public GLRenderBuffer( int format, int width, int height, int fsaa )
: base( width, height, 1, GLPixelUtil.GetClosestPixelFormat( format ), BufferUsage.WriteOnly )
{
this.GLFormat = format;
/// Generate renderbuffer
Gl.glGenRenderbuffersEXT( 1, out _renderBufferId );
/// Bind it to FBO
Gl.glBindRenderbufferEXT( Gl.GL_RENDERBUFFER_EXT, _renderBufferId );
/// Allocate storage for depth buffer
Gl.glRenderbufferStorageEXT( Gl.GL_RENDERBUFFER_EXT, format, width, height );
}