cocos2dx刮奖效果实现

刮奖效果其实挺简单的，需要用到RenderTexture来进行渲染，通过你所要渲染的图层，把该层的颜色进行设置混合就可以达到效果，具体看代码，我用的lua实现的。

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local winsize = cc.Director:sharedDirector():getWinSize();  

local dataSprite = cc.Sprite:create("Star.png")--要把这个图片刮出来  

dataSprite:setAnchorPoint(cc.p(0.5, 0.5));  

dataSprite:move(winsize.width / 2.0, winsize.height / 2.0);  

self:addChild(dataSprite)  

  

pEarse = cc.DrawNode:create()  

pEarse:drawDot(cc.p(0, 0), 5, cc.c4f(1, 0, 0, 1));  

pEarse:retain()  

  

pRTex = cc.RenderTexture:create(winsize.width, winsize.height);  

pRTex:setPosition(cc.p(winsize.width / 2, winsize.height / 2));  

--this:addChild(pRTex);  

pRTex:retain()  

  

local pBg = cc.Sprite:create("d1.png");--这个作为当“油漆层”  

pBg:setAnchorPoint(cc.p(0.5, 0.5));  

pBg:move(winsize.width / 2.0, winsize.height / 2.0);  

  

pRTex:begin();  

dataSprite:visit();  

pBg:visit();  

pRTex:endToLua();  

local layer=cc.Layer:create()  

self:addChild(layer, 1000)  

layer:addChild(pRTex);  

layer:setNodeTouch(handler(self, self.onTouchStart))  

鼠标移动代码：

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function shop.erasure(event)  

    -- body  

    print("erasure: ", event.name)  

    --todo  

    print("moved")  

    local touchPoint = event.pos  

    pEarse:setPosition(event.pos.x, event.pos.y);  

    -- 设置混合模式  

    local blendFunc = { GL_ONE, GL_ZERO };  

    pEarse:setBlendFunc(blendFunc);  

    -- 将橡皮擦的像素渲染到画布上，与原来的像素进行混合  

    pRTex:begin();  

    pEarse:visit();  

    pRTex:endToLua();  

      

end  

C++代码：

void function()

{

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     //test code  

     auto aPanelSprite = Sprite::create("potentiometerTrack.png");  

     aPanelSprite->setPosition(Vec2(s.width / 2, s.height / 2));  

     this->addChild(aPanelSprite);  

  

     pEase = DrawNode::create();  

     pEase->retain();  

     pEase->drawDot(Point(0, 0), 4.0f, Color4F(255, 0, 0, 255));  

  

     pRender = RenderTexture::create(s.width, s.height);  

     pRender->retain();  

     pRender->setPosition(Vec2(s.width / 2, s.height / 2));  

     this->addChild(pRender); //渲染纹理层需加入该父节点层  

  

  

    auto pBg = Sprite::create("potentiometerProgress.png"); //这个作为当“油漆层”  

    pBg->setAnchorPoint(Point(0.5, 0.5));  

    pBg->setPosition(Vec2(s.width / 2, s.height / 2));  

  

    pRender->begin();  

    aPanelSprite->visit();  

    pBg->visit();  

    pRender->end();  

  

    auto listener = EventListenerTouchOneByOne::create();  

    listener->setSwallowTouches(true);  

  

    listener->onTouchBegan = CC_CALLBACK_2(SpriteEaseBezier::onTouchBegan, this);  

    listener->onTouchMoved = CC_CALLBACK_2(SpriteEaseBezier::onTouchMoved, this);  

  

    auto _eventDispatcher = CCDirector::getInstance()->getEventDispatcher();  

    _eventDispatcher->addEventListenerWithFixedPriority(listener, -10);  

}  

  

bool SpriteEaseBezier::onTouchBegan(Touch *touch, Event *unused_event)  

{  

    CCLOG("SpriteEaseBezier::onTouchBegan");  

    return true;  

}  

  

void SpriteEaseBezier::onTouchMoved(Touch *touch, Event *unused_event)  

{  

    auto touchPoint = touch->getLocation();  

    pEase->setPosition(touchPoint.x, touchPoint.y);  

  

    BlendFunc blendFunc = { GL_ONE, GL_ZERO };  

    pEase->setBlendFunc(blendFunc);  

  

    pRender->begin();  

    pEase->visit();  

    pRender->end();  

    CCLOG("SpriteEaseBezier::onTouchMoved");  

}