private IDisposable establishFrameBufferViewport()
{
// Disable masking for generating the frame buffer since masking will be re-applied
// when actually drawing later on anyways. This allows more information to be captured
// in the frame buffer and helps with cached buffers being re-used.
RectangleI screenSpaceMaskingRect = new RectangleI((int)Math.Floor(screenSpaceDrawRectangle.X), (int)Math.Floor(screenSpaceDrawRectangle.Y), (int)frameBufferSize.X + 1, (int)frameBufferSize.Y + 1);
GLWrapper.PushMaskingInfo(new MaskingInfo
{
ScreenSpaceAABB = screenSpaceMaskingRect,
MaskingRect = screenSpaceDrawRectangle,
ToMaskingSpace = Matrix3.Identity,
BlendRange = 1,
AlphaExponent = 1,
}, true);
// Match viewport to FrameBuffer such that we don't draw unnecessary pixels.
GLWrapper.PushViewport(new RectangleI(0, 0, (int)frameBufferSize.X, (int)frameBufferSize.Y));
GLWrapper.PushScissor(new RectangleI(0, 0, (int)frameBufferSize.X, (int)frameBufferSize.Y));
GLWrapper.PushScissorOffset(screenSpaceMaskingRect.Location);
return(new ValueInvokeOnDisposal <BufferedDrawNode>(this, d => d.returnViewport()));
}