[cocos2d-js]cc.RenderTexture几种用法(数字图片、刮刮乐效果)

【转】http://blog.csdn.net/realcrazysun1/article/details/42393629

本文基于cocos2d-js 3.0版本引擎开发

RenderTexture用法1：数字图片

通过这张图片实现任意数字

//数字图片精灵

var PictureNumber = cc.Sprite.extend({
    m_Number:null,
    m_NumberTexture:null,
    ctor:function(){
        this._super();
        
    },
    buildNumber:function(paramNumber, paramTexture)
    {
        this.setNumber(paramNumber);
        this.setNumberTexture(cc.textureCache.addImage(paramTexture));
        return this.build();
    },
    build:function(){

        var iNumCount = (this.m_Number+"").length;   //取得字符个数
        var stSize = this.m_NumberTexture.getContentSize(); //取得纹理大小，要求纹理中每个数字都是等宽等高，并依照0123456789排列
        
        var iNumWidth = parseInt( stSize.width / 10);    //纹理中每个数字的宽度
        var iNumHeight =  parseInt( stSize.height);    //纹理中每个数字的高度

        var pRT = new cc.RenderTexture(iNumWidth * iNumCount, iNumHeight); //创建渲染纹理对象，并数字确定宽度
        
        
        
        pRT.begin();
        for (var i = 0; i < iNumCount; i++)
        {
            var pSprite   = new cc.Sprite(); //创建精灵对象，用于绘制数字
            pSprite.setAnchorPoint(0, 0);
            pSprite.setTexture(this.m_NumberTexture);
            var iNumber = (this.m_Number+"")[i];
            //设置要显示数字的纹理区域，这个区域是指参数中paramTexture中区域
            var stRect = new cc.rect(iNumber * iNumWidth, 0, iNumWidth, iNumHeight);
            pSprite.setTextureRect(stRect, false, cc.size(stRect.width, stRect.height));
            pSprite.setPosition(i * iNumWidth, 0);                  //计算显示的偏移位置
            pSprite.visit(); //渲染到pRT中
        }
        pRT.end();
        //取得生成的纹理
        this.setTexture(pRT.getSprite().getTexture());
        //设置显示的内容
        var stRect = new cc.rect(0, 0, iNumWidth * iNumCount, iNumHeight);
        this.setTextureRect(stRect, false, cc.size(stRect.width, stRect.height));
        //默认的情况下，通过CCRenderTexture得到的纹理是倒立的，这里需要做一下翻转
        this.setFlippedY(true);
    },
    
    setNumber:function(paramNumber){
        this.m_Number = paramNumber;
    },
    getNumber:function(){
        return this.m_Number;
    },
    setNumberTexture:function(paramTexture)
    {
        this.m_NumberTexture = paramTexture;
    }
});

使用方法：

var pNum = new PictureNumber();
        pNum.buildNumber(1234567, "res/number.png");
        pNum.setPosition(200, 200);
        pNum.setAnchorPoint(0, 0);

RenderTexture用法2：刮刮乐效果

主要代码如下：

var HelloWorldLayer = cc.Layer.extend({
    sprite:null,
    pEraser:null,
    pRTex:null,
    
    ctor:function () {
        //////////////////////////////
        // 1. super init first
        this._super();

        var size = cc.winSize;

        // add a "close" icon to exit the progress. it's an autorelease object
        var closeItem = new cc.MenuItemImage(
            res.CloseNormal_png,
            res.CloseSelected_png,
            function () {
                cc.log("Menu is clicked!");
            }, this);
        closeItem.attr({
            x: size.width - 20,
            y: 20,
            anchorX: 0.5,
            anchorY: 0.5
        });

        var menu = new cc.Menu(closeItem);
        menu.x = 0;
        menu.y = 0;
        this.addChild(menu, 1);

        /////////////////////////////
        // 3. add your codes below...
        // add a label shows "Hello World"
        // create and initialize a label
        var helloLabel = new cc.LabelTTF("Hello World", "Arial", 38);
        // position the label on the center of the screen
        helloLabel.x = size.width / 2;
        helloLabel.y = size.height / 2;
        // add the label as a child to this layer
        this.addChild(helloLabel, 5);

        // hello world 背景图片
        this.sprite = new cc.Sprite(res.HelloWorld_png);
        this.sprite.attr({
            x: size.width / 2,
            y: size.height / 2,
        });
        this.addChild(this.sprite, 0);
        
        //橡皮擦
        this.pEraser = new cc.DrawNode();   
        this.pEraser.drawDot(cc.p(0, 0), 20, cc.color(255, 255, 255, 0));
        this.pEraser.retain();
        
        //通过pRTex实现橡皮擦
        this.pRTex = new cc.RenderTexture(size.width,size.height);
        this.pRTex.setPosition(size.width/2, size.height/2);
        this.addChild(this.pRTex, 10);
        
        //加载等待被擦除的图片
        var pBg = new cc.Sprite(res.dirt_png);
        pBg.setPosition(size.width/2, size.height/2);
        this.pRTex.begin();
        pBg.visit();
        this.pRTex.end();

        
        
        cc.eventManager.addListener({           
            event: cc.EventListener.TOUCH_ONE_BY_ONE,         
            onTouchBegan:function(touches, event){
                cc.log("start");
                var target = event.getCurrentTarget();
                return true;
            },            
            onTouchMoved:function (touch, event) {
                var target = event.getCurrentTarget();
                target.pEraser.setPosition(touch.getLocation());
                target.eraseByBlend();
            }
        }, this);
        
        return true;
    },
    
    eraseByBlend :function()
    {
        this.pEraser.setBlendFunc(cc.GL_ONE_MINUS_SRC_ALPHA, cc.ZERO);     
        this.pRTex.begin();
        this.pEraser.visit();
        this.pRTex.end();
    }
    
});

运行效果如下：