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GameManager
mApplication = 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));}
}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 needif(mFirstFrame){#ifndef MULTITHREAD_FIX_HACK_BREAKS_CEGUIdtCore::ObserverPtr<osgViewer::GraphicsWindow> gw;if (GetWindow() != NULL){gw = GetWindow()->GetOsgViewerGraphicsWindow();}if (!singleThreaded && gw.valid() && gw->isRealized()){gw->releaseContext();}
#endifif (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();}
}
