圆形碰撞

判断两个圆的圆心距与其半径和，当两个圆的圆心距小于两圆的半径和时，表示发生了碰撞，反之则没有     void onTouchesBegan(const std::vector<Touch*>& touches, Event  *event);
    void onTouchesMoved(const std::vector<Touch*>& touches, Event  *event);
    void onTouchesEnded(const std::vector<Touch*>& touches, Event  *event);
private:
    Size size;

    bool isCollision(Sprite *sp);//检测两个矩形是否碰撞
    void ChangeLabelContent(bool isCollision);//改变文本内容
    //

    bool isCircleCollision(Point pos1,float radius1,Point pos2,float radius2);

size = Director::getInstance()->getWinSize();
    auto sp1 = Sprite::create("r1.png");
    sp1->setPosition(size/2);
    //Sprite::addChild(Node *child, int zOrder, int tag)
    addChild(sp1,0,1);
   
    auto sp2 = Sprite::create("r2.png");
    sp2->setPosition(Vec2(size.width*0.8, size.height/2));
    addChild(sp2,0,2);
   
    //添加显示碰撞信息
    auto label = Label::createWithTTF("no collision", "fonts/Marker Felt.ttf", 25);
    label->setPosition(Vec2(size.width/2, size.height*0.8));
    addChild(label,1,3);
   
   
   
    auto listener = EventListenerTouchAllAtOnce::create();
   
   
    listener->onTouchesBegan = CC_CALLBACK_2(HelloWorld::onTouchesBegan, this);
    listener->onTouchesMoved = CC_CALLBACK_2(HelloWorld::onTouchesMoved, this);
    listener->onTouchesEnded = CC_CALLBACK_2(HelloWorld::onTouchesEnded, this);
   
    Director::getInstance()->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener, this);
   
    return true;
}



void HelloWorld::onTouchesBegan(const std::vector<Touch*>& touches, Event  *event){
    auto touch = static_cast<Touch*>(touches[0]);
    auto point = touch->getLocation();
 
    auto sp1 = (Sprite*)this->getChildByTag(1);
    sp1->setPosition(point);
  
    ChangeLabelContent(isCollision(sp1));
   

}


void HelloWorld::onTouchesMoved(const std::vector<Touch*>& touches, Event  *event){

    auto touch = static_cast<Touch*>(touches[0]);
    auto point = touch->getLocation();
   
    auto sp1 = (Sprite*)this->getChildByTag(1);
    sp1->setPosition(point);
   
    ChangeLabelContent(isCollision(sp1));


}

void HelloWorld::onTouchesEnded(const std::vector<Touch*>& touches, Event  *event){

}

bool HelloWorld::isCollision(Sprite *sp){
    bool flag = false;
    auto sp2 = (Sprite*)this->getChildByTag(2);
    // 重点
    flag = isCircleCollision(sp->getPosition(), sp->getContentSize().width/2, sp2->getPosition(), sp2->getContentSize().width/2);



    return flag;
}

void HelloWorld::ChangeLabelContent(bool isCollision){
   
    auto label = (Label*)this->getChildByTag(3);
    if (isCollision) {
        label->setString("Collision!");

    }else label->setString("no collision!");

}



bool HelloWorld::isCircleCollision(Point pos1,float radius1,Point pos2,float radius2){
    // 重点
    if (pos1.getDistance(pos2)>radius1+radius2) {
        return false;
    }

    return true;
}