Add Nahida model import and preview pipeline

docs/plan/Nahida Unity式Model导入与Genshin卡通渲染正式化计划_2026-04-11.md

@@ -0,0 +1,174 @@
+# Nahida Unity式Model导入与Genshin卡通渲染正式化计划
+
+日期：2026-04-11
+
+## 1. 目标
+
+这一轮不再按“静态拆件预览”推进，而是正式切到更接近 Unity 的方案：
+
+- FBX/OBJ 等外部模型统一作为 `Model` 主资产导入
+- 场景侧通过 `Model -> GameObject hierarchy` 实例化恢复节点层级
+- `Mesh` 继续只负责底层几何与 section/material slot
+- Nahida 的卡通渲染改为“对齐 Unity 旧工程 `Genshin.shader` 语义”，而不是继续维持近似版 shader
+
+本轮仍然明确不做：
+
+- 骨骼动画
+- GPU skinning
+- `SkinnedMeshRenderer` 运行时
+- BlendShape
+- Animator / AnimationClip 播放系统
+
+## 2. 当前判断
+
+### 2.1 Model链路已经具备的能力
+
+代码里已经有以下基础设施：
+
+- `ResourceType::Model`
+- `Model` / `ModelLoader`
+- `xcmodel` artifact
+- `AssimpModelImporter`
+- `AssetDatabase` 中 `ModelImporter` 以 `Model` 为主资产导入
+- sub-asset manifest 与 `LocalID -> artifact path` 解析
+
+这说明“Unity式 Model 主资产”不是从零开始，而是缺最后几段关键闭环。
+
+### 2.2 当前最主要的缺口
+
+真正还没闭环的是：
+
+1. `Model` 还不能正式实例化成场景层级
+2. `MeshFilter/MeshRenderer` 还缺稳定的 sub-asset `AssetRef` 绑定入口
+3. 编辑器侧还没有把模型资产当成“可实例化层级对象”来用
+4. Nahida 当前 `XCCharacterToon.shader` 不是 Unity 旧工程 `Genshin.shader` 的等价移植
+5. FBX 导入后的静态 mesh 目前丢失了 Unity shader 依赖的顶点语义，尤其是 `vertex color` 与 `UV1/backUV`
+
+### 2.3 关于当前 shader 的明确结论
+
+当前使用的是：
+
+- `project/Assets/Shaders/XCCharacterToon.shader`
+
+Unity 参考原件是：
+
+- `docs/reference/NahidaUnity/Shaders/Genshin.shader`
+- `docs/reference/NahidaUnity/Shaders/GenshinInput.hlsl`
+- `docs/reference/NahidaUnity/Shaders/GenshinForwardPass.hlsl`
+- `docs/reference/NahidaUnity/Shaders/GenshinOutlinePass.hlsl`
+
+当前 shader 只是第一版近似实现，不是原 shader 原样移植。当前效果发怪，核心原因不是简单调参，而是语义缺口：
+
+1. 没有按 Unity 的 `_IS_FACE / _SPECULAR / _RIM / _NORMAL_MAP / _DOUBLE_SIDED` 关键字分支工作
+2. 面部阴影没有按 `_FaceDirection + _FaceLightMap + _FaceShadow + _FaceShadowOffset` 的逻辑算
+3. 阴影 ramp 还没有按 Unity 的 material ID 分层抽样
+4. specular 还不是 Unity 那套 `lightMap + metalMap + matcap` 路径
+5. rim 不是基于 scene depth 的 URP 风格边缘检测
+6. outline pass 还没有正式接回 `Nahida_Body_Smooth.mesh` 与 outline color 分档逻辑
+7. Unity 里还有 `MaterialUpdater.cs` 在运行时写 `_FaceDirection`，当前引擎里这条驱动链不存在
+8. 更关键的是，当前引擎导入出的 Nahida mesh 只有 `Position/Normal/Tangent/Bitangent/UV0`，缺 `Color/UV1`
+9. Unity 的 `GenshinForwardPass.hlsl` 明确依赖 `input.color.r` 与 `backUV`
+10. 这会直接破坏 body/hair 分支的 `aoFactor = lightMap.g * input.color.r` 与双面材质背面采样，因此“脸基本对、身体和头发大面积偏色”是符合代码现状的结果
+
+所以它现在看起来不像原工程，是正常结果。
+
+## 3. 本轮正式范围
+
+### Phase 1：Model实例化基础链路
+
+目标：
+
+- 把 `Model` 正式实例化为场景 `GameObject` 层级
+
+任务：
+
+- 为 `MeshFilterComponent` 增加 mesh sub-asset `AssetRef` 绑定入口
+- 为 `MeshRendererComponent` 增加 material sub-asset `AssetRef` 绑定入口
+- 保证这些 sub-asset 引用能被场景序列化稳定保存
+- 新增 `Model -> Scene hierarchy` 实例化工具
+- 恢复节点本地 TRS
+- 恢复 mesh binding 与 material slot binding
+
+验收：
+
+- 导入一个 `OBJ/FBX Model` 后，可以在场景里创建出层级对象
+- 场景存盘后 sub-asset 引用不丢
+- 不需要把 FBX 拆成手工摆放的多个静态对象
+
+### Phase 2：编辑器侧 Model使用工作流
+
+目标：
+
+- 让编辑器把 `Model` 当成 Unity 式模型资产使用
+
+任务：
+
+- 增加“从模型资产创建场景对象”的命令入口
+- 后续接到 Project/Hierarchy/Viewport 的拖拽放置链路
+- 让 Nahida 预览场景切到 `Model` 驱动的实例化路径
+
+验收：
+
+- 编辑器里不再主要依赖“手工往 `MeshFilter` 塞 FBX 路径”
+- Nahida 预览对象结构来自 `Model` 实例化，而不是手工拆件
+
+### Phase 3：Genshin shader 语义对齐
+
+目标：
+
+- 让 Nahida 使用更接近 Unity 旧工程的卡通渲染语义
+
+任务：
+
+- 先补齐静态 mesh 顶点语义链路：`Color`、`UV1/backUV`
+- 让前向渲染输入布局与 `XCCharacterToon.shader` 能真正接到 `COLOR` 与 `TEXCOORD1`
+- 恢复 body/hair 分支里的 `lightMap.g * input.color.r`
+- 恢复双面材质对 `backUV` 的切换采样
+- 按 Unity 原 shader 拆分 forward / outline 两条主路径
+- 补 `_IS_FACE / _SPECULAR / _RIM / _NORMAL_MAP / _DOUBLE_SIDED` 语义
+- 补 face shadow 正式逻辑
+- 补 outline pass 与 `Nahida_Body_Smooth.mesh`
+- 视情况补一个轻量 `_FaceDirection` 运行时驱动
+
+验收：
+
+- 角色明暗分层、面部阴影、描边、头发高光接近 Unity 参考
+
+## 4. 执行顺序
+
+这一轮按下面顺序推进：
+
+1. 先补 `Model` 实例化与 sub-asset 引用闭环
+2. 再把 Nahida 预览场景切到 `Model` 路径
+3. 再补 FBX 静态 mesh 的 `Color/UV1` 导入、artifact 保存、渲染输入布局与 shader 接线
+4. 再做 shader 语义对齐
+5. 最后做画面调参与残余语义收口
+
+不能反过来做。因为当前 shader 再怎么调，只要场景组织和资源绑定语义不对，结果都不稳定。
+
+## 5. 当前这一刀
+
+这一轮立刻执行的第一刀是：
+
+- 补齐 FBX 静态 mesh 的 `vertex color` 与 `UV1/backUV` 导入
+- 让 `BuiltinForwardPipeline` 与 `XCCharacterToon.shader` 真正吃到 `COLOR/TEXCOORD1`
+- 补 Nahida 集成诊断与回归验证，先把 body/hair 的基础色输入纠正
+- 在这个基础上继续向 Unity 式 `Model -> hierarchy` 与完整 shader 语义收口推进
+
+这是 Nahida 当前从“基础贴图都不稳定”切回“先保证静态基础颜色正确”的前置条件，也是后续继续 Unity 式正式方案的必要补丁。
+
+## 6. 2026-04-11 新发现补充
+
+在实际跑 `tests/Rendering/integration/nahida_preview_scene` 之后，问题又进一步收窄了：
+
+- Nahida 的 `Body_Mesh0` 运行时已经有 `uv1` 数值，且当前实现会在缺少第二套 UV 时回填 `uv1 = uv0`
+- 但导入器只在 `mesh.HasTextureCoords(1)` 为真时才打 `VertexAttribute::UV1` 标记
+- 结果就是：数据层面有 fallback `uv1`，语义层面却仍被当成“没有 UV1”
+- 这会导致后续依赖 `backUV` 的 shader / 诊断逻辑继续走错分支
+
+因此当前这一刀的执行重点再精确一步，变成：
+
+1. 修复 `AssimpModelImporter` / `MeshLoader` 中“fallback uv1 已写入但 `UV1` flag 未置位”的不一致
+2. 提升 `ModelImporter` 版本，强制 Nahida 现有 `.xcmodel` artifact 重导
+3. 补针对 Nahida FBX 的导入回归测试，确保 `UV1` fallback 与 `Color` 语义不会再次退化
+4. 再继续跑 Nahida 集成图验证 body/hair 基础色是否进一步收敛

