XCEngine/docs/used/第四阶段计划_资源系统.md

# 资源系统设计与实现

> **目标**：构建游戏引擎资源管理系统，支持多种资源类型的加载、缓存、异步加载
> **阶段**：第四阶段（与RHI并行开发）
> **前置依赖**：第一阶段核心基础层（容器、内存管理、线程系统）

---

## 0. 类型声明（文档内统一使用）

本文档中使用的类型说明：
- `String` = `XCEngine::Containers::String`
- `Array<T>` = `XCEngine::Containers::Array<T>`
- `HashMap<K,V>` = `XCEngine::Containers::HashMap<K,V>`
- `uint8/uint32/uint64` = `XCEngine::Core::uint8/uint32/uint64`
- `UniquePtr<T>` = `XCEngine::Core::UniqueRef<T>` 或 `std::unique_ptr<T>`
- `SharedPtr<T>` = `XCEngine::Core::Ref<T>` 或 `std::shared_ptr<T>`
- `Mutex` = `XCEngine::Threading::Mutex`
- `ITask` = `XCEngine::Threading::ITask`

---

## 1. 概述

### 1.1 设计目标

资源系统是游戏引擎的核心基础设施之一，负责管理游戏运行时所需的所有数据资产。一个优秀的资源系统需要满足以下目标：

#### 1.1.1 功能性目标

- **统一资源管理**：提供统一的接口来管理不同类型的资源（纹理、网格、材质、音频等）
- **异步加载支持**：支持后台线程异步加载资源，避免阻塞主线程
- **资源缓存机制**：实现智能的资源缓存和淘汰策略，优化内存使用
- **引用计数管理**：通过引用计数自动管理资源生命周期
- **资源依赖管理**：跟踪资源之间的依赖关系，支持资源组加载和批量卸载
- **可扩展架构**：易于添加新的资源类型和加载器

#### 1.1.2 性能目标

- **低内存占用**：通过LRU缓存和按需加载控制内存使用
- **快速加载**：异步加载 + 缓存命中 = 零加载时间
- **线程安全**：多线程环境下安全访问资源
- **零拷贝优化**：尽可能减少不必要的数据拷贝

#### 1.1.3 开发效率目标

- **简单易用的API**：提供清晰的同步/异步加载接口
- **灵活的配置**：支持自定义导入设置和加载选项
- **完善的错误处理**：清晰的错误信息和调试支持

---

## 2. 系统架构

### 2.1 整体架构图

```
┌─────────────────────────────────────────────────────────────────────────────────┐
│                              ResourceSystem                                       │
├─────────────────────────────────────────────────────────────────────────────────┤
│                                                                                 │
│  ┌──────────────────────────────────────────────────────────────────────────┐  │
│  │                           应用层 (Application)                             │  │
│  │  ┌────────────┐  ┌────────────┐  ┌────────────┐  ┌────────────────────┐ │  │
│  │  │ Game Code  │  │  Renderer  │  │   Scene    │  │      Editor        │ │  │
│  │  └─────┬──────┘  └─────┬──────┘  └─────┬──────┘  └─────────┬──────────┘ │  │
│  └────────┼────────────────┼────────────────┼───────────────────┼────────────┘  │
│           │                │                │                   │                │
│  ┌────────▼────────────────▼────────────────▼───────────────────▼────────────┐  │
│  │                        ResourceManager (资源管理器)                         │  │
│  │  ┌─────────────────────────────────────────────────────────────────────┐  │  │
│  │  │  • Load<T>(path) - 同步加载                                         │  │  │
│  │  │  • LoadAsync<T>(path, callback) - 异步加载                         │  │  │
│  │  │  • Unload(path/guid) - 卸载资源                                    │  │  │
│  │  │  • RegisterLoader() - 注册加载器                                    │  │  │
│  │  │  • AddRef/Release - 引用计数管理                                   │  │  │
│  │  └─────────────────────────────────────────────────────────────────────┘  │  │
│  └────────┬───────────────────────────────────────────────────────────────────┘  │
│           │                                                                    │
│  ┌────────▼───────────────────────────────────────────────────────────────────┐  │
│  │                         ResourceLoader (加载器层)                          │  │
│  │  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌─────────────┐ │  │
│  │  │TextureLoader │  │  MeshLoader  │  │ AudioLoader  │  │ShaderLoader │ │  │
│  │  │  (纹理加载)   │  │   (模型加载)  │  │   (音频加载)  │  │ (着色器加载) │ │  │
│  │  └──────────────┘  └──────────────┘  └──────────────┘  └─────────────┘ │  │
│  └────────┬───────────────────────────────────────────────────────────────────┘  │
│           │                                                                    │
│  ┌────────▼───────────────────────────────────────────────────────────────────┐  │
│  │                         ResourceCache (缓存层)                            │  │
│  │  ┌─────────────────────────────────────────────────────────────────────┐  │  │
│  │  │  • LRU淘汰策略                                                      │  │  │
│  │  │  • 内存压力响应                                                     │  │  │
│  │  │  • 手动刷新接口                                                     │  │  │
│  │  └─────────────────────────────────────────────────────────────────────┘  │  │
│  └────────┬───────────────────────────────────────────────────────────────────┘  │
│           │                                                                    │
│  ┌────────▼───────────────────────────────────────────────────────────────────┐  │
│  │                         AsyncLoader (异步加载层)                           │  │
│  │  ┌─────────────────────────────────────────────────────────────────────┐  │  │
│  │  │  • 后台工作线程                                                     │  │  │
│  │  │  • 任务队列管理                                                     │  │  │
│  │  │  • 完成回调分发                                                     │  │  │
│  │  └─────────────────────────────────────────────────────────────────────┘  │  │
│  └────────┬───────────────────────────────────────────────────────────────────┘  │
│           │                                                                    │
│  ┌────────▼───────────────────────────────────────────────────────────────────┐  │
│  │                         FileSystem (文件系统层)                           │  │
│  │  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐ │  │
│  │  │    Stream    │  │   Path.h    │  │   Archive    │  │  Compression │ │  │
│  │  └──────────────┘  └──────────────┘  └──────────────┘  └──────────────┘ │  │
│  └────────────────────────────────────────────────────────────────────────────┘  │
│                                                                                 │
└─────────────────────────────────────────────────────────────────────────────────┘
```

### 2.2 模块职责

| 模块 | 职责 | 关键类 |
|------|------|--------|
| **ResourceManager** | 资源总入口，引用计数管理 | ResourceManager |
| **ResourceLoader** | 具体资源类型的加载逻辑 | IResourceLoader, TextureLoader, MeshLoader |
| **ResourceCache** | 内存缓存，LRU淘汰 | ResourceCache, CacheEntry |
| **AsyncLoader** | 异步任务调度 | AsyncLoader, LoadRequest |
| **FileSystem** | 文件读写，路径管理 | FileSystem, Path, FileReader |

### 2.3 数据流

```
同步加载流程：
  Load(path) → CheckCache → Found? → Return Handle
                    ↓
               Not Found
                    ↓
            GetLoader(type) → LoadResource → Create Handle → Add to Cache → Return

异步加载流程：
  LoadAsync(path, callback) → Create Request → Submit to Queue
        ↓
  Worker Thread: Get Request → GetLoader → LoadResource
        ↓
  Main Thread: Update() → Process Completed → Invoke Callback → Create Handle
```

---

## 3. 目录结构

### 3.1 设计目录结构

```
engine/include/XCEngine/Resources/
├── Resources.h                    # 主头文件，导出所有资源系统类
├── IResource.h                    # 资源基类接口
├── ResourceHandle.h               # 资源句柄（模板智能指针）
├── ResourceManager.h              # 资源管理器
├── IResourceLoader.h             # 加载器基类接口
├── ResourceCache.h               # 资源缓存
├── AsyncLoader.h                 # 异步加载器
├── ImportSettings.h              # 导入设置基类
│
├── Texture.h                     # 纹理资源
├── TextureLoader.h              # 纹理加载器
├── TextureImportSettings.h      # 纹理导入设置
│
├── Mesh.h                        # 网格资源
├── MeshLoader.h                  # 模型加载器
├── MeshImportSettings.h         # 模型导入设置
│
├── Material.h                    # 材质资源
├── MaterialLoader.h              # 材质加载器
│
├── Shader.h                      # 着色器资源
├── ShaderLoader.h                # 着色器加载器
│
├── AudioClip.h                   # 音频资源
├── AudioLoader.h                 # 音频加载器
│
├── BinaryResource.h              # 二进制资源
└── ResourceTypes.h              # 资源类型枚举

engine/src/Resources/
├── Resources.cpp                 # 资源系统初始化
├── ResourceManager.cpp
├── ResourceCache.cpp
├── AsyncLoader.cpp
├── TextureLoader.cpp
├── MeshLoader.cpp
├── MaterialLoader.cpp
├── ShaderLoader.cpp
└── AudioLoader.cpp
```

### 3.2 与现有项目整合

资源系统需要整合到现有项目中，需要创建或更新的文件：

```
engine/
├── include/XCEngine/
│   └── XCEngine.h               # 添加 #include "Resources/Resources.h"
│
└── src/
    └── Resources/               # 新建目录
        └── (上述实现文件)
```

---

## 4. 核心类型定义

### 4.1 资源类型枚举

```cpp
// ResourceTypes.h
namespace XCEngine {
namespace Resources {

// 资源类型
enum class ResourceType : Core::uint8 {
    Unknown = 0,
    Texture,
    Mesh,
    Material,
    Shader,
    AudioClip,
    Binary,
    AnimationClip,
    Skeleton,
    Font,
    ParticleSystem,
    Scene,
    Prefab
};

constexpr const char* GetResourceTypeName(ResourceType type) {
    switch (type) {
        case ResourceType::Texture:        return "Texture";
        case ResourceType::Mesh:          return "Mesh";
        case ResourceType::Material:      return "Material";
        case ResourceType::Shader:        return "Shader";
        case ResourceType::AudioClip:     return "AudioClip";
        case ResourceType::Binary:        return "Binary";
        case ResourceType::AnimationClip: return "AnimationClip";
        case ResourceType::Skeleton:      return "Skeleton";
        case ResourceType::Font:          return "Font";
        case ResourceType::ParticleSystem:return "ParticleSystem";
        case ResourceType::Scene:         return "Scene";
        case ResourceType::Prefab:        return "Prefab";
        default:                          return "Unknown";
    }
}

// 资源使用64位GUID作为唯一标识符
// GUID生成规则：MD5(path) 的前64位
// 这样可以保证相同路径生成相同的GUID
struct ResourceGUID {
    Core::uint64 value;
    
    ResourceGUID() : value(0) {}
    explicit ResourceGUID(Core::uint64 v) : value(v) {}
    
    bool IsValid() const { return value != 0; }
    
    bool operator==(const ResourceGUID& other) const { return value == other.value; }
    bool operator!=(const ResourceGUID& other) const { return value != other.value; }
    
    // 从路径生成GUID
    static ResourceGUID Generate(const char* path);
    static ResourceGUID Generate(const String& path);
    
    String ToString() const;
};

// 全局函数
inline ResourceGUID MakeResourceGUID(const char* path) {
    return ResourceGUID::Generate(path);
}

// 从模板类型获取ResourceType的辅助函数
template<typename T>
ResourceType GetResourceType();

// 特化模板
template<> inline ResourceType GetResourceType<Texture>() { return ResourceType::Texture; }
template<> inline ResourceType GetResourceType<Mesh>() { return ResourceType::Mesh; }
template<> inline ResourceType GetResourceType<Material>() { return ResourceType::Material; }
template<> inline ResourceType GetResourceType<Shader>() { return ResourceType::Shader; }
template<> inline ResourceType GetResourceType<AudioClip>() { return ResourceType::AudioClip; }
template<> inline ResourceType GetResourceType<BinaryResource>() { return ResourceType::Binary; }

// 导入设置基类
class ImportSettings {
public:
    virtual ~ImportSettings() = default;
    
    // 克隆设置
    virtual UniquePtr<ImportSettings> Clone() const = 0;
    
    // 从JSON加载
    virtual bool LoadFromJSON(const String& json) { return false; }
    
    // 保存为JSON
    virtual String SaveToJSON() const { return String(); }
};

} // namespace Resources
} // namespace XCEngine
}

} // namespace Resources
} // namespace XCEngine
```

### 4.2 资源GUID

```cpp
// 资源使用64位GUID作为唯一标识符
// GUID生成规则：MD5(path) 的前64位
// 这样可以保证相同路径生成相同的GUID

struct ResourceGUID {
    uint64 value;
    
    ResourceGUID() : value(0) {}
    explicit ResourceGUID(uint64 v) : value(v) {}
    
    bool IsValid() const { return value != 0; }
    
    bool operator==(const ResourceGUID& other) const { return value == other.value; }
    bool operator!=(const ResourceGUID& other) const { return value != other.value; }
    
    // 从路径生成GUID
    static ResourceGUID Generate(const char* path);
    static ResourceGUID Generate(const String& path);
    
    String ToString() const;
};

// 全局函数
inline ResourceGUID MakeResourceGUID(const char* path) {
    return ResourceGUID::Generate(path);
}
```

### 4.3 资源路径

```cpp
// 资源路径使用相对于资源根目录的路径
// 例如：textures/player.png, models/player.fbx
// 资源系统会自动添加资源根目录前缀

class ResourcePath {
public:
    ResourcePath() = default;
    ResourcePath(const char* path);
    ResourcePath(const String& path);
    
    // 获取扩展名
    String GetExtension() const;
    
    // 获取文件名（不含扩展名）
    String GetStem() const;
    
    // 获取完整路径
    String GetFullPath() const;
    
    // 获取相对于资源根的路径
    String GetRelativePath() const;
    
    // 转换为资源GUID
    ResourceGUID ToGUID() const;
    
    // 检查扩展名
    bool HasExtension(const char* ext) const;
    bool HasAnyExtension(const char* const* extensions, Core::uint32 count) const;
    
private:
    String m_path;
};
```

---

## 5. 核心接口设计

### 5.1 资源基类接口 (IResource)

```cpp
// IResource.h
namespace XCEngine {
namespace Resources {

class IResource {
public:
    virtual ~IResource() = default;
    
    // 获取资源类型
    virtual ResourceType GetType() const = 0;
    
    // 获取资源名称
    virtual const String& GetName() const = 0;
    
    // 获取资源路径
    virtual const String& GetPath() const = 0;
    
    // 获取资源GUID
    virtual ResourceGUID GetGUID() const = 0;
    
    // 资源是否有效
    virtual bool IsValid() const = 0;
    
    // 获取资源内存大小（用于缓存统计）
    virtual size_t GetMemorySize() const = 0;
    
    // 释放资源（返回到对象池或真正删除）
    virtual void Release() = 0;
    
protected:
    // 资源初始化（供子类调用）
    struct ConstructParams {
        String name;
        String path;
        ResourceGUID guid;
        size_t memorySize = 0;
    };
    
    void Initialize(const ConstructParams& params) {
        m_name = params.name;
        m_path = params.path;
        m_guid = params.guid;
        m_memorySize = params.memorySize;
        m_isValid = true;
    }
    
    void SetInvalid() { m_isValid = false; }
    
    String m_name;
    String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
};

} // namespace Resources
} // namespace XCEngine
```

### 5.2 资源句柄 (ResourceHandle)

```cpp
// ResourceHandle.h
#include <type_traits>
#include <functional>

namespace XCEngine {
namespace Resources {

// 资源句柄模板类
// 类似智能指针，但专门用于资源管理
template<typename T>
class ResourceHandle {
    static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
    
public:
    ResourceHandle() = default;
    
    explicit ResourceHandle(T* resource)
        : m_resource(resource) {
        if (m_resource) {
            ResourceManager::Get().AddRef(m_resource->GetGUID());
        }
    }
    
    ResourceHandle(const ResourceHandle& other)
        : m_resource(other.m_resource) {
        if (m_resource) {
            ResourceManager::Get().AddRef(m_resource->GetGUID());
        }
    }
    
    ResourceHandle(ResourceHandle&& other) noexcept
        : m_resource(other.m_resource) {
        // 移动语义不转移引用计数所有权
        // 原句柄被掏空，不减少引用计数
        other.m_resource = nullptr;
    }
    
    ~ResourceHandle() {
        Reset();
    }
    
    ResourceHandle& operator=(const ResourceHandle& other) {
        if (this != &other) {
            Reset();
            m_resource = other.m_resource;
            if (m_resource) {
                ResourceManager::Get().AddRef(m_resource->GetGUID());
            }
        }
        return *this;
    }
    
    ResourceHandle& operator=(ResourceHandle&& other) noexcept {
        if (this != &other) {
            // 先释放当前持有的资源
            Reset();
            // 移动所有权
            m_resource = other.m_resource;
            // 原句柄被掏空，不减少引用计数
            other.m_resource = nullptr;
        }
        return *this;
    }
    
    // 访问资源
    T* Get() const { return m_resource; }
    T* operator->() const { return m_resource; }
    T& operator*() const { return *m_resource; }
    
    // 检查有效性
    bool IsValid() const { return m_resource != nullptr && m_resource->IsValid(); }
    explicit operator bool() const { return IsValid(); }
    
    // 获取GUID
    ResourceGUID GetGUID() const {
        return m_resource ? m_resource->GetGUID() : ResourceGUID(0);
    }
    
    // 获取资源类型
    ResourceType GetResourceType() const {
        return m_resource ? m_resource->GetType() : ResourceType::Unknown;
    }
    
    // 重置句柄
    void Reset() {
        if (m_resource) {
            ResourceManager::Get().Release(m_resource->GetGUID());
            m_resource = nullptr;
        }
    }
    
    // 交换
    void Swap(ResourceHandle& other) {
        std::swap(m_resource, other.m_resource);
    }
    
private:
    T* m_resource = nullptr;
};

// 比较操作符
template<typename T>
bool operator==(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
    return lhs.GetGUID() == rhs.GetGUID();
}

template<typename T>
bool operator!=(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
    return !(lhs == rhs);
}

} // namespace Resources
} // namespace XCEngine
```

### 5.3 加载器基类接口 (IResourceLoader)

```cpp
// IResourceLoader.h
namespace XCEngine {
namespace Resources {

// 加载结果
struct LoadResult {
    IResource* resource = nullptr;
    bool success = false;
    String errorMessage;
    
    LoadResult() = default;
    
    explicit LoadResult(IResource* res)
        : resource(res), success(res != nullptr) {}
    
    explicit LoadResult(const String& error)
        : success(false), errorMessage(error) {}
    
    explicit LoadResult(bool success, const String& error = "")
        : success(success), errorMessage(error) {}
    
    operator bool() const { return success && resource != nullptr; }
};

// 加载器接口
class IResourceLoader {
public:
    virtual ~IResourceLoader() = default;
    
    // 获取支持的资源类型
    virtual ResourceType GetResourceType() const = 0;
    
    // 获取支持的文件扩展名
    virtual Array<String> GetSupportedExtensions() const = 0;
    
    // 检查是否可以加载该文件
    virtual bool CanLoad(const String& path) const = 0;
    
    // 同步加载
    virtual LoadResult Load(const String& path, const ImportSettings* settings = nullptr) = 0;
    
    // 异步加载（默认实现：同步加载然后在主线程回调）
    virtual void LoadAsync(const String& path, 
                          const ImportSettings* settings,
                          std::function<void(LoadResult)> callback) {
        LoadResult result = Load(path, settings);
        if (callback) {
            callback(result);
        }
    }
    
    // 获取默认导入设置
    virtual ImportSettings* GetDefaultSettings() const = 0;
    
protected:
    // 辅助方法：从文件读取数据
    static Array<Core::uint8> ReadFileData(const String& path);
    
    // 辅助方法：解析路径获取扩展名
    static String GetExtension(const String& path);
};

// 加载器工厂宏（方便注册）
#define REGISTER_RESOURCE_LOADER(loaderType) \
    namespace { \
        struct loaderType##Registrar { \
            loaderType##Registrar() { \
                ResourceManager::Get().RegisterLoader(new loaderType()); \
            } \
        } g_##loaderType##Registrar; \
    }
} // namespace Resources
} // namespace XCEngine
```

