Add scissor support to IFrameBuffer.

OpenRA.Platforms.Default/FrameBuffer.cs

@@ -23,6 +23,7 @@ namespace OpenRA.Platforms.Default
 		readonly Color clearColor;
 		uint framebuffer, depth;
 		bool disposed;
+		bool scissored;
 
 		public FrameBuffer(Size size, ITextureInternal texture, Color clearColor)
 		{
@@ -100,6 +101,9 @@ namespace OpenRA.Platforms.Default
 
 		public void Unbind()
 		{
+			if (scissored)
+				throw new InvalidOperationException("Attempting to unbind FrameBuffer with an active scissor region.");
+
 			VerifyThreadAffinity();
 			OpenGL.glFlush();
 			OpenGL.CheckGLError();
@@ -109,6 +113,25 @@ namespace OpenRA.Platforms.Default
 			OpenGL.CheckGLError();
 		}
 
+		public void EnableScissor(Rectangle rect)
+		{
+			VerifyThreadAffinity();
+
+			OpenGL.glScissor(rect.X, rect.Y, Math.Max(rect.Width, 0), Math.Max(rect.Height, 0));
+			OpenGL.CheckGLError();
+			OpenGL.glEnable(OpenGL.GL_SCISSOR_TEST);
+			OpenGL.CheckGLError();
+			scissored = true;
+		}
+
+		public void DisableScissor()
+		{
+			VerifyThreadAffinity();
+			OpenGL.glDisable(OpenGL.GL_SCISSOR_TEST);
+			OpenGL.CheckGLError();
+			scissored = false;
+		}
+
 		public ITexture Texture
 		{
 			get

OpenRA.Platforms.Default/ThreadedGraphicsContext.cs

@@ -454,6 +454,8 @@ namespace OpenRA.Platforms.Default
 		readonly Action bind;
 		readonly Action unbind;
 		readonly Action dispose;
+		readonly Action<object> enableScissor;
+		readonly Action disableScissor;
 
 		public ThreadedFrameBuffer(ThreadedGraphicsContext device, IFrameBuffer frameBuffer)
 		{
@@ -462,6 +464,9 @@ namespace OpenRA.Platforms.Default
 			bind = frameBuffer.Bind;
 			unbind = frameBuffer.Unbind;
 			dispose = frameBuffer.Dispose;
+
+			enableScissor = rect => frameBuffer.EnableScissor((Rectangle)rect);
+			disableScissor = frameBuffer.DisableScissor;
 		}
 
 		public ITexture Texture
@@ -482,6 +487,16 @@ namespace OpenRA.Platforms.Default
 			device.Post(unbind);
 		}
 
+		public void EnableScissor(Rectangle rect)
+		{
+			device.Post(enableScissor, rect);
+		}
+
+		public void DisableScissor()
+		{
+			device.Post(disableScissor);
+		}
+
 		public void Dispose()
 		{
 			device.Post(dispose);