engine/CMakeLists.txt

@@ -325,6 +325,7 @@ add_library(XCEngine STATIC
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/AssetGUID.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/AssetRef.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/ArtifactFormats.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/ArtifactContainer.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/AssetDatabase.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/AssetImportService.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/ProjectAssetIndex.h
@@ -336,6 +337,7 @@ add_library(XCEngine STATIC
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/AsyncLoader.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Core/Asset/ResourceDependencyGraph.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Core/Asset/AssetGUID.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/Core/Asset/ArtifactContainer.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Core/Asset/AssetDatabase.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Core/Asset/AssetImportService.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Core/Asset/ProjectAssetIndex.cpp
@@ -543,10 +545,12 @@ add_library(XCEngine STATIC
 
     # Scene
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Scene/Scene.h
+    ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Scene/ModelSceneInstantiation.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Scene/SceneRuntime.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Scene/RuntimeLoop.h
     ${CMAKE_CURRENT_SOURCE_DIR}/include/XCEngine/Scene/SceneManager.h
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Scene/Scene.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/Scene/ModelSceneInstantiation.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Scene/SceneRuntime.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Scene/RuntimeLoop.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/src/Scene/SceneManager.cpp

engine/include/XCEngine/Components/MeshFilterComponent.h

@@ -22,6 +22,7 @@ public:
     const Resources::AssetRef& GetMeshAssetRef() const { return m_meshRef; }
 
     void SetMeshPath(const std::string& meshPath);
+    void SetMeshAssetRef(const Resources::AssetRef& meshRef);
     void SetMesh(const Resources::ResourceHandle<Resources::Mesh>& mesh);
     void SetMesh(Resources::Mesh* mesh);
     void ClearMesh();

engine/include/XCEngine/Components/MeshRendererComponent.h

@@ -25,6 +25,7 @@ public:
     const std::vector<Resources::AssetRef>& GetMaterialAssetRefs() const { return m_materialRefs; }
 
     void SetMaterialPath(size_t index, const std::string& materialPath);
+    void SetMaterialAssetRef(size_t index, const Resources::AssetRef& materialRef);
     void SetMaterial(size_t index, const Resources::ResourceHandle<Resources::Material>& material);
     void SetMaterial(size_t index, Resources::Material* material);
     void SetMaterials(const std::vector<Resources::ResourceHandle<Resources::Material>>& materials);

