{
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    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
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      "outputs": [],
      "source": [
        "%gui qt"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Drawing a simple quad\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import numpy as np\n\nfrom vispy import app\nfrom vispy.gloo import gl\n\nvertex_code = \"\"\"\n    uniform float scale;\n    attribute vec4 color;\n    attribute vec2 position;\n    varying vec4 v_color;\n    void main()\n    {\n        gl_Position = vec4(scale*position, 0.0, 1.0);\n        v_color = color;\n    } \"\"\"\n\nfragment_code = \"\"\"\n    varying vec4 v_color;\n    void main()\n    {\n        gl_FragColor = v_color;\n    } \"\"\"\n\n\nclass Canvas(app.Canvas):\n    def __init__(self):\n        app.Canvas.__init__(self, size=(512, 512), title='Quad (GL)',\n                            keys='interactive')\n\n    def on_initialize(self, event):\n        # Build data\n        self.data = np.zeros(4, [(\"position\", np.float32, 2),\n                                 (\"color\", np.float32, 4)])\n        self.data['color'] = [(1, 0, 0, 1), (0, 1, 0, 1),\n                              (0, 0, 1, 1), (1, 1, 0, 1)]\n        self.data['position'] = [(-1, -1), (-1, +1),\n                                 (+1, -1), (+1, +1)]\n\n        # Build & activate program\n\n        # Request a program and shader slots from GPU\n        program = gl.glCreateProgram()\n        vertex = gl.glCreateShader(gl.GL_VERTEX_SHADER)\n        fragment = gl.glCreateShader(gl.GL_FRAGMENT_SHADER)\n\n        # Set shaders source\n        gl.glShaderSource(vertex, vertex_code)\n        gl.glShaderSource(fragment, fragment_code)\n\n        # Compile shaders\n        gl.glCompileShader(vertex)\n        gl.glCompileShader(fragment)\n\n        # Attach shader objects to the program\n        gl.glAttachShader(program, vertex)\n        gl.glAttachShader(program, fragment)\n\n        # Build program\n        gl.glLinkProgram(program)\n\n        # Get rid of shaders (no more needed)\n        gl.glDetachShader(program, vertex)\n        gl.glDetachShader(program, fragment)\n\n        # Make program the default program\n        gl.glUseProgram(program)\n\n        # Build buffer\n\n        # Request a buffer slot from GPU\n        buf = gl.glCreateBuffer()\n\n        # Make this buffer the default one\n        gl.glBindBuffer(gl.GL_ARRAY_BUFFER, buf)\n\n        # Upload data\n        gl.glBufferData(gl.GL_ARRAY_BUFFER, self.data, gl.GL_DYNAMIC_DRAW)\n\n        # Bind attributes\n        stride = self.data.strides[0]\n        offset = 0\n        loc = gl.glGetAttribLocation(program, \"position\")\n        gl.glEnableVertexAttribArray(loc)\n        gl.glBindBuffer(gl.GL_ARRAY_BUFFER, buf)\n        gl.glVertexAttribPointer(loc, 3, gl.GL_FLOAT, False, stride, offset)\n\n        offset = self.data.dtype[\"position\"].itemsize\n        loc = gl.glGetAttribLocation(program, \"color\")\n        gl.glEnableVertexAttribArray(loc)\n        gl.glBindBuffer(gl.GL_ARRAY_BUFFER, buf)\n        gl.glVertexAttribPointer(loc, 4, gl.GL_FLOAT, False, stride, offset)\n\n        # Bind uniforms\n        # --------------------------------------\n        loc = gl.glGetUniformLocation(program, \"scale\")\n        gl.glUniform1f(loc, 1.0)\n\n    def on_draw(self, event):\n        gl.glClear(gl.GL_COLOR_BUFFER_BIT)\n        gl.glDrawArrays(gl.GL_TRIANGLE_STRIP, 0, 4)\n\n    def on_resize(self, event):\n        gl.glViewport(0, 0, *event.physical_size)\n\nif __name__ == '__main__':\n    c = Canvas()\n    c.show()\n    app.run()"
      ]
    }
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      "display_name": "Python 3",
      "language": "python",
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      "codemirror_mode": {
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        "version": 3
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      "file_extension": ".py",
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      "pygments_lexer": "ipython3",
      "version": "3.9.19"
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