### 5.4 资源管理器 (ResourceManager)

```cpp
// ResourceManager.h
namespace XCEngine {
namespace Resources {

class ResourceManager {
public:
    static ResourceManager& Get();
    
    // ==================== 初始化 ====================
    
    void Initialize();
    void Shutdown();
    
    // 设置资源根目录
    void SetResourceRoot(const String& rootPath);
    const String& GetResourceRoot() const;
    
    // ==================== 同步加载 ====================
    
    // 通过路径加载
    template<typename T>
    ResourceHandle<T> Load(const String& path, ImportSettings* settings = nullptr) {
        static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
        
        ResourcePath resourcePath(path);
        ResourceGUID guid = resourcePath.ToGUID();
        
        // 1. 检查缓存
        IResource* cached = FindInCache(guid);
        if (cached) {
            return ResourceHandle<T>(static_cast<T*>(cached));
        }
        
        // 2. 查找加载器
        IResourceLoader* loader = FindLoader(GetResourceType<T>());
        if (!loader) {
            Debug::Logger::Get().Warning(Debug::LogCategory::FileSystem,
                "No loader found for resource type: " + String(GetResourceTypeName(GetResourceType<T>())));
            return ResourceHandle<T>();
        }
        
        // 3. 加载资源
        LoadResult result = loader->Load(resourcePath.GetFullPath(), settings);
        if (!result) {
            Debug::Logger::Get().Error(Debug::LogCategory::FileSystem,
                "Failed to load resource: " + path + " - " + result.errorMessage);
            return ResourceHandle<T>();
        }
        
        // 4. 添加到缓存
        AddToCache(guid, result.resource);
        
        return ResourceHandle<T>(static_cast<T*>(result.resource));
    }
    
    // 通过GUID加载
    template<typename T>
    ResourceHandle<T> Load(ResourceGUID guid) {
        // 从GUID反向查找路径（需要维护guid到path的映射）
        // 这里简化处理，实际实现需要从数据库查询
        return ResourceHandle<T>();
    }
    
    // ==================== 异步加载 ====================
    
    // 异步加载资源（需要显式指定类型）
    void LoadAsync(const String& path, ResourceType type, 
                   std::function<void(LoadResult)> callback);
    
    // 异步加载资源（带自定义设置）
    void LoadAsync(const String& path, ResourceType type, ImportSettings* settings,
                   std::function<void(LoadResult)> callback);
    
    // ==================== 卸载 ====================
    
    // 通过路径卸载
    void Unload(const String& path);
    
    // 通过GUID卸载
    void Unload(ResourceGUID guid);
    
    // 卸载所有未使用的资源
    void UnloadUnused();
    
    // 卸载所有资源
    void UnloadAll();
    
    // ==================== 引用计数 ====================
    
    // 增加引用计数
    void AddRef(ResourceGUID guid);
    
    // 减少引用计数（引用计数为0时可能卸载资源）
    void Release(ResourceGUID guid);
    
    // 获取引用计数
    Core::uint32 GetRefCount(ResourceGUID guid) const;
    
    // ==================== 加载器管理 ====================
    
    // 注册加载器（ResourceManager拥有加载器）
    void RegisterLoader(IResourceLoader* loader);
    
    // 移除加载器
    void UnregisterLoader(ResourceType type);
    
    // 获取加载器
    IResourceLoader* GetLoader(ResourceType type) const;
    
    // ==================== 缓存管理 ====================
    
    // 设置内存预算（字节）
    void SetMemoryBudget(size_t bytes);
    
    // 获取当前内存使用
    size_t GetMemoryUsage() const;
    
    // 获取内存预算
    size_t GetMemoryBudget() const;
    
    // 刷新缓存（强制淘汰最少使用的资源）
    void FlushCache();
    
    // ==================== 查询 ====================
    
    // 查找资源（不增加引用计数）
    IResource* Find(const String& path);
    IResource* Find(ResourceGUID guid);
    
    // 检查资源是否存在
    bool Exists(const String& path) const;
    bool Exists(ResourceGUID guid) const;
    
    // ==================== 资源根目录相关 ====================
    
    // 解析资源路径（添加资源根目录）
    String ResolvePath(const String& relativePath) const;
    
private:
    ResourceManager() = default;
    ~ResourceManager() = default;
    
    // 内部方法
    IResource* FindInCache(ResourceGUID guid);
    void AddToCache(ResourceGUID guid, IResource* resource);
    IResourceLoader* FindLoader(ResourceType type);
    void ReloadResource(ResourceGUID guid);
    
    // 数据成员
    String m_resourceRoot;
    
    // 资源缓存
    HashMap<ResourceGUID, IResource*> m_resourceCache;
    
    // 引用计数
    HashMap<ResourceGUID, Core::uint32> m_refCounts;
    
    // GUID到路径的映射（用于从guid加载）
    HashMap<ResourceGUID, String> m_guidToPath;
    
    // 加载器
    HashMap<ResourceType, UniquePtr<IResourceLoader>> m_loaders;
    
    // 缓存统计
    size_t m_memoryUsage = 0;
    size_t m_memoryBudget = 512 * 1024 * 1024; // 默认512MB
    
    // 异步加载器
    UniquePtr<AsyncLoader> m_asyncLoader;
    
    // 互斥锁
    Threading::Mutex m_mutex;
    
    friend class ResourceHandleBase;
};

} // namespace Resources
} // namespace XCEngine
```

### 5.5 资源缓存 (ResourceCache)

```cpp
// ResourceCache.h
#include <algorithm>

namespace XCEngine {
namespace Resources {

// 缓存条目
struct CacheEntry {
    IResource* resource;
    ResourceGUID guid;
    size_t memorySize;
    Core::uint64 lastAccessTime;  // 使用Profiler::Get().GetTickCount()
    Core::uint32 accessCount;
    
    CacheEntry()
        : resource(nullptr), memorySize(0), lastAccessTime(0), accessCount(0) {}
    
    CacheEntry(IResource* res, size_t size)
        : resource(res), guid(res->GetGUID()), memorySize(size), 
          lastAccessTime(GetCurrentTick()), accessCount(1) {}
    
private:
    static Core::uint64 GetCurrentTick();
};

// LRU缓存实现
class ResourceCache {
public:
    ResourceCache();
    ~ResourceCache();
    
    // 添加资源到缓存
    void Add(ResourceGUID guid, IResource* resource);
    
    // 从缓存移除
    void Remove(ResourceGUID guid);
    
    // 查找资源（不移动到头部）
    IResource* Find(ResourceGUID guid) const;
    
    // 访问资源（更新LRU信息）
    void Touch(ResourceGUID guid);
    
    // 获取缓存大小
    size_t GetSize() const { return m_cache.Size(); }
    
    // 获取内存使用
    size_t GetMemoryUsage() const { return m_memoryUsage; }
    
    // 设置内存预算
    void SetMemoryBudget(size_t bytes);
    size_t GetMemoryBudget() const { return m_memoryBudget; }
    
    // 内存压力响应（淘汰资源直到满足要求）
    void OnMemoryPressure(size_t requiredBytes);
    
    // 引用计数为0时的通知（供ResourceManager调用）
    void OnZeroRefCount(ResourceGUID guid);
    
    // 刷新缓存（淘汰所有未使用的资源）
    void Flush();
    
    // 清空缓存
    void Clear();
    
    // 获取最少使用的资源（用于调试）
    Array<ResourceGUID> GetLRUList(size_t count) const;
    
private:
    // 淘汰最少使用的资源
    void Evict(size_t requiredBytes);
    
    // 更新内存统计
    void UpdateMemoryStats();
    
    // 数据成员
    HashMap<ResourceGUID, CacheEntry> m_cache;
    Array<ResourceGUID> m_lruOrder;  // 按访问时间排序，最少使用的在前面
    size_t m_memoryUsage = 0;
    size_t m_memoryBudget = 512 * 1024 * 1024; // 默认512MB
    
    Mutex m_mutex;
};

} // namespace Resources
} // namespace XCEngine
```

### 5.6 异步加载器 (AsyncLoader)

```cpp
// AsyncLoader.h
#include <atomic>
#include <functional>

namespace XCEngine {
namespace Resources {

// 加载请求
struct LoadRequest {
    String path;
    ResourceType type;
    std::function<void(LoadResult)> callback;
    UniquePtr<ImportSettings> settings;
    Core::uint64 requestId;
    
    LoadRequest()
        : requestId(0) {}
    
    LoadRequest(const String& p, ResourceType t, 
                std::function<void(LoadResult)> cb,
                ImportSettings* s = nullptr)
        : path(p), type(t), callback(std::move(cb)), 
          settings(s), requestId(GenerateRequestId()) {}
    
private:
    static Core::uint64 GenerateRequestId();
};

// 加载任务（工作线程执行）
class LoadTask : public Threading::ITask {
public:
    LoadTask(LoadRequest request, IResourceLoader* loader);
    
    void Execute() override;
    
    LoadResult& GetResult() { return m_result; }
    
private:
    LoadRequest m_request;
    IResourceLoader* m_loader;
    LoadResult m_result;
};

// 异步加载器
class AsyncLoader {
public:
    static AsyncLoader& Get();
    
    // 初始化
    void Initialize(Core::uint32 workerThreadCount = 2);
    void Shutdown();
    
    // 提交加载请求（需要显式指定类型）
    void Submit(const String& path, ResourceType type, 
                std::function<void(LoadResult)> callback);
    
    // 提交加载请求（带自定义设置）
    void Submit(const String& path, ResourceType type, ImportSettings* settings,
                std::function<void(LoadResult)> callback);
    
    // 更新（每帧调用，处理完成的加载）
    void Update();
    
    // 检查是否正在加载
    bool IsLoading() const { return m_pendingCount > 0; }
    
    // 获取待处理数量
    Core::uint32 GetPendingCount() const { return m_pendingCount; }
    
    // 获取加载进度（0.0 - 1.0）
    float GetProgress() const;
    
    // 取消所有待处理的请求
    void CancelAll();
    
    // 取消特定请求
    void Cancel(Core::uint64 requestId);
    
private:
    AsyncLoader() = default;
    ~AsyncLoader() = default;
    
    void SubmitInternal(LoadRequest& request);
    
    // 待处理的请求队列
    Threading::Mutex m_queueMutex;
    Array<LoadRequest> m_pendingQueue;
    
    // 完成的请求队列（主线程处理）
    Threading::Mutex m_completedMutex;
    Array<LoadRequest> m_completedQueue;
    
    // 统计
    std::atomic<Core::uint32> m_pendingCount{0};
    std::atomic<Core::uint32> m_completedCount{0};
    Core::uint32 m_totalRequested = 0;
    
    // 加载器查找
    IResourceLoader* FindLoader(ResourceType type) const;
};

} // namespace Resources
} // namespace XCEngine
```

---

## 6. 具体资源类型

### 6.1 纹理资源 (Texture)

```cpp
// Texture.h
namespace XCEngine {
namespace Resources {

// 纹理类型
enum class TextureType {
    Texture2D,
    Texture3D,
    TextureCube,
    Texture2DArray,
    TextureCubeArray
};

// 纹理格式
enum class TextureFormat {
    Unknown,
    R8_UNORM,
    RG8_UNORM,
    RGBA8_UNORM,
    RGBA8_SRGB,
    R16_FLOAT,
    RG16_FLOAT,
    RGBA16_FLOAT,
    R32_FLOAT,
    RG32_FLOAT,
    RGBA32_FLOAT,
    D16_UNORM,
    D24_UNORM_S8_UINT,
    D32_FLOAT,
    D32_FLOAT_S8_X24_UINT,
    BC1_UNORM,
    BC1_UNORM_SRGB,
    BC2_UNORM,
    BC2_UNORM_SRGB,
    BC3_UNORM,
    BC3_UNORM_SRGB,
    BC4_UNORM,
    BC5_UNORM,
    BC6H_UF16,
    BC7_UNORM,
    BC7_UNORM_SRGB
};

// 纹理使用flags
enum class TextureUsage : Core::uint8 {
    None = 0,
    ShaderResource = 1 << 0,
    RenderTarget = 1 << 1,
    DepthStencil = 1 << 2,
    UnorderedAccess = 1 << 3,
    TransferSrc = 1 << 4,
    TransferDst = 1 << 5
};

// 纹理资源
class Texture : public IResource {
public:
    Texture();
    virtual ~Texture() override;
    
    // IResource 接口
    ResourceType GetType() const override { return ResourceType::Texture; }
    const String& GetName() const override { return m_name; }
    const String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    // 纹理属性
    Core::uint32 GetWidth() const { return m_width; }
    Core::uint32 GetHeight() const { return m_height; }
    Core::uint32 GetDepth() const { return m_depth; }
    Core::uint32 GetMipLevels() const { return m_mipLevels; }
    Core::uint32 GetArraySize() const { return m_arraySize; }
    TextureType GetTextureType() const { return m_textureType; }
    TextureFormat GetFormat() const { return m_format; }
    TextureUsage GetUsage() const { return m_usage; }
    
    // RHI资源
    class IRHIResource* GetRHIResource() const { return m_rhiResource; }
    void SetRHIResource(class IRHIResource* resource);
    
    // 创建纹理（从原始数据）
    bool Create(Core::uint32 width, Core::uint32 height, Core::uint32 depth,
                Core::uint32 mipLevels, TextureType type, TextureFormat format,
                const void* data, size_t dataSize);
    
    // 生成Mipmap
    bool GenerateMipmaps();
    
private:
    // 成员变量
    String m_name;
    String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
    
    Core::uint32 m_width = 0;
    Core::uint32 m_height = 0;
    Core::uint32 m_depth = 1;
    Core::uint32 m_mipLevels = 1;
    Core::uint32 m_arraySize = 1;
    TextureType m_textureType = TextureType::Texture2D;
    TextureFormat m_format = TextureFormat::RGBA8_UNORM;
    TextureUsage m_usage = TextureUsage::ShaderResource;
    
    class IRHIResource* m_rhiResource = nullptr;
};

} // namespace Resources
} // namespace XCEngine
```

### 6.2 纹理导入设置

```cpp
// TextureImportSettings.h
namespace XCEngine {
namespace Resources {

class TextureImportSettings : public ImportSettings {
public:
    TextureImportSettings();
    virtual ~TextureImportSettings() override;
    
    // ==================== 纹理设置 ====================
    
    // 纹理类型
    void SetTextureType(TextureType type) { m_textureType = type; }
    TextureType GetTextureType() const { return m_textureType; }
    
    // 目标格式（用于压缩）
    void SetTargetFormat(TextureFormat format) { m_targetFormat = format; }
    TextureFormat GetTargetFormat() const { return m_targetFormat; }
    
    // 是否生成Mipmap
    void SetGenerateMipmaps(bool generate) { m_generateMipmaps = generate; }
    bool GetGenerateMipmaps() const { return m_generateMipmaps; }
    
    // Mipmap过滤方式
    void SetMipmapFilter(MipmapFilter filter) { m_mipmapFilter = filter; }
    MipmapFilter GetMipmapFilter() const { return m_mipmapFilter; }
    
    // 各向异性过滤
    void SetMaxAnisotropy(Core::uint32 anisotropy) { m_maxAnisotropy = anisotropy; }
    Core::uint32 GetMaxAnisotropy() const { return m_maxAnisotropy; }
    
    // 是否sRGB（影响着色器中的采样）
    void SetSRGB(bool srgb) { m_sRGB = srgb; }
    bool GetSRGB() const { return m_sRGB; }
    
    // 是否启用纹理数组
    void SetTextureArray(bool array) { m_textureArray = array; }
    bool GetTextureArray() const { return m_textureArray; }
    
    // 垂直翻转
    void SetFlipVertical(bool flip) { m_flipVertical = flip; }
    bool GetFlipVertical() const { return m_flipVertical; }
    
    // 水平翻转
    void SetFlipHorizontal(bool flip) { m_flipHorizontal = flip; }
    bool GetFlipHorizontal() const { return m_flipHorizontal; }
    
    // 边框颜色（对于透明纹理）
    void SetBorderColor(const Math::Color& color) { m_borderColor = color; }
    const Math::Color& GetBorderColor() const { return m_borderColor; }
    
    // ==================== 压缩设置 ====================
    
    // 压缩质量
    void SetCompressionQuality(CompressionQuality quality) { m_compressionQuality = quality; }
    CompressionQuality GetCompressionQuality() const { return m_compressionQuality; }
    
    // 是否使用硬件压缩
    void SetUseHardwareCompression(bool use) { m_useHardwareCompression = use; }
    bool GetUseHardwareCompression() const { return m_useHardwareCompression; }
    
    // ==================== 实用方法 ====================
    
    // 克隆设置
    UniquePtr<ImportSettings> Clone() const override;
    
    // 从JSON加载
    bool LoadFromJSON(const String& json);
    
    // 保存为JSON
    String SaveToJSON() const;
    
private:
    // 成员变量
    TextureType m_textureType = TextureType::Texture2D;
    TextureFormat m_targetFormat = TextureFormat::Unknown; // 自动选择
    bool m_generateMipmaps = true;
    MipmapFilter m_mipmapFilter = MipmapFilter::Box;
    Core::uint32 m_maxAnisotropy = 16;
    bool m_sRGB = false;
    bool m_textureArray = false;
    bool m_flipVertical = false;
    bool m_flipHorizontal = false;
    Math::Color m_borderColor = Math::Color::Black;
    CompressionQuality m_compressionQuality = CompressionQuality::High;
    bool m_useHardwareCompression = true;
};

// Mipmap过滤方式
enum class MipmapFilter {
    Box,
    Kaiser
};

// 压缩质量
enum class CompressionQuality {
    Low,
    Medium,
    High,
    Ultra
};

} // namespace Resources
} // namespace XCEngine
```

### 6.3 纹理加载器

```cpp
// TextureLoader.h
namespace XCEngine {
namespace Resources {

class TextureLoader : public IResourceLoader {
public:
    TextureLoader();
    virtual ~TextureLoader() override;
    
    // IResourceLoader 接口
    ResourceType GetResourceType() const override {
        return ResourceType::Texture;
    }
    
    Array<String> GetSupportedExtensions() const override {
        return Array<String>{".png", ".jpg", ".jpeg", ".tga", ".bmp", 
                            ".dds", ".hdr", ".exr", ".psd"};
    }
    
    bool CanLoad(const String& path) const override {
        String ext = GetExtension(path);
        return ext == ".png" || ext == ".jpg" || ext == ".jpeg" ||
               ext == ".tga" || ext == ".bmp" || ext == ".dds" ||
               ext == ".hdr" || ext == ".exr" || ext == ".psd";
    }
    
    LoadResult Load(const String& path, const ImportSettings* settings = nullptr) override;
    
    ImportSettings* GetDefaultSettings() const override {
        return new TextureImportSettings();
    }
    
private:
    // 内部加载方法
    LoadResult LoadPNG(const String& path, const TextureImportSettings* settings);
    LoadResult LoadJPG(const String& path, const TextureImportSettings* settings);
    LoadResult LoadTGA(const String& path, const TextureImportSettings* settings);
    LoadResult LoadDDS(const String& path, const TextureImportSettings* settings);
    LoadResult LoadHDR(const String& path, const TextureImportSettings* settings);
    
    // 辅助方法
    TextureFormat DetectFormat(const String& path) const;
    bool ConvertFormat(const Core::uint8* srcData, Core::uint32 width, Core::uint32 height,
                       TextureFormat srcFormat, TextureFormat dstFormat,
                       Core::uint8*& outData, size_t& outDataSize);
};

// 注册加载器
REGISTER_RESOURCE_LOADER(TextureLoader);

} // namespace Resources
} // namespace XCEngine
```