engine/include/XCEngine/Core/Asset/ArtifactContainer.h

@@ -0,0 +1,105 @@
+#pragma once
+
+#include <XCEngine/Core/Asset/AssetGUID.h>
+#include <XCEngine/Core/Asset/ResourceTypes.h>
+#include <XCEngine/Core/Containers/Array.h>
+#include <XCEngine/Core/Containers/String.h>
+#include <XCEngine/Core/Types.h>
+
+namespace XCEngine {
+namespace Resources {
+
+constexpr Core::uint32 kArtifactContainerSchemaVersion = 1;
+
+enum class ArtifactContainerCompression : Core::uint32 {
+    None = 0
+};
+
+struct ArtifactContainerEntry {
+    Containers::String name;
+    ResourceType resourceType = ResourceType::Unknown;
+    LocalID localID = kInvalidLocalID;
+    Core::uint32 flags = 0;
+    ArtifactContainerCompression compression = ArtifactContainerCompression::None;
+    Containers::Array<Core::uint8> payload;
+};
+
+struct ArtifactContainerEntryView {
+    Containers::String name;
+    ResourceType resourceType = ResourceType::Unknown;
+    LocalID localID = kInvalidLocalID;
+    Core::uint32 flags = 0;
+    ArtifactContainerCompression compression = ArtifactContainerCompression::None;
+    Core::uint64 payloadOffset = 0;
+    Core::uint64 payloadSize = 0;
+};
+
+class ArtifactContainerWriter {
+public:
+    void Clear();
+    void AddEntry(const ArtifactContainerEntry& entry);
+    void AddEntry(ArtifactContainerEntry&& entry);
+
+    const Containers::Array<ArtifactContainerEntry>& GetEntries() const { return m_entries; }
+
+    bool WriteToFile(const Containers::String& path,
+                     Containers::String* outErrorMessage = nullptr) const;
+
+private:
+    Containers::Array<ArtifactContainerEntry> m_entries;
+};
+
+class ArtifactContainerReader {
+public:
+    bool Open(const Containers::String& path,
+              Containers::String* outErrorMessage = nullptr);
+    void Close();
+
+    bool IsOpen() const { return !m_path.Empty(); }
+    const Containers::String& GetPath() const { return m_path; }
+    const Containers::Array<ArtifactContainerEntryView>& GetEntries() const { return m_entries; }
+    Core::uint32 GetEntryCount() const { return static_cast<Core::uint32>(m_entries.Size()); }
+
+    const ArtifactContainerEntryView* FindEntryByName(const Containers::String& name) const;
+    const ArtifactContainerEntryView* FindEntry(ResourceType resourceType,
+                                                LocalID localID) const;
+
+    bool ReadEntryPayload(const ArtifactContainerEntryView& entry,
+                          Containers::Array<Core::uint8>& outPayload,
+                          Containers::String* outErrorMessage = nullptr) const;
+    bool ReadEntryPayload(const Containers::String& name,
+                          Containers::Array<Core::uint8>& outPayload,
+                          Containers::String* outErrorMessage = nullptr) const;
+
+private:
+    Containers::String m_path;
+    Containers::Array<ArtifactContainerEntryView> m_entries;
+    Core::uint64 m_payloadStart = 0;
+    Core::uint64 m_payloadSize = 0;
+};
+
+bool WriteArtifactContainer(const Containers::String& path,
+                            const Containers::Array<ArtifactContainerEntry>& entries,
+                            Containers::String* outErrorMessage = nullptr);
+bool IsArtifactContainerFile(const Containers::String& path);
+Containers::String BuildArtifactContainerEntryPath(const Containers::String& containerPath,
+                                                   const Containers::String& entryName);
+bool TryParseArtifactContainerEntryPath(const Containers::String& path,
+                                        Containers::String& outContainerPath,
+                                        Containers::String& outEntryName);
+bool ReadArtifactContainerEntryPayload(const Containers::String& containerPath,
+                                       const Containers::String& entryName,
+                                       ResourceType expectedType,
+                                       Containers::Array<Core::uint8>& outPayload,
+                                       Containers::String* outErrorMessage = nullptr);
+bool ReadArtifactContainerPayloadByPath(const Containers::String& path,
+                                        ResourceType expectedType,
+                                        Containers::Array<Core::uint8>& outPayload,
+                                        Containers::String* outErrorMessage = nullptr);
+bool ReadArtifactContainerMainEntryPayload(const Containers::String& path,
+                                           ResourceType expectedType,
+                                           Containers::Array<Core::uint8>& outPayload,
+                                           Containers::String* outErrorMessage = nullptr);
+
+} // namespace Resources
+} // namespace XCEngine

engine/include/XCEngine/Rendering/Pipelines/BuiltinForwardPipeline.h

@@ -175,6 +175,7 @@ private:
         Core::uint64 materialVersion = 0;
         RHI::RHIResourceView* baseColorTextureView = nullptr;
         RHI::RHIResourceView* shadowMapTextureView = nullptr;
+        std::vector<RHI::RHIResourceView*> materialTextureViews;
     };
 
     struct ResolvedShaderPass {
@@ -305,6 +306,9 @@ private:
     const Resources::Texture* ResolveTexture(const Resources::Material* material) const;
     RHI::RHIResourceView* ResolveTextureView(const Resources::Texture* texture);
     RHI::RHIResourceView* ResolveTextureView(const VisibleRenderItem& visibleItem);
+    RHI::RHIResourceView* ResolveMaterialTextureView(
+        const Resources::Material* material,
+        const BuiltinPassResourceBindingDesc& binding);
     static LightingConstants BuildLightingConstants(const RenderLightingData& lightingData);
     static AdditionalLightConstants BuildAdditionalLightConstants(const RenderAdditionalLightData& lightData);
     bool HasSkybox(const RenderSceneData& sceneData) const;

engine/include/XCEngine/Resources/Mesh/Mesh.h

@@ -5,6 +5,7 @@
 #include <XCEngine/Core/Math/Bounds.h>
 #include <XCEngine/Core/Math/Vector2.h>
 #include <XCEngine/Core/Math/Vector3.h>
+#include <XCEngine/Core/Math/Vector4.h>
 #include <XCEngine/Core/Types.h>
 
