untie the engine from SDL2 and MiniTK

OpenRA.Platforms.Default/FrameBuffer.cs

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+#region Copyright & License Information
+/*
+ * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Diagnostics;
+using System.Drawing;
+using System.IO;
+using OpenTK.Graphics.OpenGL;
+
+namespace OpenRA.Platforms.Default
+{
+	public sealed class FrameBuffer : IFrameBuffer
+	{
+		Texture texture;
+		Size size;
+		int framebuffer, depth;
+		bool disposed;
+
+		public FrameBuffer(Size size)
+		{
+			this.size = size;
+			if (!Exts.IsPowerOf2(size.Width) || !Exts.IsPowerOf2(size.Height))
+				throw new InvalidDataException("Frame buffer size ({0}x{1}) must be a power of two".F(size.Width, size.Height));
+
+			GL.Ext.GenFramebuffers(1, out framebuffer);
+			ErrorHandler.CheckGlError();
+			GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, framebuffer);
+			ErrorHandler.CheckGlError();
+
+			// Color
+			texture = new Texture();
+			texture.SetEmpty(size.Width, size.Height);
+			GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt, FramebufferAttachment.ColorAttachment0Ext, TextureTarget.Texture2D, texture.ID, 0);
+			ErrorHandler.CheckGlError();
+
+			// Depth
+			GL.Ext.GenRenderbuffers(1, out depth);
+			ErrorHandler.CheckGlError();
+
+			GL.Ext.BindRenderbuffer(RenderbufferTarget.RenderbufferExt, depth);
+			ErrorHandler.CheckGlError();
+
+			GL.Ext.RenderbufferStorage(RenderbufferTarget.RenderbufferExt, RenderbufferStorage.DepthComponent, size.Width, size.Height);
+			ErrorHandler.CheckGlError();
+
+			GL.Ext.FramebufferRenderbuffer(FramebufferTarget.FramebufferExt, FramebufferAttachment.DepthAttachmentExt, RenderbufferTarget.RenderbufferExt, depth);
+			ErrorHandler.CheckGlError();
+
+			// Test for completeness
+			var status = GL.Ext.CheckFramebufferStatus(FramebufferTarget.FramebufferExt);
+			if (status != FramebufferErrorCode.FramebufferCompleteExt)
+			{
+				var error = "Error creating framebuffer: {0}\n{1}".F(status, new StackTrace());
+				ErrorHandler.WriteGraphicsLog(error);
+				throw new InvalidOperationException("OpenGL Error: See graphics.log for details.");
+			}
+
+			// Restore default buffer
+			GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, 0);
+			ErrorHandler.CheckGlError();
+		}
+
+		static int[] ViewportRectangle()
+		{
+			var v = new int[4];
+			unsafe
+			{
+				fixed (int* ptr = &v[0])
+					GL.GetInteger(GetPName.Viewport, ptr);
+			}
+
+			ErrorHandler.CheckGlError();
+			return v;
+		}
+
+		int[] cv = new int[4];
+		public void Bind()
+		{
+			// Cache viewport rect to restore when unbinding
+			cv = ViewportRectangle();
+
+			GL.Flush();
+			ErrorHandler.CheckGlError();
+			GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, framebuffer);
+			ErrorHandler.CheckGlError();
+			GL.Viewport(0, 0, size.Width, size.Height);
+			ErrorHandler.CheckGlError();
+			GL.ClearColor(0, 0, 0, 0);
+			ErrorHandler.CheckGlError();
+			GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
+			ErrorHandler.CheckGlError();
+		}
+
+		public void Unbind()
+		{
+			GL.Flush();
+			ErrorHandler.CheckGlError();
+			GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, 0);
+			ErrorHandler.CheckGlError();
+			GL.Viewport(cv[0], cv[1], cv[2], cv[3]);
+			ErrorHandler.CheckGlError();
+		}
+
+		public ITexture Texture { get { return texture; } }
+
+		~FrameBuffer()
+		{
+			Game.RunAfterTick(() => Dispose(false));
+		}
+
+		public void Dispose()
+		{
+			Game.RunAfterTick(() => Dispose(true));
+			GC.SuppressFinalize(this);
+		}
+
+		void Dispose(bool disposing)
+		{
+			if (disposed)
+				return;
+			disposed = true;
+			if (disposing)
+				texture.Dispose();
+			GL.Ext.DeleteFramebuffers(1, ref framebuffer);
+			ErrorHandler.CheckGlError();
+			GL.Ext.DeleteRenderbuffers(1, ref depth);
+			ErrorHandler.CheckGlError();
+		}
+	}
+}