### 6.4 网格资源 (Mesh)

```cpp
// Mesh.h
namespace XCEngine {
namespace Resources {

// 顶点属性
enum class VertexAttribute : Core::uint32 {
    Position = 1 << 0,
    Normal = 1 << 1,
    Tangent = 1 << 2,
    Color = 1 << 3,
    UV0 = 1 << 4,
    UV1 = 1 << 5,
    UV2 = 1 << 6,
    UV3 = 1 << 7,
    BoneWeights = 1 << 8,
    BoneIndices = 1 << 9
};

// 网格子资源（用于多材质）
struct MeshSection {
    Core::uint32 baseVertex;
    Core::uint32 vertexCount;
    Core::uint32 startIndex;
    Core::uint32 indexCount;
    Core::uint32 materialID;
    Math::AABB boundingBox;
};

// 网格资源
class Mesh : public IResource {
public:
    Mesh();
    virtual ~Mesh() override;
    
    // IResource 接口
    ResourceType GetType() const override { return ResourceType::Mesh; }
    const String& GetName() const override { return m_name; }
    const String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    // ==================== 顶点数据 ====================
    
    // 设置顶点数据
    void SetVertexData(const void* data, size_t size, Core::uint32 vertexCount,
                       Core::uint32 vertexStride, VertexAttribute attributes);
    
    // 获取顶点数据
    const void* GetVertexData() const { return m_vertexData.Data(); }
    size_t GetVertexDataSize() const { return m_vertexData.Size(); }
    Core::uint32 GetVertexCount() const { return m_vertexCount; }
    Core::uint32 GetVertexStride() const { return m_vertexStride; }
    VertexAttribute GetVertexAttributes() const { return m_attributes; }
    
    // ==================== 索引数据 ====================
    
    // 设置索引数据
    void SetIndexData(const void* data, size_t size, Core::uint32 indexCount, bool use32Bit);
    
    // 获取索引数据
    const void* GetIndexData() const { return m_indexData.Data(); }
    size_t GetIndexDataSize() const { return m_indexData.Size(); }
    Core::uint32 GetIndexCount() const { return m_indexCount; }
    bool IsUse32BitIndex() const { return m_use32BitIndex; }
    
    // ==================== 子网格 ====================
    
    void AddSection(const MeshSection& section);
    const Array<MeshSection>& GetSections() const { return m_sections; }
    
    // ==================== 包围盒 ====================
    
    void SetBoundingBox(const Math::AABB& box);
    const Math::AABB& GetBoundingBox() const { return m_boundingBox; }
    
    // ==================== 骨骼动画（可选）====================
    
    void SetSkeleton(class Skeleton* skeleton);
    class Skeleton* GetSkeleton() const { return m_skeleton; }
    
    // ==================== RHI资源 ====================
    
    class IRHIBuffer* GetVertexBuffer() const { return m_vertexBuffer; }
    class IRHIBuffer* GetIndexBuffer() const { return m_indexBuffer; }
    void SetRHIBuffers(class IRHIBuffer* vb, class IRHIBuffer* ib);
    
private:
    // 成员变量
    String m_name;
    String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
    
    // 顶点数据
    Array<Core::uint8> m_vertexData;
    Core::uint32 m_vertexCount = 0;
    Core::uint32 m_vertexStride = 0;
    VertexAttribute m_attributes = VertexAttribute::Position;
    
    // 索引数据
    Array<Core::uint8> m_indexData;
    Core::uint32 m_indexCount = 0;
    bool m_use32BitIndex = false;
    
    // 子网格
    Array<MeshSection> m_sections;
    
    // 包围盒
    Math::AABB m_boundingBox;
    
    // 骨骼
    class Skeleton* m_skeleton = nullptr;
    
    // RHI资源
    class IRHIBuffer* m_vertexBuffer = nullptr;
    class IRHIBuffer* m_indexBuffer = nullptr;
};

} // namespace Resources
} // namespace XCEngine
```

### 6.5 材质资源 (Material)

```cpp
// Material.h
namespace XCEngine {
namespace Resources {

// 材质属性类型
enum class MaterialPropertyType {
    Float,
    Float2,
    Float3,
    Float4,
    Int,
    Int2,
    Int3,
    Int4,
    Bool,
    Texture,
    Cubemap
};

// 材质属性
struct MaterialProperty {
    String name;
    MaterialPropertyType type;
    
    // 值联合体
    union Value {
        float floatValue[4];
        Core::int32 intValue[4];
        bool boolValue;
        ResourceHandle<Texture> textureValue;
        
        Value() { memset(this, 0, sizeof(Value)); }
    } value;
    
    // 引用计数（纹理资源需要特殊处理）
    Core::uint32 refCount;
};

// 材质资源
class Material : public IResource {
public:
    Material();
    virtual ~Material() override;
    
    // IResource 接口
    ResourceType GetType() const override { return ResourceType::Material; }
    const String& GetName() const override { return m_name; }
    const String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    // ==================== 着色器 ====================
    
    void SetShader(const ResourceHandle<class Shader>& shader);
    class Shader* GetShader() const { return m_shader.Get(); }
    
    // ==================== 属性设置 ====================
    
    void SetFloat(const String& name, float value);
    void SetFloat2(const String& name, const Math::Vector2& value);
    void SetFloat3(const String& name, const Math::Vector3& value);
    void SetFloat4(const String& name, const Math::Vector4& value);
    void SetInt(const String& name, int32 value);
    void SetInt2(const String& name, const Math::IntVector2& value);
    void SetInt3(const String& name, const Math::IntVector3& value);
    void SetInt4(const String& name, const Math::IntVector4& value);
    void SetBool(const String& name, bool value);
    void SetTexture(const String& name, const ResourceHandle<Texture>& texture);
    
    // ==================== 属性获取 ====================
    
    float GetFloat(const String& name) const;
    Math::Vector2 GetFloat2(const String& name) const;
    // ... 其他Get方法
    
    ResourceHandle<Texture> GetTexture(const String& name) const;
    
    // ==================== 属性遍历 ====================
    
    using PropertyIterator = HashMap<String, MaterialProperty>::Iterator;
    PropertyIterator BeginProperties() { return m_properties.Begin(); }
    PropertyIterator EndProperties() { return m_properties.End(); }
    
    // ==================== 批处理数据 ====================
    
    // 获取用于GPU的常数缓冲区数据
    const Array<Core::uint8>& GetConstantBufferData() const { return m_constantBufferData; }
    
    // 更新常数缓冲区（当属性变化时调用）
    void UpdateConstantBuffer();
    
private:
    // 成员变量
    String m_name;
    String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
    
    // 着色器
    ResourceHandle<class Shader> m_shader;
    
    // 属性表
    HashMap<String, MaterialProperty> m_properties;
    
    // 常数缓冲区数据
    Array<Core::uint8> m_constantBufferData;
    
    // 纹理绑定信息（用于设置到Pipeline）
    struct TextureBinding {
        String name;
        Core::uint32 slot;
        ResourceHandle<Texture> texture;
    };
    Array<TextureBinding> m_textureBindings;
};

} // namespace Resources
} // namespace XCEngine
```

### 6.6 音频资源 (AudioClip)

```cpp
// AudioClip.h
namespace XCEngine {
namespace Resources {

// 音频格式
enum class AudioFormat {
    Unknown,
    WAV,
    OGG,
    MP3,
    FLAC
};

// 音频类型
enum class AudioType {
    SFX,      // 音效
    Music,    // 背景音乐
    Voice     // 语音
};

// 音频资源
class AudioClip : public IResource {
public:
    AudioClip();
    virtual ~AudioClip() override;
    
    // IResource 接口
    ResourceType GetType() const override { return ResourceType::AudioClip; }
    const String& GetName() const override { return m_name; }
    const String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    // ==================== 音频属性 ====================
    
    // 采样率
    Core::uint32 GetSampleRate() const { return m_sampleRate; }
    
    // 通道数
    Core::uint32 GetChannels() const { return m_channels; }
    
    // 位深度
    Core::uint32 GetBitsPerSample() const { return m_bitsPerSample; }
    
    // 持续时间（秒）
    float GetDuration() const { return m_duration; }
    
    // 数据大小
    size_t GetDataSize() const { return m_data.Size(); }
    
    // 格式
    AudioFormat GetFormat() const { return m_format; }
    
    // 类型
    AudioType GetAudioType() const { return m_audioType; }
    
    // ==================== 音频数据 ====================
    
    // 获取PCM数据
    const Core::uint8* GetData() const { return m_data.Data(); }
    
    // 是否流式（不加载到内存）
    bool IsStreaming() const { return m_isStreaming; }
    
    // 设置流式
    void SetStreaming(bool streaming) { m_isStreaming = streaming; }
    
    // ==================== 播放控制 ====================
    
    // 创建音频源（用于播放）
    class IAudioSource* CreateSource() const;
    
private:
    // 成员变量
    String m_name;
    String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
    
    // 音频属性
    Core::uint32 m_sampleRate = 0;
    Core::uint32 m_channels = 0;
    Core::uint32 m_bitsPerSample = 0;
    float m_duration = 0.0f;
    AudioFormat m_format = AudioFormat::Unknown;
    AudioType m_audioType = AudioType::SFX;
    bool m_isStreaming = false;
    
    // 音频数据
    Array<Core::uint8> m_data;
};

} // namespace Resources
} // namespace XCEngine
```

---

## 7. 文件系统集成

### 7.1 文件系统接口

```cpp
// FileSystem.h (扩展现有IO模块)
namespace XCEngine {
namespace IO {

// 文件系统接口
class IFileSystem {
public:
    virtual ~IFileSystem() = default;
    
    // 文件操作
    virtual bool FileExists(const String& path) const = 0;
    virtual bool DirectoryExists(const String& path) const = 0;
    
    virtual size_t GetFileSize(const String& path) const = 0;
    virtual bool GetFileTime(const String& path, Core::uint64& outTime) const = 0;
    
    // 读取
    virtual Array<Core::uint8> ReadAllBytes(const String& path) const = 0;
    virtual String ReadAllText(const String& path) const = 0;
    virtual bool Read(const String& path, void* buffer, size_t size, size_t offset = 0) const = 0;
    
    // 写入
    virtual bool WriteAllBytes(const String& path, const void* data, size_t size) = 0;
    virtual bool WriteAllText(const String& path, const String& text) = 0;
    virtual bool Write(const String& path, const void* data, size_t size, size_t offset = 0) = 0;
    
    // 目录操作
    virtual bool CreateDirectory(const String& path) = 0;
    virtual bool DeleteDirectory(const String& path, bool recursive = false) = 0;
    virtual bool DeleteFile(const String& path) = 0;
    
    // 遍历
    virtual void EnumerateFiles(const String& path, const String& pattern, 
                               Array<String>& outFiles) const = 0;
    virtual void EnumerateDirectories(const String& path, const String& pattern,
                                     Array<String>& outDirectories) const = 0;
    
    // 获取路径信息
    virtual String GetExtension(const String& path) const = 0;
    virtual String GetFileName(const String& path) const = 0;
    virtual String GetFileNameWithoutExtension(const String& path) const = 0;
    virtual String GetDirectoryName(const String& path) const = 0;
    virtual String GetFullPath(const String& path) const = 0;
    virtual String Combine(const String& path1, const String& path2) const = 0;
};

// 获取文件系统单例
IFileSystem* GetFileSystem();
void SetFileSystem(IFileSystem* fs);

// Windows文件系统实现（默认）
class WindowsFileSystem : public IFileSystem {
public:
    // 实现Windows API调用
};

} // namespace IO
} // namespace XCEngine
```

### 7.2 资源文件系统 (ResourceFileSystem)

```cpp
// ResourceFileSystem.h
namespace XCEngine {
namespace Resources {

// 资源文件系统 - 管理资源包/归档
class ResourceFileSystem {
public:
    ResourceFileSystem();
    ~ResourceFileSystem();
    
    // 初始化
    void Initialize(const String& rootPath);
    void Shutdown();
    
    // 添加资源包
    bool AddArchive(const String& archivePath);
    bool AddDirectory(const String& directoryPath);
    
    // 移除资源包
    void RemoveArchive(const String& archivePath);
    
    // 查找资源
    bool FindResource(const String& relativePath, String& outAbsolutePath) const;
    
    // 读取资源数据
    Array<Core::uint8> ReadResource(const String& relativePath) const;
    
    // 检查资源是否存在
    bool Exists(const String& relativePath) const;
    
    // 获取资源信息
    struct ResourceInfo {
        String path;
        size_t size;
        Core::uint64 modifiedTime;
        bool inArchive;
        String archivePath;
    };
    
    bool GetResourceInfo(const String& relativePath, ResourceInfo& outInfo) const;
    
    // 枚举资源
    void EnumerateResources(const String& pattern, Array<ResourceInfo>& outResources) const;
    
private:
    // 资源包接口
    class IArchive {
    public:
        virtual ~IArchive() = default;
        virtual bool Open(const String& path) = 0;
        virtual void Close() = 0;
        virtual bool Read(const String& fileName, void* buffer, size_t size, size_t offset) const = 0;
        virtual size_t GetSize(const String& fileName) const = 0;
        virtual bool Exists(const String& fileName) const = 0;
        virtual void Enumerate(const String& pattern, Array<String>& outFiles) const = 0;
    };
    
    // 数据成员
    String m_rootPath;
    Array<UniquePtr<IArchive>> m_archives;
    Array<String> m_directories;
    
    // 缓存
    mutable HashMap<String, ResourceInfo> m_infoCache;
};

} // namespace Resources
} // namespace XCEngine
```

---

## 8. 资源打包系统

### 8.1 资源包格式

```
┌─────────────────────────────────────────────────────┐
│                    ResourcePackage                  │
├─────────────────────────────────────────────────────┤
│  Header (固定大小)                                  │
│  ├── Magic: "XCRP" (4 bytes)                      │
│  ├── Version: uint16                               │
│  ├── Manifest Size: uint32                        │
│  ├── Asset Count: uint32                          │
│  └── Data Offset: uint64                          │
├─────────────────────────────────────────────────────┤
│  Manifest (JSON/二进制)                             │
│  ├── File 1: { path, offset, size, checksum }      │
│  ├── File 2: { path, offset, size, checksum }     │
│  └── ...                                          │
├─────────────────────────────────────────────────────┤
│  Data Section                                     │
│  ├── File 1 Data (对齐到16字节)                    │
│  ├── File 2 Data                                  │
│  └── ...                                          │
└─────────────────────────────────────────────────────┘
```

### 8.2 资源包构建器

```cpp
// ResourcePackageBuilder.h
namespace XCEngine {
namespace Resources {

class ResourcePackageBuilder {
public:
    ResourcePackageBuilder();
    ~ResourcePackageBuilder();
    
    // 添加文件
    bool AddFile(const String& sourcePath, const String& relativePath);
    
    // 添加目录
    bool AddDirectory(const String& sourceDir, const String& relativeBase = "");
    
    // 设置输出路径
    void SetOutputPath(const String& path) { m_outputPath = path; }
    
    // 构建包
    bool Build();
    
    // 获取进度
    float GetProgress() const { return m_progress; }
    
    // 获取错误信息
    const String& GetError() const { return m_error; }
    
private:
    // 文件条目
    struct FileEntry {
        String sourcePath;
        String relativePath;
        size_t size;
        uint64 checksum;
    };
    
    // 成员变量
    String m_outputPath;
    Array<FileEntry> m_files;
    float m_progress = 0.0f;
    String m_error;
    
    // 辅助方法
    Core::uint64 CalculateChecksum(const void* data, size_t size);
    bool WriteHeader(FileWriter& writer, size_t dataOffset);
    bool WriteManifest(FileWriter& writer);
    bool WriteData(FileWriter& writer);
};

} // namespace Resources
} // namespace XCEngine
```

---

## 9. 资源依赖管理

### 9.1 依赖图

```cpp
// ResourceDependencyGraph.h
namespace XCEngine {
namespace Resources {

// 资源依赖节点
struct DependencyNode {
    ResourceGUID guid;
    ResourceType type;
    Array<ResourceGUID> dependencies;  // 当前资源依赖的资源
    Array<ResourceGUID> dependents;    // 依赖当前资源的资源
    Core::uint32 refCount = 0;
};

// 依赖图
class ResourceDependencyGraph {
public:
    ResourceDependencyGraph();
    ~ResourceDependencyGraph();
    
    // 添加节点
    void AddNode(ResourceGUID guid, ResourceType type);
    
    // 添加依赖关系
    void AddDependency(ResourceGUID owner, ResourceGUID dependency);
    
    // 移除节点
    void RemoveNode(ResourceGUID guid);
    
    // 移除依赖关系
    void RemoveDependency(ResourceGUID owner, ResourceGUID dependency);
    
    // 获取依赖（当前资源依赖的资源）
    Array<ResourceGUID> GetDependencies(ResourceGUID guid) const;
    
    // 获取依赖者（依赖当前资源的资源）
    Array<ResourceGUID> GetDependents(ResourceGUID guid) const;
    
    // 获取传递依赖（所有层级的依赖）
    Array<ResourceGUID> GetAllDependencies(ResourceGUID guid) const;
    
    // 引用计数管理
    void IncrementRefCount(ResourceGUID guid);
    void DecrementRefCount(ResourceGUID guid);
    Core::uint32 GetRefCount(ResourceGUID guid) const;
    
    // 查找循环依赖
    bool HasCircularDependency(ResourceGUID guid, Array<ResourceGUID>& outCycle) const;
    
    // 拓扑排序（用于加载顺序）
    Array<ResourceGUID> TopologicalSort() const;
    
    // 加载资源组及其所有依赖
    Array<ResourceGUID> LoadWithDependencies(const String& entryPath);
    
    // 卸载资源组（仅当没有依赖者时）
    bool Unload(ResourceGUID guid);
    
private:
    HashMap<ResourceGUID, DependencyNode> m_nodes;
};

} // namespace Resources
} // namespace XCEngine
```

---

## 10. 实现顺序

### 10.1 阶段划分

```
阶段 4.1: 基础框架 (3天)
    ├── 4.1.1 ResourceTypes.h - 资源类型枚举
    ├── 4.1.2 IResource.h - 资源基类接口
    ├── 4.1.3 ResourceHandle.h - 资源句柄
    ├── 4.1.4 IResourceLoader.h - 加载器接口
    └── 4.1.5 ResourceManager.h/cpp - 资源管理器基础

阶段 4.2: 缓存系统 (2天)
    ├── 4.2.1 ResourceCache.h/cpp - LRU缓存实现
    └── 4.2.2 与ResourceManager集成

阶段 4.3: 异步加载 (2天)
    ├── 4.3.1 AsyncLoader.h/cpp - 异步加载器
    ├── 4.3.2 与TaskSystem集成
    └── 4.3.3 完成回调机制

阶段 4.4: 具体资源类型 (4天)
    ├── 4.4.1 Texture + TextureLoader - 纹理资源
    ├── 4.4.2 Mesh + MeshLoader - 网格资源  
    ├── 4.4.3 Material + MaterialLoader - 材质资源
    └── 4.4.4 AudioClip + AudioLoader - 音频资源

阶段 4.5: 文件系统集成 (2天)
    ├── 4.5.1 ResourceFileSystem - 资源文件系统
    └── 4.5.2 资源包支持

阶段 4.6: 依赖管理 (2天)
    ├── 4.6.1 ResourceDependencyGraph - 依赖图
    └── 4.6.2 资源组加载/卸载

阶段 4.7: 测试与集成 (2天)
    ├── 4.7.1 单元测试
    └── 4.7.2 与现有mvs集成
```

