cocos2dx 3.2 裁剪节点 ClippingNode

效果1：

效果2：

代码：

//
//[1].背景图片
    Sprite* bg = Sprite::create("HelloWorld.png");
    bg->setPosition(visibleSize / 2);
    this->addChild(bg, -1);

//[2].创建主题文字 : gameTitle
    Sprite* gameTitle = Sprite::create("game_title.png");

    //获取尺寸大小
    Size clipSize = gameTitle->getContentSize();

//[3].创建底板的发光图片 : spark
    Sprite* spark = Sprite::create("spark.png");
    spark->setPosition(-clipSize.width, 0);

//[4].创建裁剪节点 : clippingNode
    ClippingNode* clippingNode = ClippingNode::create();
    clippingNode->setPosition(visibleSize / 2);
    this->addChild(clippingNode);

    clippingNode->setAlphaThreshold(0.05f); //设置alpha闸值
    clippingNode->setContentSize(clipSize); //设置尺寸大小

    clippingNode->setStencil(gameTitle);   //设置模板stencil
    clippingNode->addChild(gameTitle, 1);  //先添加标题,会完全显示出来,因为跟模板一样大小
    clippingNode->addChild(spark,2);       //会被裁减

//[5].左右移动spark
    MoveTo* moveAction = MoveTo::create(2.0f, Vec2(clipSize.width, 0));
    MoveTo* moveBackAction = MoveTo::create(2.0f, Vec2(-clipSize.width, 0));
    spark->runAction(RepeatForever::create(Sequence::create(moveAction, moveBackAction, NULL)));

效果3：

1.1、素材

1.2、在HelloWorld.h中添加如下变量与函数

//
    ClippingNode* holesClipper; //裁剪节点
    Node* holesStencil;         //模板节点
    Node* holes;                //底板节点

    //触摸回调
    void onTouchesBegan(const std::vector<Touch*>& touches, Event *unused_event);
    //添加小洞
    void pokeHoleAtPoint(Vec2 point);
//

1.3、在HelloWorld.cpp中的init()中创建裁剪节点ClippingNode

//
//[1].背景图片(Layer层中)
    Sprite* bg = Sprite::create("HelloWorld.png");
    bg->setPosition(visibleSize / 2);
    this->addChild(bg);

//[2].创建裁剪节点 : holesClipper
    holesClipper = ClippingNode::create();
    holesClipper->setPosition(visibleSize / 2);
    this->addChild(holesClipper);

    //属性设置
    holesClipper->setInverted(true);        //倒置显示，未被裁剪下来的剩余部分
    holesClipper->setAlphaThreshold(0.5f);  //设置alpha透明度闸值
    holesClipper->runAction(RepeatForever::create(RotateBy::create(1, 45))); //旋转动作

//[3].创建模板 : holesStencil
    holesStencil = Node::create();
    holesClipper->setStencil(holesStencil); //设置模板节点

    //添加一个模板遮罩 ball
    holesStencil->addChild(Sprite::create("ball.png"), -1);

//[4].创建底板 : holes
    holes = Node::create();
    holesClipper->addChild(holes); //设置底板

    //添加另一个底板内容 blocks
    Sprite* content = Sprite::create("blocks.png");
    holesClipper->addChild(content, -1, "content");

//[5].触摸事件
    auto listener = EventListenerTouchAllAtOnce::create();
    listener->onTouchesBegan = CC_CALLBACK_2(HelloWorld::onTouchesBegan, this);
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener, this);
//

1.4、设置触摸事件回调。当触摸点在底板区域内部，则“打洞”

//
void HelloWorld::onTouchesBegan(const std::vector<Touch*>& touches, Event *unused_event)
{
//[1].获取触点, 转换为相对holesClipper节点的 相对坐标
    Vec2 point = touches[0]->getLocation();
    point = holesClipper->convertToNodeSpace(point);

//[2].获取底板区域矩形Rect
    Sprite* content = (Sprite*)holesClipper->getChildByName("content");
    Size contentSize = content->getContentSize();
    Rect rect = Rect(-contentSize.width / 2, -contentSize.height / 2, contentSize.width, contentSize.height);

//[3].触摸点在底板内部, 进行"打洞"
    if (rect.containsPoint(point))
    {
        pokeHoleAtPoint(point);
    }
}
//

  1.5、实现“打洞”操作函数

//
void HelloWorld::pokeHoleAtPoint(Vec2 point)
{
    CCLOG("Add a Hole!!!");

//[1].添加底板内容 : 一个洞的痕迹
    auto hole = Sprite::create("hole_effect.png");
    hole->setPosition(point);
    holes->addChild(hole);

//[2].添加模板内容 : 一个小洞
    auto holeStencil = Sprite::create("hole_stencil.png");
    holeStencil->setPosition(point);
    holesStencil->addChild(holeStencil);

//[3].动作效果 : 放大缩小
    holesClipper->runAction(Sequence::create(ScaleTo::create(0.05f, 1.05f), ScaleTo::create(0.05f, 1.0f), NULL));
}
//