a compute buffer as being signed integers.
        /// </summary>
        ComputeTypeUInt = 0x20,

        /// <summary>
        /// Specifies the type of data in a compute buffer as being floating point values.
        /// </summary>
        ComputeTypeFloat = 0x30,

        /// <summary>
        /// Buffer will be read by a compute shader.
        /// </summary>
        ComputeRead = 0x100,

        /// <summary>
        /// Buffer will be written into by a compute shader. It cannot be accessed by the CPU.
        /// </summary>
        ComputeWrite = 0x200,

        /// <summary>
        /// Buffer is the source of indirect draw commands.
        /// </summary>
        DrawIndirect = 0x400,

        /// <summary>
        /// Buffer will resize on update if a different quantity of data is passed. If this flag is not set
        /// the data will be trimmed to fit in the existing buffer size. Effective only for dynamic buffers.
        /// </summary>
        AllowResize = 0x800,

        /// <summary>
        /// Buffer is using 32-bit indices. Useful only for index buffers.
        /// </summary>
        Index32 = 0x1000,

        /// <summary>
        /// Buffer will be read and written by a compute shader.
        /// </summary>
        ComputeReadWrite = ComputeRead | ComputeWrite
    }

    /// <summary>
    /// Specifies flags for clearing surfaces.
    /// </summary>
    [Flags]
    public enum ClearTargets : short {
        /// <summary>
        /// Don't clear anything.
        /// </summary>
        None = 0,

        /// <summary>
        /// Clear the color channels.
        /// </summary>
        Color = 0x1,

        /// <summary>
        /// Clear the depth buffer.
        /// </summary>
        Depth = 0x2,

        /// <summary>
        /// Clear the stencil buffer.
        /// </summary>
        Stencil = 0x4,

        /// <summary>
        /// Discard the first color framebuffer.
        /// </summary>
        DiscardColor0 = 0x8,

        /// <summary>
        /// Discard the second color framebuffer.
        /// </summary>
        DiscardColor1 = 0x10,

        /// <summary>
        /// Discard the third color framebuffer.
        /// </summary>
        DiscardColor2 = 0x20,

        /// <summary>
        /// Discard the fourth color framebuffer.
        /// </summary>
        DiscardColor3 = 0x40,

        /// <summary>
        /// Discard the fifth color framebuffer.
        /// </summary>
        DiscardColor4 = 0x80,

        /// <summary>
        /// Discard the sixth color framebuffer.
        /// </summary>
        DiscardColor5 = 0x100,

        /// <summary>
        /// Discard the seventh color framebuffer.
        /// </summary>
        DiscardColor6 = 0x200,

        /// <summary>
        /// Discard the eighth color framebuffer.
        /// </summary>
        DiscardColor7 = 0x400,

        /// <summary>
        /// Discard the depth buffer.
        /// </summary>
        DiscardDepth = 0x800,

        /// <summary>
        /// Discard the stencil buffer.
        /// </summary>
        DiscardStencil = 0x1000,
    }

    /// <summary>
    /// Describes access rights for a compute buffer.
    /// </summary>
    public enum ComputeBufferAccess {
        /// <summary>
        /// The buffer can only be read.
        /// </summary>
        Read,

        /// <summary>
        /// The buffer can only be written to.
        /// </summary>
        Write,

        /// <summary>
        /// The buffer can be read and written.
        /// </summary>
        ReadWrite
    }

    /// <summary>
    /// Addresses a particular face of a cube map.
    /// </summary>
    public enum CubeMapFace : byte {
        /// <summary>
        /// The right face.
        /// </summary>
        Right,

        /// <summary>
        /// The left face.
        /// </summary>
        Left,

        /// <summary>
        /// The top face.
        /// </summary>
        Top,

        /// <summary>
        /// The bottom face.
        /// </summary>
        Bottom,

        /// <summary>
        /// The front face.
        /// </summary>
        Front,

        /// <summary>
        /// The back face.
        /// </summary>
        Back
    }

    /// <summary>
    /// Specifies debug text colors.
    /// </summary>
    public enum DebugColor {
        /// <summary>
        /// Black.
        /// </summary>
        Black,

        /// <summary>
        /// Blue.
        /// </summary>
        Blue,

        /// <summary>
        /// Green.
        /// </summary>
        Green,

        /// <summary>
        /// Cyan.
        /// </summary>
        Cyan,

        /// <summary>
        /// Red.
        /// </summary>
        Red,

        /// <summary>
        /// Magenta.
        /// </summary>
        Magenta,

        /// <summary>
        /// Brown.
        /// </summary>
        Brown,

        /// <summary>
        /// Light gray.
        /// </summary>
        LightGray,

        /// <summary>
        /// Dark gray.
        /// </summary>
        DarkGray,

        /// <summary>
        /// Light blue.
        /// </summary>
        LightBlue,

        /// <summary>
        /// Light green.
        /// </summary>
        LightGreen,

        /// <summary>
        /// Light cyan.
        /// </summary>
        LightCyan,

        /// <summary>
        /// Light red.
        /// </summary>
        LightRed,

        /// <summary>
        /// Light magenta.
        /// </summary>
        LightMagenta,

        /// <summary>
        /// Yellow.
        /// </summary>
        Yellow,

        /// <summary>
        /// White.
        /// </summary>
        White
    }

    /// <summary>
    /// Specifies various debug options.
    /// </summary>
    [Flags]
    public enum DebugFeatures {
        /// <summary>
        /// Don't enable any debugging features.
        /// </summary>
        None = 0,

        /// <summary>
        /// Force wireframe rendering.
        /// </summary>
        Wireframe = 0x1,

        /// <summary>
        /// When set, all rendering calls are skipped. This is useful when profiling to
        /// find bottlenecks between the CPU and GPU.
        /// </summary>
        InfinitelyFastHardware = 0x2,

        /// <summary>
        /// Display internal statistics.
        /// </summary>
        DisplayStatistics = 0x4,

        /// <summary>
        /// Display debug text.
        /// </summary>
        DisplayText = 0x8,

        /// <summary>
        /// Enable the internal library performance profiler.
        /// </summary>
        Profiler = 0x10
    }

    /// <summary>
    /// Specifies various capabilities supported by the rendering device.
    /// </summary>
    [Flags]
    public enum DeviceFeatures : long {
        /// <summary>
        /// No extra features supported.
        /// </summary>
        None = 0,

        /// <summary>
        /// Device supports alpha to coverage.
        /// </summary>
        AlphaToCoverage = 0x1,

        /// <summary>
        /// Device supports independent blending of simultaneous render targets.
        /// </summary>
        BlendIndependent = 0x2,

        /// <summary>
        /// Device supports compute shaders.
        /// </summary>
        Compute = 0x4,

        /// <summary>
        /// Device supports conservative rasterization.
        /// </summary>
        ConservativeRasterization = 0x8,

        /// <summary>
        /// Device supports indirect drawing via GPU buffers.
        /// </summary>
        DrawIndirect = 0x10,

        /// <summary>
        /// Fragment shaders can access depth values.
        /// </summary>
        FragmentDepth = 0x20,

        /// <summary>
        /// Device supports ordering of fragment output.
        /// </summary>
        FragmentOrdering = 0x40,

        /// <summary>
        /// Read/write framebuffer attachments are supported.
        /// </summary>
        FramebufferRW = 0x80,

