cocos2d-X 显示不规则图片方法（遮罩）

游戏中经常会使用一些mask， 来做遮罩，实现不规则图的显示，在cocos2d-x中

函数实现如下:

.h

static CCSprite* createMaskedSprite(CCSprite* src, const char* maskFile);

.cpp

CCSprite*  GOEUtilies::createMaskedSprite(CCSprite* src, const char* maskFile)
{
    CCSprite * mask = CCSprite::create(maskFile);

    assert(src);
    assert(mask);

    CCSize srcContent = src->getContentSize();
    CCSize maskContent = mask->getContentSize();

    CCRenderTexture * rt = CCRenderTexture::create(srcContent.width, srcContent.height, kTexture2DPixelFormat_RGBA8888);

    float ratiow = srcContent.width / maskContent.width;
    float ratioh = srcContent.height / maskContent.height;
    mask->setScaleX(ratiow);
    mask->setScaleY(ratioh);

    mask->setPosition(ccp(srcContent.width / 2, srcContent.height / 2));
    src->setPosition(ccp(srcContent.width / 2, srcContent.height / 2));

    ccBlendFunc blendFunc2 = { GL_ONE, GL_ZERO };
    mask->setBlendFunc(blendFunc2);
    ccBlendFunc blendFunc3 = { GL_DST_ALPHA, GL_ZERO };
    src->setBlendFunc(blendFunc3);

    rt->begin();
    mask->visit();
    src->visit();
    rt->end();

    CCSprite * retval = CCSprite::createWithTexture(rt->getSprite()->getTexture());
    retval->setFlipY(true);
    return retval;
}

 

使用方法为：

GOEUtilies::createMaskedSprite(sprite,"mask.png")；