/// <summary>
        /// Sets the current render target.
        /// </summary>
        private void SetRenderTargetInternal(RenderTarget2D renderTarget,
                                             Color?clearColor = null, Double?clearDepth = null, Int32?clearStencil = null)
        {
            Ultraviolet.ValidateResource(renderTarget);

            var usage = renderTarget?.RenderTargetUsage ?? backBufferRenderTargetUsage;

            if (usage == RenderTargetUsage.PlatformContents)
            {
                usage = Capabilities.SupportsPreservingRenderTargetContentInHardware ?
                        RenderTargetUsage.PreserveContents :
                        RenderTargetUsage.DiscardContents;
            }

            var oglRenderTarget = (OpenGLRenderTarget2D)renderTarget;

            if (oglRenderTarget != this.renderTarget)
            {
                var targetName = gl.DefaultFramebuffer;
                var targetSize = Size2.Zero;

                if (oglRenderTarget != null)
                {
                    oglRenderTarget.ValidateStatus();

                    targetName = oglRenderTarget.OpenGLName;
                    targetSize = renderTarget.Size;
                }
                else
                {
                    var currentWindow = Ultraviolet.GetPlatform().Windows.GetCurrent();
                    if (currentWindow != null)
                    {
                        targetSize = currentWindow.DrawableSize;
                    }
                }

                OpenGLState.BindFramebuffer(targetName);

                if (this.renderTarget != null)
                {
                    this.renderTarget.UnbindWrite();
                }

                this.renderTarget = oglRenderTarget;

                if (this.renderTarget != null)
                {
                    this.renderTarget.BindWrite();
                }

                this.viewport = default(Viewport);
                SetViewport(new Viewport(0, 0, targetSize.Width, targetSize.Height));

                if (usage == RenderTargetUsage.DiscardContents)
                {
                    Clear(clearColor ?? Color.FromArgb(0xFF442288), clearDepth ?? 1.0, clearStencil ?? 0);
                }
            }
        }