        /// <summary>
        /// A graphics debugger is present.
        /// </summary>
        GraphicsDebugger = 0x100,

        /// <summary>
        /// Devices supports HDR10 rendering.
        /// </summary>
        HDR10 = 0x400,

        /// <summary>
        /// Device supports high-DPI rendering.
        /// </summary>
        HighDPI = 0x800,

        /// <summary>
        /// Device supports 32-bit indices.
        /// </summary>
        Index32 = 0x1000,

        /// <summary>
        /// Device supports instancing.
        /// </summary>
        Instancing = 0x2000,

        /// <summary>
        /// Device supports occlusion queries.
        /// </summary>
        OcclusionQuery = 0x4000,

        /// <summary>
        /// Device supports multithreaded rendering.
        /// </summary>
        RendererMultithreaded = 0x8000,

        /// <summary>
        /// Indicates whether the device can render to multiple swap chains.
        /// </summary>
        SwapChain = 0x10000,

        /// <summary>
        /// Device supports 2D texture arrays.
        /// </summary>
        Texture2DArray = 0x20000,

        /// <summary>
        /// Device supports 3D textures.
        /// </summary>
        Texture3D = 0x40000,

        /// <summary>
        /// Device supports texture blits.
        /// </summary>
        TextureBlit = 0x80000,

        /// <summary>
        /// Device supports other texture comparison modes.
        /// </summary>
        TextureCompareExtended = 0x100000,

        /// <summary>
        /// Device supports "Less than or equal to" texture comparison mode.
        /// </summary>
        TextureCompareLessEqual = 0x200000,

        /// <summary>
        /// Device supports all texture comparison modes.
        /// </summary>
        TextureCompareAll = TextureCompareLessEqual | TextureCompareExtended,

        /// <summary>
        /// Device supports cubemap texture arrays.
        /// </summary>
        TextureCubeArray = 0x400000,

        /// <summary>
        /// Device supports directly accessing texture data.
        /// </summary>
        TextureDirectAccess = 0x800000,

        /// <summary>
        /// Device supports reading back texture data.
        /// </summary>
        TextureReadBack = 0x1000000,

        /// <summary>
        /// Device supports 16-bit floats as vertex attributes.
        /// </summary>
        VertexAttributeHalf = 0x2000000,

        /// <summary>
        /// UInt10 vertex attributes are supported.
        /// </summary>
        VertexAttributeUInt10 = 0x4000000,

        /// <summary>
        /// Devices supports rendering with VertexID only.
        /// </summary>
        VertexID = 0x8000000
    }

    /// <summary>
    /// Specifies various error types that can be reported by bgfx.
    /// </summary>
    public enum ErrorType {
        /// <summary>
        /// A debug check failed; the program can safely continue, but the issue should be investigated.
        /// </summary>
        DebugCheck,

        /// <summary>
        /// The program tried to compile an invalid shader.
        /// </summary>
        InvalidShader,

        /// <summary>
        /// An error occurred during bgfx library initialization.
        /// </summary>
        UnableToInitialize,

        /// <summary>
        /// Failed while trying to create a texture.
        /// </summary>
        UnableToCreateTexture,

        /// <summary>
        /// The graphics device was lost and the library was unable to recover.
        /// </summary>
        DeviceLost
    }

    /// <summary>
    /// Specifies results of an occlusion query.
    /// </summary>
    public enum OcclusionQueryResult {
        /// <summary>
        /// Objects are invisible.
        /// </summary>
        Invisible,

        /// <summary>
        /// Objects are visible.
        /// </summary>
        Visible,

        /// <summary>
        /// Result is not ready or is unknown.
        /// </summary>
        NoResult
    }

    /// <summary>
    /// Specifies the supported rendering backend APIs.
    /// </summary>
    public enum RendererBackend {
        /// <summary>
        /// No backend given.
        /// </summary>
        Noop,

        /// <summary>
        /// Direct3D 9
        /// </summary>
        Direct3D9,

        /// <summary>
        /// Direct3D 11
        /// </summary>
        Direct3D11,

        /// <summary>
        /// Direct3D 12
        /// </summary>
        Direct3D12,

        /// <summary>
        /// PlayStation 4's GNM
        /// </summary>
        GNM,

        /// <summary>
        /// Apple Metal.
        /// </summary>
        Metal,

        /// <summary>
        /// OpenGL ES
        /// </summary>
        OpenGLES,

        /// <summary>
        /// OpenGL
        /// </summary>
        OpenGL,

        /// <summary>
        /// Vulkan
        /// </summary>
        Vulkan,

        /// <summary>
        /// Used during initialization; specifies that the library should
        /// pick the best renderer for the running hardware and OS.
        /// </summary>
        Default
    }

    /// <summary>
    /// Specifies results of manually rendering a single frame.
    /// </summary>
    public enum RenderFrameResult {
        /// <summary>
        /// No device context has been created yet.
        /// </summary>
        NoContext,

        /// <summary>
        /// The frame was rendered.
        /// </summary>
        Render,

        /// <summary>
        /// The internal semaphore timed out; rendering was skipped.
        /// </summary>
        Timeout,

        /// <summary>
        /// Rendering is done; the program should exit.
        /// </summary>
        Exiting
    }

    /// <summary>
    /// Specifies various settings to change during a reset call.
    /// </summary>
    [Flags]
    public enum ResetFlags {
        /// <summary>
        /// No features to change.
        /// </summary>
        None = 0,

        /// <summary>
        /// Not yet supported.
        /// </summary>
        Fullscreen = 0x1,

        /// <summary>
        /// Enable 2x multisampling.
        /// </summary>
        MSAA2x = 0x10,

        /// <summary>
        /// Enable 4x multisampling.
        /// </summary>
        MSAA4x = 0x20,

        /// <summary>
        /// Enable 8x multisampling.
        /// </summary>
        MSAA8x = 0x30,

        /// <summary>
        /// Enable 16x multisampling.
        /// </summary>
        MSAA16x = 0x40,

        /// <summary>
        /// Enable v-sync.
        /// </summary>
        Vsync = 0x80,

        /// <summary>
        /// Use the maximum anisotropic filtering level available.
        /// </summary>
        MaxAnisotropy = 0x100,

        /// <summary>
        /// Begin screen capture.
        /// </summary>
        Capture = 0x200,

        /// <summary>
        /// Flush all commands to the device after rendering.
        /// </summary>
        FlushAfterRender = 0x2000,

        /// <summary>
        /// Flip the backbuffer immediately after rendering for reduced latency.
        /// Only useful when multithreading is disabled.
        /// </summary>
        FlipAfterRender = 0x4000,

        /// <summary>
        /// Write data to the backbuffer in non-linear sRGB format.
        /// </summary>
        SrgbBackbuffer = 0x8000,

        /// <summary>
        /// Enable HDR10 rendering.
        /// </summary>
        HDR10 = 0x10000,

        /// <summary>
        /// Enable High-DPI rendering.
        /// </summary>
        HighDPI = 0x20000,

        /// <summary>
        /// Enables depth clamping.
        /// </summary>
        DepthClamp = 0x40000,

        /// <summary>
        /// Suspends rendering.
        /// </summary>
        Suspend = 0x80000
    }

    /// <summary>
    /// Flags that control frame buffer resolve.
    /// </summary>
    public enum ResolveFlags : byte {
        /// <summary>
        /// No particular flags specified.
        /// </summary>
        None = 0,

