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

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,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,iNumWidth * iNumCount,iNumHeight);
		this.setTextureRect(stRect,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);

运行如下：

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(255,255,0));
        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：

参考链接 点击打开链接