copy method

Implementation

@override
WebGLMultipleRenderTargets copy(WebGLRenderTarget source) {
  dispose();

  width = source.width;
  height = source.height;
  depth = source.depth;

  viewport.setValues(0, 0, width.toDouble(), height.toDouble());
  scissor.setValues(0, 0, width.toDouble(), height.toDouble());

  depthBuffer = source.depthBuffer;
  stencilBuffer = source.stencilBuffer;
  if (source.depthTexture != null) {
    depthTexture = source.depthTexture!.clone();
  }
  if(texture is GroupTexture){
    final children = (texture as GroupTexture).children;
    children.length = 0;

    final sc = (source.texture as GroupTexture).children;
    for (int i = 0, il = sc.length; i < il; i++) {
      children[i] = sc[i].clone();
    }
  }

  return this;
}