 namespace XCEngine {
@@ -38,6 +39,8 @@ struct StaticMeshVertex {
     Math::Vector3 tangent = Math::Vector3::Zero();
     Math::Vector3 bitangent = Math::Vector3::Zero();
     Math::Vector2 uv0 = Math::Vector2::Zero();
+    Math::Vector2 uv1 = Math::Vector2::Zero();
+    Math::Vector4 color = Math::Vector4::One();
 };
 
 struct MeshSection {

engine/include/XCEngine/Scene/ModelSceneInstantiation.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <XCEngine/Core/Asset/AssetRef.h>
+#include <XCEngine/Core/Containers/String.h>
+#include <XCEngine/Resources/Model/Model.h>
+
+#include <vector>
+
+namespace XCEngine {
+
+namespace Components {
+class GameObject;
+class Scene;
+}
+
+struct ModelSceneInstantiationResult {
+    Components::GameObject* rootObject = nullptr;
+    std::vector<Components::GameObject*> nodeObjects;
+    std::vector<Components::GameObject*> meshObjects;
+};
+
+bool InstantiateModelHierarchy(
+    Components::Scene& scene,
+    const Resources::Model& model,
+    const Resources::AssetRef& modelAssetRef,
+    Components::GameObject* parent = nullptr,
+    ModelSceneInstantiationResult* outResult = nullptr,
+    Containers::String* outErrorMessage = nullptr);
+
+bool InstantiateModelHierarchy(
+    Components::Scene& scene,
+    const Containers::String& modelPath,
+    Components::GameObject* parent = nullptr,
+    ModelSceneInstantiationResult* outResult = nullptr,
+    Containers::String* outErrorMessage = nullptr);
+
+} // namespace XCEngine

engine/src/Components/MeshFilterComponent.cpp

@@ -106,6 +106,31 @@ void MeshFilterComponent::SetMeshPath(const std::string& meshPath) {
     }
 }
 
+void MeshFilterComponent::SetMeshAssetRef(const Resources::AssetRef& meshRef) {
+    m_pendingMeshLoad.reset();
+    m_asyncMeshLoadRequested = false;
+    m_mesh.Reset();
+    m_meshPath.clear();
+    m_meshRef = meshRef;
+    if (!m_meshRef.IsValid()) {
+        return;
+    }
+
+    Containers::String resolvedPath;
+    if (Resources::ResourceManager::Get().TryResolveAssetPath(m_meshRef, resolvedPath)) {
+        m_meshPath = ToStdString(resolvedPath);
+    }
+
+    if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
+        return;
+    }
+
+    m_mesh = Resources::ResourceManager::Get().Load<Resources::Mesh>(m_meshRef);
+    if (m_mesh.Get() != nullptr && m_meshPath.empty()) {
+        m_meshPath = ToStdString(m_mesh->GetPath());
+    }
+}
+
 void MeshFilterComponent::SetMesh(const Resources::ResourceHandle<Resources::Mesh>& mesh) {
     m_pendingMeshLoad.reset();
     m_asyncMeshLoadRequested = false;
@@ -271,7 +296,8 @@ void MeshFilterComponent::ResolvePendingMesh() {
     }
 
     m_meshPath = ToStdString(m_mesh->GetPath());
-    if (!Resources::ResourceManager::Get().TryGetAssetRef(m_meshPath.c_str(), Resources::ResourceType::Mesh, m_meshRef)) {
+    if (!m_meshRef.IsValid() &&
+        !Resources::ResourceManager::Get().TryGetAssetRef(m_meshPath.c_str(), Resources::ResourceType::Mesh, m_meshRef)) {
         m_meshRef.Reset();
     }
 

engine/src/Components/MeshRendererComponent.cpp

@@ -193,6 +193,32 @@ void MeshRendererComponent::SetMaterialPath(size_t index, const std::string& mat
     }
 }
 
+void MeshRendererComponent::SetMaterialAssetRef(size_t index, const Resources::AssetRef& materialRef) {
+    EnsureMaterialSlot(index);
+    m_pendingMaterialLoads[index].reset();
+    m_asyncMaterialLoadRequested[index] = false;
+    m_materials[index].Reset();
+    m_materialPaths[index].clear();
+    m_materialRefs[index] = materialRef;
+    if (!m_materialRefs[index].IsValid()) {
+        return;
+    }
+
+    Containers::String resolvedPath;
+    if (Resources::ResourceManager::Get().TryResolveAssetPath(m_materialRefs[index], resolvedPath)) {
+        m_materialPaths[index] = ToStdString(resolvedPath);
+    }
+
+    if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
+        return;
+    }
+
+    m_materials[index] = Resources::ResourceManager::Get().Load<Resources::Material>(m_materialRefs[index]);
+    if (m_materials[index].Get() != nullptr && m_materialPaths[index].empty()) {
+        m_materialPaths[index] = MaterialPathFromHandle(m_materials[index]);
+    }
+}
+
 void MeshRendererComponent::SetMaterial(size_t index, const Resources::ResourceHandle<Resources::Material>& material) {
     EnsureMaterialSlot(index);
     m_pendingMaterialLoads[index].reset();
@@ -445,7 +471,8 @@ void MeshRendererComponent::ResolvePendingMaterials() {
         }
 
         m_materialPaths[index] = MaterialPathFromHandle(m_materials[index]);
-        if (!Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[index].c_str(),
+        if (!m_materialRefs[index].IsValid() &&
+            !Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[index].c_str(),
                                                               Resources::ResourceType::Material,
                                                               m_materialRefs[index])) {
             m_materialRefs[index].Reset();

