Cocos2dx 定义可以修改颜色的Sprite（shader的使用）

1、头文件：

class EffectSprite;//自定义Sprite
//
// Effect参考官方实例
//
class Effect : public Ref
{
public:
    GLProgramState* getGLProgramState() const { return _glprogramstate; }
    virtual void setTarget(EffectSprite *sprite){}

protected:
    bool initGLProgramState(const std::string &fragmentFilename);
    Effect();
    virtual ~Effect();
    GLProgramState *_glprogramstate;
#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID || CC_TARGET_PLATFORM == CC_PLATFORM_WP8 || CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    std::string _fragSource;
    EventListenerCustom* _backgroundListener;
#endif
};

2、源文件：

class EffectSprite : public Sprite
{
public:
    static EffectSprite *create(const std::string& filename) {
        auto ret = new (std::nothrow) EffectSprite;
        if (ret && ret->initWithFile(filename)) {
            ret->autorelease();
            return ret;
        }
        CC_SAFE_RELEASE(ret);
        return nullptr;
    }

    void setEffect(Effect* effect) {
        _defaultEffect = nullptr;
        if (_defaultEffect != effect) {
            effect->setTarget(this);

            CC_SAFE_RELEASE(_defaultEffect);
            _defaultEffect = effect;
            CC_SAFE_RETAIN(_defaultEffect);

            setGLProgramState(_defaultEffect->getGLProgramState());
        }
    }

    void draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) override
    {
#if CC_USE_CULLING
        // Don't do calculate the culling if the transform was not updated
        _insideBounds = (flags & FLAGS_TRANSFORM_DIRTY) ? renderer->checkVisibility(transform, _contentSize) : _insideBounds;

        if (_insideBounds)
#endif
        {
             //normal effect: order == 0
            _quadCommand.init(_globalZOrder, _texture->getName(), getGLProgramState(), _blendFunc, &_quad, 1, transform, flags);
            renderer->addCommand(&_quadCommand);
        }
    }
protected:
    Effect* _defaultEffect;
};
// Grey
class EffectGreyScale : public Effect
{
public:
    CREATE_FUNC(EffectGreyScale);

protected:
    bool init() {
        initGLProgramState("example_greyScale.fsh");
        return true;
    }
};
//
// Effect参考官方实例
//
bool Effect::initGLProgramState(const std::string &fragmentFilename)
{
    auto fileUtiles = FileUtils::getInstance();
    auto fragmentFullPath = fileUtiles->fullPathForFilename(fragmentFilename);
    auto fragSource = fileUtiles->getStringFromFile(fragmentFullPath);
    auto glprogram = GLProgram::createWithByteArrays(ccPositionTextureColor_noMVP_vert, fragSource.c_str());

#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID || CC_TARGET_PLATFORM == CC_PLATFORM_WP8 || CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    _fragSource = fragSource;
#endif

    _glprogramstate = GLProgramState::getOrCreateWithGLProgram(glprogram);
    _glprogramstate->retain();

    return _glprogramstate != nullptr;
}

Effect::Effect()
: _glprogramstate(nullptr)
{
#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID || CC_TARGET_PLATFORM == CC_PLATFORM_WP8 || CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    _backgroundListener = EventListenerCustom::create(EVENT_RENDERER_RECREATED,
        [this](EventCustom*)
    {
        auto glProgram = _glprogramstate->getGLProgram();
        glProgram->reset();
        glProgram->initWithByteArrays(ccPositionTextureColor_noMVP_vert, _fragSource.c_str());
        glProgram->link();
        glProgram->updateUniforms();
    }
    );
    Director::getInstance()->getEventDispatcher()->addEventListenerWithFixedPriority(_backgroundListener, -1);
#endif
}

Effect::~Effect()
{
    CC_SAFE_RELEASE_NULL(_glprogramstate);
#if (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID || CC_TARGET_PLATFORM == CC_PLATFORM_WP8 || CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    Director::getInstance()->getEventDispatcher()->removeEventListener(_backgroundListener);
#endif
}

3、example_greyScale.fsh（颜色定义）

#ifdef GL_ES
precision mediump float;
#endif

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

void main(void)
{
    vec4 c = texture2D(CC_Texture0, v_texCoord);
    gl_FragColor.xyz = vec3(0.2126*c.r + 0.7152*c.g + 0.0722*c.b);
    gl_FragColor.w = c.w;
}

4、使用代码：

EffectSprite* _sprite = EffectSprite::create("blueSprite.png");
_sprite->setPosition(Vec2(200, visibleSize.height / 2));
addChild(_sprite);