### 10.2 详细任务列表

```
任务 4.1.1: ResourceTypes.h
    实现：
    - ResourceType 枚举（Texture, Mesh, Material, Shader, AudioClip等）
    - GetResourceTypeName() 函数
    - ResourceGUID 结构体

任务 4.1.2: IResource.h
    实现：
    - IResource 抽象基类
    - 纯虚方法：GetType(), GetName(), GetPath(), GetGUID(), IsValid(), GetMemorySize(), Release()
    - 虚析构函数

任务 4.1.3: ResourceHandle.h
    实现：
    - ResourceHandle<T> 模板类
    - 构造/析构（自动引用计数）
    - operator->(), Get(), IsValid()
    - 移动语义支持

任务 4.1.4: IResourceLoader.h
    实现：
    - IResourceLoader 抽象基类
    - LoadResult 结构体
    - GetResourceType(), GetSupportedExtensions(), CanLoad(), Load()
    - REGISTER_RESOURCE_LOADER 宏

任务 4.1.5: ResourceManager.h/cpp
    实现：
    - ResourceManager 单例
    - Initialize()/Shutdown()
    - Load<T>(path) 模板方法
    - Unload(path/guid)
    - AddRef()/Release()
    - RegisterLoader()
    - SetMemoryBudget()

任务 4.2.1: ResourceCache.h/cpp
    实现：
    - CacheEntry 结构体
    - ResourceCache 类
    - Add(), Remove(), Find(), Touch()
    - SetMemoryBudget(), OnMemoryPressure()
    - LRU淘汰逻辑

任务 4.3.1: AsyncLoader.h/cpp
    实现：
    - LoadRequest 结构体
    - AsyncLoader 单例
    - Submit<T>(path, callback)
    - Update() - 处理完成队列
    - IsLoading(), GetProgress()

任务 4.4.1: Texture + TextureLoader
    实现：
    - Texture 类（继承IResource）
    - TextureImportSettings 类
    - TextureLoader 类（继承IResourceLoader）
    - 使用stb_image加载PNG/JPG/TGA
    - REGISTER_RESOURCE_LOADER(TextureLoader)

任务 4.4.2: Mesh + MeshLoader
    实现：
    - Mesh 类（继承IResource）
    - MeshSection 结构体
    - MeshImportSettings 类
    - MeshLoader 类（使用Assimp）
    - 支持OBJ/glTF格式
    - REGISTER_RESOURCE_LOADER(MeshLoader)

任务 4.4.3: Material + MaterialLoader
    实现：
    - Material 类
    - MaterialProperty 结构体
    - MaterialLoader 类（解析JSON格式）
    - REGISTER_RESOURCE_LOADER(MaterialLoader)

任务 4.4.4: AudioClip + AudioLoader
    实现：
    - AudioClip 类
    - AudioLoader 类
    - 支持WAV格式
    - REGISTER_RESOURCE_LOADER(AudioLoader)

任务 4.5.1: ResourceFileSystem
    实现：
    - ResourceFileSystem 类
    - IArchive 接口
    - AddArchive(), AddDirectory()
    - ReadResource(), Exists()

任务 4.6.1: ResourceDependencyGraph
    实现：
    - DependencyNode 结构体
    - ResourceDependencyGraph 类
    - AddDependency(), RemoveDependency()
    - GetDependencies(), GetDependents()
    - TopologicalSort()
```

---

## 11. 详细执行计划

> 本节详细说明如何逐步实现资源系统，包括每个文件的具体内容、实现步骤、测试方法和集成要点。

### 11.1 文件创建清单

首先，需要创建以下目录结构和文件：

```
engine/include/XCEngine/Resources/
├── Resources.h                    # 主头文件
├── ResourceTypes.h               # 资源类型枚举
├── ImportSettings.h              # 导入设置基类
├── IResource.h                   # 资源基类接口
├── ResourceHandle.h              # 资源句柄
├── ResourceManager.h             # 资源管理器
├── IResourceLoader.h            # 加载器基类
├── ResourceCache.h               # 资源缓存
├── AsyncLoader.h                 # 异步加载器
├── Texture.h                     # 纹理资源
├── TextureLoader.h               # 纹理加载器
├── TextureImportSettings.h       # 纹理导入设置
├── Mesh.h                        # 网格资源
├── MeshLoader.h                  # 网格加载器
├── MeshImportSettings.h          # 网格导入设置
├── Material.h                    # 材质资源
├── MaterialLoader.h              # 材质加载器
├── Shader.h                      # 着色器资源
├── ShaderLoader.h                # 着色器加载器
├── AudioClip.h                   # 音频资源
├── AudioLoader.h                 # 音频加载器
└── BinaryResource.h              # 二进制资源

engine/src/Resources/
├── Resources.cpp                 # 资源系统初始化
├── ResourceManager.cpp           # 资源管理器实现
├── ResourceCache.cpp             # 缓存实现
├── AsyncLoader.cpp               # 异步加载实现
├── TextureLoader.cpp             # 纹理加载实现
├── MeshLoader.cpp                # 网格加载实现
├── MaterialLoader.cpp            # 材质加载实现
├── ShaderLoader.cpp              # 着色器加载实现
└── AudioLoader.cpp               # 音频加载实现
```

### 11.2 第一阶段：基础框架（天1-3）

#### 步骤 11.2.1 创建主头文件 Resources.h

```cpp
// Resources.h
#pragma once

#include "ResourceTypes.h"
#include "ImportSettings.h"
#include "IResource.h"
#include "ResourceHandle.h"
#include "ResourceManager.h"
#include "IResourceLoader.h"
#include "ResourceCache.h"
#include "AsyncLoader.h"

// 具体资源类型
#include "Texture.h"
#include "TextureLoader.h"
#include "TextureImportSettings.h"
#include "Mesh.h"
#include "MeshLoader.h"
#include "MeshImportSettings.h"
#include "Material.h"
#include "MaterialLoader.h"
#include "Shader.h"
#include "ShaderLoader.h"
#include "AudioClip.h"
#include "AudioLoader.h"
#include "BinaryResource.h"
```

#### 步骤 11.2.2 实现 ResourceTypes.h

**文件**: `engine/include/XCEngine/Resources/ResourceTypes.h`

```cpp
#pragma once
#include "../Core/Types.h"
#include "../Containers/String.h"
#include "../Containers/Array.h"
#include <cstdint>

namespace XCEngine {
namespace Resources {

// 资源类型枚举
enum class ResourceType : Core::uint8 {
    Unknown = 0,
    Texture,
    Mesh,
    Material,
    Shader,
    AudioClip,
    Binary,
    AnimationClip,
    Skeleton,
    Font,
    ParticleSystem,
    Scene,
    Prefab
};

constexpr const char* GetResourceTypeName(ResourceType type) {
    switch (type) {
        case ResourceType::Texture:        return "Texture";
        case ResourceType::Mesh:          return "Mesh";
        case ResourceType::Material:      return "Material";
        case ResourceType::Shader:        return "Shader";
        case ResourceType::AudioClip:     return "AudioClip";
        case ResourceType::Binary:         return "Binary";
        case ResourceType::AnimationClip: return "AnimationClip";
        case ResourceType::Skeleton:      return "Skeleton";
        case ResourceType::Font:          return "Font";
        case ResourceType::ParticleSystem:return "ParticleSystem";
        case ResourceType::Scene:         return "Scene";
        case ResourceType::Prefab:        return "Prefab";
        default:                          return "Unknown";
    }
}

// ResourceGUID - 64位唯一标识符
struct ResourceGUID {
    Core::uint64 value;
    
    ResourceGUID() : value(0) {}
    explicit ResourceGUID(Core::uint64 v) : value(v) {}
    
    bool IsValid() const { return value != 0; }
    
    bool operator==(const ResourceGUID& other) const { return value == other.value; }
    bool operator!=(const ResourceGUID& other) const { return value != other.value; }
    
    static ResourceGUID Generate(const char* path);
    static ResourceGUID Generate(const Containers::String& path);
    
    Containers::String ToString() const;
};

inline ResourceGUID MakeResourceGUID(const char* path) {
    return ResourceGUID::Generate(path);
}

// 模板特化获取ResourceType
template<typename T>
ResourceType GetResourceType();

template<> inline ResourceType GetResourceType<class Texture>() { return ResourceType::Texture; }
template<> inline ResourceType GetResourceType<class Mesh>() { return ResourceType::Mesh; }
template<> inline ResourceType GetResourceType<class Material>() { return ResourceType::Material; }
template<> inline ResourceType GetResourceType<class Shader>() { return ResourceType::Shader; }
template<> inline ResourceType GetResourceType<class AudioClip>() { return ResourceType::AudioClip; }
template<> inline ResourceType GetResourceType<class BinaryResource>() { return ResourceType::Binary; }

// 导入设置基类
class ImportSettings {
public:
    virtual ~ImportSettings() = default;
    
    virtual UniquePtr<ImportSettings> Clone() const = 0;
    virtual bool LoadFromJSON(const Containers::String& json) { return false; }
    virtual Containers::String SaveToJSON() const { return Containers::String(); }
};

} // namespace Resources
} // namespace XCEngine
```

**实现文件** `engine/src/Resources/ResourceTypes.cpp`:
```cpp
#include "Resources/ResourceTypes.h"
#include <algorithm>

namespace XCEngine {
namespace Resources {

// 简单哈希实现（实际项目中可使用MD5）
ResourceGUID ResourceGUID::Generate(const char* path) {
    Core::uint64 hash = 14695981039346656037ULL; // FNV offset basis
    
    while (*path) {
        hash ^= static_cast<Core::uint64>(*path);
        hash *= 1099511628211ULL; // FNV prime
        path++;
    }
    
    return ResourceGUID(hash);
}

ResourceGUID ResourceGUID::Generate(const Containers::String& path) {
    return Generate(path.CStr());
}

Containers::String ResourceGUID::ToString() const {
    char buffer[17];
    snprintf(buffer, sizeof(buffer), "%016llx", value);
    return Containers::String(buffer);
}

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.2.3 实现 IResource.h

**文件**: `engine/include/XCEngine/Resources/IResource.h`

```cpp
#pragma once
#include "ResourceTypes.h"
#include "../Containers/String.h"

namespace XCEngine {
namespace Resources {

class IResource {
public:
    virtual ~IResource() = default;
    
    virtual ResourceType GetType() const = 0;
    virtual const Containers::String& GetName() const = 0;
    virtual const Containers::String& GetPath() const = 0;
    virtual ResourceGUID GetGUID() const = 0;
    virtual bool IsValid() const = 0;
    virtual size_t GetMemorySize() const = 0;
    virtual void Release() = 0;

protected:
    struct ConstructParams {
        Containers::String name;
        Containers::String path;
        ResourceGUID guid;
        size_t memorySize = 0;
    };
    
    void Initialize(const ConstructParams& params) {
        m_name = params.name;
        m_path = params.path;
        m_guid = params.guid;
        m_memorySize = params.memorySize;
        m_isValid = true;
    }
    
    void SetInvalid() { m_isValid = false; }
    
    Containers::String m_name;
    Containers::String m_path;
    ResourceGUID m_guid;
    bool m_isValid = false;
    size_t m_memorySize = 0;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.2.4 实现 ResourceHandle.h

**文件**: `engine/include/XCEngine/Resources/ResourceHandle.h`

```cpp
#pragma once
#include "IResource.h"
#include <type_traits>
#include <functional>

namespace XCEngine {
namespace Resources {

template<typename T>
class ResourceHandle {
    static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
    
public:
    ResourceHandle() = default;
    
    explicit ResourceHandle(T* resource)
        : m_resource(resource) {
        if (m_resource) {
            ResourceManager::Get().AddRef(m_resource->GetGUID());
        }
    }
    
    ResourceHandle(const ResourceHandle& other)
        : m_resource(other.m_resource) {
        if (m_resource) {
            ResourceManager::Get().AddRef(m_resource->GetGUID());
        }
    }
    
    ResourceHandle(ResourceHandle&& other) noexcept
        : m_resource(other.m_resource) {
        other.m_resource = nullptr;
    }
    
    ~ResourceHandle() {
        Reset();
    }
    
    ResourceHandle& operator=(const ResourceHandle& other) {
        if (this != &other) {
            Reset();
            m_resource = other.m_resource;
            if (m_resource) {
                ResourceManager::Get().AddRef(m_resource->GetGUID());
            }
        }
        return *this;
    }
    
    ResourceHandle& operator=(ResourceHandle&& other) noexcept {
        if (this != &other) {
            Reset();
            m_resource = other.m_resource;
            other.m_resource = nullptr;
        }
        return *this;
    }
    
    T* Get() const { return m_resource; }
    T* operator->() const { return m_resource; }
    T& operator*() const { return *m_resource; }
    
    bool IsValid() const { return m_resource != nullptr && m_resource->IsValid(); }
    explicit operator bool() const { return IsValid(); }
    
    ResourceGUID GetGUID() const {
        return m_resource ? m_resource->GetGUID() : ResourceGUID(0);
    }
    
    ResourceType GetResourceType() const {
        return m_resource ? m_resource->GetType() : ResourceType::Unknown;
    }
    
    void Reset() {
        if (m_resource) {
            ResourceManager::Get().Release(m_resource->GetGUID());
            m_resource = nullptr;
        }
    }
    
    void Swap(ResourceHandle& other) {
        std::swap(m_resource, other.m_resource);
    }
    
private:
    T* m_resource = nullptr;
};

template<typename T>
bool operator==(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
    return lhs.GetGUID() == rhs.GetGUID();
}

template<typename T>
bool operator!=(const ResourceHandle<T>& lhs, const ResourceHandle<T>& rhs) {
    return !(lhs == rhs);
}

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.2.5 实现 IResourceLoader.h

**文件**: `engine/include/XCEngine/Resources/IResourceLoader.h`

```cpp
#pragma once
#include "IResource.h"
#include "ResourceTypes.h"
#include "../Containers/String.h"
#include "../Containers/Array.h"
#include <functional>

namespace XCEngine {
namespace Resources {

struct LoadResult {
    IResource* resource = nullptr;
    bool success = false;
    Containers::String errorMessage;
    
    LoadResult() = default;
    explicit LoadResult(IResource* res) : resource(res), success(res != nullptr) {}
    explicit LoadResult(const Containers::String& error) : success(false), errorMessage(error) {}
    explicit LoadResult(bool success, const Containers::String& error = "") 
        : success(success), errorMessage(error) {}
    
    operator bool() const { return success && resource != nullptr; }
};

class IResourceLoader {
public:
    virtual ~IResourceLoader() = default;
    
    virtual ResourceType GetResourceType() const = 0;
    virtual Containers::Array<Containers::String> GetSupportedExtensions() const = 0;
    virtual bool CanLoad(const Containers::String& path) const = 0;
    virtual LoadResult Load(const Containers::String& path, const ImportSettings* settings = nullptr) = 0;
    
    virtual void LoadAsync(const Containers::String& path, 
                          const ImportSettings* settings,
                          std::function<void(LoadResult)> callback) {
        LoadResult result = Load(path, settings);
        if (callback) {
            callback(result);
        }
    }
    
    virtual ImportSettings* GetDefaultSettings() const = 0;

protected:
    static Containers::Array<Core::uint8> ReadFileData(const Containers::String& path);
    static Containers::String GetExtension(const Containers::String& path);
};

#define REGISTER_RESOURCE_LOADER(loaderType) \
    namespace { \
        struct loaderType##Registrar { \
            loaderType##Registrar() { \
                ResourceManager::Get().RegisterLoader(new loaderType()); \
            } \
        } g_##loaderType##Registrar; \
    }

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.2.6 实现 ResourceManager.h

**文件**: `engine/include/XCEngine/Resources/ResourceManager.h`

```cpp
#pragma once
#include "IResourceLoader.h"
#include "ResourceCache.h"
#include "AsyncLoader.h"
#include "../Containers/String.h"
#include "../Containers/Array.h"
#include "../Containers/HashMap.h"
#include "../Threading/Mutex.h"
#include "../Debug/Logger.h"

namespace XCEngine {
namespace Resources {

class ResourceManager {
public:
    static ResourceManager& Get();
    
    void Initialize();
    void Shutdown();
    
    void SetResourceRoot(const Containers::String& rootPath);
    const Containers::String& GetResourceRoot() const;
    
    template<typename T>
    ResourceHandle<T> Load(const Containers::String& path, ImportSettings* settings = nullptr) {
        static_assert(std::is_base_of_v<IResource, T>, "T must derive from IResource");
        
        // 实现见文档Section 5.4
    }
    
    void LoadAsync(const Containers::String& path, ResourceType type, 
                   std::function<void(LoadResult)> callback);
    void LoadAsync(const Containers::String& path, ResourceType type, ImportSettings* settings,
                   std::function<void(LoadResult)> callback);
    
    void Unload(const Containers::String& path);
    void Unload(ResourceGUID guid);
    void UnloadUnused();
    void UnloadAll();
    
    void AddRef(ResourceGUID guid);
    void Release(ResourceGUID guid);
    Core::uint32 GetRefCount(ResourceGUID guid) const;
    
    void RegisterLoader(IResourceLoader* loader);
    void UnregisterLoader(ResourceType type);
    IResourceLoader* GetLoader(ResourceType type) const;
    
    void SetMemoryBudget(size_t bytes);
    size_t GetMemoryUsage() const;
    size_t GetMemoryBudget() const;
    void FlushCache();
    
    IResource* Find(const Containers::String& path);
    IResource* Find(ResourceGUID guid);
    bool Exists(const Containers::String& path) const;
    bool Exists(ResourceGUID guid) const;
    
    Containers::String ResolvePath(const Containers::String& relativePath) const;

private:
    ResourceManager() = default;
    ~ResourceManager() = default;
    
    IResource* FindInCache(ResourceGUID guid);
    void AddToCache(ResourceGUID guid, IResource* resource);
    IResourceLoader* FindLoader(ResourceType type);
    void ReloadResource(ResourceGUID guid);
    
    Containers::String m_resourceRoot;
    Containers::HashMap<ResourceGUID, IResource*> m_resourceCache;
    Containers::HashMap<ResourceGUID, Core::uint32> m_refCounts;
    Containers::HashMap<ResourceGUID, Containers::String> m_guidToPath;
    Containers::HashMap<ResourceType, UniquePtr<IResourceLoader>> m_loaders;
    
    size_t m_memoryUsage = 0;
    size_t m_memoryBudget = 512 * 1024 * 1024;
    
    UniquePtr<AsyncLoader> m_asyncLoader;
    Threading::Mutex m_mutex;
    
    friend class ResourceHandleBase;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.2.7 实现 ResourceManager.cpp

**文件**: `engine/src/Resources/ResourceManager.cpp`

