cocos2d-x C++ 原始工程引擎運行機制解析

新建一個工程，相信感興趣的同學都想知道cocos引擎都是如何運行的

想知道是如何運行的，看懂四個文件即可

話不多說，上代碼：

1、首先解釋?AppDelegate.h

#ifndef  _APP_DELEGATE_H_
#define  _APP_DELEGATE_H_

#include "cocos2d.h"

/**
@brief    The cocos2d Application.

Private inheritance here hides part of interface from Director.
*/  //從這里可以看到AppDelegate繼承了cocos2d::Application ，而cocos2d::Application是cocos2d-x引擎提供的基類
class  AppDelegate : private cocos2d::Application
{
public:
    AppDelegate();
    virtual ~AppDelegate();
    /*
     
     */
    virtual void initGLContextAttrs();

    /**
    @brief    Implement Director and Scene init code here.
    @return true    Initialize success, app continue.
    @return false   Initialize failed, app terminate.
        *游戲啟動時調用的函數，在這里可以初始化導演對象和場景對象
    */
    virtual bool applicationDidFinishLaunching();

    /**
    @brief  Called when the application moves to the background
    @param  the pointer of the application
        *游戲進入后臺時調用的函數
    */
    virtual void applicationDidEnterBackground();

    /**
    @brief  Called when the application reenters the foreground
    @param  the pointer of the application
        *游戲進入前臺時調用的函數
    */
    virtual void applicationWillEnterForeground();
};

#endif // _APP_DELEGATE_H_

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2、AppDelegate.cpp

#include "AppDelegate.h"
#include "HelloWorldScene.h"USING_NS_CC;//這個是cocos2d－x提供的一個宏，它是用來替換 using namespace cocos2d語句的。static cocos2d::Size designResolutionSize = cocos2d::Size(480, 320);
static cocos2d::Size smallResolutionSize = cocos2d::Size(480, 320);
static cocos2d::Size mediumResolutionSize = cocos2d::Size(1024, 768);
static cocos2d::Size largeResolutionSize = cocos2d::Size(2048, 1536);AppDelegate::AppDelegate()
{
}AppDelegate::~AppDelegate() 
{
}// if you want a different context, modify the value of glContextAttrs
// it will affect all platforms
void AppDelegate::initGLContextAttrs()
{// set OpenGL context attributes: red,green,blue,alpha,depth,stencilGLContextAttrs glContextAttrs = {8, 8, 8, 8, 24, 8};GLView::setGLContextAttrs(glContextAttrs);
}// if you want to use the package manager to install more packages,  
// don't modify or remove this function
static int register_all_packages()
{return 0; //flag for packages manager
}// 游戲啟動時調用的函數
bool AppDelegate::applicationDidFinishLaunching() {// initialize directorauto director = Director::getInstance();//初始化導演類auto glview = director->getOpenGLView();if(!glview) {
#if (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32) || (CC_TARGET_PLATFORM == CC_PLATFORM_MAC) || (CC_TARGET_PLATFORM == CC_PLATFORM_LINUX)glview = GLViewImpl::createWithRect("NotesDamo", cocos2d::Rect(0, 0, designResolutionSize.width, designResolutionSize.height));
#elseglview = GLViewImpl::create("NotesDamo");
#endifdirector->setOpenGLView(glview);//設置導演類的OpenGL視圖
    }// turn on display FPSdirector->setDisplayStats(true);//設置是否在屏幕上顯示幀率信息(一般都是為了測試，實際發布時是不會顯示的)// set FPS. the default value is 1.0/60 if you don't call thisdirector->setAnimationInterval(1.0f / 60);//一秒執行60幀// Set the design resolutionglview->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, ResolutionPolicy::NO_BORDER);auto frameSize = glview->getFrameSize();// if the frame's height is larger than the height of medium size.if (frameSize.height > mediumResolutionSize.height){        director->setContentScaleFactor(MIN(largeResolutionSize.height/designResolutionSize.height, largeResolutionSize.width/designResolutionSize.width));}// if the frame's height is larger than the height of small size.else if (frameSize.height > smallResolutionSize.height){        director->setContentScaleFactor(MIN(mediumResolutionSize.height/designResolutionSize.height, mediumResolutionSize.width/designResolutionSize.width));}// if the frame's height is smaller than the height of medium size.else{        director->setContentScaleFactor(MIN(smallResolutionSize.height/designResolutionSize.height, smallResolutionSize.width/designResolutionSize.width));}register_all_packages();// create a scene. it's an autorelease objectauto scene = HelloWorld::createScene();//創建導演類對象scene// rundirector->runWithScene(scene);//運行該場景(會使游戲進入該場景)return true;
}// This function will be called when the app is inactive. Note, when receiving a phone call it is invoked.//游戲進入后臺時調用的函數
void AppDelegate::applicationDidEnterBackground() {Director::getInstance()->stopAnimation();//停止場景中的動畫// if you use SimpleAudioEngine, it must be paused// 停止背景音樂，默認時注釋掉的// SimpleAudioEngine::getInstance()->pauseBackgroundMusic();
}// this function will be called when the app is active again
// 游戲進入前臺時調用的函數
void AppDelegate::applicationWillEnterForeground() {Director::getInstance()->startAnimation();//開始場景中的動畫// if you use SimpleAudioEngine, it must resume here// 繼續背景音樂的，默認是注釋掉的// SimpleAudioEngine::getInstance()->resumeBackgroundMusic();
}

