分析cocos2dx 3.3运行流程

概述<1>不管在哪个平台xode也好，windows下也好，都先进入: cocos2d::Application *app =cocos2d::Application::getInstance(); app->run(); intApplication::run() {     if (applicationDidFinishLaunching())      {         [[CCDirect

<1>不管在哪个平台xode也好，windows下也好，都先进入:

cocos2d::Application *app =Application::getInstance();

app->run();

intApplication::run()

{

if (applicationDIDFinishLaunching())

{

[[CCDirectorCallersharedDirectorCaller]startMainLoop];

}

return0;

}

<2>在开始游戏循环之前，先进入,进行分辨率设置

boolAppDelegate::applicationDIDFinishLaunching() {

// initialize director

auto director =Director::getInstance();

auto glvIEw = director->getopenGLVIEw();

if(!glvIEw) {

glvIEw = GLVIEwImpl::create("Cpp Empty Test");

director->setopenGLVIEw(glvIEw);

}

director->setopenGLVIEw(glvIEw);

// Set the design resolution

glvIEw->setDesignResolutionSize(designResolutionSize.wIDth,designResolutionSize.height,ResolutionPolicy::NO_border);

Size frameSize = glvIEw->getFrameSize();

vector<string> searchPath;

// In this demo,we select resource according to the frame's height.

// If the resource size is different from design resolution size,you need to set contentScaleFactor.

// We use the ratio of resource's height to the height of design resolution,

// this can make sure that the resource's height Could fit for the height of design resolution.

// if the frame's height is larger than the height of medium resource size,select large resource.

if (frameSize.height >mediumResource.size.height)

{

searchPath.push_back(largeResource.directory);

director->setContentScaleFactor(MIN(largeResource.size.height/designResolutionSize.height,largeResource.size.wIDth/designResolutionSize.wIDth));

}

// if the frame's height is larger than the height of small resource size,select medium resource.

elseif (frameSize.height >smallResource.size.height)

{

searchPath.push_back(mediumResource.directory);

director->setContentScaleFactor(MIN(mediumResource.size.height/designResolutionSize.height,mediumResource.size.wIDth/designResolutionSize.wIDth));

}

// if the frame's height is smaller than the height of medium resource size,select small resource.

else

{

searchPath.push_back(smallResource.directory);

director->setContentScaleFactor(MIN(smallResource.size.height/designResolutionSize.height,smallResource.size.wIDth/designResolutionSize.wIDth));

}

// set searching path

fileUtils::getInstance()->setSearchPaths(searchPath);

// turn on display FPS

director->setdisplayStats(true);

// set FPS. the default value is 1.0/60 if you don't call this

director->setAnimationInterval(1.0 /60);

// create a scene. it's an autorelease object

auto scene =HelloWorld::scene();

// run

director->runWithScene(scene);

returntrue;

}

<3>资源分辨率设置过之后，每一帧调用一次函数doCaller

-(voID) startMainLoop

{

// Director::setAnimationInterval() is called,we should invalIDate it first

[selfstopMainLoop];

displaylink = [NSClassFromString(@"CAdisplaylink")displaylinkWithTarget:selfselector:@selector(doCaller:)];

[displaylinksetFrameInterval:self.interval];

[displaylinkaddToRunLoop:[NSRunLoopcurrentRunLoop]forMode:NSDefaultRunLoopMode];

}

<4>每一帧都进行mainLoop函数

-(voID) doCaller: (ID) sender

{

cocos2d::Director* director =cocos2d::Director::getInstance();

[EAGLContextsetCurrentContext: [(CCEAGLVIEw*)director->getopenGLVIEw()->getEAGLVIEw()context]];

director->mainLoop();

}

<5>

voIDdisplaylinkDirector::mainLoop()

{

if (_purgeDirectorInNextLoop)

{

_purgeDirectorInNextLoop =false;

purgeDirector();

}

elseif (_restartDirectorInNextLoop)

{

_restartDirectorInNextLoop =false;

restartDirector();

}

elseif (! _invalID)

{

drawScene();

// release the objects

PoolManager::getInstance()->getCurrentPool()->clear();

}

}

<6>绘制玩每一帧都，都会被刚添加到自动管理池autoReleasePool中的对象进行一次遍历。

voID autoreleasePool::clear()

{

#if defined(COCOS2D_DEBUG) && (COCOS2D_DEBUG > 0)

_isClearing = true;

#endif

std::vector<Ref*> releasings;

releasings.swap(_managedobjectArray);

for (const auto &obj : releasings)

{

obj->release();

}

_isClearing = false;

#endif

}

总结：

std::vector<Ref*> releasings;

releasings.swap(_managedobjectArray);

这行代码很有意思，将releasings和_managedobjectArray内容进行交换，交换后，_managedobjectArray就为空了，然后将releasings遍历一遍，将引用计数减去1，为0的就回收内存了。

<7>

// Draw the Scene

voIDDirector::drawScene()

{

// calculate "global" dt

calculateDeltaTime();

if (_openGLVIEw)

{

_openGLVIEw->pollEvents();

}

//tick before glClear: issue #533

if (!_paused)

{

_scheduler->update(_deltaTime);

_eventdispatcher->dispatchEvent(_eventAfterUpdate);

}

_renderer->clear();

experimental::FrameBuffer::clearallFBOs();

/* to avoID flickr,nextScene MUST be here: after tick and before draw.