engine/src/Core/Asset/ArtifactContainer.cpp

@@ -0,0 +1,571 @@
+#include <XCEngine/Core/Asset/ArtifactContainer.h>
+
+#include <array>
+#include <cstring>
+#include <filesystem>
+#include <fstream>
+#include <limits>
+#include <vector>
+
+namespace XCEngine {
+namespace Resources {
+
+namespace fs = std::filesystem;
+
+namespace {
+
+constexpr const char* kArtifactContainerEntryPathToken = "@entry=";
+
+struct ArtifactContainerFileHeader {
+    char magic[8] = { 'X', 'C', 'A', 'R', 'T', '0', '1', '\0' };
+    Core::uint32 schemaVersion = kArtifactContainerSchemaVersion;
+    Core::uint32 entryCount = 0;
+    Core::uint64 directorySize = 0;
+    Core::uint64 payloadSize = 0;
+    Core::uint64 contentHashHigh = 0;
+    Core::uint64 contentHashLow = 0;
+};
+
+struct ArtifactContainerEntryHeader {
+    Core::uint32 resourceType = 0;
+    Core::uint32 compression = 0;
+    Core::uint32 flags = 0;
+    Core::uint32 nameLength = 0;
+    Core::uint64 localID = 0;
+    Core::uint64 payloadOffset = 0;
+    Core::uint64 payloadSize = 0;
+};
+
+class IncrementalArtifactHasher {
+public:
+    void Append(const void* data, size_t size) {
+        if (data == nullptr || size == 0) {
+            return;
+        }
+
+        m_hasBytes = true;
+        const auto* bytes = static_cast<const Core::uint8*>(data);
+        for (size_t index = 0; index < size; ++index) {
+            m_high ^= static_cast<Core::uint64>(bytes[index]);
+            m_high *= 1099511628211ULL;
+
+            m_low ^= static_cast<Core::uint64>(bytes[index]);
+            m_low *= 1099511628211ULL;
+        }
+    }
+
+    AssetGUID Finish() const {
+        if (!m_hasBytes) {
+            return AssetGUID();
+        }
+        return AssetGUID(m_high, m_low);
+    }
+
+private:
+    bool m_hasBytes = false;
+    Core::uint64 m_high = 14695981039346656037ULL;
+    Core::uint64 m_low = 1099511628211ULL ^ 0x9e3779b97f4a7c15ULL;
+};
+
+Containers::String MakeError(const char* message) {
+    return Containers::String(message == nullptr ? "" : message);
+}
+
+bool TryWriteBytes(std::ofstream& output, const void* data, size_t size) {
+    output.write(static_cast<const char*>(data), static_cast<std::streamsize>(size));
+    return static_cast<bool>(output);
+}
+
+void AppendBytes(const void* data, size_t size, std::vector<Core::uint8>& outBytes) {
+    if (data == nullptr || size == 0) {
+        return;
+    }
+
+    const auto* begin = static_cast<const Core::uint8*>(data);
+    outBytes.insert(outBytes.end(), begin, begin + size);
+}
+
+bool IsExpectedMagic(const ArtifactContainerFileHeader& header) {
+    return std::memcmp(header.magic, "XCART01", 7) == 0 &&
+           header.schemaVersion == kArtifactContainerSchemaVersion;
+}
+
+} // namespace
+
+void ArtifactContainerWriter::Clear() {
+    m_entries.Clear();
+}
+
+void ArtifactContainerWriter::AddEntry(const ArtifactContainerEntry& entry) {
+    m_entries.PushBack(entry);
+}
+
+void ArtifactContainerWriter::AddEntry(ArtifactContainerEntry&& entry) {
+    m_entries.PushBack(std::move(entry));
+}
+
+bool ArtifactContainerWriter::WriteToFile(const Containers::String& path,
+                                          Containers::String* outErrorMessage) const {
+    return WriteArtifactContainer(path, m_entries, outErrorMessage);
+}
+
+bool WriteArtifactContainer(const Containers::String& path,
+                            const Containers::Array<ArtifactContainerEntry>& entries,
+                            Containers::String* outErrorMessage) {
+    std::vector<Core::uint8> directoryBytes;
+    Core::uint64 payloadBytes = 0;
+
+    for (const ArtifactContainerEntry& entry : entries) {
+        if (entry.name.Length() > std::numeric_limits<Core::uint32>::max()) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("ArtifactContainer entry name is too long.");
+            }
+            return false;
+        }
+
+        const Core::uint64 entryPayloadSize = static_cast<Core::uint64>(entry.payload.Size());
+        if (payloadBytes > std::numeric_limits<Core::uint64>::max() - entryPayloadSize) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("ArtifactContainer payload size overflow.");
+            }
+            return false;
+        }
+
+        ArtifactContainerEntryHeader entryHeader = {};
+        entryHeader.resourceType = static_cast<Core::uint32>(entry.resourceType);
+        entryHeader.compression = static_cast<Core::uint32>(entry.compression);
+        entryHeader.flags = entry.flags;
+        entryHeader.nameLength = static_cast<Core::uint32>(entry.name.Length());
+        entryHeader.localID = entry.localID;
+        entryHeader.payloadOffset = payloadBytes;
+        entryHeader.payloadSize = entryPayloadSize;
+        AppendBytes(&entryHeader, sizeof(entryHeader), directoryBytes);
+        AppendBytes(entry.name.CStr(), entry.name.Length(), directoryBytes);
+
+        payloadBytes += entryPayloadSize;
+    }
+
+    IncrementalArtifactHasher hasher;
+    if (!directoryBytes.empty()) {
+        hasher.Append(directoryBytes.data(), directoryBytes.size());
+    }
+    for (const ArtifactContainerEntry& entry : entries) {
+        if (!entry.payload.Empty()) {
+            hasher.Append(entry.payload.Data(), entry.payload.Size());
+        }
+    }
+
+    ArtifactContainerFileHeader fileHeader = {};
+    fileHeader.entryCount = static_cast<Core::uint32>(entries.Size());
+    fileHeader.directorySize = static_cast<Core::uint64>(directoryBytes.size());
+    fileHeader.payloadSize = payloadBytes;
+    const AssetGUID contentHash = hasher.Finish();
+    fileHeader.contentHashHigh = contentHash.high;
+    fileHeader.contentHashLow = contentHash.low;
+
+    std::error_code ec;
+    const fs::path targetPath(path.CStr());
+    if (!targetPath.parent_path().empty()) {
+        fs::create_directories(targetPath.parent_path(), ec);
+        if (ec) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("Failed to create ArtifactContainer parent directory.");
+            }
+            return false;
+        }
+    }
+
+    std::ofstream output(targetPath, std::ios::binary | std::ios::trunc);
+    if (!output.is_open()) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to open ArtifactContainer output file.");
+        }
+        return false;
+    }
+
+    if (!TryWriteBytes(output, &fileHeader, sizeof(fileHeader)) ||
+        (!directoryBytes.empty() &&
+         !TryWriteBytes(output, directoryBytes.data(), directoryBytes.size()))) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to write ArtifactContainer header or directory.");
+        }
+        return false;
+    }
+
