cocos2dx v3.0 主循环

<pre name="code" class="cpp">int Application::run(){    // Initialize instance and cocos2d.    if (! applicationDidFinishLaunching())    {        return 0;    }    long lastTime = 0L;    long curTime = 0L;    auto director = Director::getInstance();    auto glview = director->getOpenGLView();    // Retain glview to avoid glview being released in the while loop    glview->retain();    while (!glview->windowShouldClose())    {        lastTime = getCurrentMillSecond();        //1? director循环</span>        director->mainLoop();        //2?  这里的glview就是AppDelegate.cpp中GLView::create得到、并使用Director::setOpenGLView设置的。</span>        //在许多平台下没这函数。。</span>        glview->pollEvents();        //sleep， 使得达到指定帧率。 帧率是由cpu及所需的运算量决定。</span>        curTime = getCurrentMillSecond();        if (curTime - lastTime < _animationInterval)        {            usleep((_animationInterval - curTime + lastTime)*1000);        }    }    /* Only work on Desktop    *  Director::mainLoop is really one frame logic    *  when we want to close the window, we should call Director::end();    *  then call Director::mainLoop to do release of internal resources    */    if (glview->isOpenGLReady())    {        director->end();        director->mainLoop();        director = nullptr;    }    glview->release();    return -1;}void DisplayLinkDirector::mainLoop(){    //调用Director::end时才为true。</span>    if (_purgeDirectorInNextLoop)    {        _purgeDirectorInNextLoop = false;        purgeDirector();    }    else if (! _invalid)    {//_invalid. 初始值为false。 当StartAnimation时为false， StopAnimation时为true。</span>        //3 ....</span>        drawScene();             // release the objects</span>        //对当前AutoReleasePool中所有object调用一次release</span>        PoolManager::getInstance()->getCurrentPool()->clear();    }}void Director::drawScene(){    // calculate "global" dt</span>    //计算_deltaTime。 也就是本次drawScene与上次调用drawScene的时间差。</span>    calculateDeltaTime();        // skip one flame when _deltaTime equal to zero.    if(_deltaTime < FLT_EPSILON)    {        return;    }    if (_openGLView)    {   //在许多平台下， 该函数没有或者为空。        _openGLView->pollInputEvents();    }    //tick before glClear: issue #533    if (! _paused)//Dierctor::pause时设置该值为true； Director::resume时设置该值为false    {        //update的逻辑：</span>        //对_updateNegList, _update0List, _updatePosList 三种priority的调用回调。 这三种都是使用Schedule::scheduleUpdate加入的定时器</span>        //对_hashForTimers调用回调。 这种是使用Schedule::schedule加入的定时器。</span>        //然后依次从<span style="font-family: Arial, Helvetica, sans-serif;">_updateNegList, _update0List, _updatePosList中删除需要删除的定时器</span></span>        _scheduler->update(_deltaTime);        //dispatch逻辑</span>        //如果Event::Type::TOUCH， 找到单点触摸的listener和多点触摸的listener； 先执行单点触摸的回调， 然后执行多点触摸的回调</span>        //否则可能为ACCELERATION/CUSTOM/KEYBOARD/MOUSE，找到对应的listener的associateNode， 执行_onEvent，如果返回_onEvent返回true、且调用了Event::stopPropagation()， 则不再向后传递事件。游戏开发之旅上说的是调用EventListener::setSwallowTouches(false)。</span>        _eventDispatcher->dispatchEvent(_eventAfterUpdate);    }    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    /* to avoid flickr, nextScene MUST be here: after tick and before draw.     XXX: Which bug is this one. It seems that it can't be reproduced with v0.9 */    //如果调用了replaceScene/push/pop/popToSceneStackLevel之后， _nextScene就有效。</span>    if (_nextScene)    {        setNextScene();    }    kmGLPushMatrix();    // global identity matrix is needed... come on kazmath!    kmMat4 identity;    kmMat4Identity(&identity);    // draw the scene    //_runingScene始终有效。 只有当刚Director::init时以及Director::purgeDirector时才会被设为NULL</span>    if (_runningScene)    {        _runningScene->visit(_renderer, identity, false);        _eventDispatcher->dispatchEvent(_eventAfterVisit);    }    // draw the notifications node    //是被Director::setNotificationNode设置的Node</span>    if (_notificationNode)    {        //!!!!这里是绘制。将children按zOrder排序递归绘制： 先绘制_localZOrder<0的childrenNode；然后绘制自己；再绘制剩下的childrenNode</span>        //这里的绘制， 只是将Node的{_globalZOrder, _texture->getName(), _shaderProgram, _blendFunc,...>构造成一个QuadCommand，放入 Rendererde 的容器中</span>        _notificationNode->visit(_renderer, identity, false);    }    if (_displayStats)    {//显示统计信息。 Director::setDisplayStats(true);        showStats();    }     //!!!!这里是真正的绘制。。 这里有BatchCommand之类的处理。</span>    _renderer->render();    _eventDispatcher->dispatchEvent(_eventAfterDraw);    kmGLPopMatrix();    _totalFrames++;    // swap buffers    if (_openGLView)    {        _openGLView->swapBuffers();    }    if (_displayStats)    {        calculateMPF();    }}