Lyra Starter Game 中 GameFeature 类（如 ShooterCore）的加载流程
Lyra Starter Game 中 GameFeature 类（如 ShooterCore）的加载流程
1. GameFeature 系统概述
GameFeature 是 Unreal Engine 5 的一个核心插件系统，用于模块化地扩展游戏功能。在 Lyra Starter Game 中，ShooterCore 是一个典型的 GameFeature 插件，它提供了射击游戏的核心玩法系统。
2. GameFeature 核心组件
2.1 UGameFeatureData 类
UGameFeatureData 是 GameFeature 的核心数据资产类，定义在引擎的 GameFeatures 插件中：
// 定义在 C:\UnrealEngine-5.6.1-release\Engine\Plugins\Runtime\GameFeatures\Source\GameFeatures\Public\GameFeatureData.hUCLASS(MinimalAPI)classUGameFeatureData:publicUPrimaryDataAsset{GENERATED_BODY()// 游戏特性的主要行为定义UPROPERTY(EditDefaultsOnly,Instanced,Category="Game Feature | Actions")TArray<TObjectPtr<UGameFeatureAction>>Actions;// 需要扫描的主资产类型UPROPERTY(EditAnywhere,Category="Game Feature | Asset Manager")TArray<FPrimaryAssetTypeInfo>PrimaryAssetTypesToScan;};2.2 UGameFeatureAction 类
UGameFeatureAction 是 GameFeature 的具体行为实现，每个 GameFeatureData 包含多个 Action，用于执行特定功能：
GameFeatureAction_AddAbilities：添加游戏能力GameFeatureAction_AddInputBinding：添加输入绑定GameFeatureAction_AddWidget：添加 UI 控件GameFeatureAction_AddGameplayCuePath：添加游戏玩法提示路径
3. ShooterCore 插件结构
ShooterCore 插件是一个典型的 GameFeature 插件，其结构如下：
ShooterCore/ ├── Content/ │ └── ShooterCore.uasset # GameFeatureData 配置文件 ├── Source/ │ └── ShooterCoreRuntime/ # 运行时代码 │ ├── Private/ # 私有实现 │ └── Public/ # 公共接口 └── ShooterCore.uplugin # 插件描述文件4. GameFeature 加载流程
4.1 插件注册阶段
- 插件发现：引擎启动时，会扫描所有已启用的 GameFeature 插件
- GameFeatureData 加载：为每个 GameFeature 插件加载其 GameFeatureData 配置文件（如 ShooterCore.uasset）
- 观察者通知：调用所有观察者的
OnGameFeatureRegistering方法
Lyra 项目中，ULyraGameFeature_AddGameplayCuePaths是一个观察者，用于在注册阶段添加 GameplayCue 路径：
// 定义在 LyraGameFeaturePolicy.cppvoidULyraGameFeature_AddGameplayCuePaths::OnGameFeatureRegistering(constUGameFeatureData*GameFeatureData,constFString&PluginName,constFString&PluginURL){for(constUGameFeatureAction*Action:GameFeatureData->GetActions()){if(constUGameFeatureAction_AddGameplayCuePath*AddGameplayCueGFA=Cast<UGameFeatureAction_AddGameplayCuePath>(Action)){// 添加 GameplayCue 路径constTArray<FDirectoryPath>&DirsToAdd=AddGameplayCueGFA->GetDirectoryPathsToAdd();if(ULyraGameplayCueManager*GCM=ULyraGameplayCueManager::Get()){for(constFDirectoryPath&Directory:DirsToAdd){FString MutablePath=Directory.Path;UGameFeaturesSubsystem::FixPluginPackagePath(MutablePath,PluginRootPath,false);GCM->AddGameplayCueNotifyPath(MutablePath,false);}// 重新构建运行时库GCM->InitializeRuntimeObjectLibrary();}}}}4.2 插件加载阶段
- 依赖检查：检查插件的依赖是否已满足
- 资源预加载：根据 GameFeatureData 配置预加载所需资源
- 观察者通知：调用所有观察者的
OnGameFeatureLoading方法
Lyra 项目中，ULyraGameFeature_HotfixManager是一个观察者，用于在加载阶段处理热修复：
// 定义在 LyraGameFeaturePolicy.cppvoidULyraGameFeature_HotfixManager::OnGameFeatureLoading(constUGameFeatureData*GameFeatureData,constFString&PluginURL){if(ULyraHotfixManager*HotfixManager=Cast<ULyraHotfixManager>(UOnlineHotfixManager::Get(nullptr))){HotfixManager->RequestPatchAssetsFromIniFiles();}}4.3 插件激活阶段
- Action 激活：遍历 GameFeatureData 中的所有 GameFeatureAction，调用它们的
OnGameFeatureActivating方法 - 世界集成：将 GameFeature 集成到当前游戏世界中
- 观察者通知：调用所有观察者的
OnGameFeatureActivating方法