        /// <summary>
        /// Automatically generate mipmaps.
        /// </summary>
        AutoGenMips = 0x1
    }

    /// <summary>
    /// Specifies various texture flags.
    /// </summary>
    [Flags]
    public enum TextureFlags : long {
        /// <summary>
        /// No flags set.
        /// </summary>
        None = 0x00000000,

        /// <summary>
        /// Mirror the texture in the U coordinate.
        /// </summary>
        MirrorU = 0x00000001,

        /// <summary>
        /// Clamp the texture in the U coordinate.
        /// </summary>
        ClampU = 0x00000002,

        /// <summary>
        /// Use a border color for addresses outside the range in the U coordinate.
        /// </summary>
        BorderU = 0x00000003,

        /// <summary>
        /// Mirror the texture in the V coordinate.
        /// </summary>
        MirrorV = 0x00000004,

        /// <summary>
        /// Clamp the texture in the V coordinate.
        /// </summary>
        ClampV = 0x00000008,

        /// <summary>
        /// Use a border color for addresses outside the range in the V coordinate.
        /// </summary>
        BorderV = 0x0000000c,

        /// <summary>
        /// Mirror the texture in the W coordinate.
        /// </summary>
        MirrorW = 0x00000010,

        /// <summary>
        /// Clamp the texture in the W coordinate.
        /// </summary>
        ClampW = 0x00000020,

        /// <summary>
        /// Use a border color for addresses outside the range in the W coordinate.
        /// </summary>
        BorderW = 0x00000030,

        /// <summary>
        /// Mirror the texture in the U,V, and W coordinates.
        /// </summary>
        MirrorUVW = MirrorU | MirrorV | MirrorW,

        /// <summary>
        /// Clamp the texture in the U,V, and W coordinates.
        /// </summary>
        ClampUVW = ClampU | ClampV | ClampW,

        /// <summary>
        /// Use a border color for addresses outside the range in the U,V, and W coordinates.
        /// </summary>
        BorderUVW = BorderU | BorderV | BorderW,

        /// <summary>
        /// Use point filtering for texture minification.
        /// </summary>
        MinFilterPoint = 0x00000040,

        /// <summary>
        /// Use anisotropic filtering for texture minification.
        /// </summary>
        MinFilterAnisotropic = 0x00000080,

        /// <summary>
        /// Use point filtering for texture magnification.
        /// </summary>
        MagFilterPoint = 0x00000100,

        /// <summary>
        /// Use anisotropic filtering for texture magnification.
        /// </summary>
        MagFilterAnisotropic = 0x00000200,

        /// <summary>
        /// Use point filtering for texture mipmaps.
        /// </summary>
        MipFilterPoint = 0x00000400,

        /// <summary>
        /// Use point filtering for minification, magnification, and texture mipmaps.
        /// </summary>
        FilterPoint = MinFilterPoint | MagFilterPoint | MipFilterPoint,

        /// <summary>
        /// Use a "less than" operator when comparing textures.
        /// </summary>
        CompareLess = 0x00010000,

        /// <summary>
        /// Use a "less than or equal" operator when comparing textures.
        /// </summary>
        CompareLessEqual = 0x00020000,

        /// <summary>
        /// Use an equality operator when comparing textures.
        /// </summary>
        CompareEqual = 0x00030000,

        /// <summary>
        /// Use a "greater than or equal" operator when comparing textures.
        /// </summary>
        CompareGreaterEqual = 0x00040000,

        /// <summary>
        /// Use a "greater than" operator when comparing textures.
        /// </summary>
        CompareGreater = 0x00050000,

        /// <summary>
        /// Use an inequality operator when comparing textures.
        /// </summary>
        CompareNotEqual = 0x00060000,

        /// <summary>
        /// Never compare two textures as equal.
        /// </summary>
        CompareNever = 0x00070000,

        /// <summary>
        /// Always compare two textures as equal.
        /// </summary>
        CompareAlways = 0x00080000,

        /// <summary>
        /// Sample stencil instead of depth.
        /// </summary>
        SampleStencil = 0x100000,

        /// <summary>
        /// Perform MSAA sampling on the texture.
        /// </summary>
        MSAASample = 0x800000000,

        /// <summary>
        /// The texture will be used as a render target.
        /// </summary>
        RenderTarget = 0x1000000000,

        /// <summary>
        /// The render target texture support 2x multisampling.
        /// </summary>
        RenderTargetMultisample2x = 0x2000000000,

        /// <summary>
        /// The render target texture support 4x multisampling.
        /// </summary>
        RenderTargetMultisample4x = 0x3000000000,

        /// <summary>
        /// The render target texture support 8x multisampling.
        /// </summary>
        RenderTargetMultisample8x = 0x4000000000,

        /// <summary>
        /// The render target texture support 16x multisampling.
        /// </summary>
        RenderTargetMultisample16x = 0x5000000000,

        /// <summary>
        /// The texture is only writeable (render target).
        /// </summary>
        RenderTargetWriteOnly = 0x8000000000,

        /// <summary>
        /// Texture is the target of compute shader writes.
        /// </summary>
        ComputeWrite = 0x100000000000,

        /// <summary>
        /// Texture data is in non-linear sRGB format.
        /// </summary>
        Srgb = 0x200000000000,

        /// <summary>
        /// Texture can be used as the destination of a blit operation.
        /// </summary>
        BlitDestination = 0x400000000000,

        /// <summary>
        /// Texture data can be read back.
        /// </summary>
        ReadBack = 0x800000000000
    }

    /// <summary>
    /// Specifies the format of a texture's data.
    /// </summary>
    /// <remarks>
    /// Check Caps flags for hardware format support.
    /// </remarks>
    public enum TextureFormat {
        /// <summary>
        /// Block compression with three color channels, 1 bit alpha.
        /// </summary>
        BC1,

        /// <summary>
        /// Block compression with three color channels, 4 bits alpha.
        /// </summary>
        BC2,

        /// <summary>
        /// Block compression with three color channels, 8 bits alpha.
        /// </summary>
        BC3,

        /// <summary>
        /// Block compression for 1-channel color.
        /// </summary>
        BC4,

        /// <summary>
        /// Block compression for 2-channel color.
        /// </summary>
        BC5,

        /// <summary>
        /// Block compression for three-channel HDR color.
        /// </summary>
        BC6H,

        /// <summary>
        /// Highest quality block compression.
        /// </summary>
        BC7,

        /// <summary>
        /// Original ETC block compression.
        /// </summary>
        ETC1,

        /// <summary>
        /// Improved ETC block compression (no alpha).
        /// </summary>
        ETC2,

        /// <summary>
        /// Improved ETC block compression with full alpha.
        /// </summary>
        ETC2A,

        /// <summary>
        /// Improved ETC block compression with 1-bit punchthrough alpha.
        /// </summary>
        ETC2A1,

        /// <summary>
        /// PVRTC1 compression (2 bits per pixel)
        /// </summary>
        PTC12,

        /// <summary>
        /// PVRTC1 compression (4 bits per pixel)
        /// </summary>
        PTC14,

        /// <summary>
        /// PVRTC1 compression with alpha (2 bits per pixel)
        /// </summary>
        PTC12A,

        /// <summary>
        /// PVRTC1 compression with alpha (4 bits per pixel)
        /// </summary>
        PTC14A,

