_createRenderCmd() {
    if (cc._renderType === cc._RENDER_TYPE_CANVAS) {
      return InstancedSprite.prototype._createRenderCmd.call(this);
    }
    return new CausticPrismaticGlowSprite.WebGLRenderCmd(this);
  }
*************************************************************************
 CausticPrismaticGlowSprite
 var CausticPrismaticGlowSprite = InstancedSprite
 CausticPrismaticGlowSprite.create()
 - procedurally generated caustic prismatic glow sprite
 - this sprite is pooled, so that it may be reused with better performance
 - this sprite is instanced, so all instances of it will appear the same
 - use sprite.setTextureRect(cc.rect(x, y, w, h)) to define the size of the sprite
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