//Opacity 0完全透明 255完全不透明//ALPHA 0完全透明 1完全不透明CCRenderTexture* pRT = CCRenderTexture::create(480,320);pRT->setPosition(Point(480,320));addChild(pRT,1);CCSprite* pSpr1 = CCSprite::create("1.png");pSpr1->setAnchorPoint(CCPoint::ZERO);ccBlendFunc blend;blend.src = GL_ONE;blend.dst = GL_ZERO;pSpr1->setBlendFunc(blend);CCSprite* pSpr2 = CCSprite::create("HelloWorld.png");pSpr2->setPosition(ccp(0,0));pSpr2->setAnchorPoint(CCPoint::ZERO);ccBlendFunc blend1;blend1.src = GL_DST_ALPHA;//GL_ONE_MINUS_DST_ALPHA //GL_ONEblend1.dst = GL_ZERO;//GL_ONE_MINUS_SRC_ALPHA;pSpr2->setBlendFunc(blend1);pRT->clear(1,0,0,0);pRT->begin();pSpr1->visit();pSpr2->visit();pRT->end();

　　效果就是第2张图片和第1张图片重叠的地方由第1张图片的alpha值来决定