cocos2dx阴影层的实现

效果图

//ShadowLayer.h

class ShadowLayer : public CCLayer

{

protected:

    ShadowLayer()

    :m_pRender(NULL)

    ,m_pShadow(NULL)

    {}

    ~ShadowLayer()

    {

        CC_SAFE_RELEASE(m_pRender);

        CC_SAFE_RELEASE(m_pShadow);

    }

public:

    static ShadowLayer* create(CCNode* pRender,const CCPoint& ptOffset=ccp(-5.0f,-5.0f),const ccColor4F& col = ccc4f(,,,0.5f) );

    virtual bool init();

    virtual void update(float delta)override;

    virtual void setOffset(const CCPoint& ptOffset);

    virtual void setShadowColor(const ccColor4F& col);

    CC_SYNTHESIZE_RETAIN(CCNode*,m_pRender,Render);

private:

    CCRenderTexture*    m_pRT;

    CCRenderTexture*    m_pShadow;

};

//ShadowLayer.h

ShadowLayer* ShadowLayer::create(CCNode* pRender,const CCPoint& ptOffset/*t=ccp(-5.0f,-5.0f)*/,const ccColor4F& col/* = ccc4f(0,0,0,0.5f)*/ )

{

    ShadowLayer *pRet = new ShadowLayer();

    if (pRet && pRet->init())

    {

        pRet->autorelease();

        pRet->setRender(pRender);

        pRet->setShadowColor(col);

        pRet->setOffset(ptOffset);

        return pRet;

    }

    else

    {

        delete pRet;

        pRet = NULL;

        return NULL;

    }

}

bool ShadowLayer::init()

{

    if (CCLayer::init())

    {

        CCSize sz = getContentSize();

        m_pRT = CCRenderTexture::create(sz.width,sz.height);

        m_pRT->setPosition(sz.width/,sz.height/);

        addChild(m_pRT);

        m_pShadow = CCRenderTexture::create(sz.width,sz.height);

        m_pShadow->setPosition(ccp(sz.width/,sz.height/));

        ccBlendFunc tBlendFunc = {GL_DST_ALPHA, GL_NONE};

        //ccBlendFunc tBlendFunc = {GL_ONE, GL_NONE};

        m_pShadow->getSprite()->setBlendFunc(tBlendFunc);

        m_pShadow->retain();

        scheduleUpdate();

    }

    return true;

}

void ShadowLayer::update(float delta)

{

    m_pRT->clear(,,,);

    m_pRT->begin();

    if (m_pRender)

    {

        m_pRender->visit();

    }

    m_pShadow->visit();

    m_pRT->end();

}

void ShadowLayer::setShadowColor(const ccColor4F& col)

{

    m_pShadow->beginWithClear(col.r,col.g,col.b,col.a);

    m_pShadow->end();

}

void ShadowLayer::setOffset( const CCPoint& ptOffset )

{

    setPosition(ptOffset);

}