+    for (const ArtifactContainerEntry& entry : entries) {
+        if (!entry.payload.Empty() &&
+            !TryWriteBytes(output, entry.payload.Data(), entry.payload.Size())) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("Failed to write ArtifactContainer payload.");
+            }
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool IsArtifactContainerFile(const Containers::String& path) {
+    std::ifstream input(path.CStr(), std::ios::binary);
+    if (!input.is_open()) {
+        return false;
+    }
+
+    ArtifactContainerFileHeader fileHeader = {};
+    input.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));
+    return input && IsExpectedMagic(fileHeader);
+}
+
+Containers::String BuildArtifactContainerEntryPath(const Containers::String& containerPath,
+                                                   const Containers::String& entryName) {
+    if (containerPath.Empty() || entryName.Empty()) {
+        return Containers::String();
+    }
+
+    Containers::String result = containerPath;
+    result += kArtifactContainerEntryPathToken;
+    result += entryName;
+    return result;
+}
+
+bool TryParseArtifactContainerEntryPath(const Containers::String& path,
+                                        Containers::String& outContainerPath,
+                                        Containers::String& outEntryName) {
+    outContainerPath.Clear();
+    outEntryName.Clear();
+
+    const std::string text(path.CStr());
+    const std::string token(kArtifactContainerEntryPathToken);
+    const size_t tokenPos = text.rfind(token);
+    if (tokenPos == std::string::npos) {
+        return false;
+    }
+
+    const size_t entryNamePos = tokenPos + token.length();
+    if (tokenPos == 0 || entryNamePos >= text.length()) {
+        return false;
+    }
+
+    outContainerPath = Containers::String(text.substr(0, tokenPos).c_str());
+    outEntryName = Containers::String(text.substr(entryNamePos).c_str());
+    return !outContainerPath.Empty() && !outEntryName.Empty();
+}
+
+bool ArtifactContainerReader::Open(const Containers::String& path,
+                                   Containers::String* outErrorMessage) {
+    Close();
+
+    std::ifstream input(path.CStr(), std::ios::binary);
+    if (!input.is_open()) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to open ArtifactContainer file.");
+        }
+        return false;
+    }
+
+    ArtifactContainerFileHeader fileHeader = {};
+    input.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));
+    if (!input || !IsExpectedMagic(fileHeader)) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer header is invalid.");
+        }
+        return false;
+    }
+
+    input.seekg(0, std::ios::end);
+    const std::streamoff fileSize = input.tellg();
+    const Core::uint64 expectedFileSize =
+        static_cast<Core::uint64>(sizeof(fileHeader)) +
+        fileHeader.directorySize +
+        fileHeader.payloadSize;
+    if (fileSize < static_cast<std::streamoff>(sizeof(fileHeader)) ||
+        expectedFileSize != static_cast<Core::uint64>(fileSize)) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer file size does not match header.");
+        }
+        return false;
+    }
+
+    input.seekg(static_cast<std::streamoff>(sizeof(fileHeader)), std::ios::beg);
+    std::vector<Core::uint8> directoryBytes(static_cast<size_t>(fileHeader.directorySize));
+    if (!directoryBytes.empty()) {
+        input.read(reinterpret_cast<char*>(directoryBytes.data()),
+                   static_cast<std::streamsize>(directoryBytes.size()));
+        if (!input) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("Failed to read ArtifactContainer directory.");
+            }
+            return false;
+        }
+    }
+
+    Containers::Array<ArtifactContainerEntryView> parsedEntries;
+    parsedEntries.Reserve(fileHeader.entryCount);
+
+    size_t cursor = 0;
+    for (Core::uint32 entryIndex = 0; entryIndex < fileHeader.entryCount; ++entryIndex) {
+        if (cursor + sizeof(ArtifactContainerEntryHeader) > directoryBytes.size()) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("ArtifactContainer directory is truncated.");
+            }
+            return false;
+        }
+
+        ArtifactContainerEntryHeader entryHeader = {};
+        std::memcpy(&entryHeader, directoryBytes.data() + cursor, sizeof(entryHeader));
+        cursor += sizeof(entryHeader);
+
+        if (cursor + entryHeader.nameLength > directoryBytes.size()) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("ArtifactContainer entry name is truncated.");
+            }
+            return false;
+        }
+
+        if (entryHeader.payloadOffset > fileHeader.payloadSize ||
+            entryHeader.payloadSize > fileHeader.payloadSize - entryHeader.payloadOffset) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("ArtifactContainer entry payload range is invalid.");
+            }
+            return false;
+        }
+
+        ArtifactContainerEntryView& view = parsedEntries.EmplaceBack();
+        view.name = Containers::String(
+            reinterpret_cast<const char*>(directoryBytes.data() + cursor),
+            entryHeader.nameLength);
+        view.resourceType = static_cast<ResourceType>(entryHeader.resourceType);
+        view.localID = entryHeader.localID;
+        view.flags = entryHeader.flags;
+        view.compression = static_cast<ArtifactContainerCompression>(entryHeader.compression);
+        view.payloadOffset = entryHeader.payloadOffset;
+        view.payloadSize = entryHeader.payloadSize;
+        cursor += entryHeader.nameLength;
+    }
+
+    if (cursor != directoryBytes.size()) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer directory has trailing garbage.");
+        }
+        return false;
+    }
+
+    IncrementalArtifactHasher hasher;
+    if (!directoryBytes.empty()) {
+        hasher.Append(directoryBytes.data(), directoryBytes.size());
+    }
+
+    std::array<Core::uint8, 4096> buffer = {};
+    Core::uint64 remainingPayloadBytes = fileHeader.payloadSize;
+    while (remainingPayloadBytes > 0) {
+        const size_t chunkSize = static_cast<size_t>(std::min<Core::uint64>(
+            remainingPayloadBytes,
+            static_cast<Core::uint64>(buffer.size())));
+        input.read(reinterpret_cast<char*>(buffer.data()), static_cast<std::streamsize>(chunkSize));
+        if (!input) {
+            if (outErrorMessage != nullptr) {
+                *outErrorMessage = MakeError("Failed to hash ArtifactContainer payload.");
+            }
+            return false;
+        }
+
+        hasher.Append(buffer.data(), chunkSize);
+        remainingPayloadBytes -= static_cast<Core::uint64>(chunkSize);
