  gl.renderbufferStorageMultisample(gl.RENDERBUFFER, 4, gl.DEPTH_COMPONENT16, this.renderbufferWidth, this.renderbufferHeight);

          gl.bindFramebuffer(gl.FRAMEBUFFER, this.multisampleFramebuffer);
          gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, this.colorRenderbuffer);
          gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthRenderbuffer);

          this.MRTR = gl.getExtension('WEBGL_multisampled_render_to_textur