//-----------------------------------------------------------------------------------------
private bool _InitVao()
{
// Create VAO object to hold vertex shader inputs and attach it to our context. As
// OpenGL requires the VAO object (whether or not it's used) we do this here.
GL.GenVertexArrays(1, out _vertexArrayName);
GL.BindVertexArray(_vertexArrayName);
GL.BindBuffer(BufferTarget.ArrayBuffer, Buffers.GetName(Buffers.Type.VERTEX));
GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 0, 0);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
// Enable the vertex attribute. Note we don't have to be bound to do this!
GL.EnableVertexAttribArray(0);
return(true);
}
//-----------------------------------------------------------------------------------------
protected override void OnRenderFrame(FrameEventArgs e)
{
// Clear the window with given color
GL.ClearBuffer(ClearBuffer.Color, 0, Statics.colorGreen);
for (int cubeId = 0; cubeId < 24; cubeId++)
{
this._UpdateTransform(cubeId);
// Reset atomic counter
uint data = 0;
GL.BindBuffer(BufferTarget.AtomicCounterBuffer, Buffers.GetName(Buffers.Type.ATOMIC_COUNTER));
GL.ClearBufferSubData(BufferTarget.AtomicCounterBuffer, PixelInternalFormat.R8ui, IntPtr.Zero,
(IntPtr)sizeof(uint), PixelFormat.Rgba, All.UnsignedInt, ref data);
GL.BindBuffer(BufferTarget.AtomicCounterBuffer, 0);
// Attach our atomic buffer to our contexts atomic counter buffer binding point
GL.BindBufferBase(BufferRangeTarget.AtomicCounterBuffer, 0, Buffers.GetName(Buffers.Type.ATOMIC_COUNTER));
// Use first program object to calculate object area
GL.UseProgram(_shaderProgramName[0]);
//GL.ColorMask( false, false, false, false ); // disable writing to framebuffer
// Set the transformation matrix for current program object
GL.UniformMatrix4(_uniformNames[0], false, ref _transformMatrix);
// Run our shader to update our atomic counter
GL.DrawArrays(PrimitiveType.Triangles, 0, 36);
GL.BindBufferBase(BufferRangeTarget.UniformBuffer, 0, Buffers.GetName(Buffers.Type.ATOMIC_COUNTER));
// Switch to our second program to actually draw the cube
GL.UseProgram(_shaderProgramName[1]);
//GL.ColorMask( true, true, true, true ); // enable writing to framebuffer
GL.UniformMatrix4(_uniformNames[1], false, ref _transformMatrix);
GL.DrawArrays(PrimitiveType.Triangles, 0, 36);
}
SwapBuffers();
}
//-----------------------------------------------------------------------------------------
private bool _InitBuffers()
{
float[] vertexData = new float[]
{
// back
-0.25f, 0.25f, -0.25f, -0.25f, -0.25f, -0.25f, 0.25f, -0.25f, -0.25f,
0.25f, -0.25f, -0.25f, 0.25f, 0.25f, -0.25f, -0.25f, 0.25f, -0.25f,
// right
0.25f, -0.25f, -0.25f, 0.25f, -0.25f, 0.25f, 0.25f, 0.25f, -0.25f,
0.25f, -0.25f, 0.25f, 0.25f, 0.25f, 0.25f, 0.25f, 0.25f, -0.25f,
// front
0.25f, -0.25f, 0.25f, -0.25f, -0.25f, 0.25f, 0.25f, 0.25f, 0.25f,
-0.25f, -0.25f, 0.25f, -0.25f, 0.25f, 0.25f, 0.25f, 0.25f, 0.25f,
// left
-0.25f, -0.25f, 0.25f, -0.25f, -0.25f, -0.25f, -0.25f, 0.25f, 0.25f,
-0.25f, -0.25f, -0.25f, -0.25f, 0.25f, -0.25f, -0.25f, 0.25f, 0.25f,
// bottom
-0.25f, -0.25f, 0.25f, 0.25f, -0.25f, 0.25f, 0.25f, -0.25f, -0.25f,
0.25f, -0.25f, -0.25f, -0.25f, -0.25f, -0.25f, -0.25f, -0.25f, 0.25f,
// top
-0.25f, 0.25f, -0.25f, 0.25f, 0.25f, -0.25f, 0.25f, 0.25f, 0.25f,
0.25f, 0.25f, 0.25f, -0.25f, 0.25f, 0.25f, -0.25f, 0.25f, -0.25f
};
GL.GenBuffers(Buffers.GetCount(), Buffers.Names);
GL.BindBuffer(BufferTarget.ArrayBuffer, Buffers.GetName(Buffers.Type.VERTEX));
GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(sizeof(float) * 4 * vertexData.Length),
vertexData, BufferUsageHint.StaticDraw);
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GL.BindBuffer(BufferTarget.AtomicCounterBuffer, Buffers.GetName(Buffers.Type.ATOMIC_COUNTER));
GL.BufferData(BufferTarget.AtomicCounterBuffer, (IntPtr)sizeof(uint),
IntPtr.Zero, BufferUsageHint.DynamicCopy);
GL.BindBuffer(BufferTarget.AtomicCounterBuffer, 0);
return(true);
}