```cpp
#include "Resources/ResourceManager.h"
#include "Resources/ResourceHandle.h"

namespace XCEngine {
namespace Resources {

ResourceManager& ResourceManager::Get() {
    static ResourceManager instance;
    return instance;
}

void ResourceManager::Initialize() {
    m_asyncLoader = UniquePtr<AsyncLoader>(new AsyncLoader());
    m_asyncLoader->Initialize(2); // 默认2个工作线程
}

void ResourceManager::Shutdown() {
    UnloadAll();
    m_asyncLoader->Shutdown();
    m_asyncLoader.Reset();
}

void ResourceManager::SetResourceRoot(const Containers::String& rootPath) {
    m_resourceRoot = rootPath;
}

const Containers::String& ResourceManager::GetResourceRoot() const {
    return m_resourceRoot;
}

void ResourceManager::AddRef(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_refCounts.Find(guid);
    if (it == m_refCounts.End()) {
        m_refCounts.Insert(guid, 1);
    } else {
        it->second++;
    }
    
    if (!m_resourceCache.Contains(guid)) {
        ReloadResource(guid);
    }
}

void ResourceManager::Release(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_refCounts.Find(guid);
    if (it != m_refCounts.End()) {
        it->second--;
        
        if (it->second == 0) {
            m_refCounts.Erase(guid);
            m_cache.OnZeroRefCount(guid);
        }
    }
}

Core::uint32 ResourceManager::GetRefCount(ResourceGUID guid) const {
    std::lock_guard lock(m_mutex);
    
    auto it = m_refCounts.Find(guid);
    return it != m_refCounts.End() ? it->second : 0;
}

void ResourceManager::RegisterLoader(IResourceLoader* loader) {
    std::lock_guard lock(m_mutex);
    m_loaders.Insert(loader->GetResourceType(), UniquePtr<IResourceLoader>(loader));
}

IResourceLoader* ResourceManager::GetLoader(ResourceType type) const {
    std::lock_guard lock(m_mutex);
    
    auto it = m_loaders.Find(type);
    return it != m_loaders.End() ? it->second.Get() : nullptr;
}

IResourceLoader* ResourceManager::FindLoader(ResourceType type) {
    return GetLoader(type);
}

IResource* ResourceManager::FindInCache(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_resourceCache.Find(guid);
    return it != m_resourceCache.End() ? it->second : nullptr;
}

void ResourceManager::AddToCache(ResourceGUID guid, IResource* resource) {
    std::lock_guard lock(m_mutex);
    
    m_resourceCache.Insert(guid, resource);
    m_memoryUsage += resource->GetMemorySize();
    m_cache.Add(guid, resource);
    
    if (m_memoryUsage > m_memoryBudget) {
        m_cache.OnMemoryPressure(m_memoryUsage - m_memoryBudget);
    }
}

void ResourceManager::Unload(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_resourceCache.Find(guid);
    if (it != m_resourceCache.End()) {
        IResource* resource = it->second;
        m_resourceCache.Erase(guid);
        m_memoryUsage -= resource->GetMemorySize();
        resource->Release();
    }
}

void ResourceManager::UnloadAll() {
    std::lock_guard lock(m_mutex);
    
    for (auto& pair : m_resourceCache) {
        pair.second->Release();
    }
    m_resourceCache.Clear();
    m_refCounts.Clear();
    m_memoryUsage = 0;
}

void ResourceManager::SetMemoryBudget(size_t bytes) {
    m_memoryBudget = bytes;
}

size_t ResourceManager::GetMemoryUsage() const {
    return m_memoryUsage;
}

size_t ResourceManager::GetMemoryBudget() const {
    return m_memoryBudget;
}

void ResourceManager::FlushCache() {
    m_cache.Flush();
}

IResource* ResourceManager::Find(const Containers::String& path) {
    ResourceGUID guid = MakeResourceGUID(path.CStr());
    return Find(guid);
}

IResource* ResourceManager::Find(ResourceGUID guid) {
    return FindInCache(guid);
}

bool ResourceManager::Exists(const Containers::String& path) const {
    return Find(MakeResourceGUID(path.CStr())) != nullptr;
}

bool ResourceManager::Exists(ResourceGUID guid) const {
    return false; // 需要实现
}

Containers::String ResourceManager::ResolvePath(const Containers::String& relativePath) const {
    return m_resourceRoot + "/" + relativePath;
}

void ResourceManager::LoadAsync(const Containers::String& path, ResourceType type,
                               std::function<void(LoadResult)> callback) {
    LoadAsync(path, type, nullptr, callback);
}

void ResourceManager::LoadAsync(const Containers::String& path, ResourceType type, 
                               ImportSettings* settings,
                               std::function<void(LoadResult>)> callback) {
    m_asyncLoader->Submit(path, type, settings, callback);
}

void ResourceManager::Unload(const Containers::String& path) {
    Unload(MakeResourceGUID(path.CStr()));
}

void ResourceManager::UnloadUnused() {
    // 实现清理未使用资源
}

void ResourceManager::UnregisterLoader(ResourceType type) {
    m_loaders.Erase(type);
}

void ResourceManager::ReloadResource(ResourceGUID guid) {
    // 实现重新加载逻辑
}

} // namespace Resources
} // namespace XCEngine
```

### 11.3 第二阶段：缓存系统（天4-5）

#### 步骤 11.3.1 实现 ResourceCache.h

**文件**: `engine/include/XCEngine/Resources/ResourceCache.h`

```cpp
#pragma once
#include "ResourceTypes.h"
#include "../Containers/HashMap.h"
#include "../Containers/Array.h"
#include "../Threading/Mutex.h"
#include <algorithm>

namespace XCEngine {
namespace Resources {

struct CacheEntry {
    IResource* resource;
    ResourceGUID guid;
    size_t memorySize;
    Core::uint64 lastAccessTime;
    Core::uint32 accessCount;
    
    CacheEntry() : resource(nullptr), memorySize(0), lastAccessTime(0), accessCount(0) {}
    CacheEntry(IResource* res, size_t size)
        : resource(res), guid(res->GetGUID()), memorySize(size),
          lastAccessTime(GetCurrentTick()), accessCount(1) {}
    
private:
    static Core::uint64 GetCurrentTick();
};

class ResourceCache {
public:
    ResourceCache();
    ~ResourceCache();
    
    void Add(ResourceGUID guid, IResource* resource);
    void Remove(ResourceGUID guid);
    IResource* Find(ResourceGUID guid) const;
    void Touch(ResourceGUID guid);
    
    size_t GetSize() const { return m_cache.Size(); }
    size_t GetMemoryUsage() const { return m_memoryUsage; }
    
    void SetMemoryBudget(size_t bytes);
    size_t GetMemoryBudget() const { return m_memoryBudget; }
    
    void OnMemoryPressure(size_t requiredBytes);
    void OnZeroRefCount(ResourceGUID guid);
    void Flush();
    void Clear();
    
    Containers::Array<ResourceGUID> GetLRUList(size_t count) const;

private:
    void Evict(size_t requiredBytes);
    void UpdateMemoryStats();
    
    Containers::HashMap<ResourceGUID, CacheEntry> m_cache;
    Containers::Array<ResourceGUID> m_lruOrder;
    size_t m_memoryUsage = 0;
    size_t m_memoryBudget = 512 * 1024 * 1024;
    
    Threading::Mutex m_mutex;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.3.2 实现 ResourceCache.cpp

**文件**: `engine/src/Resources/ResourceCache.cpp`

```cpp
#include "Resources/ResourceCache.h"

namespace XCEngine {
namespace Resources {

// 简单的时间戳实现，实际可使用Profiler::Get().GetTickCount()
static Core::uint64 g_currentTick = 0;
Core::uint64 CacheEntry::GetCurrentTick() {
    return ++g_currentTick;
}

ResourceCache::ResourceCache() = default;
ResourceCache::~ResourceCache() = default;

void ResourceCache::Add(ResourceGUID guid, IResource* resource) {
    std::lock_guard lock(m_mutex);
    
    if (m_cache.Contains(guid)) {
        return; // 已存在
    }
    
    CacheEntry entry(resource, resource->GetMemorySize());
    m_cache.Insert(guid, entry);
    m_lruOrder.Add(guid);
    m_memoryUsage += entry.memorySize;
}

void ResourceCache::Remove(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_cache.Find(guid);
    if (it != m_cache.End()) {
        m_memoryUsage -= it->second.memorySize;
        m_cache.Erase(guid);
        
        for (auto lit = m_lruOrder.Begin(); lit != m_lruOrder.End(); ++lit) {
            if (*lit == guid) {
                m_lruOrder.Erase(lit);
                break;
            }
        }
    }
}

IResource* ResourceCache::Find(ResourceGUID guid) const {
    std::lock_guard lock(m_mutex);
    
    auto it = m_cache.Find(guid);
    return it != m_cache.End() ? it->second.resource : nullptr;
}

void ResourceCache::Touch(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_cache.Find(guid);
    if (it != m_cache.End()) {
        it->second.lastAccessTime = CacheEntry::GetCurrentTick();
        it->second.accessCount++;
    }
}

void ResourceCache::SetMemoryBudget(size_t bytes) {
    std::lock_guard lock(m_mutex);
    m_memoryBudget = bytes;
}

void ResourceCache::OnMemoryPressure(size_t requiredBytes) {
    std::lock_guard lock(m_mutex);
    
    if (m_memoryUsage + requiredBytes <= m_memoryBudget) {
        return;
    }
    
    size_t targetRelease = (m_memoryUsage + requiredBytes) - m_memoryBudget;
    Evict(targetRelease);
}

void ResourceCache::OnZeroRefCount(ResourceGUID guid) {
    // 引用计数为0时，标记资源可以被淘汰
    // 实际淘汰由LRU策略决定
}

void ResourceCache::Evict(size_t requiredBytes) {
    size_t released = 0;
    
    for (auto it = m_lruOrder.Begin(); it != m_lruOrder.End() && released < requiredBytes; ) {
        ResourceGUID guid = *it;
        auto cacheIt = m_cache.Find(guid);
        
        if (cacheIt != m_cache.End()) {
            CacheEntry& entry = cacheIt->second;
            
            if (ResourceManager::Get().GetRefCount(guid) == 0) {
                size_t entrySize = entry.memorySize;
                
                m_cache.Erase(guid);
                m_memoryUsage -= entrySize;
                released += entrySize;
                
                entry.resource->Release();
                it = m_lruOrder.Erase(it);
            } else {
                ++it;
            }
        } else {
            ++it;
        }
    }
}

void ResourceCache::Flush() {
    std::lock_guard lock(m_mutex);
    
    for (auto& pair : m_cache) {
        if (ResourceManager::Get().GetRefCount(pair.first) == 0) {
            pair.second.resource->Release();
        }
    }
    
    m_cache.Clear();
    m_lruOrder.Clear();
    m_memoryUsage = 0;
}

void ResourceCache::Clear() {
    std::lock_guard lock(m_mutex);
    m_cache.Clear();
    m_lruOrder.Clear();
    m_memoryUsage = 0;
}

Containers::Array<ResourceGUID> ResourceCache::GetLRUList(size_t count) const {
    std::lock_guard lock(m_mutex);
    
    Containers::Array<ResourceGUID> result;
    size_t n = std::min(count, static_cast<size_t>(m_lruOrder.Size()));
    
    for (size_t i = 0; i < n; i++) {
        result.Add(m_lruOrder[i]);
    }
    
    return result;
}

} // namespace Resources
} // namespace XCEngine
```

### 11.4 第三阶段：异步加载（天6-7）

#### 步骤 11.4.1 实现 AsyncLoader.h

**文件**: `engine/include/XCEngine/Resources/AsyncLoader.h`

```cpp
#pragma once
#include "IResourceLoader.h"
#include "../Containers/Array.h"
#include "../Threading/Mutex.h"
#include <atomic>
#include <functional>

namespace XCEngine {
namespace Resources {

struct LoadRequest {
    Containers::String path;
    ResourceType type;
    std::function<void(LoadResult)> callback;
    UniquePtr<ImportSettings> settings;
    Core::uint64 requestId;
    
    LoadRequest() : requestId(0) {}
    
    LoadRequest(const Containers::String& p, ResourceType t,
                std::function<void(LoadResult)> cb, ImportSettings* s = nullptr)
        : path(p), type(t), callback(std::move(cb)),
          settings(s), requestId(GenerateRequestId()) {}
    
private:
    static Core::uint64 GenerateRequestId();
};

class LoadTask : public Threading::ITask {
public:
    LoadTask(LoadRequest request, IResourceLoader* loader);
    
    void Execute() override;
    LoadResult& GetResult() { return m_result; }

private:
    LoadRequest m_request;
    IResourceLoader* m_loader;
    LoadResult m_result;
};

class AsyncLoader {
public:
    static AsyncLoader& Get();
    
    void Initialize(Core::uint32 workerThreadCount = 2);
    void Shutdown();
    
    void Submit(const Containers::String& path, ResourceType type,
                std::function<void(LoadResult)> callback);
    void Submit(const Containers::String& path, ResourceType type, ImportSettings* settings,
                std::function<void(LoadResult)> callback);
    
    void Update();
    bool IsLoading() const { return m_pendingCount > 0; }
    Core::uint32 GetPendingCount() const { return m_pendingCount; }
    float GetProgress() const;
    void CancelAll();
    void Cancel(Core::uint64 requestId);

private:
    AsyncLoader() = default;
    ~AsyncLoader() = default;
    
    void SubmitInternal(LoadRequest& request);
    IResourceLoader* FindLoader(ResourceType type) const;
    
    Threading::Mutex m_queueMutex;
    Containers::Array<LoadRequest> m_pendingQueue;
    
    Threading::Mutex m_completedMutex;
    Containers::Array<LoadRequest> m_completedQueue;
    
    std::atomic<Core::uint32> m_pendingCount{0};
    std::atomic<Core::uint32> m_completedCount{0};
    Core::uint32 m_totalRequested = 0;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.4.2 实现 AsyncLoader.cpp

**文件**: `engine/src/Resources/AsyncLoader.cpp`

```cpp
#include "Resources/AsyncLoader.h"
#include "Resources/ResourceManager.h"
#include "../Threading/TaskSystem.h"

namespace XCEngine {
namespace Resources {

Core::uint64 LoadRequest::GenerateRequestId() {
    static std::atomic<Core::uint64> s_requestId{0};
    return ++s_requestId;
}

LoadTask::LoadTask(LoadRequest request, IResourceLoader* loader)
    : m_request(std::move(request)), m_loader(loader) {}

void LoadTask::Execute() {
    m_result = m_loader->Load(m_request.path, m_request.settings.Get());
    
    // 放入完成队列
    AsyncLoader::Get().QueueCompleted(std::move(m_request), std::move(m_result));
}

AsyncLoader& AsyncLoader::Get() {
    static AsyncLoader instance;
    return instance;
}

void AsyncLoader::Initialize(Core::uint32 workerThreadCount) {
    // TaskSystem已初始化，此处不需要额外操作
}

void AsyncLoader::Shutdown() {
    CancelAll();
}

void AsyncLoader::Submit(const Containers::String& path, ResourceType type,
                         std::function<void(LoadResult)> callback) {
    Submit(path, type, nullptr, callback);
}

void AsyncLoader::Submit(const Containers::String& path, ResourceType type,
                        ImportSettings* settings, std::function<void(LoadResult)> callback) {
    LoadRequest request(path, type, callback, settings);
    SubmitInternal(request);
}

void AsyncLoader::SubmitInternal(LoadRequest& request) {
    IResourceLoader* loader = FindLoader(request.type);
    if (!loader) {
        if (request.callback) {
            LoadResult result(Containers::String("No loader for type: ") + 
                           GetResourceTypeName(request.type));
            request.callback(result);
        }
        return;
    }
    
    {
        std::lock_guard lock(m_queueMutex);
        m_pendingQueue.Add(request);
        m_pendingCount++;
        m_totalRequested++;
    }
    
    // 提交到任务系统
    auto task = new LoadTask(request, loader);
    Threading::TaskSystem::Get().Submit(UniquePtr<ITask>(task));
}

void AsyncLoader::Update() {
    Containers::Array<LoadRequest> completed;
    
    {
        std::lock_guard lock(m_completedMutex);
        completed = std::move(m_completedQueue);
        m_completedQueue.Clear();
    }
    
    for (auto& request : completed) {
        m_pendingCount--;
        
        if (request.callback) {
            request.callback(m_completedResults[request.requestId]);
        }
    }
    
    m_completedResults.Clear();
}

float AsyncLoader::GetProgress() const {
    if (m_totalRequested == 0) return 1.0f;
    return static_cast<float>(m_totalRequested - m_pendingCount) / m_totalRequested;
}

void AsyncLoader::CancelAll() {
    std::lock_guard lock(m_queueMutex);
    m_pendingQueue.Clear();
    m_pendingCount = 0;
}

void AsyncLoader::Cancel(Core::uint64 requestId) {
    std::lock_guard lock(m_queueMutex);
    
    for (auto it = m_pendingQueue.Begin(); it != m_pendingQueue.End(); ++it) {
        if (it->requestId == requestId) {
            m_pendingQueue.Erase(it);
            m_pendingCount--;
            return;
        }
    }
}

IResourceLoader* AsyncLoader::FindLoader(ResourceType type) const {
    return ResourceManager::Get().GetLoader(type);
}

} // namespace Resources
} // namespace XCEngine
```

### 11.5 第四阶段：具体资源类型（天8-11）

#### 步骤 11.5.1 实现 Texture 及其加载器

**文件**: `engine/include/XCEngine/Resources/Texture.h`

```cpp
#pragma once
#include "IResource.h"
#include "../Core/Types.h"

namespace XCEngine {
namespace Resources {

enum class TextureType {
    Texture2D, Texture3D, TextureCube, Texture2DArray, TextureCubeArray
};

enum class TextureFormat {
    Unknown, R8_UNORM, RG8_UNORM, RGBA8_UNORM, RGBA8_SRGB,
    R16_FLOAT, RG16_FLOAT, RGBA16_FLOAT,
    R32_FLOAT, RG32_FLOAT, RGBA32_FLOAT,
    D16_UNORM, D24_UNORM_S8_UINT, D32_FLOAT, D32_FLOAT_S8_X24_UINT,
    BC1_UNORM, BC1_UNORM_SRGB, BC2_UNORM, BC2_UNORM_SRGB,
    BC3_UNORM, BC3_UNORM_SRGB, BC4_UNORM, BC5_UNORM, BC6H_UF16,
    BC7_UNORM, BC7_UNORM_SRGB
};

enum class TextureUsage : Core::uint8 {
    None = 0, ShaderResource = 1 << 0, RenderTarget = 1 << 1,
    DepthStencil = 1 << 2, UnorderedAccess = 1 << 3,
    TransferSrc = 1 << 4, TransferDst = 1 << 5
};

class Texture : public IResource {
public:
    Texture();
    virtual ~Texture() override;
    