        /// <summary>
        /// PVRTC2 compression with alpha (2 bits per pixel)
        /// </summary>
        PTC22,

        /// <summary>
        /// PVRTC2 compression with alpha (4 bits per pixel)
        /// </summary>
        PTC24,

        /// <summary>
        /// ATC RGB (4 bits per pixel)
        /// </summary>
        ATC,

        /// <summary>
        /// ATCE RGBA with explicit alpha (8 bits per pixel)
        /// </summary>
        ATCE,

        /// <summary>
        /// ATCE RGBA with interpolated alpha (8 bits per pixel)
        /// </summary>
        ATCI,

        /// <summary>
        /// ASTC 4x4 8.0 bpp
        /// </summary>
        ASTC4x4,

        /// <summary>
        /// ASTC 5x5 5.12 bpp
        /// </summary>
        ASTC5x5,

        /// <summary>
        /// ASTC 6x6 3.56 bpp
        /// </summary>
        ASTC6x6,

        /// <summary>
        /// ASTC 8x5 3.20 bpp
        /// </summary>
        ASTC8x5,

        /// <summary>
        /// ASTC 8x6 2.67 bpp
        /// </summary>
        ASTC8x6,

        /// <summary>
        /// ASTC 10x5 2.56 bpp
        /// </summary>
        ASTC10x5,

        /// <summary>
        /// Unknown texture format.
        /// </summary>
        Unknown,

        /// <summary>
        /// 1-bit single channel.
        /// </summary>
        R1,

        /// <summary>
        /// 8-bit single channel (alpha).
        /// </summary>
        A8,

        /// <summary>
        /// 8-bit single channel.
        /// </summary>
        R8,

        /// <summary>
        /// 8-bit single channel (integer).
        /// </summary>
        R8I,

        /// <summary>
        /// 8-bit single channel (unsigned).
        /// </summary>
        R8U,

        /// <summary>
        /// 8-bit single channel (signed).
        /// </summary>
        R8S,

        /// <summary>
        /// 16-bit single channel.
        /// </summary>
        R16,

        /// <summary>
        /// 16-bit single channel (integer).
        /// </summary>
        R16I,

        /// <summary>
        /// 16-bit single channel (unsigned).
        /// </summary>
        R16U,

        /// <summary>
        /// 16-bit single channel (float).
        /// </summary>
        R16F,

        /// <summary>
        /// 16-bit single channel (signed).
        /// </summary>
        R16S,

        /// <summary>
        /// 32-bit single channel (integer).
        /// </summary>
        R32I,

        /// <summary>
        /// 32-bit single channel (unsigned).
        /// </summary>
        R32U,

        /// <summary>
        /// 32-bit single channel (float).
        /// </summary>
        R32F,

        /// <summary>
        /// 8-bit two channel.
        /// </summary>
        RG8,

        /// <summary>
        /// 8-bit two channel (integer).
        /// </summary>
        RG8I,

        /// <summary>
        /// 8-bit two channel (unsigned).
        /// </summary>
        RG8U,

        /// <summary>
        /// 8-bit two channel (signed).
        /// </summary>
        RG8S,

        /// <summary>
        /// 16-bit two channel.
        /// </summary>
        RG16,

        /// <summary>
        /// 16-bit two channel (integer).
        /// </summary>
        RG16I,

        /// <summary>
        /// 16-bit two channel (unsigned).
        /// </summary>
        RG16U,

        /// <summary>
        /// 16-bit two channel (float).
        /// </summary>
        RG16F,

        /// <summary>
        /// 16-bit two channel (signed).
        /// </summary>
        RG16S,

        /// <summary>
        /// 32-bit two channel (integer).
        /// </summary>
        RG32I,

        /// <summary>
        /// 32-bit two channel (unsigned).
        /// </summary>
        RG32U,

        /// <summary>
        /// 32-bit two channel (float).
        /// </summary>
        RG32F,

        /// <summary>
        /// 8-bit three channel.
        /// </summary>
        RGB8,

        /// <summary>
        /// 8-bit three channel (integer).
        /// </summary>
        RGB8I,

        /// <summary>
        /// 8-bit three channel (unsigned).
        /// </summary>
        RGB8U,

        /// <summary>
        /// 8-bit three channel (signed).
        /// </summary>
        RGB8S,

        /// <summary>
        /// 9-bit three channel floating point with shared 5-bit exponent.
        /// </summary>
        RGB9E5F,

        /// <summary>
        /// 8-bit BGRA color.
        /// </summary>
        BGRA8,

        /// <summary>
        /// 8-bit RGBA color.
        /// </summary>
        RGBA8,

        /// <summary>
        /// 8-bit RGBA color (integer).
        /// </summary>
        RGBA8I,

        /// <summary>
        /// 8-bit RGBA color (unsigned).
        /// </summary>
        RGBA8U,

        /// <summary>
        /// 8-bit RGBA color (signed).
        /// </summary>
        RGBA8S,

        /// <summary>
        /// 16-bit RGBA color.
        /// </summary>
        RGBA16,

        /// <summary>
        /// 16-bit RGBA color (integer).
        /// </summary>
        RGBA16I,

        /// <summary>
        /// 16-bit RGBA color (unsigned).
        /// </summary>
        RGBA16U,

        /// <summary>
        /// 16-bit RGBA color (float).
        /// </summary>
        RGBA16F,

        /// <summary>
        /// 16-bit RGBA color (signed).
        /// </summary>
        RGBA16S,

        /// <summary>
        /// 32-bit RGBA color (integer).
        /// </summary>
        RGBA32I,

        /// <summary>
        /// 32-bit RGBA color (unsigned).
        /// </summary>
        RGBA32U,

        /// <summary>
        /// 32-bit RGBA color (float).
        /// </summary>
        RGBA32F,

        /// <summary>
        /// 5-6-6 color.
        /// </summary>
        R5G6B5,

        /// <summary>
        /// 4-bit RGBA color.
        /// </summary>
        RGBA4,

        /// <summary>
        /// 5-bit RGB color with 1-bit alpha.
        /// </summary>
        RGB5A1,

        /// <summary>
        /// 10-bit RGB color with 2-bit alpha.
        /// </summary>
        RGB10A2,

        /// <summary>
        /// 11-11-10 color (float).
        /// </summary>
        RG11B10F,

        /// <summary>
        /// Unknown depth format.
        /// </summary>
        UnknownDepth,

        /// <summary>
        /// 16-bit depth.
        /// </summary>
        D16,

        /// <summary>
        /// 24-bit depth.
        /// </summary>
        D24,

        /// <summary>
        /// 24-bit depth, 8-bit stencil.
        /// </summary>
        D24S8,

        /// <summary>
        /// 32-bit depth.
        /// </summary>
        D32,

        /// <summary>
        /// 16-bit depth (float).
        /// </summary>
        D16F,

        /// <summary>
        /// 24-bit depth (float).
        /// </summary>
        D24F,

        /// <summary>
        /// 32-bit depth (float).
        /// </summary>
        D32F,

        /// <summary>
        /// 8-bit stencil.
        /// </summary>
        D0S8
    }

    /// <summary>
    /// Indicates the level of support for a specific texture format.
    /// </summary>
    [Flags]
    public enum TextureFormatSupport {
        /// <summary>
        /// The format is unsupported.
        /// </summary>
        Unsupported = 0x0,

