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：

cpp 复制代码

// 定义在 C:\UnrealEngine-5.6.1-release\Engine\Plugins\Runtime\GameFeatures\Source\GameFeatures\Public\GameFeatureData.h
UCLASS(MinimalAPI)
class UGameFeatureData : public UPrimaryDataAsset
{
    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：

复制代码

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：

cpp 复制代码

// 定义在 LyraGameFeaturePolicy.cpp
void ULyraGameFeature_AddGameplayCuePaths::OnGameFeatureRegistering(const UGameFeatureData* GameFeatureData, const FString& PluginName, const FString& PluginURL)
{
    for (const UGameFeatureAction* Action : GameFeatureData->GetActions())
    {
        if (const UGameFeatureAction_AddGameplayCuePath* AddGameplayCueGFA = Cast<UGameFeatureAction_AddGameplayCuePath>(Action))
        {
            // 添加 GameplayCue 路径
            const TArray<FDirectoryPath>& DirsToAdd = AddGameplayCueGFA->GetDirectoryPathsToAdd();
            if (ULyraGameplayCueManager* GCM = ULyraGameplayCueManager::Get())
            {
                for (const FDirectoryPath& 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：

cpp 复制代码

// 定义在 LyraGameFeaturePolicy.cpp
void ULyraGameFeature_HotfixManager::OnGameFeatureLoading(const UGameFeatureData* GameFeatureData, const FString& 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：

cpp 复制代码

// 定义在 GameFeatureAction_AddAbilities.cpp
void UGameFeatureAction_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：

json 复制代码

{
    "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：

cpp 复制代码

// 定义在 ShooterCoreRuntimeModule.cpp
void FShooterCoreRuntimeModule::StartupModule()
{
    // 模块初始化逻辑
}

void FShooterCoreRuntimeModule::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：

cpp 复制代码

// 定义在 LyraGameFeaturePolicy.h
UCLASS(MinimalAPI, Config = Game)
class ULyraGameFeaturePolicy : public UGameFeaturesProjectPolicies
{
    GENERATED_BODY()
    
public:
    // 获取单例实例
    static ULyraGameFeaturePolicy& Get();
    
    // 初始化游戏特性管理器
    virtual void InitGameFeatureManager() override;
    
    // 关闭游戏特性管理器
    virtual void ShutdownGameFeatureManager() override;
    
    // 获取游戏特性加载模式
    virtual void GetGameFeatureLoadingMode(bool& bLoadClientData, bool& bLoadServerData) const override;
};

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。