    ResourceType GetType() const override { return ResourceType::Texture; }
    const Containers::String& GetName() const override { return m_name; }
    const Containers::String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    Core::uint32 GetWidth() const { return m_width; }
    Core::uint32 GetHeight() const { return m_height; }
    Core::uint32 GetDepth() const { return m_depth; }
    Core::uint32 GetMipLevels() const { return m_mipLevels; }
    Core::uint32 GetArraySize() const { return m_arraySize; }
    TextureType GetTextureType() const { return m_textureType; }
    TextureFormat GetFormat() const { return m_format; }
    TextureUsage GetUsage() const { return m_usage; }
    
    class IRHIResource* GetRHIResource() const { return m_rhiResource; }
    void SetRHIResource(class IRHIResource* resource);
    
    bool Create(Core::uint32 width, Core::uint32 height, Core::uint32 depth,
                Core::uint32 mipLevels, TextureType type, TextureFormat format,
                const void* data, size_t dataSize);
    bool GenerateMipmaps();

private:
    Core::uint32 m_width = 0;
    Core::uint32 m_height = 0;
    Core::uint32 m_depth = 1;
    Core::uint32 m_mipLevels = 1;
    Core::uint32 m_arraySize = 1;
    TextureType m_textureType = TextureType::Texture2D;
    TextureFormat m_format = TextureFormat::RGBA8_UNORM;
    TextureUsage m_usage = TextureUsage::ShaderResource;
    
    class IRHIResource* m_rhiResource = nullptr;
};

} // namespace Resources
} // namespace XCEngine
```

**实现要点**:
1. 使用stb_image库加载PNG/JPG/TGA
2. 支持生成Mipmap
3. 完成后创建RHI资源

#### 步骤 11.5.2 实现 Mesh 及其加载器

**文件**: `engine/include/XCEngine/Resources/Mesh.h`

```cpp
#pragma once
#include "IResource.h"
#include "../Containers/Array.h"
#include "../Math/AABB.h"

namespace XCEngine {
namespace Resources {

enum class VertexAttribute : Core::uint32 {
    Position = 1 << 0, Normal = 1 << 1, Tangent = 1 << 2,
    Color = 1 << 3, UV0 = 1 << 4, UV1 = 1 << 5,
    UV2 = 1 << 6, UV3 = 1 << 7, BoneWeights = 1 << 8, BoneIndices = 1 << 9
};

struct MeshSection {
    Core::uint32 baseVertex;
    Core::uint32 vertexCount;
    Core::uint32 startIndex;
    Core::uint32 indexCount;
    Core::uint32 materialID;
    Math::AABB boundingBox;
};

class Mesh : public IResource {
public:
    Mesh();
    virtual ~Mesh() override;
    
    ResourceType GetType() const override { return ResourceType::Mesh; }
    const Containers::String& GetName() const override { return m_name; }
    const Containers::String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    void SetVertexData(const void* data, size_t size, Core::uint32 vertexCount,
                       Core::uint32 vertexStride, VertexAttribute attributes);
    const void* GetVertexData() const { return m_vertexData.Data(); }
    size_t GetVertexDataSize() const { return m_vertexData.Size(); }
    Core::uint32 GetVertexCount() const { return m_vertexCount; }
    Core::uint32 GetVertexStride() const { return m_vertexStride; }
    VertexAttribute GetVertexAttributes() const { return m_attributes; }
    
    void SetIndexData(const void* data, size_t size, Core::uint32 indexCount, bool use32Bit);
    const void* GetIndexData() const { return m_indexData.Data(); }
    size_t GetIndexDataSize() const { return m_indexData.Size(); }
    Core::uint32 GetIndexCount() const { return m_indexCount; }
    bool IsUse32BitIndex() const { return m_use32BitIndex; }
    
    void AddSection(const MeshSection& section);
    const Containers::Array<MeshSection>& GetSections() const { return m_sections; }
    
    void SetBoundingBox(const Math::AABB& box);
    const Math::AABB& GetBoundingBox() const { return m_boundingBox; }
    
    class IRHIBuffer* GetVertexBuffer() const { return m_vertexBuffer; }
    class IRHIBuffer* GetIndexBuffer() const { return m_indexBuffer; }
    void SetRHIBuffers(class IRHIBuffer* vb, class IRHIBuffer* ib);

private:
    Containers::Array<Core::uint8> m_vertexData;
    Core::uint32 m_vertexCount = 0;
    Core::uint32 m_vertexStride = 0;
    VertexAttribute m_attributes = VertexAttribute::Position;
    
    Containers::Array<Core::uint8> m_indexData;
    Core::uint32 m_indexCount = 0;
    bool m_use32BitIndex = false;
    
    Containers::Array<MeshSection> m_sections;
    Math::AABB m_boundingBox;
    
    class IRHIBuffer* m_vertexBuffer = nullptr;
    class IRHIBuffer* m_indexBuffer = nullptr;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.5.3 实现 Material 及其加载器

**文件**: `engine/include/XCEngine/Resources/Material.h`

```cpp
#pragma once
#include "IResource.h"
#include "ResourceHandle.h"
#include "Texture.h"
#include "../Containers/HashMap.h"
#include "../Math/Vector2.h"
#include "../Math/Vector3.h"
#include "../Math/Vector4.h"

namespace XCEngine {
namespace Resources {

enum class MaterialPropertyType {
    Float, Float2, Float3, Float4,
    Int, Int2, Int3, Int4,
    Bool, Texture, Cubemap
};

struct MaterialProperty {
    Containers::String name;
    MaterialPropertyType type;
    
    union Value {
        float floatValue[4];
        Core::int32 intValue[4];
        bool boolValue;
        ResourceHandle<Texture> textureValue;
        
        Value() { memset(this, 0, sizeof(Value)); }
    } value;
    
    Core::uint32 refCount;
};

class Material : public IResource {
public:
    Material();
    virtual ~Material() override;
    
    ResourceType GetType() const override { return ResourceType::Material; }
    const Containers::String& GetName() const override { return m_name; }
    const Containers::String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override;
    
    void SetShader(const ResourceHandle<class Shader>& shader);
    class Shader* GetShader() const { return m_shader.Get(); }
    
    void SetFloat(const Containers::String& name, float value);
    void SetFloat2(const Containers::String& name, const Math::Vector2& value);
    void SetFloat3(const Containers::String& name, const Math::Vector3& value);
    void SetFloat4(const Containers::String& name, const Math::Vector4& value);
    void SetInt(const Containers::String& name, int32 value);
    void SetBool(const Containers::String& name, bool value);
    void SetTexture(const Containers::String& name, const ResourceHandle<Texture>& texture);
    
    float GetFloat(const Containers::String& name) const;
    ResourceHandle<Texture> GetTexture(const Containers::String& name) const;
    
    const Containers::Array<Core::uint8>& GetConstantBufferData() const { return m_constantBufferData; }
    void UpdateConstantBuffer();

private:
    ResourceHandle<class Shader> m_shader;
    Containers::HashMap<Containers::String, MaterialProperty> m_properties;
    Containers::Array<Core::uint8> m_constantBufferData;
    
    struct TextureBinding {
        Containers::String name;
        Core::uint32 slot;
        ResourceHandle<Texture> texture;
    };
    Containers::Array<TextureBinding> m_textureBindings;
};

} // namespace Resources
} // namespace XCEngine
```

#### 步骤 11.5.4 实现 AudioClip 及其加载器

类似实现，支持WAV格式加载。

### 11.6 第五阶段：文件系统集成（天12-13）

#### 步骤 11.6.1 实现 ResourceFileSystem

**文件**: `engine/include/XCEngine/Resources/ResourceFileSystem.h`

```cpp
#pragma once
#include "ResourceTypes.h"
#include "../Containers/String.h"
#include "../Containers/Array.h"
#include "../Containers/HashMap.h"

namespace XCEngine {
namespace Resources {

class ResourceFileSystem {
public:
    ResourceFileSystem();
    ~ResourceFileSystem();
    
    void Initialize(const Containers::String& rootPath);
    void Shutdown();
    
    bool AddArchive(const Containers::String& archivePath);
    bool AddDirectory(const Containers::String& directoryPath);
    void RemoveArchive(const Containers::String& archivePath);
    
    bool FindResource(const Containers::String& relativePath, 
                     Containers::String& outAbsolutePath) const;
    Containers::Array<Core::uint8> ReadResource(const Containers::String& relativePath) const;
    bool Exists(const Containers::String& relativePath) const;
    
    struct ResourceInfo {
        Containers::String path;
        size_t size;
        Core::uint64 modifiedTime;
        bool inArchive;
        Containers::String archivePath;
    };
    
    bool GetResourceInfo(const Containers::String& relativePath, ResourceInfo& outInfo) const;
    void EnumerateResources(const Containers::String& pattern, 
                          Containers::Array<ResourceInfo>& outResources) const;

private:
    class IArchive {
    public:
        virtual ~IArchive() = default;
        virtual bool Open(const Containers::String& path) = 0;
        virtual void Close() = 0;
        virtual bool Read(const Containers::String& fileName, void* buffer, 
                         size_t size, size_t offset) const = 0;
        virtual size_t GetSize(const Containers::String& fileName) const = 0;
        virtual bool Exists(const Containers::String& fileName) const = 0;
        virtual void Enumerate(const Containers::String& pattern, 
                              Containers::Array<Containers::String>& outFiles) const = 0;
    };
    
    Containers::String m_rootPath;
    Containers::Array<UniquePtr<IArchive>> m_archives;
    Containers::Array<Containers::String> m_directories;
    mutable Containers::HashMap<Containers::String, ResourceInfo> m_infoCache;
};

} // namespace Resources
} // namespace XCEngine
```

### 11.7 第六阶段：依赖管理（天14-15）

#### 步骤 11.7.1 实现 ResourceDependencyGraph

```cpp
// 见文档Section 9
```

### 11.8 第七阶段：测试与集成（天16-17）

#### 步骤 11.8.1 单元测试

创建测试用例：
1. 资源加载/卸载
2. 引用计数
3. 缓存淘汰
4. 异步加载
5. 多线程安全

#### 步骤 11.8.2 集成到现有mvs项目

在示例应用中使用资源系统加载纹理和模型。

### 11.9 每日任务清单

| 天数 | 任务 | 完成标准 |
|------|------|----------|
| 1 | 创建目录结构 + Resources.h + ResourceTypes.h | 编译通过 |
| 2 | IResource.h + ResourceHandle.h | 智能指针正常工作 |
| 3 | IResourceLoader.h + ResourceManager.h框架 | 加载器接口完成 |
| 4 | ResourceCache.h/cpp | LRU淘汰正常 |
| 5 | ResourceManager与Cache集成 | 引用计数正常 |
| 6 | AsyncLoader.h/cpp框架 | 任务提交正常 |
| 7 | 异步回调机制 | 主线程回调正常 |
| 8 | Texture.h + 基础加载 | PNG加载成功 |
| 9 | Texture RHI资源创建 | 渲染器能使用 |
| 10 | Mesh.h + 加载器 | OBJ加载成功 |
| 11 | Material.h + 加载器 | JSON材质加载 |
| 12 | ResourceFileSystem | 目录/归档支持 |
| 13 | 资源打包Builder | 打包成功 |
| 14 | DependencyGraph | 依赖关系正确 |
| 15 | 资源组加载 | 批量加载正常 |
| 16 | 单元测试 | 测试通过 |
| 17 | 集成测试 | 示例运行正常 |

---

## 12. 测试设计

> 本节详细说明资源系统的测试设计，确保每个阶段完成后都能立即进行测试验收。测试采用Google Test框架，与现有项目保持一致。

### 12.1 测试目录结构

```
tests/
├── Resources/                           # 新增资源系统测试
│   ├── CMakeLists.txt                   # 构建配置
│   ├── fixtures/
│   │   └── ResourcesTestFixture.h      # 测试夹具基类
│   ├── test_resource_types.cpp          # 资源类型测试
│   ├── test_resource_guid.cpp            # GUID生成测试
│   ├── test_iresource.cpp                # 资源接口测试
│   ├── test_resource_handle.cpp           # 资源句柄测试
│   ├── test_resource_cache.cpp           # 缓存测试
│   ├── test_async_loader.cpp             # 异步加载测试
│   ├── test_texture.cpp                   # 纹理资源测试
│   ├── test_mesh.cpp                     # 网格资源测试
│   ├── test_material.cpp                 # 材质资源测试
│   ├── test_audio_clip.cpp               # 音频资源测试
│   ├── test_resource_manager.cpp         # 资源管理器测试
│   ├── test_resource_filesystem.cpp      # 文件系统测试
│   ├── test_resource_dependency.cpp      # 依赖管理测试
│   └── test_data/
│       ├── test_texture.png              # 测试用纹理
│       ├── test_mesh.obj                # 测试用模型
│       └── test_material.json            # 测试用材质
```

### 12.2 测试夹具基类

**文件**: `tests/Resources/fixtures/ResourcesTestFixture.h`

```cpp
#pragma once

#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceManager.h>
#include <XCEngine/Resources/AsyncLoader.h>
#include <XCEngine/Containers/String.h>

namespace XCEngine {
namespace Resources {
namespace Test {

class ResourcesTestFixture : public ::testing::Test {
protected:
    static void SetUpTestSuite() {
        // 初始化资源系统
        ResourceManager::Get().Initialize();
        ResourceManager::Get().SetResourceRoot("tests/Resources/test_data/");
        AsyncLoader::Get().Initialize(2);
    }
    
    static void TearDownTestSuite() {
        ResourceManager::Get().UnloadAll();
        AsyncLoader::Get().Shutdown();
        ResourceManager::Get().Shutdown();
    }
    
    void SetUp() override {
        // 每个测试前清空缓存
        ResourceManager::Get().UnloadAll();
        ResourceManager::Get().FlushCache();
    }
    
    void TearDown() override {
        // 每个测试后确保清空资源
        ResourceManager::Get().UnloadAll();
    }
    
    // 辅助方法：获取测试数据目录
    Containers::String GetTestDataPath(const Containers::String& filename) {
        return Containers::String("tests/Resources/test_data/") + filename;
    }
};

} // namespace Test
} // namespace Resources
} // namespace XCEngine
```

### 12.3 第一阶段测试：基础框架（天1-3完成后）

#### 测试 12.3.1 资源类型枚举测试

**文件**: `tests/Resources/test_resource_types.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceTypes.h>

using namespace XCEngine::Resources;

namespace {

TEST(Resources_Types, ResourceType_EnumValues) {
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Unknown), 0);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Texture), 1);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Mesh), 2);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Material), 3);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Shader), 4);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::AudioClip), 5);
    EXPECT_EQ(static_cast<Core::uint8>(ResourceType::Binary), 6);
}

TEST(Resources_Types, GetResourceTypeName) {
    EXPECT_STREQ(GetResourceTypeName(ResourceType::Texture), "Texture");
    EXPECT_STREQ(GetResourceTypeName(ResourceType::Mesh), "Mesh");
    EXPECT_STREQ(GetResourceTypeName(ResourceType::Material), "Material");
    EXPECT_STREQ(GetResourceTypeName(ResourceType::Unknown), "Unknown");
}

TEST(Resources_Types, GetResourceType_TemplateSpecializations) {
    EXPECT_EQ(GetResourceType<Texture>(), ResourceType::Texture);
    EXPECT_EQ(GetResourceType<Mesh>(), ResourceType::Mesh);
    EXPECT_EQ(GetResourceType<Material>(), ResourceType::Material);
    EXPECT_EQ(GetResourceType<Shader>(), ResourceType::Shader);
    EXPECT_EQ(GetResourceType<AudioClip>(), ResourceType::AudioClip);
    EXPECT_EQ(GetResourceType<BinaryResource>(), ResourceType::Binary);
}

} // namespace
```

#### 测试 12.3.2 ResourceGUID测试

**文件**: `tests/Resources/test_resource_guid.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceTypes.h>

using namespace XCEngine::Resources;

namespace {

TEST(Resources_GUID, DefaultConstructor) {
    ResourceGUID guid;
    EXPECT_FALSE(guid.IsValid());
    EXPECT_EQ(guid.value, 0);
}

TEST(Resources_GUID, ValueConstructor) {
    ResourceGUID guid(12345);
    EXPECT_TRUE(guid.IsValid());
    EXPECT_EQ(guid.value, 12345);
}

TEST(Resources_GUID, Generate_FromCString) {
    ResourceGUID guid1 = ResourceGUID::Generate("textures/player.png");
    ResourceGUID guid2 = ResourceGUID::Generate("textures/player.png");
    
    // 相同路径应生成相同GUID
    EXPECT_EQ(guid1, guid2);
    EXPECT_TRUE(guid1.IsValid());
}

TEST(Resources_GUID, Generate_FromString) {
    Containers::String path = "models/player.fbx";
    ResourceGUID guid = ResourceGUID::Generate(path);
    EXPECT_TRUE(guid.IsValid());
}

TEST(Resources_GUID, Generate_DifferentPaths) {
    ResourceGUID guid1 = ResourceGUID::Generate("textures/a.png");
    ResourceGUID guid2 = ResourceGUID::Generate("textures/b.png");
    
    // 不同路径应生成不同GUID
    EXPECT_NE(guid1, guid2);
}

TEST(Resources_GUID, ToString) {
    ResourceGUID guid(0x1234567890ABCDEF);
    Containers::String str = guid.ToString();
    
    EXPECT_EQ(str.Size(), 16u);
    EXPECT_STREQ(str.CStr(), "1234567890abcdef");
}

TEST(Resources_GUID, MakeResourceGUID_Helper) {
    ResourceGUID guid = MakeResourceGUID("test/path");
    EXPECT_TRUE(guid.IsValid());
}

TEST(Resources_GUID, EqualityOperators) {
    ResourceGUID guid1(100);
    ResourceGUID guid2(100);
    ResourceGUID guid3(200);
    
    EXPECT_TRUE(guid1 == guid2);
    EXPECT_TRUE(guid1 != guid3);
}

} // namespace
```

#### 测试 12.3.3 资源句柄测试

**文件**: `tests/Resources/test_resource_handle.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceHandle.h>
#include <XCEngine/Resources/ResourceManager.h>

using namespace XCEngine::Resources;

// 测试用伪资源
class TestResource : public IResource {
public:
    TestResource(const Containers::String& name) {
        ConstructParams params;
        params.name = name;
        params.path = name;
        params.guid = ResourceGUID::Generate(name.CStr());
        params.memorySize = 1024;
        Initialize(params);
    }
    
    ResourceType GetType() const override { return ResourceType::Binary; }
    const Containers::String& GetName() const override { return m_name; }
    const Containers::String& GetPath() const override { return m_path; }
    ResourceGUID GetGUID() const override { return m_guid; }
    bool IsValid() const override { return m_isValid; }
    size_t GetMemorySize() const override { return m_memorySize; }
    void Release() override { delete this; }
};

namespace {

TEST(Resources_Handle, DefaultConstructor) {
    ResourceHandle<TestResource> handle;
    EXPECT_FALSE(handle.IsValid());
    EXPECT_EQ(handle.Get(), nullptr);
}

TEST(Resources_Handle, ConstructorWithValidResource) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle(resource);
    
    EXPECT_TRUE(handle.IsValid());
    EXPECT_EQ(handle.Get(), resource);
    EXPECT_EQ(handle->GetName().CStr(), Containers::String("test_resource"));
}

TEST(Resources_Handle, CopyConstructor_AddsRef) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle1(resource);
    
    Core::uint32 refCountBefore = ResourceManager::Get().GetRefCount(resource->GetGUID());
    
    ResourceHandle<TestResource> handle2(handle1);
    
    Core::uint32 refCountAfter = ResourceManager::Get().GetRefCount(resource->GetGUID());
    EXPECT_EQ(refCountAfter, refCountBefore + 1);
}

TEST(Resources_Handle, MoveConstructor_DoesNotAddRef) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle1(resource);
    
    Core::uint32 refCountBefore = ResourceManager::Get().GetRefCount(resource->GetGUID());
    
    ResourceHandle<TestResource> handle2(std::move(handle1));
    
    // 移动语义不应增加引用计数
    EXPECT_EQ(handle1.Get(), nullptr);
    EXPECT_EQ(handle2.Get(), resource);
}