        /// <summary>
        /// The format is supported for 2D color data and operations.
        /// </summary>
        Color2D = 0x1,

        /// <summary>
        /// The format is supported for 2D sRGB operations.
        /// </summary>
        Srgb2D = 0x2,

        /// <summary>
        /// The format is supported for 2D textures through library emulation.
        /// </summary>
        Emulated2D = 0x4,

        /// <summary>
        /// The format is supported for 3D color data and operations.
        /// </summary>
        Color3D = 0x8,

        /// <summary>
        /// The format is supported for 3D sRGB operations.
        /// </summary>
        Srgb3D = 0x10,

        /// <summary>
        /// The format is supported for 3D textures through library emulation.
        /// </summary>
        Emulated3D = 0x20,

        /// <summary>
        /// The format is supported for cube color data and operations.
        /// </summary>
        ColorCube = 0x40,

        /// <summary>
        /// The format is supported for cube sRGB operations.
        /// </summary>
        SrgbCube = 0x80,

        /// <summary>
        /// The format is supported for cube textures through library emulation.
        /// </summary>
        EmulatedCube = 0x100,

        /// <summary>
        /// The format is supported for vertex texturing.
        /// </summary>
        Vertex = 0x200,

        /// <summary>
        /// The format is supported for compute image operations.
        /// </summary>
        Image = 0x400,

        /// <summary>
        /// The format is supported for framebuffers.
        /// </summary>
        Framebuffer = 0x800,

        /// <summary>
        /// The format is supported for MSAA framebuffers.
        /// </summary>
        FramebufferMSAA = 0x1000,

        /// <summary>
        /// The format is supported for MSAA sampling.
        /// </summary>
        MSAA = 0x2000,

        /// <summary>
        /// The format supports auto-generated mipmaps.
        /// </summary>
        MipsAutogen = 0x4000
    }

    /// <summary>
    /// Specifies possible primitive topologies.
    /// </summary>
    public enum Topology {
        /// <summary>
        /// List of triangles.
        /// </summary>
        TriangleList,

        /// <summary>
        /// Strip of triangles.
        /// </summary>
        TriangleStrip,

        /// <summary>
        /// List of lines.
        /// </summary>
        LineList,

        /// <summary>
        /// Strip of lines.
        /// </summary>
        LineStrip,

        /// <summary>
        /// List of points.
        /// </summary>
        PointList
    }

    /// <summary>
    /// Specifies the type of uniform data.
    /// </summary>
    public enum UniformType {
        /// <summary>
        /// Texture sampler.
        /// </summary>
        Sampler,

        /// <summary>
        /// 4D vector.
        /// </summary>
        Vector4 = 2,

        /// <summary>
        /// 3x3 matrix.
        /// </summary>
        Matrix3x3,

        /// <summary>
        ///4x4 matrix.
        /// </summary>
        Matrix4x4
    }

    /// <summary>
    /// Specifies known vendor IDs.
    /// </summary>
    public enum Vendor {
        /// <summary>
        /// No vendor specified.
        /// </summary>
        None = 0,

        /// <summary>
        /// Special flag to use platform's software rasterizer, if available.
        /// </summary>
        SoftwareRasterizer = 0x1,

        /// <summary>
        /// AMD
        /// </summary>
        AMD = 0x1002,

        /// <summary>
        /// Intel
        /// </summary>
        Intel = 0x8086,

        /// <summary>
        /// NVIDIA
        /// </summary>
        Nvidia = 0x10de,

        /// <summary>
        /// Microsoft
        /// </summary>
        Microsoft = 0x1414
    }

    /// <summary>
    /// Specifies data types for vertex attributes.
    /// </summary>
    public enum VertexAttributeType {
        /// <summary>
        /// One-byte unsigned integer.
        /// </summary>
        UInt8,

        /// <summary>
        /// 10-bit unsigned integer.
        /// </summary>
        /// <remarks>
        /// Availability depends on Caps flags.
        /// </remarks>
        UInt10,

        /// <summary>
        /// Two-byte signed integer.
        /// </summary>
        Int16,

        /// <summary>
        /// Two-byte float.
        /// </summary>
        /// <remarks>
        /// Availability depends on Caps flags.
        /// </remarks>
        Half,

        /// <summary>
        /// Four-byte float.
        /// </summary>
        Float
    }

    /// <summary>
    /// Specifies vertex attribute usages.
    /// </summary>
    public enum VertexAttributeUsage {
        /// <summary>
        /// Position data.
        /// </summary>
        Position,

        /// <summary>
        /// Normals.
        /// </summary>
        Normal,

        /// <summary>
        /// Tangents.
        /// </summary>
        Tangent,

        /// <summary>
        /// Bitangents.
        /// </summary>
        Bitangent,

        /// <summary>
        /// First color channel.
        /// </summary>
        Color0,

        /// <summary>
        /// Second color channel.
        /// </summary>
        Color1,

        /// <summary>
        /// Third color channel.
        /// </summary>
        Color2,

        /// <summary>
        /// Fourth color channel.
        /// </summary>
        Color3,

        /// <summary>
        /// Indices.
        /// </summary>
        Indices,

        /// <summary>
        /// Animation weights.
        /// </summary>
        Weight,

        /// <summary>
        /// First texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord0,

        /// <summary>
        /// Second texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord1,

        /// <summary>
        /// Third texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord2,

        /// <summary>
        /// Fourth texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord3,

        /// <summary>
        /// Fifth texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord4,

        /// <summary>
        /// Sixth texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord5,

        /// <summary>
        /// Seventh texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord6,

        /// <summary>
        /// Eighth texture coordinate channel (arbitrary data).
        /// </summary>
        TexCoord7
    }

    /// <summary>
    /// Specifies possible sorting modes for a view.
    /// </summary>
    public enum ViewMode {
        /// <summary>
        /// Default sorting method.
        /// </summary>
        Default,

        /// <summary>
        /// Do each draw in the order it is issued.
        /// </summary>
        Sequential,

        /// <summary>
        /// Sort each draw by depth, ascending.
        /// </summary>
        DepthAscending,

        /// <summary>
        /// Sort each draw by depth, descending.
        /// </summary>
        DepthDescending
    }

    /// <summary>
    /// Delegate type for callback functions.
    /// </summary>
    /// <param name="userData">User-provided data to the original allocation call.</param>
    [SuppressUnmanagedCodeSecurity]
    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate void ReleaseCallback (IntPtr userData);

    [SuppressUnmanagedCodeSecurity]
    unsafe static class NativeMethods {
#pragma warning disable IDE1006 // Naming Styles

