Render via an intermediate frame buffer.

OpenRA.Game/Graphics/PlatformInterfaces.cs

@@ -41,6 +41,8 @@ namespace OpenRA
 
 		Size WindowSize { get; }
 		float WindowScale { get; }
+		Size SurfaceSize { get; }
+
 		event Action<float, float> OnWindowScaleChanged;
 
 		void PumpInput(IInputHandler inputHandler);
@@ -62,7 +64,7 @@ namespace OpenRA
 		IFrameBuffer CreateFrameBuffer(Size s);
 		IFrameBuffer CreateFrameBuffer(Size s, Color clearColor);
 		IShader CreateShader(string name);
-		void EnableScissor(int left, int top, int width, int height);
+		void EnableScissor(int x, int y, int width, int height);
 		void DisableScissor();
 		void SaveScreenshot(string path);
 		void Present();

OpenRA.Game/Graphics/SpriteRenderer.cs

@@ -160,9 +160,9 @@ namespace OpenRA.Graphics
 			shader.SetVec("Scroll", scroll.X, scroll.Y, scroll.Y);
 			shader.SetVec("r1",
 				zoom * 2f / screen.Width,
-				-zoom * 2f / screen.Height,
+				zoom * 2f / screen.Height,
 				-depthScale * zoom / screen.Height);
-			shader.SetVec("r2", -1, 1, 1 - depthOffset);
+			shader.SetVec("r2", -1, -1, 1 - depthOffset);
 
 			// Texture index is sampled as a float, so convert to pixels then scale
 			shader.SetVec("DepthTextureScale", 128 * depthScale * zoom / screen.Height);