cocos2dx-js RenderTexture 将多张图片合并成一张图片

var sprite = new cc.Sprite("about_btn.png");
var sprite2 = new cc.Sprite("add5.png");

//创建画布
var rend = new cc.RenderTexture( starManager.winSize.width, starManager.winSize.height );

sprite.setPosition(400,starManager.winSize.height/4);
sprite2.setPosition(200,200);
//设置精灵的坐标为cocos坐标
sprite.setPosition(cc.director.convertToGL(sprite.getPosition()));
sprite2.setPosition(cc.director.convertToGL(sprite2.getPosition()));
//画
rend.begin();
sprite.visit();
sprite2.visit();
rend.end();

var spt=new cc.Sprite();
spt.setSpriteFrame(rend.getSprite().getSpriteFrame());//这里必须重新创建精灵，否则会报错
spt.setAnchorPoint(cc.p(0,0));
spt.setOpacity(100);
this.addChild(spt);