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_update_texture_2d (ushort handle, ushort layer, byte mip, ushort x, ushort y, ushort width, ushort height, MemoryBlock.DataPtr* memory, ushort pitch);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_update_texture_3d (ushort handle, byte mip, ushort x, ushort y, ushort z, ushort width, ushort height, ushort depth, MemoryBlock.DataPtr* memory);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_update_texture_cube (ushort handle, ushort layer, CubeMapFace side, byte mip, ushort x, ushort y, ushort width, ushort height, MemoryBlock.DataPtr* memory, ushort pitch);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_get_avail_transient_index_buffer (int num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_get_avail_transient_vertex_buffer (int num, ref VertexLayout.Data decl);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_get_avail_instance_data_buffer (int num, ushort stride);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_alloc_transient_index_buffer (out TransientIndexBuffer tib, int num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_alloc_transient_vertex_buffer (out TransientVertexBuffer tvb, int num, ref VertexLayout.Data decl);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.U1)]
        public static extern bool bgfx_alloc_transient_buffers (out TransientVertexBuffer tvb, ref VertexLayout.Data decl, ushort numVertices, out TransientIndexBuffer tib, ushort numIndices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_alloc_instance_data_buffer (out InstanceDataBuffer.NativeStruct ptr, int num, ushort stride);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_dispatch (ushort id, ushort program, uint numX, uint numY, uint numZ);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_dispatch_indirect (ushort id, ushort program, ushort indirectHandle, ushort start, ushort num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_texture (byte stage, ushort sampler, ushort texture, uint flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_image (byte stage, ushort texture, byte mip, TextureFormat format, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_compute_index_buffer (byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_compute_vertex_buffer (byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_compute_dynamic_index_buffer (byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_compute_dynamic_vertex_buffer (byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_compute_indirect_buffer (byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_frame_buffer (ushort width, ushort height, TextureFormat format, TextureFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_frame_buffer_name(ushort handle, [MarshalAs(UnmanagedType.LPStr)] string name, int len);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_frame_buffer_scaled (BackbufferRatio ratio, TextureFormat format, TextureFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_frame_buffer_from_handles (byte count, ushort* handles, [MarshalAs(UnmanagedType.U1)] bool destroyTextures);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_frame_buffer_from_attachment (byte count, FrameBuffer.NativeAttachment* attachment, [MarshalAs(UnmanagedType.U1)] bool destroyTextures);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_frame_buffer_from_nwh (IntPtr nwh, ushort width, ushort height, TextureFormat depthFormat);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_frame_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_frame_buffer (ushort id, ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_program (ushort vsh, ushort fsh, [MarshalAs(UnmanagedType.U1)] bool destroyShaders);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_compute_program (ushort csh, [MarshalAs(UnmanagedType.U1)] bool destroyShaders);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_program (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern Capabilities.Caps* bgfx_get_caps ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_decl_begin (ref VertexLayout.Data decl, RendererBackend backend);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_decl_add (ref VertexLayout.Data decl, VertexAttributeUsage attribute, byte count, VertexAttributeType type, [MarshalAs(UnmanagedType.U1)] bool normalized, [MarshalAs(UnmanagedType.U1)] bool asInt);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_decl_skip (ref VertexLayout.Data decl, byte count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_decl_end (ref VertexLayout.Data decl);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_vertex_buffer (MemoryBlock.DataPtr* memory, ref VertexLayout.Data decl, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_vertex_buffer_name(ushort handle, [MarshalAs(UnmanagedType.LPStr)] string name, int len);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_vertex_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_uniform ([MarshalAs(UnmanagedType.LPStr)] string name, UniformType type, ushort arraySize);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_get_uniform_info (ushort handle, out Uniform.Info info);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_uniform (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_texture (MemoryBlock.DataPtr* mem, TextureFlags flags, byte skip, out Texture.TextureInfo info);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_texture_2d (ushort width, ushort _height, [MarshalAs(UnmanagedType.U1)] bool hasMips, ushort numLayers, TextureFormat format, TextureFlags flags, MemoryBlock.DataPtr* mem);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_texture_2d_scaled (BackbufferRatio ratio, [MarshalAs(UnmanagedType.U1)] bool hasMips, ushort numLayers, TextureFormat format, TextureFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_texture_3d (ushort width, ushort _height, ushort _depth, [MarshalAs(UnmanagedType.U1)] bool hasMips, TextureFormat format, TextureFlags flags, MemoryBlock.DataPtr* mem);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_texture_cube (ushort size, [MarshalAs(UnmanagedType.U1)] bool hasMips, ushort numLayers, TextureFormat format, TextureFlags flags, MemoryBlock.DataPtr* mem);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_texture_name(ushort handle, [MarshalAs(UnmanagedType.LPStr)] string name, int len);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr bgfx_get_direct_access_ptr (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_texture (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_calc_texture_size (ref Texture.TextureInfo info, ushort width, ushort height, ushort depth, [MarshalAs(UnmanagedType.U1)] bool cubeMap, [MarshalAs(UnmanagedType.U1)] bool hasMips, ushort numLayers, TextureFormat format);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.U1)]
        public static extern bool bgfx_is_texture_valid (ushort depth, [MarshalAs(UnmanagedType.U1)] bool cubeMap, ushort numLayers, TextureFormat format, TextureFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_shader (MemoryBlock.DataPtr* memory);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_get_shader_uniforms (ushort handle, Uniform[] uniforms, ushort max);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_shader_name(ushort handle, [MarshalAs(UnmanagedType.LPStr)] string name, int len);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_shader (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern MemoryBlock.DataPtr* bgfx_alloc (int size);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern MemoryBlock.DataPtr* bgfx_copy (IntPtr data, int size);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern MemoryBlock.DataPtr* bgfx_make_ref_release (IntPtr data, int size, IntPtr releaseFn, IntPtr userData);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_index_buffer (MemoryBlock.DataPtr* memory, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_index_buffer_name(ushort handle, [MarshalAs(UnmanagedType.LPStr)] string name, int len);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_index_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_dynamic_index_buffer (int indexCount, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_dynamic_index_buffer_mem (MemoryBlock.DataPtr* memory, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_update_dynamic_index_buffer (ushort handle, int startIndex, MemoryBlock.DataPtr* memory);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_dynamic_index_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_dynamic_vertex_buffer (int vertexCount, ref VertexLayout.Data decl, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_dynamic_vertex_buffer_mem (MemoryBlock.DataPtr* memory, ref VertexLayout.Data decl, BufferFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_update_dynamic_vertex_buffer (ushort handle, int startVertex, MemoryBlock.DataPtr* memory);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_dynamic_vertex_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_indirect_buffer (int size);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_indirect_buffer (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_image_swizzle_bgra8 (IntPtr dst, int width, int height, int pitch, IntPtr src);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_image_rgba8_downsample_2x2 (IntPtr dst, int width, int height, int pitch, IntPtr src);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_platform_data (ref PlatformData data);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern InternalData* bgfx_get_internal_data ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern RenderFrameResult bgfx_render_frame (int timeoutMs);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr bgfx_override_internal_texture_ptr (ushort handle, IntPtr ptr);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr bgfx_override_internal_texture (ushort handle, ushort width, ushort height, byte numMips, TextureFormat format, TextureFlags flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern PerfStats.Stats* bgfx_get_stats ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern RendererBackend bgfx_get_renderer_type ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_shutdown ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_reset (int width, int height, ResetFlags flags, TextureFormat format);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_frame ([MarshalAs(UnmanagedType.U1)] bool capture);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_debug (DebugFeatures flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_marker ([MarshalAs(UnmanagedType.LPStr)] string marker);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_dbg_text_clear (byte color, [MarshalAs(UnmanagedType.U1)] bool smallText);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_set_transform (float* matrix, ushort count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_stencil (uint frontFace, uint backFace);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_touch (ushort id);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_submit (ushort id, ushort programHandle, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_submit_occlusion_query (ushort id, ushort programHandle, ushort queryHandle, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_submit_indirect (ushort id, ushort programHandle, ushort indirectHandle, ushort start, ushort num, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_discard ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_name (ushort id, [MarshalAs(UnmanagedType.LPStr)] string name);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_rect (ushort id, ushort x, ushort y, ushort width, ushort height);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_rect_auto (ushort id, ushort x, ushort y, BackbufferRatio ratio);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_scissor (ushort id, ushort x, ushort y, ushort width, ushort height);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_clear (ushort id, ClearTargets flags, int rgba, float depth, byte stencil);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_clear_mrt (ushort id, ClearTargets flags, float depth, byte stencil, byte rt0, byte rt1, byte rt2, byte rt3, byte rt4, byte rt5, byte rt6, byte rt7);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_palette_color (byte index, float* color);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_mode (ushort id, ViewMode mode);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_view_transform (ushort id, float* view, float* proj);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_request_screen_shot (ushort handle, [MarshalAs(UnmanagedType.LPStr)] string filePath);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_state (ulong state, int rgba);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_pack (float* input, [MarshalAs(UnmanagedType.U1)] bool inputNormalized, VertexAttributeUsage attribute, ref VertexLayout.Data decl, IntPtr data, int index);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_unpack (float* output, VertexAttributeUsage attribute, ref VertexLayout.Data decl, IntPtr data, int index);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_vertex_convert (ref VertexLayout.Data destDecl, IntPtr destData, ref VertexLayout.Data srcDecl, IntPtr srcData, int num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_weld_vertices (ushort* output, ref VertexLayout.Data decl, IntPtr data, ushort num, float epsilon);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern byte bgfx_get_supported_renderers (byte max, RendererBackend[] backends);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern sbyte* bgfx_get_renderer_name (RendererBackend backend);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_init_ctor (InitSettings.Native* ptr);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.U1)]
        public static extern bool bgfx_init (InitSettings.Native* ptr);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_dbg_text_printf (ushort x, ushort y, byte color, [MarshalAs(UnmanagedType.LPStr)] string format, [MarshalAs(UnmanagedType.LPStr)] string args);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_dbg_text_printf (ushort x, ushort y, byte color, byte* format, IntPtr args);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_dbg_text_image (ushort x, ushort y, ushort width, ushort height, IntPtr data, ushort pitch);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_index_buffer (ushort handle, int firstIndex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_dynamic_index_buffer (ushort handle, int firstIndex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_vertex_buffer (byte stream, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_dynamic_vertex_buffer (byte stream, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_uniform (ushort handle, void* value, ushort arraySize);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_transform_cached (int cache, ushort num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_set_scissor (ushort x, ushort y, ushort width, ushort height);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_scissor_cached (ushort cache);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_transient_vertex_buffer (byte stream, ref TransientVertexBuffer tvb, int startVertex, int numVertices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_transient_index_buffer (ref TransientIndexBuffer tib, int startIndex, int numIndices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_vertex_count (int numVertices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_instance_count (int numInstances);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_instance_data_buffer (ref InstanceDataBuffer.NativeStruct idb, uint start, uint num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_instance_data_from_vertex_buffer (ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_instance_data_from_dynamic_vertex_buffer (ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_reset_view (ushort id);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_blit (ushort id, ushort dst, byte dstMip, ushort dstX, ushort dstY, ushort dstZ, ushort src,
                                             byte srcMip, ushort srcX, ushort srcY, ushort srcZ, ushort width, ushort height, ushort depth);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern uint bgfx_read_texture (ushort handle, IntPtr data, byte mip);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_get_texture (ushort handle, byte attachment);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_create_occlusion_query ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_destroy_occlusion_query (ushort handle);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern OcclusionQueryResult bgfx_get_result (ushort handle, int* pixels);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_set_condition (ushort handle, [MarshalAs(UnmanagedType.U1)] bool visible);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_vsnprintf(sbyte* str, IntPtr count, [MarshalAs(UnmanagedType.LPStr)] string format, IntPtr argList);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern IntPtr bgfx_begin ();