TEST(Resources_Handle, Destructor_ReleasesRef) {
    TestResource* resource = new TestResource("test_resource");
    {
        ResourceHandle<TestResource> handle(resource);
        EXPECT_TRUE(handle.IsValid());
    }
    // handle销毁后应释放引用
    // 注意：此时资源应该被卸载（因为引用计数为0）
}

TEST(Resources_Handle, Reset) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle(resource);
    
    EXPECT_TRUE(handle.IsValid());
    handle.Reset();
    
    EXPECT_FALSE(handle.IsValid());
    EXPECT_EQ(handle.Get(), nullptr);
}

TEST(Resources_Handle, ArrowOperator) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle(resource);
    
    EXPECT_STREQ(handle->GetName().CStr(), "test_resource");
    EXPECT_EQ(handle->GetGUID(), resource->GetGUID());
}

TEST(Resources_Handle, BoolOperator) {
    ResourceHandle<TestResource> emptyHandle;
    TestResource* resource = new TestResource("test");
    ResourceHandle<TestResource> validHandle(resource);
    
    EXPECT_FALSE(emptyHandle);
    EXPECT_TRUE(validHandle);
}

TEST(Resources_Handle, GetGUID) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle(resource);
    
    EXPECT_EQ(handle.GetGUID(), resource->GetGUID());
    EXPECT_TRUE(handle.GetGUID().IsValid());
}

TEST(Resources_Handle, GetResourceType) {
    TestResource* resource = new TestResource("test_resource");
    ResourceHandle<TestResource> handle(resource);
    
    EXPECT_EQ(handle.GetResourceType(), ResourceType::Binary);
}

TEST(Resources_Handle, EqualityOperators) {
    TestResource* resource = new TestResource("test");
    ResourceHandle<TestResource> handle1(resource);
    ResourceHandle<TestResource> handle2(resource);
    
    EXPECT_TRUE(handle1 == handle2);
    
    TestResource* resource2 = new TestResource("test2");
    ResourceHandle<TestResource> handle3(resource2);
    
    EXPECT_TRUE(handle1 != handle3);
}

} // namespace
```

### 12.4 第二阶段测试：缓存系统（天4-5完成后）

#### 测试 12.4.1 资源缓存测试

**文件**: `tests/Resources/test_resource_cache.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceCache.h>
#include "fixtures/ResourcesTestFixture.h"

using namespace XCEngine::Resources;

namespace {

class ResourceCache_Test : public ResourcesTestFixture {
protected:
    void SetUp() override {
        ResourcesTestFixture::SetUp();
        m_cache = new ResourceCache();
    }
    
    void TearDown() override {
        delete m_cache;
        ResourcesTestFixture::TearDown();
    }
    
    ResourceCache* m_cache;
};

TEST_F(ResourceCache_Test, AddResource) {
    TestResource* resource = new TestResource("test1");
    ResourceGUID guid = resource->GetGUID();
    
    m_cache->Add(guid, resource);
    
    EXPECT_EQ(m_cache->GetSize(), 1u);
    EXPECT_EQ(m_cache->GetMemoryUsage(), resource->GetMemorySize());
}

TEST_F(ResourceCache_Test, FindResource) {
    TestResource* resource = new TestResource("test1");
    ResourceGUID guid = resource->GetGUID();
    
    m_cache->Add(guid, resource);
    
    IResource* found = m_cache->Find(guid);
    EXPECT_EQ(found, resource);
}

TEST_F(ResourceCache_Test, FindNonExistent) {
    ResourceGUID guid(9999);
    IResource* found = m_cache->Find(guid);
    EXPECT_EQ(found, nullptr);
}

TEST_F(ResourceCache_Test, RemoveResource) {
    TestResource* resource = new TestResource("test1");
    ResourceGUID guid = resource->GetGUID();
    
    m_cache->Add(guid, resource);
    m_cache->Remove(guid);
    
    EXPECT_EQ(m_cache->GetSize(), 0u);
    EXPECT_EQ(m_cache->Find(guid), nullptr);
}

TEST_F(ResourceCache_Test, Touch_UpdatesAccessTime) {
    TestResource* resource = new TestResource("test1");
    ResourceGUID guid = resource->GetGUID();
    
    m_cache->Add(guid, resource);
    m_cache->Touch(guid);
    
    // Touch后应能找到资源
    EXPECT_EQ(m_cache->Find(guid), resource);
}

TEST_F(ResourceCache_Test, MemoryBudget) {
    m_cache->SetMemoryBudget(1024); // 1KB
    
    EXPECT_EQ(m_cache->GetMemoryBudget(), 1024u);
}

TEST_F(ResourceCache_Test, OnMemoryPressure_EvictUnreferenced) {
    m_cache->SetMemoryBudget(512);
    
    // 添加多个资源
    for (int i = 0; i < 5; i++) {
        TestResource* resource = new TestResource(Containers::String("test") + Containers::String::FromInt(i));
        m_cache->Add(resource->GetGUID(), resource);
    }
    
    // 触发内存压力
    m_cache->OnMemoryPressure(1024);
    
    // 应该有资源被淘汰
    // 具体数量取决于LRU策略
}

TEST_F(ResourceCache_Test, Clear) {
    for (int i = 0; i < 3; i++) {
        TestResource* resource = new TestResource(Containers::String("test") + Containers::String::FromInt(i));
        m_cache->Add(resource->GetGUID(), resource);
    }
    
    m_cache->Clear();
    
    EXPECT_EQ(m_cache->GetSize(), 0u);
    EXPECT_EQ(m_cache->GetMemoryUsage(), 0u);
}

TEST_F(ResourceCache_Test, GetLRUList) {
    // 添加资源并访问
    TestResource* r1 = new TestResource("test1");
    TestResource* r2 = new TestResource("test2");
    TestResource* r3 = new TestResource("test3");
    
    m_cache->Add(r1->GetGUID(), r1);
    m_cache->Add(r2->GetGUID(), r2);
    m_cache->Add(r3->GetGUID(), r3);
    
    // 访问r1使其最新
    m_cache->Touch(r1->GetGUID());
    
    auto lru = m_cache->GetLRUList(2);
    
    // r1应该是最新的，不应在LRU列表前几位
    EXPECT_GE(lru.Size(), 0u);
}

} // namespace
```

### 12.5 第三阶段测试：异步加载（天6-7完成后）

#### 测试 12.5.1 异步加载器测试

**文件**: `tests/Resources/test_async_loader.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/AsyncLoader.h>
#include "fixtures/ResourcesTestFixture.h"
#include <atomic>

using namespace XCEngine::Resources;

namespace {

class AsyncLoader_Test : public ResourcesTestFixture {
protected:
    void SetUp() override {
        ResourcesTestFixture::SetUp();
    }
};

TEST_F(AsyncLoader_Test, Submit_IncrementsPendingCount) {
    AsyncLoader& loader = AsyncLoader::Get();
    
    Core::uint32 pendingBefore = loader.GetPendingCount();
    
    // 注意：需要先注册加载器，否则会立即失败
    // 这里测试API本身
    EXPECT_GE(pendingBefore, 0u);
}

TEST_F(AsyncLoader_Test, Update_ProcessesCompletedRequests) {
    AsyncLoader& loader = AsyncLoader::Get();
    
    // 调用Update处理完成队列
    loader.Update();
    
    // 不应崩溃
    EXPECT_TRUE(true);
}

TEST_F(AsyncLoader_Test, IsLoading) {
    AsyncLoader& loader = AsyncLoader::Get();
    
    bool isLoading = loader.IsLoading();
    
    EXPECT_FALSE(isLoading); // 初始状态
}

TEST_F(AsyncLoader_Test, GetProgress) {
    AsyncLoader& loader = AsyncLoader::Get();
    
    float progress = loader.GetProgress();
    
    // 0.0 - 1.0之间
    EXPECT_GE(progress, 0.0f);
    EXPECT_LE(progress, 1.0f);
}

TEST_F(AsyncLoader_Test, CancelAll) {
    AsyncLoader& loader = AsyncLoader::Get();
    
    loader.CancelAll();
    
    EXPECT_EQ(loader.GetPendingCount(), 0u);
}

TEST_F(AsyncLoader_Test, CallbackInvocation) {
    std::atomic<int> callbackCount{0};
    
    // 模拟回调
    auto callback = [&callbackCount](LoadResult result) {
        callbackCount++;
    };
    
    // 调用Update确保没有pending请求
    AsyncLoader::Get().Update();
    
    EXPECT_EQ(callbackCount, 0);
}

} // namespace
```

### 12.6 第四阶段测试：具体资源类型（天8-11完成后）

#### 测试 12.6.1 纹理资源测试

**文件**: `tests/Resources/test_texture.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/Texture.h>
#include <XCEngine/Resources/TextureLoader.h>
#include "fixtures/ResourcesTestFixture.h"

using namespace XCEngine::Resources;

namespace {

class Texture_Test : public ResourcesTestFixture {
protected:
    void SetUp() override {
        ResourcesTestFixture::SetUp();
    }
};

TEST_F(Texture_Test, DefaultConstructor) {
    Texture texture;
    
    EXPECT_FALSE(texture.IsValid());
    EXPECT_EQ(texture.GetType(), ResourceType::Texture);
}

TEST_F(Texture_Test, GetDimensions_Default) {
    Texture texture;
    
    EXPECT_EQ(texture.GetWidth(), 0u);
    EXPECT_EQ(texture.GetHeight(), 0u);
    EXPECT_EQ(texture.GetDepth(), 1u);
    EXPECT_EQ(texture.GetMipLevels(), 1u);
}

TEST_F(Texture_Test, GetTextureType_Default) {
    Texture texture;
    
    EXPECT_EQ(texture.GetTextureType(), TextureType::Texture2D);
}

TEST_F(Texture_Test, GetFormat_Default) {
    Texture texture;
    
    EXPECT_EQ(texture.GetFormat(), TextureFormat::RGBA8_UNORM);
}

TEST_F(Texture_Test, Create) {
    Texture texture;
    
    bool result = texture.Create(
        256, 256, 1, 1,
        TextureType::Texture2D,
        TextureFormat::RGBA8_UNORM,
        nullptr, 0
    );
    
    EXPECT_TRUE(result);
    EXPECT_EQ(texture.GetWidth(), 256u);
    EXPECT_EQ(texture.GetHeight(), 256u);
    EXPECT_TRUE(texture.IsValid());
}

TEST_F(Texture_Test, CreateWithMipmaps) {
    Texture texture;
    
    bool result = texture.Create(
        256, 256, 1, 4,
        TextureType::Texture2D,
        TextureFormat::RGBA8_UNORM,
        nullptr, 0
    );
    
    EXPECT_TRUE(result);
    EXPECT_EQ(texture.GetMipLevels(), 4u);
}

TEST_F(Texture_Test, GetMemorySize) {
    Texture texture;
    
    // 256x256 RGBA8 = 256*256*4 = 262144 bytes
    texture.Create(256, 256, 1, 1, TextureType::Texture2D, 
                   TextureFormat::RGBA8_UNORM, nullptr, 0);
    
    size_t memorySize = texture.GetMemorySize();
    EXPECT_GT(memorySize, 0u);
}

TEST_F(Texture_Test, GetName) {
    Texture texture;
    ConstructParams params;
    params.name = "TestTexture";
    params.path = "textures/test.png";
    params.guid = ResourceGUID::Generate("test");
    params.memorySize = 1024;
    texture.Initialize(params);
    
    EXPECT_STREQ(texture.GetName().CStr(), "TestTexture");
}

TEST_F(Texture_Test, GetPath) {
    Texture texture;
    ConstructParams params;
    params.name = "TestTexture";
    params.path = "textures/test.png";
    params.guid = ResourceGUID::Generate("test");
    params.memorySize = 1024;
    texture.Initialize(params);
    
    EXPECT_STREQ(texture.GetPath().CStr(), "textures/test.png");
}

TEST_F(Texture_Test, TextureLoader_CanLoad) {
    TextureLoader loader;
    
    EXPECT_TRUE(loader.CanLoad("textures/test.png"));
    EXPECT_TRUE(loader.CanLoad("textures/test.jpg"));
    EXPECT_TRUE(loader.CanLoad("textures/test.tga"));
    EXPECT_FALSE(loader.CanLoad("models/test.obj"));
}

TEST_F(Texture_Test, TextureLoader_GetSupportedExtensions) {
    TextureLoader loader;
    auto extensions = loader.GetSupportedExtensions();
    
    EXPECT_GE(extensions.Size(), 5u);
}

TEST_F(Texture_Test, TextureLoader_GetResourceType) {
    TextureLoader loader;
    
    EXPECT_EQ(loader.GetResourceType(), ResourceType::Texture);
}

TEST_F(Texture_Test, TextureLoader_GetDefaultSettings) {
    TextureLoader loader;
    ImportSettings* settings = loader.GetDefaultSettings();
    
    EXPECT_NE(settings, nullptr);
    EXPECT_TRUE(dynamic_cast<TextureImportSettings*>(settings) != nullptr);
    
    delete settings;
}

TEST_F(Texture_Test, TextureImportSettings_Defaults) {
    TextureImportSettings settings;
    
    EXPECT_EQ(settings.GetTextureType(), TextureType::Texture2D);
    EXPECT_TRUE(settings.GetGenerateMipmaps());
    EXPECT_EQ(settings.GetMaxAnisotropy(), 16u);
}

TEST_F(Texture_Test, TextureImportSettings_Modify) {
    TextureImportSettings settings;
    
    settings.SetTextureType(TextureType::TextureCube);
    settings.SetGenerateMipmaps(false);
    settings.SetMaxAnisotropy(8);
    settings.SetSRGB(true);
    
    EXPECT_EQ(settings.GetTextureType(), TextureType::TextureCube);
    EXPECT_FALSE(settings.GetGenerateMipmaps());
    EXPECT_EQ(settings.GetMaxAnisotropy(), 8u);
    EXPECT_TRUE(settings.GetSRGB());
}

} // namespace
```

#### 测试 12.6.2 网格资源测试

**文件**: `tests/Resources/test_mesh.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/Mesh.h>
#include "fixtures/ResourcesTestFixture.h"

using namespace XCEngine::Resources;

namespace {

class Mesh_Test : public ResourcesTestFixture {};

TEST_F(Mesh_Test, DefaultConstructor) {
    Mesh mesh;
    
    EXPECT_FALSE(mesh.IsValid());
    EXPECT_EQ(mesh.GetType(), ResourceType::Mesh);
}

TEST_F(Mesh_Test, GetVertexCount_Default) {
    Mesh mesh;
    
    EXPECT_EQ(mesh.GetVertexCount(), 0u);
}

TEST_F(Mesh_Test, GetIndexCount_Default) {
    Mesh mesh;
    
    EXPECT_EQ(mesh.GetIndexCount(), 0u);
}

TEST_F(Mesh_Test, SetVertexData) {
    Mesh mesh;
    
    // 简单顶点数据：位置
    float vertices[] = {
        0.0f, 0.0f, 0.0f,
        1.0f, 0.0f, 0.0f,
        0.0f, 1.0f, 0.0f
    };
    
    mesh.SetVertexData(vertices, sizeof(vertices), 3, 12, VertexAttribute::Position);
    
    EXPECT_EQ(mesh.GetVertexCount(), 3u);
    EXPECT_EQ(mesh.GetVertexStride(), 12u);
    EXPECT_TRUE(mesh.GetVertexAttributes() & VertexAttribute::Position);
}

TEST_F(Mesh_Test, SetIndexData) {
    Mesh mesh;
    
    // 三角形索引
    uint16_t indices[] = {0, 1, 2};
    
    mesh.SetIndexData(indices, sizeof(indices), 3, false);
    
    EXPECT_EQ(mesh.GetIndexCount(), 3u);
    EXPECT_FALSE(mesh.IsUse32BitIndex());
}

TEST_F(Mesh_Test, SetIndexData_32Bit) {
    Mesh mesh;
    
    uint32_t indices[] = {0, 1, 2, 0, 2, 3};
    
    mesh.SetIndexData(indices, sizeof(indices), 6, true);
    
    EXPECT_EQ(mesh.GetIndexCount(), 6u);
    EXPECT_TRUE(mesh.IsUse32BitIndex());
}

TEST_F(Mesh_Test, AddSection) {
    Mesh mesh;
    
    MeshSection section;
    section.baseVertex = 0;
    section.vertexCount = 3;
    section.startIndex = 0;
    section.indexCount = 3;
    section.materialID = 0;
    
    mesh.AddSection(section);
    
    EXPECT_EQ(mesh.GetSections().Size(), 1u);
}

TEST_F(Mesh_Test, BoundingBox) {
    Mesh mesh;
    
    Math::AABB box;
    box.Min = Math::Vector3(0, 0, 0);
    box.Max = Math::Vector3(1, 1, 1);
    
    mesh.SetBoundingBox(box);
    
    EXPECT_EQ(mesh.GetBoundingBox().Min, Math::Vector3(0, 0, 0));
    EXPECT_EQ(mesh.GetBoundingBox().Max, Math::Vector3(1, 1, 1));
}

TEST_F(Mesh_Test, VertexAttribute_Enum) {
    // 测试顶点属性标志
    VertexAttribute attrs = VertexAttribute::Position | VertexAttribute::Normal | VertexAttribute::UV0;
    
    EXPECT_TRUE(attrs & VertexAttribute::Position);
    EXPECT_TRUE(attrs & VertexAttribute::Normal);
    EXPECT_TRUE(attrs & VertexAttribute::UV0);
    EXPECT_FALSE(attrs & VertexAttribute::Tangent);
}

} // namespace
```

#### 测试 12.6.3 材质资源测试

**文件**: `tests/Resources/test_material.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/Material.h>
#include "fixtures/ResourcesTestFixture.h"

using namespace XCEngine::Resources;

namespace {

class Material_Test : public ResourcesTestFixture {};

TEST_F(Material_Test, DefaultConstructor) {
    Material material;
    
    EXPECT_FALSE(material.IsValid());
    EXPECT_EQ(material.GetType(), ResourceType::Material);
}

TEST_F(Material_Test, SetFloat) {
    Material material;
    
    material.SetFloat("Metallic", 0.5f);
    
    EXPECT_FLOAT_EQ(material.GetFloat("Metallic"), 0.5f);
}

TEST_F(Material_Test, SetFloat2) {
    Material material;
    
    material.SetFloat2("UVScale", Math::Vector2(2.0f, 3.0f));
    
    Math::Vector2 value = material.GetFloat2("UVScale");
    EXPECT_FLOAT_EQ(value.x, 2.0f);
    EXPECT_FLOAT_EQ(value.y, 3.0f);
}

TEST_F(Material_Test, SetFloat3) {
    Material material;
    
    material.SetFloat3("Albedo", Math::Vector3(1.0f, 0.0f, 0.0f));
    
    Math::Vector3 value = material.GetFloat3("Albedo");
    EXPECT_FLOAT_EQ(value.x, 1.0f);
    EXPECT_FLOAT_EQ(value.y, 0.0f);
    EXPECT_FLOAT_EQ(value.z, 0.0f);
}

TEST_F(Material_Test, SetFloat4) {
    Material material;
    
    material.SetFloat4("Color", Math::Vector4(1.0f, 1.0f, 1.0f, 0.5f));
    
    Math::Vector4 value = material.GetFloat4("Color");
    EXPECT_FLOAT_EQ(value.w, 0.5f);
}

TEST_F(Material_Test, SetInt) {
    Material material;
    
    material.SetInt("RenderQueue", 2000);
    
    EXPECT_EQ(material.GetInt("RenderQueue"), 2000);
}

TEST_F(Material_Test, SetBool) {
    Material material;
    
    material.SetBool("EnableInstancing", true);
    
    EXPECT_TRUE(material.GetBool("EnableInstancing"));
}

TEST_F(Material_Test, SetTexture) {
    Material material;
    
    // 创建测试纹理
    Texture* tex = new Texture();
    tex->Initialize({"TestTex", "test.png", ResourceGUID::Generate("test"), 1024});
    
    ResourceHandle<Texture> handle(tex);
    material.SetTexture("MainTex", handle);
    
    // 验证纹理设置成功
    // 注意：需要实现GetTexture方法
}

TEST_F(Material_Test, PropertyNotFound) {
    Material material;
    
    // 查询不存在的属性应有默认值
    EXPECT_FLOAT_EQ(material.GetFloat("NonExistent"), 0.0f);
}

} // namespace
```

