private void PanelLoad(object sender, EventArgs e)
{
    // VBO
    SetupVBO();
    // camera setup
    SetupCamera();
    // FBO
    SetupFBO();
}

private void SetupVBO()
{
   GL.Arb.GenBuffers(1, out _vbo.VboID);
   GL.Arb.BindBuffer(BufferTargetArb.ArrayBuffer, _vbo.VboID);
   GL.Arb.BufferData(BufferTargetArb.ArrayBuffer,
                     (IntPtr)(data.Length * 10 * sizeof(float)),
                     data,
                     BufferUsageArb.StaticDraw);

   GL.Arb.GenBuffers(1, out _vbo.EboID);
   GL.Arb.BindBuffer(BufferTargetArb.ElementArrayBuffer, _vbo.EboID);
   GL.Arb.BufferData(BufferTargetArb.ElementArrayBuffer,
                     (IntPtr)(indices.Length * sizeof(uint)),
                     indices,
                     BufferUsageArb.StaticDraw);

   GL.InterleavedArrays(InterleavedArrayFormat.C4fN3fV3f, 0, IntPtr.Zero);
}

private void SetupFBO()
{
   GL.Enable(EnableCap.DepthTest);
   GL.ClearDepth(1.0);
   GL.DepthFunc(DepthFunction.Lequal);

   GL.Disable(EnableCap.CullFace);
   GL.PolygonMode(MaterialFace.Back, PolygonMode.Line);
            
   // create color tex
   GL.GenTextures(1, out _fbo.TextureID);
   GL.BindTexture(TextureTarget.Texture2D, _fbo.TextureID);
   GL.TexImage2D(TextureTarget.Texture2D,
                 0,
                 PixelInternalFormat.Rgb8,
                 _panel.Width,
                 _panel.Height,
                 0,
                 PixelFormat.Rgba,
                 PixelType.UnsignedByte,
                 IntPtr.Zero);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToBorder);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToBorder);

   // create depth tex
   GL.GenTextures(1, out _fbo.DepthBufferID);
   GL.BindTexture(TextureTarget.Texture2D, _fbo.DepthBufferID);
   GL.TexImage2D(TextureTarget.Texture2D,
                 0,
                 (PixelInternalFormat)All.DepthComponent,
                 _panel.Width,
                 _panel.Height,
                 0,
                 PixelFormat.DepthComponent,
                 PixelType.UnsignedInt,
                 IntPtr.Zero);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToBorder);
   GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToBorder);
            
   // create FBO
   GL.Ext.GenFramebuffers(1, out _fbo.FboID);
   GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, _fbo.FboID);
   GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt,
                               FramebufferAttachment.ColorAttachment0Ext,
                               TextureTarget.Texture2D,
                               _fbo.TextureID,
                               0);
   GL.Ext.FramebufferTexture2D(FramebufferTarget.FramebufferExt,
                               FramebufferAttachment.DepthAttachment,
                               TextureTarget.Texture2D,
                               _fbo.DepthBufferID,
                               0);

   CheckFBO();

   GL.PushAttrib(AttribMask.ViewportBit);
   {
      GL.Viewport(0, 0, _panel.Width, _panel.Height);

      // clear the screen in red, to make it very obvious what the clear affected. only the FBO, not the real framebuffer
      GL.ClearColor(1f, 0f, 0f, 0f);
      GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

      RenderVBO();
   }
   GL.PopAttrib();
   GL.Ext.BindFramebuffer(FramebufferTarget.FramebufferExt, 0); // disable rendering into the FBO

   //GL.ClearColor(.1f, .2f, .3f, 0f);
   GL.ClearColor(Color4.Red);
   GL.Color3(1f, 1f, 1f);

   GL.Enable(EnableCap.Texture2D); // enable Texture Mapping
   GL.BindTexture(TextureTarget.Texture2D, 0); // bind default texture

}

private void RenderVBO()
{
   //    #region OpenGL-Setup
   GL.Viewport(0, 0, _panel.Width, _panel.Height);
   var look = cam.ModelViewProjectionMatrix;
   GL.MatrixMode(MatrixMode.Projection);
   GL.LoadMatrix(ref look);

   GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

   //GL.Enable(EnableCap.DepthTest);
   //GL.Enable(EnableCap.Blend);
   GL.MatrixMode(MatrixMode.Modelview);
   GL.LoadIdentity();

   GL.PolygonMode(MaterialFace.Front, PolygonMode.Fill);
   GL.PolygonMode(MaterialFace.Back, PolygonMode.Fill);

   //GL.Color3(.3, .3, .3);

   GL.EnableClientState(ArrayCap.VertexArray);
   GL.EnableClientState(ArrayCap.ColorArray);
   GL.EnableClientState(ArrayCap.NormalArray);

   GL.Arb.BindBuffer(BufferTargetArb.ArrayBuffer, _vbo.VboID);
   GL.Arb.BindBuffer(BufferTargetArb.ElementArrayBuffer, _vbo.EboID);

   GL.ColorPointer(4, ColorPointerType.Float, 10 * sizeof(float), IntPtr.Zero);
   GL.NormalPointer(NormalPointerType.Float, 10 * sizeof(float), (IntPtr)(4 * sizeof(float)));
   GL.VertexPointer(3, VertexPointerType.Float, 10 * sizeof(float), (IntPtr)(7 * sizeof(float)));

   GL.DrawElements(BeginMode.Triangles, _vbo.NumElements, DrawElementsType.UnsignedInt, IntPtr.Zero);

   GL.DisableClientState(ArrayCap.NormalArray);
   GL.DisableClientState(ArrayCap.ColorArray);
   GL.DisableClientState(ArrayCap.VertexArray);
}

private void PanelPaint(object sender, EventArgs e)
{
   GL.Viewport(0, 0, _panel.Width, _panel.Height);
   var look = cam.ModelViewProjectionMatrix;
   GL.MatrixMode(MatrixMode.Projection);
   GL.LoadMatrix(ref look);

   //GL.ClearColor(Color4.DarkGray);
   GL.ClearColor(Color4.Red);
   GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

   GL.Enable(EnableCap.DepthTest);
   GL.Enable(EnableCap.Blend);
   GL.MatrixMode(MatrixMode.Modelview);
   GL.LoadIdentity();

   GL.PolygonMode(MaterialFace.Front, PolygonMode.Fill);
   GL.PolygonMode(MaterialFace.Back, PolygonMode.Fill);

   GL.Color3(.3, .3, .3);
            
   GL.PushMatrix();
   {
      // Draw the Color Texture
      GL.Translate(-1.1f, 0f, 0f);
      GL.BindTexture(TextureTarget.Texture2D, _fbo.TextureID);
      GL.Begin(BeginMode.Quads);
      {
         GL.TexCoord2(0f, 1f);
         GL.Vertex2(-1.0f, 1.0f);
         GL.TexCoord2(0.0f, 0.0f);
         GL.Vertex2(-1.0f, -1.0f);
         GL.TexCoord2(1.0f, 0.0f);
         GL.Vertex2(1.0f, -1.0f);
         GL.TexCoord2(1.0f, 1.0f);
         GL.Vertex2(1.0f, 1.0f);
      }
      GL.End();

      // Draw the Depth Texture
      GL.Translate(+2.2f, 0f, 0f);
      GL.BindTexture(TextureTarget.Texture2D, _fbo.DepthBufferID);
      GL.Begin(BeginMode.Quads);
      {
         GL.TexCoord2(0f, 1f);
         GL.Vertex2(-1.0f, 1.0f);
         GL.TexCoord2(0.0f, 0.0f);
         GL.Vertex2(-1.0f, -1.0f);
         GL.TexCoord2(1.0f, 0.0f);
         GL.Vertex2(1.0f, -1.0f);
         GL.TexCoord2(1.0f, 1.0f);
         GL.Vertex2(1.0f, 1.0f);
      }
      GL.End();
   }
   GL.PopMatrix();

   _panel.SwapBuffers();
}