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_end (IntPtr encoder);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_marker (IntPtr encoder, [MarshalAs(UnmanagedType.LPStr)] string marker);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_state (IntPtr encoder, ulong state, int rgba);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_condition (IntPtr encoder, ushort handle, [MarshalAs(UnmanagedType.U1)] bool visible);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_stencil(IntPtr encoder, uint frontFace, uint backFace);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern ushort bgfx_encoder_set_scissor(IntPtr encoder, ushort x, ushort y, ushort width, ushort height);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_scissor_cached(IntPtr encoder, ushort cache);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_set_transform(IntPtr encoder, float* matrix, ushort count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_transform_cached(IntPtr encoder, int cache, ushort num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_uniform(IntPtr encoder, ushort handle, void* value, ushort arraySize);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_index_buffer(IntPtr encoder, ushort handle, int firstIndex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_dynamic_index_buffer(IntPtr encoder, ushort handle, int firstIndex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_vertex_buffer(IntPtr encoder, byte stream, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_dynamic_vertex_buffer(IntPtr encoder, byte stream, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_transient_vertex_buffer(IntPtr encoder, byte stream, ref TransientVertexBuffer tvb, int startVertex, int numVertices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_transient_index_buffer(IntPtr encoder, ref TransientIndexBuffer tib, int startIndex, int numIndices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_vertex_count (IntPtr encoder, int numVertices);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_instance_data_buffer(IntPtr encoder, ref InstanceDataBuffer.NativeStruct idb, uint start, uint num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_instance_data_from_vertex_buffer(IntPtr encoder, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_instance_data_from_dynamic_vertex_buffer(IntPtr encoder, ushort handle, int startVertex, int count);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_texture(IntPtr encoder, byte stage, ushort sampler, ushort texture, uint flags);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_touch(IntPtr encoder, ushort id);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_submit(IntPtr encoder, ushort id, ushort programHandle, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_submit_occlusion_query(IntPtr encoder, ushort id, ushort programHandle, ushort queryHandle, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_submit_indirect(IntPtr encoder, ushort id, ushort programHandle, ushort indirectHandle, ushort start, ushort num, int depth, [MarshalAs(UnmanagedType.U1)] bool preserveState);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_image(IntPtr encoder, byte stage, ushort texture, byte mip, TextureFormat format, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_compute_index_buffer(IntPtr encoder, byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_compute_vertex_buffer(IntPtr encoder, byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_compute_dynamic_index_buffer(IntPtr encoder, byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_compute_dynamic_vertex_buffer(IntPtr encoder, byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_set_compute_indirect_buffer(IntPtr encoder, byte stage, ushort handle, ComputeBufferAccess access);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_dispatch(IntPtr encoder, ushort id, ushort program, uint numX, uint numY, uint numZ);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern int bgfx_encoder_dispatch_indirect(IntPtr encoder, ushort id, ushort program, ushort indirectHandle, ushort start, ushort num);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_discard(IntPtr encoder);

        [DllImport(DllName, CallingConvention = CallingConvention.Cdecl)]
        public static extern void bgfx_encoder_blit(IntPtr encoder, ushort id, ushort dst, byte dstMip, ushort dstX, ushort dstY, ushort dstZ, ushort src,
                                                    byte srcMip, ushort srcX, ushort srcY, ushort srcZ, ushort width, ushort height, ushort depth);