### 12.7 第五阶段测试：资源管理器（天3-5完成后）

#### 测试 12.7.1 资源管理器测试

**文件**: `tests/Resources/test_resource_manager.cpp`

```cpp
#include <gtest/gtest.h>
#include <XCEngine/Resources/ResourceManager.h>
#include "fixtures/ResourcesTestFixture.h"

using namespace XCEngine::Resources;

namespace {

class ResourceManager_Test : public ResourcesTestFixture {};

TEST_F(ResourceManager_Test, GetSingleton) {
    ResourceManager& manager = ResourceManager::Get();
    
    EXPECT_EQ(&manager, &ResourceManager::Get());
}

TEST_F(ResourceManager_Test, SetResourceRoot) {
    ResourceManager& manager = ResourceManager::Get();
    
    manager.SetResourceRoot("resources/");
    
    EXPECT_STREQ(manager.GetResourceRoot().CStr(), "resources/");
}

TEST_F(ResourceManager_Test, SetMemoryBudget) {
    ResourceManager& manager = ResourceManager::Get();
    
    manager.SetMemoryBudget(1024 * 1024); // 1MB
    
    EXPECT_EQ(manager.GetMemoryBudget(), 1024u * 1024u);
}

TEST_F(ResourceManager_Test, GetMemoryUsage_Initial) {
    ResourceManager& manager = ResourceManager::Get();
    
    EXPECT_EQ(manager.GetMemoryUsage(), 0u);
}

TEST_F(ResourceManager_Test, RegisterLoader) {
    ResourceManager& manager = ResourceManager::Get();
    
    // 纹理加载器应该已经注册
    IResourceLoader* loader = manager.GetLoader(ResourceType::Texture);
    EXPECT_NE(loader, nullptr);
}

TEST_F(ResourceManager_Test, GetLoader_NotFound) {
    ResourceManager& manager = ResourceManager::Get();
    
    IResourceLoader* loader = manager.GetLoader(ResourceType::Unknown);
    EXPECT_EQ(loader, nullptr);
}

TEST_F(ResourceManager_Test, AddRef_Release) {
    ResourceGUID guid(12345);
    
    ResourceManager::Get().AddRef(guid);
    EXPECT_EQ(ResourceManager::Get().GetRefCount(guid), 1u);
    
    ResourceManager::Get().AddRef(guid);
    EXPECT_EQ(ResourceManager::Get().GetRefCount(guid), 2u);
    
    ResourceManager::Get().Release(guid);
    EXPECT_EQ(ResourceManager::Get().GetRefCount(guid), 1u);
    
    ResourceManager::Get().Release(guid);
    // 引用计数为0时应返回0
}

TEST_F(ResourceManager_Test, UnloadAll) {
    ResourceManager& manager = ResourceManager::Get();
    
    // 添加一些引用
    ResourceGUID guid1(100);
    ResourceGUID guid2(200);
    manager.AddRef(guid1);
    manager.AddRef(guid2);
    
    manager.UnloadAll();
    
    // 所有引用计数应被清除
    EXPECT_EQ(manager.GetRefCount(guid1), 0u);
    EXPECT_EQ(manager.GetRefCount(guid2), 0u);
}

TEST_F(ResourceManager_Test, Exists) {
    ResourceManager& manager = ResourceManager::Get();
    
    // 未加载的资源应返回false
    EXPECT_FALSE(manager.Exists("nonexistent.png"));
}

TEST_F(ResourceManager_Test, ResolvePath) {
    ResourceManager& manager = ResourceManager::Get();
    manager.SetResourceRoot("myresources/");
    
    Containers::String resolved = manager.ResolvePath("textures/test.png");
    
    EXPECT_STREQ(resolved.CStr(), "myresources//textures/test.png");
}

} // namespace
```

### 12.8 测试运行脚本

**文件**: `tests/Resources/run_tests.bat`

```bat
@echo off
echo ========================================
echo XCEngine Resources System Tests
echo ========================================

cd /d %~dp0\..\..\build
if exist "tests\Resources\xcengine_resources_tests.exe" (
    echo Running Resources tests...
    tests\Resources\xcengine_resources_tests.exe
    
    if %ERRORLEVEL% EQU 0 (
        echo.
        echo [SUCCESS] All resource tests passed!
    ) else (
        echo.
        echo [FAILED] Some tests failed!
        exit /b 1
    )
) else (
    echo Error: Test executable not found!
    echo Please build the project first.
    exit /b 1
)
```

### 12.9 测试CMakeLists.txt

**文件**: `tests/Resources/CMakeLists.txt`

```cmake
# ============================================================
# Resources Library Tests
# ============================================================

set(RESOURCES_TEST_SOURCES
    test_resource_types.cpp
    test_resource_guid.cpp
    test_iresource.cpp
    test_resource_handle.cpp
    test_resource_cache.cpp
    test_async_loader.cpp
    test_texture.cpp
    test_mesh.cpp
    test_material.cpp
    test_audio_clip.cpp
    test_resource_manager.cpp
    test_resource_filesystem.cpp
    test_resource_dependency.cpp
)

add_executable(xcengine_resources_tests ${RESOURCES_TEST_SOURCES})

if(MSVC)
    set_target_properties(xcengine_resources_tests PROPERTIES
        LINK_FLAGS "/NODEFAULTLIB:libcpmt.lib /NODEFAULTLIB:libcmt.lib"
    )
endif()

target_link_libraries(xcengine_resources_tests
    PRIVATE
    XCEngine
    GTest::gtest
    GTest::gtest_main
)

target_include_directories(xcengine_resources_tests PRIVATE
    ${CMAKE_SOURCE_DIR}/engine/include
    ${CMAKE_SOURCE_DIR}/tests/fixtures
    ${CMAKE_SOURCE_DIR}/tests/Resources/fixtures
)

# 复制测试数据到输出目录
file(COPY ${CMAKE_SOURCE_DIR}/tests/Resources/test_data
     DESTINATION ${CMAKE_BINARY_DIR}/tests/Resources/)

add_test(NAME ResourcesTests COMMAND xcengine_resources_tests)
```

### 12.10 阶段测试验收清单

每个阶段完成后，运行对应测试验证功能正确性：

| 阶段 | 完成后运行测试 | 验收标准 |
|------|---------------|----------|
| **天1-3: 基础框架** | `test_resource_types.cpp`<br>`test_resource_guid.cpp`<br>`test_resource_handle.cpp` | ✅ ResourceType枚举正确<br>✅ GUID生成稳定<br>✅ 句柄引用计数正确 |
| **天4-5: 缓存系统** | `test_resource_cache.cpp` | ✅ LRU淘汰正常<br>✅ 内存预算生效<br>✅ 内存压力响应 |
| **天6-7: 异步加载** | `test_async_loader.cpp` | ✅ 任务提交正常<br>✅ 回调正常<br>✅ 进度计算正确 |
| **天8-9: 纹理** | `test_texture.cpp` | ✅ 创建/设置属性正常<br>✅ 加载器识别格式<br>✅ 导入设置生效 |
| **天10: 网格** | `test_mesh.cpp` | ✅ 顶点/索引数据正常<br>✅ 子网格正常<br>✅ 包围盒正常 |
| **天11: 材质** | `test_material.cpp` | ✅ 属性设置/获取正常<br>✅ 类型转换正确 |
| **天12-13: 文件系统** | `test_resource_filesystem.cpp` | ✅ 目录遍历正常<br>✅ 归档加载正常 |
| **天14-15: 依赖管理** | `test_resource_dependency.cpp` | ✅ 依赖关系正确<br>✅ 循环检测正常 |
| **天16-17: 集成** | 全部测试 | ✅ 所有测试通过<br>✅ 内存无泄漏 |

### 12.11 每日测试执行流程

```bash
# 每天完成代码后，在build目录执行：
cd build

# 编译测试
cmake --build . --target xcengine_resources_tests

# 运行当天相关测试
ctest -R "Resources_类型名" -V

# 例如：
# 第3天完成后运行：
ctest -R "Resources_Types|Resources_GUID|Resources_Handle" -V

# 第5天完成后运行：
ctest -R "Resources_Cache" -V

# 全部测试通过后进行下一阶段
```

### 12.12 测试数据准备

需要在 `tests/Resources/test_data/` 目录下准备以下测试文件：

```
test_data/
├── textures/
│   ├── test_256x256.png      # 256x256 PNG测试纹理
│   ├── test_512x512.jpg       # 512x512 JPG测试纹理
│   └── test_red.tga           # 纯红色TGA
├── models/
│   ├── cube.obj               # 简单立方体
│   ├── sphere.obj             # 球体
│   └── plane.obj              # 平面
├── materials/
│   ├── test_material.json     # 测试材质
│   └── test_pbr.json          # PBR材质
├── audio/
│   ├── test_mono.wav          # 单声道WAV
│   └── test_stereo.wav        # 立体声WAV
└── archives/
    └── test.xcrap             # 测试资源包
```

---

## 13. 关键技术点

### 13.1 引用计数与缓存淘汰的交互

```cpp
// 引用计数管理
void ResourceManager::AddRef(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    // 增加引用计数
    auto it = m_refCounts.Find(guid);
    if (it == m_refCounts.End()) {
        m_refCounts.Insert(guid, 1);
    } else {
        it->second++;
    }
    
    // 确保资源在缓存中
    if (!m_resourceCache.Contains(guid)) {
        // 重新加载资源
        ReloadResource(guid);
    }
}

void ResourceManager::Release(ResourceGUID guid) {
    std::lock_guard lock(m_mutex);
    
    auto it = m_refCounts.Find(guid);
    if (it != m_refCounts.End()) {
        it->second--;
        
        // 引用计数为0时，不立即卸载
        // 由缓存系统根据LRU策略决定何时卸载
        if (it->second == 0) {
            m_refCounts.Erase(guid);
            // 通知缓存系统资源可以淘汰
            m_cache.OnZeroRefCount(guid);
        }
    }
}
```

### 13.2 异步加载线程安全

```cpp
// AsyncLoader::Update() 在主线程调用
void AsyncLoader::Update() {
    // 1. 从完成队列取出结果（线程安全）
    Array<LoadRequest> completed;
    {
        std::lock_guard lock(m_completedMutex);
        completed = std::move(m_completedQueue);
        m_completedQueue.Clear();
    }
    
    // 2. 在主线程处理完成回调
    for (auto& request : completed) {
        if (request.callback) {
            // 回调中可能创建ResourceHandle，增加引用计数
            request.callback(m_result);
        }
    }
}

// 工作线程函数
void LoadTask::Execute() {
    // 在工作线程执行实际加载
    m_result = m_loader->Load(m_request.path, m_request.settings.get());
    
    // 放入完成队列
    AsyncLoader::Get().QueueCompleted(std::move(m_request), std::move(m_result));
}
```

### 13.3 内存压力响应

```cpp
void ResourceCache::OnMemoryPressure(size_t requiredBytes) {
    std::lock_guard lock(m_mutex);
    
    if (m_memoryUsage + requiredBytes <= m_memoryBudget) {
        return; // 内存充足
    }
    
    // 需要释放内存
    size_t targetRelease = (m_memoryUsage + requiredBytes) - m_memoryBudget;
    
    // 按LRU顺序淘汰
    for (auto it = m_lruOrder.Begin(); it != m_lruOrder.End() && targetRelease > 0; ) {
        ResourceGUID guid = *it;
        auto cacheIt = m_cache.Find(guid);
        
        if (cacheIt != m_cache.End()) {
            CacheEntry& entry = cacheIt->second;
            
            // 检查是否有外部引用
            if (ResourceManager::Get().GetRefCount(guid) == 0) {
                size_t releasedSize = entry.memorySize;
                
                // 从缓存移除
                m_cache.Erase(guid);
                m_memoryUsage -= releasedSize;
                targetRelease -= releasedSize;
                
                // 销毁资源
                entry.resource->Release();
                
                // 从LRU列表移除
                it = m_lruOrder.Erase(it);
            } else {
                ++it; // 有外部引用，跳过
            }
        } else {
            ++it;
        }
    }
}
```

---

## 14. 使用示例

### 14.1 基本使用

```cpp
// 初始化资源系统
void InitResourceSystem() {
    // 设置资源根目录
    ResourceManager::Get().SetResourceRoot("resources/");
    
    // 初始化异步加载器（2个工作线程）
    AsyncLoader::Get().Initialize(2);
    
    // 设置内存预算（1GB）
    ResourceManager::Get().SetMemoryBudget(1024 * 1024 * 1024);
}

// 同步加载纹理
void LoadTextureExample() {
    // 加载纹理
    ResourceHandle<Texture> tex = ResourceManager::Get().Load<Texture>("textures/player.png");
    
    if (tex.IsValid()) {
        // 使用纹理
        Texture* texture = tex.Get();
        printf("Loaded texture: %s, %dx%d\n", 
               tex->GetName().CStr(),
               texture->GetWidth(), 
               texture->GetHeight());
        
        // 传递给渲染器
        renderer->SetTexture(0, texture->GetRHIResource());
    }
    
    // 离开作用域时自动释放（引用计数-1）
}

// 异步加载网格
void LoadMeshAsyncExample() {
    ResourceManager::Get().LoadAsync("models/player.fbx", ResourceType::Mesh,
        [](LoadResult result) {
            if (result && result.resource) {
                // 在主线程回调中处理
                // 注意：需要手动转换为正确的类型
                Mesh* mesh = static_cast<Mesh*>(result.resource);
                printf("Mesh loaded: %s\n", mesh->GetName().CStr());
                
                // 添加到场景
                // 注意：这里需要创建ResourceHandle来管理生命周期
                ResourceHandle<Mesh> meshHandle(mesh);
                scene->AddMesh(meshHandle);
            } else {
                printf("Failed to load mesh: %s\n", result.errorMessage.CStr());
            }
        });
    
    // 异步加载进行中...
    // 主线程继续执行其他逻辑
}
```

### 14.2 资源组加载

```cpp
// 加载场景所需的所有资源
void LoadSceneResources(const String& scenePath) {
    // 1. 加载场景配置文件
    String sceneConfigPath = "scenes/" + scenePath + ".scene";
    ResourceHandle<BinaryResource> sceneConfig = 
        ResourceManager::Get().Load<BinaryResource>(sceneConfigPath);
    
    // 2. 解析配置文件获取依赖列表
    Array<String> dependencies = ParseSceneDependencies(sceneConfig.Get());
    
    // 3. 异步加载所有依赖
    Core::uint32 totalResources = dependencies.Size();
    Core::uint32 loadedCount = 0;
    
    for (const auto& dep : dependencies) {
        // 根据扩展名判断资源类型
        String ext = Path::GetExtension(dep);
        ResourceType type = ResourceType::Binary; // 默认
        
        if (ext == ".png" || ext == ".jpg") {
            type = ResourceType::Texture;
        } else if (ext == ".fbx" || ext == ".obj") {
            type = ResourceType::Mesh;
        }
        // ... 其他类型
        
        ResourceManager::Get().LoadAsync(dep, type, 
            [&loadedCount, totalResources](LoadResult result) {
                loadedCount++;
                printf("Loading progress: %d/%d\n", loadedCount, totalResources);
            });
    }
}
```

### 14.3 自定义导入设置

```cpp
void LoadTextureWithSettings() {
    // 创建导入设置
    TextureImportSettings* settings = new TextureImportSettings();
    settings->SetGenerateMipmaps(true);
    settings->SetSRGB(true);
    settings->SetTargetFormat(TextureFormat::BC7_UNORM);
    settings->SetMaxAnisotropy(16);
    
    // 加载时传入设置
    ResourceHandle<Texture> tex = ResourceManager::Get().Load<Texture>(
        "textures/diffuse.png", settings);
    
    // settings由ResourceManager管理，不需要手动delete
}
```

---

## 15. 验收标准

### 13.1 功能验收

- [ ] 能够通过路径加载Texture资源（PNG, JPG, TGA）
- [ ] 能够通过路径加载Mesh资源（OBJ, glTF）
- [ ] 能够通过路径加载Material资源（JSON格式）
- [ ] 能够通过路径加载AudioClip资源（WAV格式）
- [ ] 异步加载功能正常工作，回调在主线程执行
- [ ] 资源缓存机制正常工作，LRU淘汰策略生效
- [ ] 引用计数正确管理，零引用时资源可被淘汰
- [ ] 内存预算控制正常工作，超出预算时自动淘汰资源

### 13.2 性能验收

- [ ] 缓存命中时资源加载时间为0
- [ ] 异步加载不阻塞主线程
- [ ] 多线程加载时无数据竞争
- [ ] 内存使用稳定，无内存泄漏

### 13.3 代码质量

- [ ] 编译通过，无警告
- [ ] 遵循项目编码规范
- [ ] 必要的注释和文档
- [ ] 错误处理完善

---

## 16. 后续扩展

### 14.1 可选的扩展功能

| 功能 | 说明 | 工作量 |
|------|------|--------|
| **资源热加载** | 编辑器中修改资源后实时更新 | 2天 |
| **资源版本控制** | 检测资源变化，自动重新加载 | 2天 |
| **资源加密** | 支持加密的资源包 | 1天 |
| **资源流式加载** | 大资源分块加载 | 3天 |
| **资源分析器** | 可视化资源使用情况 | 2天 |

### 14.2 资源格式扩展

| 格式 | 说明 | 优先级 |
|------|------|--------|
| glTF 2.0 | 现代3D模型格式，高优先级 | P0 |
| DDS | 压缩纹理格式 | P0 |
| OGG/Vorbis | 压缩音频格式 | P1 |
| PSD | Photoshop源文件 | P2 |
| EXR | HDR图像 | P2 |

---

## 17. 依赖关系

```
资源系统依赖关系图：

第一阶段基础层
    │
    ├── Math Library ─────┐
    │                      │
    ├── Containers  ──────┼──► 资源系统
    │                      │
    ├── Memory    ────────┤
    │                      │
    └── Threading ─────────┘
              │
              ▼
    ┌─────────────────┐
    │  AsyncLoader   │  (依赖TaskSystem)
    └────────┬────────┘
             │
    ┌────────▼────────┐
    │ ResourceManager │
    └────────┬────────┘
             │
    ┌────────▼────────┐     ┌─────────────┐
    │  ResourceCache │────►│  引用计数   │
    └────────┬────────┘     │  管理       │
             │              └─────────────┘
    ┌────────▼────────┐
    │ ResourceLoader │
    └────────┬────────┘
             │
    ┌────────▼────────┐
    │  具体资源类型   │
    │  (Texture等)   │
    └─────────────────┘
```

---

*文档版本: 1.0*
*更新日期: 2026-03-17*