{
  name: "deferred_indirect",
  configurations: [
    {
      name: "DEFAULT"
    }
  ],
  uniforms: [
    { name: "u_albedo",             type: "sampler2D", value: 0 },
    { name: "u_normal",             type: "sampler2D", value: 1 },
    { name: "u_emission",           type: "sampler2D", value: 2 },
    { name: "u_depth",              type: "sampler2D", value: 3 },
    { name: "u_irradiance",         type: "samplerCM", value: 4 },
    { name: "u_prefilter",          type: "samplerCM", value: 5 },
    { name: "u_scale_bias",         type: "sampler2D", value: 6 },
    { name: "u_inverse_projection", type: "f32x4x4" },
    { name: "u_camera_position",    type: "f32x3" },
    { name: "u_resolution",         type: "f32x2" }
  ],
  shaders: [
    {
      type: "vertex",
      imports: [
        "fullscreen_triangle"
      ],
      outputs: [
        { name: "vs_coordinate", type: "f32x2" }
      ],
      source: "
        void main() {
          f32x4 triangle = fullscreen_triangle();
          rx_position = f32x4(triangle.xy, 0.0, 1.0);
          vs_coordinate = triangle.zw;
        }
      "
    },{
      type: "fragment",
      inputs: [
        { name: "vs_coordinate", type: "f32x2" }
      ],
      outputs: [
        { name: "fs_color",      type: "f32x4" }
      ],
      imports: [
        "position_from_depth",
        "normal_decode",
        "bayer"
      ],
      source: "
        f32x3 approximate_specular_ibl(f32x3 specular_color, f32 roughness, f32x3 n, f32x3 v) {
          f32 n_dot_v = max(0.0, dot(n, v));
          f32x3 r = reflect(-v, n);
          f32x3 prefiltered_color = rx_textureCMLod(u_prefilter, r, roughness * 5.0).rgb;
          f32x2 brdf = rx_texture2D(u_scale_bias, f32x2(roughness, n_dot_v)).rg;
          return prefiltered_color * (specular_color * brdf.x + brdf.y);
        }

        void main() {
          f32x4 sample_albedo = rx_texture2D(u_albedo, vs_coordinate);
          f32x4 sample_normal = rx_texture2D(u_normal, vs_coordinate);
          f32x4 sample_emission = rx_texture2D(u_emission, vs_coordinate);
          f32 sample_depth = rx_texture2D(u_depth, vs_coordinate).r;

          f32x3 albedo = sample_albedo.rgb;
          f32x3 normal = normal_decode(sample_normal.rg);

          f32 roughness = sample_normal.b;
          f32 metalness = sample_normal.a;

          f32x3 position = position_from_depth(
            vs_coordinate, u_inverse_projection, sample_depth);

          f32x3 v = normalize(u_camera_position - position);

          f32x3 base_color = sample_albedo.rgb;
          f32x3 diffuse_color = base_color * (1.0 - metalness);
          f32x3 specular_color = mix(f32x3(0.04), base_color, metalness);

          f32x3 irradiance = rx_textureCM(u_irradiance, normal).rgb;
          f32x3 indirect_diffuse = diffuse_color * irradiance + sample_emission.rgb;
          f32x3 indirect_specular = approximate_specular_ibl(
            specular_color, roughness, normal, v);

          // When approximating indirect specular the result is severely
          // undersampled due to the low-resolution and low-bitdepth prefilter'd
          // environment map. This results in both ringing and banding artifacts,
          // apply an ordered dither to the result of specular to spread this
          // error out across several pixels rather than being concentrated.
          indirect_specular += bayer_16x16(vs_coordinate * u_resolution) / 255.0;

          fs_color = f32x4(sample_albedo.a * (indirect_diffuse + indirect_specular), 1.0);
        }
      "
    }
  ]
}