#pragma warning restore IDE1006 // Naming Styles

#if DEBUG
        const string DllName = "bgfx_debug.dll";
#else
        const string DllName = "bgfx.dll";
#endif
    }

    unsafe struct CallbackShim {
        IntPtr vtbl;
        IntPtr reportError;
        IntPtr reportDebug;
        IntPtr profilerBegin;
        IntPtr profilerBeginLiteral;
        IntPtr profilerEnd;
        IntPtr getCachedSize;
        IntPtr getCacheEntry;
        IntPtr setCacheEntry;
        IntPtr saveScreenShot;
        IntPtr captureStarted;
        IntPtr captureFinished;
        IntPtr captureFrame;

        public static unsafe IntPtr CreateShim (ICallbackHandler handler) {
            if (handler == null)
                return IntPtr.Zero;

            if (savedDelegates != null)
                throw new InvalidOperationException("Callbacks should only be initialized once; bgfx can only deal with one set at a time.");

            var memory = Marshal.AllocHGlobal(Marshal.SizeOf<CallbackShim>());
            var shim = (CallbackShim*)memory;
            var saver = new DelegateSaver(handler, shim);

            // the shim uses the unnecessary ctor slot to act as a vtbl pointer to itself,
            // so that the same block of memory can act as both bgfx_callback_interface_t and bgfx_callback_vtbl_t
            shim->vtbl = memory + IntPtr.Size;

            // cache the data so we can free it later
            shimMemory = memory;
            savedDelegates = saver;

            return memory;
        }

        public static void FreeShim () {
            if (savedDelegates == null)
                return;

            savedDelegates = null;
            Marshal.FreeHGlobal(shimMemory);
        }

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
        delegate void ReportErrorHandler (IntPtr thisPtr, string fileName, ushort line, ErrorType errorType, string message);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
        delegate void ReportDebugHandler (IntPtr thisPtr, string fileName, ushort line, string format, IntPtr args);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
        delegate void ProfilerBeginHandler (IntPtr thisPtr, sbyte* name, int abgr, sbyte* filePath, ushort line);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate void ProfilerEndHandler (IntPtr thisPtr);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate int GetCachedSizeHandler (IntPtr thisPtr, long id);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate bool GetCacheEntryHandler (IntPtr thisPtr, long id, IntPtr data, int size);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate void SetCacheEntryHandler (IntPtr thisPtr, long id, IntPtr data, int size);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
        delegate void SaveScreenShotHandler (IntPtr thisPtr, string path, int width, int height, int pitch, IntPtr data, int size, [MarshalAs(UnmanagedType.U1)] bool flipVertical);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate void CaptureStartedHandler (IntPtr thisPtr, int width, int height, int pitch, TextureFormat format, [MarshalAs(UnmanagedType.U1)] bool flipVertical);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate void CaptureFinishedHandler (IntPtr thisPtr);

        [SuppressUnmanagedCodeSecurity]
        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
        delegate void CaptureFrameHandler (IntPtr thisPtr, IntPtr data, int size);

        // We're creating delegates to a user's interface methods; we're then converting those delegates
        // to native pointers and passing them into native code. If we don't save the references to the
        // delegates in managed land somewhere, the GC will think they're unreferenced and clean them
        // up, leaving native holding a bag of pointers into nowhere land.
        class DelegateSaver {
            ICallbackHandler handler;
            ReportErrorHandler reportError;
            ReportDebugHandler reportDebug;
            ProfilerBeginHandler profilerBegin;
            ProfilerBeginHandler profilerBeginLiteral;
            ProfilerEndHandler profilerEnd;
            GetCachedSizeHandler getCachedSize;
            GetCacheEntryHandler getCacheEntry;
            SetCacheEntryHandler setCacheEntry;
            SaveScreenShotHandler saveScreenShot;
            CaptureStartedHandler captureStarted;
            CaptureFinishedHandler captureFinished;
            CaptureFrameHandler captureFrame;

            public unsafe DelegateSaver (ICallbackHandler handler, CallbackShim* shim) {
                this.handler = handler;
                reportError = ReportError;
                reportDebug = ReportDebug;
                profilerBegin = ProfilerBegin;
                profilerBeginLiteral = ProfilerBegin;
                profilerEnd = ProfilerEnd;
                getCachedSize = GetCachedSize;
                getCacheEntry = GetCacheEntry;
                setCacheEntry = SetCacheEntry;
                saveScreenShot = SaveScreenShot;
                captureStarted = CaptureStarted;
                captureFinished = CaptureFinished;
                captureFrame = CaptureFrame;

                shim->reportError = Marshal.GetFunctionPointerForDelegate(reportError);
                shim->reportDebug = Marshal.GetFunctionPointerForDelegate(reportDebug);
                shim->profilerBegin = Marshal.GetFunctionPointerForDelegate(profilerBegin);
                shim->profilerBeginLiteral = Marshal.GetFunctionPointerForDelegate(profilerBeginLiteral);
                shim->profilerEnd = Marshal.GetFunctionPointerForDelegate(profilerEnd);
                shim->getCachedSize = Marshal.GetFunctionPointerForDelegate(getCachedSize);
                shim->getCacheEntry = Marshal.GetFunctionPointerForDelegate(getCacheEntry);
                shim->setCacheEntry = Marshal.GetFunctionPointerForDelegate(setCacheEntry);
                shim->saveScreenShot = Marshal.GetFunctionPointerForDelegate(saveScreenShot);
                shim->captureStarted = Marshal.GetFunctionPointerForDelegate(captureStarted);
                shim->captureFinished = Marshal.GetFunctionPointerForDelegate(captureFinished);
                shim->captureFrame = Marshal.GetFunctionPointerForDelegate(captureFrame);
            }

            void ReportError (IntPtr thisPtr, string fileName, ushort line, ErrorType errorType, string message) {
                handler.ReportError(fileName, line, errorType, message);
            }

            void ReportDebug (IntPtr thisPtr, string fileName, ushort line, string format, IntPtr args) {
                handler.ReportDebug(fileName, line, format, args);
            }

            void ProfilerBegin (IntPtr thisPtr, sbyte* name, int color, sbyte* filePath, ushort line) {
                handler.ProfilerBegin(new string(name), color, new string(filePath), line);
            }

            void ProfilerEnd (IntPtr thisPtr) {
                handler.ProfilerEnd();
            }

            int GetCachedSize (IntPtr thisPtr, long id) {
                return handler.GetCachedSize(id);
            }

            bool GetCacheEntry (IntPtr thisPtr, long id, IntPtr data, int size) {
                return handler.GetCacheEntry(id, data, size);
            }

            void SetCacheEntry (IntPtr thisPtr, long id, IntPtr data, int size) {
                handler.SetCacheEntry(id, data, size);
            }

            void SaveScreenShot (IntPtr thisPtr, string path, int width, int height, int pitch, IntPtr data, int size, bool flipVertical) {
                handler.SaveScreenShot(path, width, height, pitch, data, size, flipVertical);
            }

            void CaptureStarted (IntPtr thisPtr, int width, int height, int pitch, TextureFormat format, bool flipVertical) {
                handler.CaptureStarted(width, height, pitch, format, flipVertical);
            }

            void CaptureFinished (IntPtr thisPtr) {
                handler.CaptureFinished();
            }

            void CaptureFrame (IntPtr thisPtr, IntPtr data, int size) {
                handler.CaptureFrame(data, size);
            }
        }

        static IntPtr shimMemory;
        static DelegateSaver savedDelegates;
    }
}