以GameFeatureAction_AddAbilities为例，它会在激活时为指定的 Actor 类添加能力：
// 定义在 GameFeatureAction_AddAbilities.cppvoidUGameFeatureAction_AddAbilities::OnGameFeatureActivating(FGameFeatureActivatingContext&Context){FPerContextData&ActiveData=ContextData.FindOrAdd(Context);if(!ensureAlways(ActiveData.ActiveExtensions.IsEmpty())||!ensureAlways(ActiveData.ComponentRequests.IsEmpty())){Reset(ActiveData);}Super::OnGameFeatureActivating(Context);}4.4 插件运行阶段
GameFeature 激活后，其定义的功能（如能力、输入、UI 等）将在游戏中生效。
4.5 插件停用阶段
- Action 停用：遍历 GameFeatureData 中的所有 GameFeatureAction，调用它们的
OnGameFeatureDeactivating方法 - 资源清理：清理 GameFeature 使用的资源
- 观察者通知：调用所有观察者的
OnGameFeatureDeactivating方法
4.6 插件卸载阶段
- 资源卸载：卸载 GameFeature 使用的资源
- 插件移除：从系统中移除 GameFeature
- 观察者通知：调用所有观察者的
OnGameFeatureUnregistering方法
5. ShooterCore 插件的具体加载流程
5.1 插件描述文件
ShooterCore.uplugin 定义了插件的基本信息和依赖：
{"FileVersion":3,"Version":1,"VersionName":"1.0","FriendlyName":"ShooterCore","Description":"Gameplay systems for Game1 / Shooter Game","Category":"Game Features","ExplicitlyLoaded":true,"EnabledByDefault":false,"BuiltInInitialFeatureState":"Registered","Modules":[{"Name":"ShooterCoreRuntime","Type":"Runtime","LoadingPhase":"Default"}],"Plugins":[{"Name":"GameplayAbilities","Enabled":true},{"Name":"ModularGameplay","Enabled":true},// 其他依赖插件]}5.2 运行时模块初始化
ShooterCoreRuntimeModule.cpp 定义了模块的初始化和关闭逻辑：
// 定义在 ShooterCoreRuntimeModule.cppvoidFShooterCoreRuntimeModule::StartupModule(){// 模块初始化逻辑}voidFShooterCoreRuntimeModule::ShutdownModule(){// 模块关闭逻辑}5.3 GameFeatureData 配置
ShooterCore.uasset 配置文件包含了 ShooterCore 的所有 GameFeatureAction，如：
- 添加射击游戏的核心能力
- 注册输入映射
- 添加 UI 控件
- 配置游戏玩法提示
6. Lyra 自定义的 GameFeature 策略
LyraGameFeaturePolicy 是 Lyra 项目自定义的 GameFeature 策略类，用于控制 GameFeature 的加载模式和观察者：
// 定义在 LyraGameFeaturePolicy.hUCLASS(MinimalAPI,Config=Game)classULyraGameFeaturePolicy:publicUGameFeaturesProjectPolicies{GENERATED_BODY()public:// 获取单例实例staticULyraGameFeaturePolicy&Get();// 初始化游戏特性管理器virtualvoidInitGameFeatureManager()override;// 关闭游戏特性管理器virtualvoidShutdownGameFeatureManager()override;// 获取游戏特性加载模式virtualvoidGetGameFeatureLoadingMode(bool&bLoadClientData,bool&bLoadServerData)constoverride;};7. 总结
GameFeature 是 Lyra Starter Game 中实现模块化功能扩展的核心机制，ShooterCore 作为一个典型的 GameFeature 插件，其加载流程遵循了 Unreal Engine 5 的 GameFeature 生命周期：
- 注册阶段：发现插件并加载 GameFeatureData
- 加载阶段：检查依赖并预加载资源
- 激活阶段：执行 GameFeatureAction 并集成到游戏世界
- 运行阶段：功能生效
- 停用阶段：清理资源和功能
- 卸载阶段：移除插件
通过这种模块化的设计，Lyra Starter Game 可以灵活地扩展和管理游戏功能，提高代码的可维护性和复用性。
关键文件路径
- GameFeature 核心定义：
C:\UnrealEngine-5.6.1-release\Engine\Plugins\Runtime\GameFeatures\Source\GameFeatures\Public\GameFeatureData.h - Lyra GameFeature 策略：
c:\Users\ChenChao\Documents\GitCode\LyraStarterGame_5.6\Source\LyraGame\GameFeatures\LyraGameFeaturePolicy.h - ShooterCore 插件描述：
c:\Users\ChenChao\Documents\GitCode\LyraStarterGame_5.6\Plugins\GameFeatures\ShooterCore\ShooterCore.uplugin - GameFeatureAction 实现：
c:\Users\ChenChao\Documents\GitCode\LyraStarterGame_5.6\Source\LyraGame\GameFeatures\
通过理解 GameFeature 的加载流程，开发者可以更好地利用这一机制来扩展和定制 Lyra Starter Game 的功能。