9. Cocos2d-x 游戏编程 之 多点触碰

上一篇内容讲了 单点触碰，然后这篇接着讲 多点触碰。多点触碰就是说，多个手指同时在屏幕上操作，然后触发监听器，回调方法实现功能而已。

1、先了解这个代码如何在手机上调试。因为这个是关乎到多个手指触碰才能触发的监听器，所以说，在模拟器上实现不了手指的触碰。必须在真机上跑才行。

其实很简单，只要在项目中的 ios 这个文件夹中的 AppController.mm 文件里边的 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary
*)launchOptions { } 方法内 补上一句 [eaglView setMultipleTouchEnabled:YES]; 就行了，详细请看图：

2、然后，我们就要上代码了，很简单的，只不过是在单点触碰的基础上把 onTouchBegan 等这些个单词变成复数 onTouchesBegan 等词而已，上过英语课的都懂。

代码（Firth.h）：

#include "cocos2d.h"

USING_NS_CC;

class FirthTest : public cocos2d::Layer
{
/* TouchAllAtOnce */
private:
    double _distance;   //两个触摸点之间的距离
    double _deltax;     //x 轴的改变值
    double _deltay;     //y 轴的改变值
    Sprite *_bgSprite;  //精灵
    double _mscale;     //缩放比例
public:
    static cocos2d::Scene* createScene();

    virtual bool init();

    /* TouchAllAtOnce */
    void onTouchesBegan(const std::vector<Touch *> &touches, cocos2d::Event *event);
    void onTouchesMoved(const std::vector<Touch *> &touches, cocos2d::Event *event);
    void onTouchesEnded(const std::vector<Touch *> &touches, cocos2d::Event *event);
    void onTouchesCancelled(const std::vector<Touch *> &touches, cocos2d::Event *event);

    void menuCloseCallback(cocos2d::Ref* pSender);

    void scale9();

    CREATE_FUNC(FirthTest);
};
#endif /* defined(__HelloWorld__Fireth__) */

（Firth.cpp）

USING_NS_CC;

Scene* FirthTest::createScene()
{
    auto scene = Scene::create();
    auto layer = FirthTest::create();
    scene->addChild(layer);
    return scene;
}

bool FirthTest::init()
{
    if ( !Layer::init() )
    {
        return false;
    }
    /**
     *  获得可见OpenGL视图大小
     */
    Size size = Director::getInstance()->getVisibleSize();

    /**
     *  获得可见OpenGL视图起始点(0,0)
     */
    Vec2 origin = Director::getInstance()->getVisibleOrigin();

    /**
     *  创建菜单项
     */
    auto closeItem = MenuItemImage::create(
                                           "CloseNormal.png",
                                           "CloseSelected.png",
                                           CC_CALLBACK_1(FirthTest::menuCloseCallback, this));

    closeItem->setPosition(Vec2(origin.x + size.width - closeItem->getContentSize().width/2 ,
                                origin.y + closeItem->getContentSize().height/2));

    /**
     *  创建菜单
     */
    auto menu = Menu::create(closeItem, NULL);
    menu->setPosition(Vec2::ZERO);
    this->addChild(menu, 1);

    /**
     *  创建标题
     */
    auto title = Label::createWithSystemFont("多点触碰", "", 50);
    title->setPosition(size.width / 2 , size.height * 0.9);
    this->addChild(title);

    /**
     *  创建一个精灵
     */
    _bgSprite = Sprite::create("HelloWorld.png");
    _bgSprite->setPosition(Vec2(size.width / 2 + origin.x , size.height / 2 + origin.y));
    this->addChild(_bgSprite , 0);

    _mscale = 1.0;

    /**
     *  创建多点触碰监听器
     */
    auto listener = EventListenerTouchAllAtOnce::create();

    listener->onTouchesBegan = CC_CALLBACK_2(FirthTest::onTouchesBegan, this);
    listener->onTouchesMoved = CC_CALLBACK_2(FirthTest::onTouchesMoved, this);
    listener->onTouchesEnded = CC_CALLBACK_2(FirthTest::onTouchesMoved, this);
    listener->onTouchesCancelled = CC_CALLBACK_2(FirthTest::onTouchesMoved, this);

    /**
     *  注册监听事件
     */
    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener, this);

    return true;
}
void FirthTest::onTouchesBegan(const std::vector<Touch *> &touches, cocos2d::Event *event)
{
    if (touches.size() >= 2) {

        //获取第一个点
        auto touch1 = touches.at(0);

        Vec2 myPoint1 = touch1->getLocation();

        //获取第二个点
        auto touch2 = touches.at(1);

        Vec2 myPoint2 = touch2->getLocation();

        /**
         *  勾股定理，算出两点距离
         */
        _distance = sqrt((myPoint2.x - myPoint1.x) * (myPoint2.x - myPoint1.x) +
                         (myPoint2.x - myPoint1.x) * (myPoint2.y - myPoint1.y));

    }
}

void FirthTest::onTouchesMoved(const std::vector<Touch *> &touches, cocos2d::Event *event)
{
    if (touches.size() >= 2) {
        //获取第一个点
        auto touch1 = touches.at(0);

        Vec2 myPoint1 = touch1->getLocation();

        //获取第二个点
        auto touch2 = touches.at(1);

        Vec2 myPoint2 = touch2->getLocation();

        /**
         *  勾股定理，算出两点距离
         */
        double mdistance = sqrt((myPoint2.x - myPoint1.x) * (myPoint2.x - myPoint1.x) +
                         (myPoint2.x - myPoint1.x) * (myPoint2.y - myPoint1.y));
        <span class="s1" style="font-family: Arial, Helvetica, sans-serif;">// </span><span class="s2" style="font-family: Arial, Helvetica, sans-serif;">新的距离</span><span class="s1" style="font-family: Arial, Helvetica, sans-serif;">/</span><span class="s2" style="font-family: Arial, Helvetica, sans-serif;">老的距离</span><span class="s1" style="font-family: Arial, Helvetica, sans-serif;">*</span><span class="s2" style="font-family: Arial, Helvetica, sans-serif;">原来的缩放比例，即为新的缩放比例</span>
        _mscale = mdistance / _distance * _mscale;

        _distance = mdistance;
        //设置新的比例
        _bgSprite->setScale(_mscale);
    }
}
void FirthTest::onTouchesEnded(const std::vector<Touch *> &touches, cocos2d::Event *event)
{}
void FirthTest::onTouchesCancelled(const std::vector<Touch *> &touches, cocos2d::Event *event)
{}

void FirthTest::menuCloseCallback(Ref* pSender)
{
#if (CC_TARGET_PLATFORM == CC_PLATFORM_WP8) || (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)
    MessageBox("You pressed the close button. Windows Store Apps do not implement a close button.","Alert");
    return;
#endif

    Director::getInstance()->end();

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
    exit(0);
#endif
}

其实代码没有难度，就看注释吧，挺详细的了。

第九章，结束！

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