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3、HelloWorldScene.h

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"


/*
 *在這里我們可以看出，HelloWorld類繼承了cocos2d::Layer類；它被稱為層(layer)，這些層被放到了場景(scene)中，場景類是：cocos2d::Scene；
    注意：HelloWorld.h雖然命名為場景，但是它內部定義的HelloWorld類是一個層
 */
//HelloWorld繼承了cocos2d::Layer，HelloWorld是一個層，而不是場景。
class HelloWorld : public cocos2d::Layer
{
    
public:
    
    static cocos2d::Menu* m_pSelectedItem();
    
    virtual ~HelloWorld(){}
    
    static cocos2d::Scene* createScene();//聲明創建當前的層HelloWorld所在場景的靜態函數createScene()；
    
    virtual bool init();//聲明初始化層HelloWorld實例函數。
    
    // a selector callback
    void menuCloseCallback(cocos2d::Ref* pSender);//聲明菜單回調函數menuCloseCallback，用于觸摸菜單事件的回調。
    
    CREATE_FUNC(HelloWorld);//CREATE_FUNC是cocos2d-x中定義的一個宏(作用是：創建一個靜態函數"static create()"，該函數可以用來創建層)；
    
    
    
    // implement the "static create()" method manually
    
};

#endif // __HELLOWORLD_SCENE_H__

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4、HelloWorldScene.cpp

#include "HelloWorldScene.h"
#include "SimpleAudioEngine.h"

USING_NS_CC;
/*
 說明：createScene()函數式是在游戲應用啟動的時候，在AppDelegate中的bool AppDelegate::applicationDidFinishLaunching()函數中通過 auto scene = HelloWorld::createScene()語句調用的。
    createScene()中做了三件事情，首先創建了HelloWorld層所在的場景對象，其次創建了HelloWorld層，最后將HelloWorld層添加到場景scene中；
 */
Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();
    
    // 'layer' is an autorelease object
    // 當調用到這句創建層的時候，會調用HelloWorld的實例函數init()，達到初始化HelloWorld層的目的。
    auto layer = HelloWorld::create();

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

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //
    // 1. super init first
    // 初始化父類
    if ( !Layer::init() )
    {
        return false;
    }
    
    auto visibleSize = Director::getInstance()->getVisibleSize();
    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
    // 增加一個菜單項，單機的時候退出程序
    auto closeItem = MenuItemImage::create(
                                           "CloseNormal.png",
                                           "CloseSelected.png",
                                           CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
    
    closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
                                origin.y + closeItem->getContentSize().height/2));

    // create menu, it's an autorelease object
    auto menu = Menu::create(closeItem, NULL);
    menu->setPosition(Vec2::ZERO);//自定義菜單對象的位置
    this->addChild(menu, 1);//把菜單對象添加到當前HelloWorld層上

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

    // add a label shows "Hello World"
    // create and initialize a label
    
    //添加label標簽標題
    auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);
    
    // position the label on the center of the screen
    label->setPosition(Vec2(origin.x + visibleSize.width/2,
                            origin.y + visibleSize.height - label->getContentSize().height));

    // add the label as a child to this layer
    this->addChild(label, 1);

    // add "HelloWorld" splash screen"
    //添加精靈，也就是cocos2d-x的logo，定義到屏幕中央
    auto sprite = Sprite::create("HelloWorld.png");

    // position the sprite on the center of the screen
    sprite->setPosition(Vec2(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));

    // add the sprite as a child to this layer
    this->addChild(sprite, 0);
    
    
    return true;
}

// 菜單回調函數(返回主界面)
void HelloWorld::menuCloseCallback(Ref* pSender)
{
    //Close the cocos2d-x game scene and quit the application
    Director::getInstance()->end();

    #if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)//IOS表示iOS平臺
    exit(0);
#endif
    
    /*To navigate back to native iOS screen(if present) without quitting the application  ,do not use Director::getInstance()->end() and exit(0) as given above,instead trigger a custom event created in RootViewController.mm as below*/
    
    //EventCustom customEndEvent("game_scene_close_event");
    //_eventDispatcher->dispatchEvent(&customEndEvent);
    
    
    
    
//    PhysicsShape物理引擎類精靈(也屬于精靈)
    
    
//    節點
    //(1)創建節點
    Node * chilNode = Node::create();
    //(2)查找子節點
    Node *node = node ->getChildByTag(123);
    //(3)增加新的子節點
    node->addChild(chilNode,0,123);
    //(4)刪除子節點，并停止該節點上的一切動作
    node->removeChildByTag(123,true);
    //(5)通過NOde指針刪除節點
    node ->removeChild(node);
    //(6)刪除所有子節點，并停止這些節點上的一切動作
    node ->removeAllChildrenWithCleanup(true);
    //(7)從父節點中刪除 node 節點，并停止該節點上的一切動作。
    node->removeFromParentAndCleanup(true);
    /*Node重要屬性*/
//    setPosition; 坐標
//    setAnchorPoint(Vce2(0.5,.05)); 錨點
    
    
    
    
    //坐標
//    Vec2 touchLocation = touch ->getLocationInView();
//    Vec2 touchLocation2 = Director::getInstance()->convertToGL(touchLocation);
    
    
}


/**
 cocos2d-x的事件響應機制：即菜單層最先接收到系統事件，則排在后面的是精靈層，最后是背景層，在事件的傳遞過程中 ，如果有一個層處理了該事件，則排在后面的層將不再接受到該事件。
 */

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