+    }
+
+    const AssetGUID expectedHash(fileHeader.contentHashHigh, fileHeader.contentHashLow);
+    const AssetGUID actualHash = hasher.Finish();
+    if (expectedHash != actualHash) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer content hash mismatch.");
+        }
+        return false;
+    }
+
+    m_path = path;
+    m_entries = std::move(parsedEntries);
+    m_payloadStart =
+        static_cast<Core::uint64>(sizeof(ArtifactContainerFileHeader)) +
+        fileHeader.directorySize;
+    m_payloadSize = fileHeader.payloadSize;
+    return true;
+}
+
+void ArtifactContainerReader::Close() {
+    m_path.Clear();
+    m_entries.Clear();
+    m_payloadStart = 0;
+    m_payloadSize = 0;
+}
+
+const ArtifactContainerEntryView* ArtifactContainerReader::FindEntryByName(
+    const Containers::String& name) const {
+    for (const ArtifactContainerEntryView& entry : m_entries) {
+        if (entry.name == name) {
+            return &entry;
+        }
+    }
+    return nullptr;
+}
+
+const ArtifactContainerEntryView* ArtifactContainerReader::FindEntry(
+    ResourceType resourceType,
+    LocalID localID) const {
+    for (const ArtifactContainerEntryView& entry : m_entries) {
+        if (entry.resourceType == resourceType && entry.localID == localID) {
+            return &entry;
+        }
+    }
+    return nullptr;
+}
+
+bool ArtifactContainerReader::ReadEntryPayload(const ArtifactContainerEntryView& entry,
+                                               Containers::Array<Core::uint8>& outPayload,
+                                               Containers::String* outErrorMessage) const {
+    outPayload.Clear();
+    if (!IsOpen()) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer is not open.");
+        }
+        return false;
+    }
+
+    if (entry.payloadOffset > m_payloadSize ||
+        entry.payloadSize > m_payloadSize - entry.payloadOffset) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer entry payload range is invalid.");
+        }
+        return false;
+    }
+
+    if (entry.payloadSize == 0) {
+        return true;
+    }
+
+    if (entry.payloadSize > static_cast<Core::uint64>(std::numeric_limits<size_t>::max())) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer entry payload is too large.");
+        }
+        return false;
+    }
+
+    std::ifstream input(m_path.CStr(), std::ios::binary);
+    if (!input.is_open()) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to reopen ArtifactContainer file.");
+        }
+        return false;
+    }
+
+    input.seekg(static_cast<std::streamoff>(m_payloadStart + entry.payloadOffset), std::ios::beg);
+    if (!input) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to seek ArtifactContainer payload.");
+        }
+        return false;
+    }
+
+    outPayload.ResizeUninitialized(static_cast<size_t>(entry.payloadSize));
+    input.read(reinterpret_cast<char*>(outPayload.Data()),
+               static_cast<std::streamsize>(entry.payloadSize));
+    if (!input) {
+        outPayload.Clear();
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("Failed to read ArtifactContainer payload.");
+        }
+        return false;
+    }
+
+    return true;
+}
+
+bool ArtifactContainerReader::ReadEntryPayload(const Containers::String& name,
+                                               Containers::Array<Core::uint8>& outPayload,
+                                               Containers::String* outErrorMessage) const {
+    const ArtifactContainerEntryView* entry = FindEntryByName(name);
+    if (entry == nullptr) {
+        outPayload.Clear();
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer entry was not found.");
+        }
+        return false;
+    }
+
+    return ReadEntryPayload(*entry, outPayload, outErrorMessage);
+}
+
+bool ReadArtifactContainerEntryPayload(const Containers::String& containerPath,
+                                       const Containers::String& entryName,
+                                       ResourceType expectedType,
+                                       Containers::Array<Core::uint8>& outPayload,
+                                       Containers::String* outErrorMessage) {
+    outPayload.Clear();
+
+    ArtifactContainerReader reader;
+    if (!reader.Open(containerPath, outErrorMessage)) {
+        return false;
+    }
+
+    const ArtifactContainerEntryView* entry = reader.FindEntryByName(entryName);
+    if (entry == nullptr) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer entry was not found.");
+        }
+        return false;
+    }
+
+    if (expectedType != ResourceType::Unknown && entry->resourceType != expectedType) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer entry resource type did not match.");
+        }
+        return false;
+    }
+
+    return reader.ReadEntryPayload(*entry, outPayload, outErrorMessage);
+}
+
+bool ReadArtifactContainerPayloadByPath(const Containers::String& path,
+                                        ResourceType expectedType,
+                                        Containers::Array<Core::uint8>& outPayload,
+                                        Containers::String* outErrorMessage) {
+    Containers::String containerPath;
+    Containers::String entryName;
+    if (TryParseArtifactContainerEntryPath(path, containerPath, entryName)) {
+        return ReadArtifactContainerEntryPayload(
+            containerPath,
+            entryName,
+            expectedType,
+            outPayload,
+            outErrorMessage);
+    }
+
+    return ReadArtifactContainerMainEntryPayload(path, expectedType, outPayload, outErrorMessage);
+}
+
+bool ReadArtifactContainerMainEntryPayload(const Containers::String& path,
+                                           ResourceType expectedType,
+                                           Containers::Array<Core::uint8>& outPayload,
+                                           Containers::String* outErrorMessage) {
+    outPayload.Clear();
+
+    ArtifactContainerReader reader;
+    if (!reader.Open(path, outErrorMessage)) {
+        return false;
+    }
+
+    const ArtifactContainerEntryView* entry = reader.FindEntry(expectedType, kMainAssetLocalID);
+    if (entry == nullptr) {
+        entry = reader.FindEntryByName("main");
+    }
+    if (entry == nullptr) {
+        if (outErrorMessage != nullptr) {
+            *outErrorMessage = MakeError("ArtifactContainer main entry was not found.");
+        }
+        return false;
+    }
+
+    return reader.ReadEntryPayload(*entry, outPayload, outErrorMessage);
+}
+
+} // namespace Resources
+} // namespace XCEngine

