1         private Framebuffer CreateFramebuffer(int width, int height)
 2         {
 3             var texture = new Texture(TextureTarget.Texture2D,
 4                 new NullImageFiller(width, height, GL.GL_RGBA, GL.GL_RGBA, GL.GL_UNSIGNED_BYTE),
 5                 new SamplerParameters(
 6                     TextureWrapping.Repeat,
 7                     TextureWrapping.Repeat,
 8                     TextureWrapping.Repeat,
 9                     TextureFilter.Linear,
10                     TextureFilter.Linear));
11             texture.Initialize();
12             this.BindingTexture = texture;
13             Renderbuffer colorBuffer = Renderbuffer.CreateColorbuffer(width, height, GL.GL_RGBA);
14             Renderbuffer depthBuffer = Renderbuffer.CreateDepthbuffer(width, height, DepthComponentType.DepthComponent24);
15             var framebuffer = new Framebuffer();
16             framebuffer.Bind();
17             framebuffer.Attach(colorBuffer);//0
18             framebuffer.Attach(texture);//1
19             framebuffer.Attach(depthBuffer);// special
20             framebuffer.SetDrawBuffers(GL.GL_COLOR_ATTACHMENT0 + 1);// as in 1 in framebuffer.Attach(texture);//1
21             framebuffer.CheckCompleteness();
22             framebuffer.Unbind();
23             return framebuffer;
24         }

 1         public void RenderBeforeChildren(RenderEventArgs arg)
 2         {
 3             if (this.Width <= 0 || this.Height <= 0) { return; }
 4
 5             var viewport = new int[4];
 6             GL.Instance.GetIntegerv((uint)GetTarget.Viewport, viewport);
 7
 8             this.framebuffer = this.helper.GetFramebuffer(this.Width, this.Height);
 9             framebuffer.Bind();
10             GL.Instance.Viewport(0, 0, this.Width, this.Height);
11             {
12                 int[] value = new int[4];
13                 GL.Instance.GetIntegerv((uint)GetTarget.ColorClearValue, value);
14                 {
15                     vec3 color = this.BackgroundColor.ToVec3();
16                     GL.Instance.ClearColor(color.x, color.y, color.z, 0.0f); // 0.0f for alpha channel, in case that transparent background is needed.
17                     GL.Instance.Clear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT | GL.GL_STENCIL_BUFFER_BIT);
18                 }
19                 {
20                     var args = new RenderEventArgs(this.Camera);
21                     foreach (var item in this.Children)
22                     {
23                         RenderAction.Render(item, args);
24                     }
25                 }
26                 {
27                     GL.Instance.ClearColor(value[0], value[1], value[2], value[3]);// recover clear color.
28                 }
29             }
30             GL.Instance.Viewport(viewport[0], viewport[1], viewport[2], viewport[3]);// recover viewport.
31             this.framebuffer.Unbind();
32         }