Delta3d框架学习--程序启动过程详解

一个Delta3d程序启动过程详解

一、初始化一个dtGame::GameApplication的实例，dtGame::GameApplication* app = new dtGame::GameApplication();

设置游戏库的名称，SetGameLibraryName("libname")；

调用app->Config("config.xml");Config内容如下：

//解析GameEntryPoint的dll，获取相关函数指针dtUtil::LibrarySharingManager& lsm = dtUtil::LibrarySharingManager::GetInstance();std::string libName = GetGameLibraryName();mEntryPointLib = lsm.LoadSharedLibrary(libName);dtUtil::LibrarySharingManager::LibraryHandle::SYMBOL_ADDRESS createAddr;dtUtil::LibrarySharingManager::LibraryHandle::SYMBOL_ADDRESS destroyAddr;createAddr = mEntryPointLib->FindSymbol("CreateGameEntryPoint");destroyAddr = mEntryPointLib->FindSymbol("DestroyGameEntryPoint");mCreateFunction  = reinterpret_cast<CreateEntryPointFn>(createAddr);mDestroyFunction = reinterpret_cast<DestroyEntryPointFn>(destroyAddr);//创建Aplication和GameManagermApplication = mEntryPoint->CreateApplication(configFileName);mGameManager = new dtGame::GameManager(*mApplication->GetScene());//执行相关初始化mEntryPoint->Initialize(*mApplication, mArgc, mArgv);mApplication->Config();mEntryPoint->OnStartup(*mApplication, *mGameManager);//开始系统循环dtCore::System::GetInstance().Start(); 

在GameEntryPoint中的OnStartUp函数中将相应的组件添加至游戏管理器GameManager中；

在dtCore::System中有一个定时的循环，在循环中发送相关的消息（System::MESSAGE_FRAME等），然后在dtABC::BaseABC中的OnMessage()中进行消息响应。

void BaseABC::OnMessage(MessageData* data){   if (data->message == dtCore::System::MESSAGE_EVENT_TRAVERSAL)   {      EventTraversal(*static_cast<const double*>(data->userData));   }   else if (data->message == dtCore::System::MESSAGE_PRE_FRAME)   {      PreFrame(*static_cast<const double*>(data->userData));   }   else if (data->message == dtCore::System::MESSAGE_FRAME)   {      Frame(*static_cast<const double*>(data->userData));   }   else if (data->message == dtCore::System::MESSAGE_POST_FRAME)   {      PostFrame(*static_cast<const double*>(data->userData));   }   else if (data->message == dtCore::System::MESSAGE_PAUSE)   {      Pause(*static_cast<const double*>(data->userData));   }}

在Frame函数中进行模型的渲染

void Application::Frame(const double deltaSimTime){   if(!mCompositeViewer->done())   {      bool singleThreaded = mCompositeViewer->getThreadingModel() == osgViewer::ViewerBase::SingleThreaded;      //NOTE: The OSG frame() advances the clock and does three traversals, event, update, and render.      //We are moving the event traversal to be its own message so we can reliably accept input during the      //typical Delta3D update of PreFrame().  The only exception to this is that we need      if(mFirstFrame)      {#ifndef MULTITHREAD_FIX_HACK_BREAKS_CEGUI         dtCore::ObserverPtr<osgViewer::GraphicsWindow> gw;         if (GetWindow() != NULL)         {            gw = GetWindow()->GetOsgViewerGraphicsWindow();         }         if (!singleThreaded && gw.valid() && gw->isRealized())         {            gw->releaseContext();         }#endif         if (singleThreaded) { GetCompositeViewer()->setReleaseContextAtEndOfFrameHint(false); }         mCompositeViewer->setUpThreading();         mCompositeViewer->frame(dtCore::System::GetInstance().GetSimTimeSinceStartup());         mFirstFrame = false;      }      // NOTE: The new version OSG (2.2) relies on absolute frame time      // to update drawables; especially particle systems.      // The time delta will be ignored here and the absolute simulation      // time passed to the OSG scene updater.      mCompositeViewer->advance(dtCore::System::GetInstance().GetSimTimeSinceStartup());      mCompositeViewer->updateTraversal();      mCompositeViewer->renderingTraversals();   }}