1、Cocos2d-x程序运行过程

Cocos2d-x工程组织形式如图所示：

Classes一般用来放用户自己编写的类。在Win32下，可以看到main.cpp和main.h两个文件，程序的入口就是在main.cpp中。

int APIENTRY _tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR    lpCmdLine,int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // create the application instance
    AppDelegate app;
    CCEGLView* eglView = CCEGLView::sharedOpenGLView();
    eglView->setViewName("block");
    eglView->setFrameSize(320,480);
    return CCApplication::sharedApplication()->run();
}

在CCAppliction.cpp中：

CCApplication* CCApplication::sharedApplication()
{
    CC_ASSERT(sm_pSharedApplication);
    return sm_pSharedApplication;
}

// sharedApplication pointer
CCApplication * CCApplication::sm_pSharedApplication = 0;

那么该成员是在那创建的!? 首先需要了解下面这几个类：

AppDelegate – app代理类，继承自CCApplication

class AppDelegate:privatecocos2d::CCApplication

CCApplication – app应用类，继承自CCApplicationProtocol

class CC_DLLCCApplication:public CCApplicationProtocol

CCApplicationProtocol是一个虚类，定义了一些接口函数

class CC_DLL CCApplicationProtocol
{
public:
	virtual ~CCApplicationProtocol() {}
	virtual bool applicationDidFinishLaunching() = 0;
	virtual void applicationDidEnterBackground() = 0;
	virtual void applicationWillEnterForeground() = 0;
	virtual void setAnimationInterval(double interval) = 0;
	virtual ccLanguageType getCurrentLanguage() = 0;
	virtual TargetPlatform getTargetPlatform() = 0;
};

上图就表示出了整个的过程，有个问题就是sm_pSharedApplication = this，那么这个this代表的究竟是什么意思呢？

上述中的this应该事项的是CCApplication的父类，也就是AppDelegate，因为在构造的过程中先去构造父类，父类构造后再构造子类。实际上就是使用AppDelegate类来进行设计。

在CCAplication::run()中通过调用applicationDidFinishLaunching()来启动程序，也就是网上很多资料都说的程序入口。

int CCApplication::run()
{
    PVRFrameEnableControlWindow(false);

    // Main message loop:
    MSG msg;
    LARGE_INTEGER nFreq;
    LARGE_INTEGER nLast;
    LARGE_INTEGER nNow;

    QueryPerformanceFrequency(&nFreq);
    QueryPerformanceCounter(&nLast);

    // Initialize instance and cocos2d.
    if (!applicationDidFinishLaunching())
    {
        return 0;
    }

    CCEGLView* pMainWnd = CCEGLView::sharedOpenGLView();
    pMainWnd->centerWindow();
    ShowWindow(pMainWnd->getHWnd(),SW_SHOW);

    while (1)
    {
        if (! PeekMessage(&msg,NULL,PM_REMOVE))
        {
            // Get current time tick.
            QueryPerformanceCounter(&nNow);

            // If it's the time to draw next frame,draw it,else sleep a while.
            if (nNow.QuadPart - nLast.QuadPart > m_nAnimationInterval.QuadPart)
            {
                nLast.QuadPart = nNow.QuadPart;
                CCDirector::sharedDirector()->mainLoop();
            }
            else
            {
                Sleep(0);
            }
            continue;
        }

        if (WM_QUIT == msg.message)
        {
            // Quit message loop.
            break;
        }

        // Deal with windows message.
        if (! m_hAccelTable || ! TranslateAccelerator(msg.hwnd,m_hAccelTable,&msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int) msg.wParam;
}

对于cocos2d的用户来说：

在applicationDidFinishLaunching中调用自己设计的场景类就可以实现自己想要的功能。

bool AppDelegate::applicationDidFinishLaunching() {
    // initialize director
    CCDirector* pDirector = CCDirector::sharedDirector();
    CCEGLView* pEGLView = CCEGLView::sharedOpenGLView();

    pDirector->setOpenGLView(pEGLView);
	//pEGLView->setDesignResolutionSize(480,320,kResolutionUnKnown);
	pEGLView->setDesignResolutionSize(320,480,kResolutionShowAll);
    // turn on display FPS
    pDirector->setDisplayStats(true);
    // set FPS. the default value is 1.0/60 if you don't call this
    pDirector->setAnimationInterval(1.0 / 60);

    // create a scene. it's an autorelease object
	CCScene *pScene = MainScene::CreateScene();

    // run
    pDirector->runWithScene(pScene);

    return true;
}

2、Cocos2d的逻辑结构

Cocos2d游戏是通过一系列的元素来进行定义的，其中包括：导演，场景，层，演员。元素具有以下特点：

一个导演同一时间只能运行一个场景；

一个场景当中，可以同时加载多个层；

一个层同可以加载多个精灵；

层中还可以加层。