public void Dispose()
            {
                GC.SuppressFinalize(this);

                ColorBuffer   = null;
                DepthBuffer   = null;
                StencilBuffer = null;
                fbo           = null;
            }
            public Buffer_Stencil StencilBuffer;            // optional

            public _Attachment(FrameBuffer fbo, bool createDefaultBuff = true)
            {
                this.fbo = fbo;
                if (createDefaultBuff)
                {
                    // required
                    ColorBuffer    = new Buffer_Color[MAX_COLOR_BUFF];
                    ColorBuffer[0] = new Buffer_Color(fbo.W, fbo.H);
                    // required
                    DepthBuffer = new Buffer_Depth(fbo.W, fbo.H);
                }
            }