* FIXME: Which BUG is this one. It seems that it can't be reproduced with v0.9

*/

if (_nextScene)

{

setNextScene();

}

pushmatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

if (_runningScene)

{

#if (CC_USE_PHYSICS || (CC_USE_3D_PHYSICS && CC_ENABLE_BulLET_INTEGRATION) || CC_USE_NAVMESH)

_runningScene->stepPhysicsAndNavigation(_deltaTime);

#endif

//clear draw stats

_renderer->clearDrawStats();

//render the scene

_runningScene->render(_renderer);

_eventdispatcher->dispatchEvent(_eventAfterVisit);

}

// draw the notifications node

if (_notificationNode)

{

_notificationNode->visit(_renderer,Mat4::IDENTITY,0);

}

if (_displayStats)

{

showStats();

}

_renderer->render();

_eventdispatcher->dispatchEvent(_eventAfterDraw);

popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

_totalFrames++;

// swap buffers

if (_openGLVIEw)

{

_openGLVIEw->swapBuffers();

}

if (_displayStats)

{

calculateMPF();

}

}

<8>在Scene中调用其render方法回执场景。

voIDScene::render(Renderer* renderer)

{

auto director =Director::getInstance();

Camera* defaultCamera =nullptr;

constauto& transform =getNodetoParenttransform();

for (constauto& camera :getCameras())

{

if (!camera->isVisible())

continue;

Camera::_visitingCamera = camera;

if (Camera::_visitingCamera->getCameraFlag() == CameraFlag::DEFAulT)

{

defaultCamera = Camera::_visitingCamera;

}

director->pushmatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);

director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION,Camera::_visitingCamera->getVIEwProjectionMatrix());

camera->apply();

//clear background with max depth

camera->clearBackground();

//visit the scene

visit(renderer,transform,0);

#if CC_USE_NAVMESH

if (_navMesh &&_navMeshDeBUGCamera == camera)

{

_navMesh->deBUGDraw(renderer);

}

#endif

renderer->render();

director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);

}

#if CC_USE_3D_PHYSICS && CC_ENABLE_BulLET_INTEGRATION

if (_physics3DWorld &&_physics3DWorld->isDeBUGDrawEnabled())

{

_physics3dDeBUGCamera !=nullptr ?_physics3dDeBUGCamera->getVIEwProjectionMatrix() : defaultCamera->getVIEwProjectionMatrix());

_physics3DWorld->deBUGDraw(renderer);

renderer->render();

director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);

}

#endif

Camera::_visitingCamera =nullptr;

experimental::FrameBuffer::applyDefaultFBO();

}

<9>Scene其实也是一个Node，递归绘制自身及其子节点

voIDNode::visit(Renderer* renderer,constMat4 &parenttransform,uint32_t parentFlags)

{

// quick return if not visible. children won't be drawn.

if (!_visible)

{

return;

}

uint32_t flags =processparentFlags(parenttransform,parentFlags);

// important:

// To ease the migration to v3.0,we still support the Mat4 stack,0)"> // but it is deprecated and your code should not rely on it

_director->pushmatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

_director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW,_modelVIEwtransform);

bool visibleByCamera =isVisitableByVisitingCamera();

int i =0;

if(!_children.empty())

{

sortAllChildren();

// draw children zOrder < 0

for( ; i <_children.size(); i++ )

{

auto node =_children.at(i);

if (node && node->_localZOrder <0)

node->visit(renderer,_modelVIEwtransform,flags);

else

break;

}

// self draw

if (visibleByCamera)

this->draw(renderer,flags);

for(auto it=_children.cbegin()+i; it != _children.cend(); ++it)

(*it)->visit(renderer,flags);

}

elseif (visibleByCamera)

{

this->draw(renderer,flags);

}

_director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

// FIX ME: Why need to set _orderOfArrival to 0??

// Please refer tohttps://github.com/cocos2d/cocos2d-x/pull/6920

// reset for next frame

// _orderOfArrival = 0;

}

首先绘制_localZOrder < 0的，其次在for(autoit=_children.cbegin()+i; it !=cend(); ++it)绘制 >=0 的
<10>

voIDNode::sortAllChildren()

{

if (_reorderChildDirty)

{

std::sort(std::begin(_children),std::end(_children),nodeComparisonLess);

_reorderChildDirty =false;

}

}

bool nodeComparisonLess(Node* n1,Node* n2)

{

return( n1->getLocalZOrder() < n2->getLocalZOrder() ||

( n1->getLocalZOrder() == n2->getLocalZOrder() && n1->getorderOfArrival() < n2->getorderOfArrival() )

);

}

总结

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