3.1 第一个场景 HelloWorldScene

HelloWorldScene.h

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"
#include "Box2D/Box2D.h"
#include "SimpleAudioEngine.h"

class HelloWorld : public cocos2d::CCLayer
{
public:
    // Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone
    virtual bool init();  

    // there's no 'id' in cpp, so we recommand to return the exactly class pointer
    static cocos2d::CCScene* scene();
    
    // a selector callback
    void menuCloseCallback(CCObject* pSender);

    // implement the "static node()" method manually
    CREATE_FUNC(HelloWorld);
};

#endif  // __HELLOWORLD_SCENE_H__

HelloWorldScene.cpp

#include "HelloWorldScene.h"
using namespace cocos2d;


CCScene* HelloWorld::scene()
{
    CCScene * scene = NULL;
    do 
    {
        // 'scene' is an autorelease object
        scene = CCScene::create();
        CC_BREAK_IF(! scene);

        // 'layer' is an autorelease object
        HelloWorld *layer = HelloWorld::create();
        CC_BREAK_IF(! layer);

        // add layer as a child to scene
        scene->addChild(layer);
    } while (0);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    bool bRet = false;
    do 
    {
        //p1 = this;
        //////////////////////////////////////////////////////////////////////////
        // super init first
        //////////////////////////////////////////////////////////////////////////

        CC_BREAK_IF(! CCLayer::init());

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

        // 1. Add a menu item with "X" image, which is clicked to quit the program.

        // Create a "close" menu item with close icon, it's an auto release object.
        CCMenuItemImage *pCloseItem = CCMenuItemImage::create(
            "CloseNormal.png",
            "CloseSelected.png",
            this,
            menu_selector(HelloWorld::menuCloseCallback));
        CC_BREAK_IF(! pCloseItem);

        // Place the menu item bottom-right conner.
        pCloseItem->setPosition(ccp(CCDirector::sharedDirector()->getWinSize().width - 20, 20));

        // Create a menu with the "close" menu item, it's an auto release object.
        CCMenu* pMenu = CCMenu::create(pCloseItem, NULL);
        pMenu->setPosition(CCPointZero);
        CC_BREAK_IF(! pMenu);

        // Add the menu to HelloWorld layer as a child layer.
        this->addChild(pMenu, 1);

        // 2. Add a label shows "Hello World".

        // Create a label and initialize with string "Hello World".
        CCLabelTTF* pLabel = CCLabelTTF::create("Hello World", "Arial", 24);
        CC_BREAK_IF(! pLabel);

        // Get window size and place the label upper. 
        CCSize size = CCDirector::sharedDirector()->getWinSize();
        pLabel->setPosition(ccp(size.width / 2, size.height - 50));

        // Add the label to HelloWorld layer as a child layer.
        this->addChild(pLabel, 1);

        // 3. Add add a splash screen, show the cocos2d splash image.
        CCSprite* pSprite = CCSprite::create("HelloWorld.png");
        CC_BREAK_IF(! pSprite);

        // Place the sprite on the center of the screen
        pSprite->setPosition(ccp(size.width/2, size.height/2));

        // Add the sprite to HelloWorld layer as a child layer.
        this->addChild(pSprite, 0);

        bRet = true;
    } while (0);

    return bRet;
}

void HelloWorld::menuCloseCallback(CCObject* pSender)
{
    // "close" menu item clicked
    CCDirector::sharedDirector()->end();
}

这是一个 cocos2d-x 引擎使用者 最初级的入门篇章， 上面的注释已经很清楚了，没什么难点，你会看懂的 believe yourself！！！ Come on ， baby.

下面看一下 CREATE_FUNC 这个宏的定义：

/**
 * define a create function for a specific type, such as CCLayer
 * @__TYPE__ class type to add create(), such as CCLayer
 */
#define CREATE_FUNC(__TYPE__) 
static __TYPE__* create() 
{ 
    __TYPE__ *pRet = new __TYPE__(); 
    if (pRet && pRet->init()) 
    { 
        pRet->autorelease(); 
        return pRet; 
    } 
    else 
    { 
        delete pRet; 
        pRet = NULL; 
        return NULL; 
    } 
}

看似高端 大气 上档次 ， 其实也很容易理解 

定义 CREATE_FUNC

创建实例（new） 

判断成功与否（if）  自动释放内存（autorelease）   返回实例（return） 
创建失败（else）   删除实例（delete）