HelloWorld入门

HelloWorld入门
    代码解释：
        AppDelegate.h类是Cocos2d-x引擎要求实现的游戏应用委托对象，在Cocos2d-x游戏
    运行的不同生命周期阶段会触发他的不同函数
        AppDelegate继承了cocos2d::Application,是Cocos2d-x引擎提供的基类

　　　　AppDelegate.h
        

#ifndef  _APP_DELEGATE_H_
#define  _APP_DELEGATE_H_

#include "cocos2d.h"

/**
@brief    The cocos2d Application.

The reason for implement as private inheritance is to hide some interface call by Director.
*/
class  AppDelegate : private cocos2d::Application
{
public:
    AppDelegate();
    virtual ~AppDelegate();

    /**
    @brief    Implement Director and Scene init code here.
    @return true    Initialize success, app continue.
    @return false   Initialize failed, app terminate.
    */
    /*
        *游戏启动时调用的函数，在这里可以初始化导演对象和场景对象
    */
    virtual bool applicationDidFinishLaunching();

    /**
    @brief  The function be called when the application enter background
    @param  the pointer of the application
    */
    /*
        *游戏进入后台时调用的函数
    */
    virtual void applicationDidEnterBackground();

    /**
    @brief  The function be called when the application enter foreground
    @param  the pointer of the application
    */
    /*
        *游戏进入前台时调用的函数
    */
    virtual void applicationWillEnterForeground();
};

#endif // _APP_DELEGATE_H_

        
        AppDelegate.cpp

#include "AppDelegate.h"
#include "HelloWorldScene.h"

USING_NS_CC;//是用来替换using namespace cocos2d

AppDelegate::AppDelegate() {

}

AppDelegate::~AppDelegate()
{
}

bool AppDelegate::applicationDidFinishLaunching() {
    // initialize director
    //初始化director
    auto director = Director::getInstance();
    auto glview = director->getOpenGLView();
    if (!glview) {
        glview = GLView::create("My Game");
        director->setOpenGLView(glview);//设置导演类的OpenGL视图
    }

    // turn on display FPS
    //设置是否在屏幕上显示帧率等信息，一般是为了测试，实际发布时会影响游戏的外观，所以就不显示了
    director->setDisplayStats(true);

    // set FPS. the default value is 1.0/60 if you don't call this
    //设定定时器1.0/60秒间隔一次，即设定帧率为60
    director->setAnimationInterval(1.0 / 60);

    // create a scene. it's an autorelease object
    //创建场景的对象Sence
    auto scene = HelloWorld::createScene();

    // run
    //运行该场景，使游戏进入该场景
    director->runWithScene(scene);

    return true;
}

// This function will be called when the app is inactive. When comes a phone call,it's be invoked too
void AppDelegate::applicationDidEnterBackground() {
    //停止场景中的动画
    Director::getInstance()->stopAnimation();

    // if you use SimpleAudioEngine, it must be pause
    //停止背景音乐
    // SimpleAudioEngine::getInstance()->pauseBackgroundMusic();
}

// this function will be called when the app is active again 
void AppDelegate::applicationWillEnterForeground() {
    //开始游戏场景中的动画
    Director::getInstance()->startAnimation();

    // if you use SimpleAudioEngine, it must resume here
    //继续背景音乐
    // SimpleAudioEngine::getInstance()->resumeBackgroundMusic();
}

        HelloWorld类继承cocos2d::Layer类，他被成为层(layer)，这些层被放到场景(scene)场景类是cocos2d::Scene
        
        HelloWorldScene.h
        

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"

class HelloWorld : public cocos2d::Layer//继承了Layer是一个层不是场景
{
public:
    // there's no 'id' in cpp, so we recommend returning the class instance pointer
    // 声明创建当前层HelloWorld所在场景的静态函数createScene()
    static cocos2d::Scene* createScene();

    // Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone
    virtual bool init();//初始化层的实例函数
    
    // a selector callback
    void menuCloseCallback(cocos2d::Ref* pSender);//声明菜单回掉函数，用于触摸菜单时间的回掉
    
    // implement the "static create()" method manually
    CREATE_FUNC(HelloWorld);//创建一个静态函数create，可以创建层
};

#endif // __HELLOWORLD_SCENE_H__

        
        
        HelloWorldScene.cpp

#include "HelloWorldScene.h"

USING_NS_CC;

/*
    *做了三件事，首先创建HelloWorld层所在的场景对象
    *其次创建类HelloWorld层
    *最后将HelloWorld层添加到场景scene中
*/
Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();//创建HelloWorld层所在的场景对象
    
    // 'layer' is an autorelease object
    auto layer = HelloWorld::create();//创建类HelloWorld层

    // add layer as a child to scene
    scene->addChild(layer);//最后将HelloWorld层添加到场景scene中

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    //初始化父类Layer
    if ( !Layer::init() )
    {
        return false;
    }
    
    //定义视图的可视化尺寸
    Size visibleSize = Director::getInstance()->getVisibleSize();
    //定义视图的可视化原点
    Vec2 origin = Director::getInstance()->getVisibleOrigin();

    /////////////////////////////
    // 2. add a menu item with "X" image, which is clicked to quit the program
    //    you may modify it.

    // add a "close" icon to exit the progress. it's an autorelease object
    //增加一个菜单项，单击它的时候退出程序
    //创建一个图片菜单项对象，单击该菜单项的时候回掉menuCloseCallback函数
    auto closeItem = MenuItemImage::create(
                                           "CloseNormal.png",
                                           "CloseSelected.png",
                                           CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
    //菜单项的位置
    closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
                                origin.y + closeItem->getContentSize().height/2));

    // create menu, it's an autorelease object
    //创建Menu菜单对象
    auto menu = Menu::create(closeItem, NULL);
    //定义菜单对象的位置
    menu->setPosition(Vec2::ZERO);
    //把菜单项对象添加到当前层上
    this->addChild(menu, 1);

    /////////////////////////////
    // 3. add your codes below...

    // add a label shows "Hello World"
    // create and initialize a label
    //在下面添加自己的代码
    //创建一个LabelTTF标签对象
    auto label = LabelTTF::create("Hello World", "Arial", 24);
    
    // position the label on the center of the screen
    //设置标签对象位置为水平居中，在垂直方向上与屏幕顶对齐
    label->setPosition(Vec2(origin.x + visibleSize.width/2,
                            origin.y + visibleSize.height - label->getContentSize().height));

    // add the label as a child to this layer
    //将文本对象添加到层中
    this->addChild(label, 1);

    // add "HelloWorld" splash screen"
    //创建精灵Sprite对象
    auto sprite = Sprite::create("HelloWorld.png");

    // position the sprite on the center of the screen
    //设置精灵对象的位置，是屏幕的中央
    sprite->setPosition(Vec2(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));

    // add the sprite as a child to this layer
    //将精灵添加到层中
    this->addChild(sprite, 0);
    
    return true;

}


void HelloWorld::menuCloseCallback(Ref* pSender)
{
    //CC_TARGET_PLATFORM读取当前运行的平台的宏
#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
}