_createRenderCmd() {
    if (cc._renderType === cc._RENDER_TYPE_CANVAS) {
      return this._super();
    }
    return new FXDistortionSprite.WebGLRenderCmd(this);
  }
*************************************************************************
FXDistortionSprite
var FXDistortionSprite = FXSprite
FXDistortionSprite.create()
 - distortion created based on a texture's brightness at each pixel
**************************************************************************