engine/src/Core/Asset/AssetDatabase.cpp

@@ -75,6 +75,9 @@ bool SerializeMaterialArtifactPayload(
     const AssetDatabase* assetDatabase);
 bool SerializeShaderArtifactPayload(const Shader& shader,
                                     Containers::Array<Core::uint8>& outPayload);
+bool SerializeMeshArtifactPayload(const Mesh& mesh,
+                                  const std::vector<Containers::String>& materialArtifactPaths,
+                                  Containers::Array<Core::uint8>& outPayload);
 bool WriteSingleEntryArtifactContainerFile(const fs::path& artifactPath,
                                            ResourceType resourceType,
                                            const Containers::Array<Core::uint8>& payload);
@@ -1225,11 +1228,28 @@ bool WriteShaderArtifactFile(const fs::path& artifactPath, const Shader& shader)
 bool WriteMeshArtifactFile(const fs::path& artifactPath,
                            const Mesh& mesh,
                            const std::vector<Containers::String>& materialArtifactPaths) {
+    Containers::Array<Core::uint8> payload;
+    if (!SerializeMeshArtifactPayload(mesh, materialArtifactPaths, payload)) {
+        return false;
+    }
+
     std::ofstream output(artifactPath, std::ios::binary | std::ios::trunc);
     if (!output.is_open()) {
         return false;
     }
 
+    if (!payload.Empty()) {
+        output.write(reinterpret_cast<const char*>(payload.Data()), static_cast<std::streamsize>(payload.Size()));
+    }
+
+    return static_cast<bool>(output);
+}
+
+bool SerializeMeshArtifactPayload(const Mesh& mesh,
+                                  const std::vector<Containers::String>& materialArtifactPaths,
+                                  Containers::Array<Core::uint8>& outPayload) {
+    std::ostringstream output(std::ios::binary | std::ios::out);
+
     MeshArtifactHeader header;
     header.vertexCount = mesh.GetVertexCount();
     header.vertexStride = mesh.GetVertexStride();
@@ -1259,7 +1279,13 @@ bool WriteMeshArtifactFile(const fs::path& artifactPath,
         WriteString(output, NormalizeArtifactPathString(materialArtifactPath));
     }
 
-    return static_cast<bool>(output);
+    if (!output) {
+        outPayload.Clear();
+        return false;
+    }
+
+    outPayload = ToByteArray(output.str());
+    return true;
 }
 
 void DestroyImportedMesh(Mesh* mesh) {
@@ -1438,6 +1464,20 @@ bool AssetDatabase::TryResolveAssetPath(const AssetRef& assetRef, Containers::St
     }
 
     auto resolveFromArtifactRecord = [&](const ArtifactRecord& artifactRecord) -> bool {
+        const Containers::String absoluteMainArtifactPath =
+            NormalizePathString(fs::path(m_projectRoot.CStr()) / artifactRecord.mainArtifactPath.CStr());
+
+        ArtifactContainerReader reader;
+        Containers::String containerError;
+        if (reader.Open(absoluteMainArtifactPath, &containerError)) {
+            const ArtifactContainerEntryView* entry =
+                reader.FindEntry(assetRef.resourceType, assetRef.localID);
+            if (entry != nullptr) {
+                outPath = BuildArtifactContainerEntryPath(absoluteMainArtifactPath, entry->name);
+                return true;
+            }
+        }
+
         const fs::path manifestPath =
             fs::path(m_projectRoot.CStr()) /
             artifactRecord.artifactDirectory.CStr() /
@@ -2170,7 +2210,7 @@ Core::uint32 AssetDatabase::GetCurrentImporterVersion(const Containers::String&
     }
 
     if (importerName == "ModelImporter") {
-        return 10;
+        return 12;
     }
 
     if (importerName == "GaussianSplatImporter") {
@@ -2557,21 +2597,24 @@ bool AssetDatabase::ImportModelAsset(const SourceAssetRecord& sourceRecord,
     std::vector<ArtifactDependencyRecord> dependencies;
     CollectModelDependencies(sourceRecord, importedTexturePaths, dependencies);
     const Containers::String artifactKey = BuildArtifactKey(sourceRecord, dependencies);
-    const Containers::String artifactDir = BuildArtifactDirectory(artifactKey);
-    const Containers::String mainArtifactPath =
-        NormalizePathString(fs::path(artifactDir.CStr()) / "main.xcmodel");
+    const Containers::String legacyArtifactDir = BuildArtifactDirectory(artifactKey);
+    const Containers::String mainArtifactPath = BuildArtifactFilePath(artifactKey, ".xcmodel");
+    const Containers::String artifactDir =
+        NormalizePathString(fs::path(mainArtifactPath.CStr()).parent_path());
 
     std::error_code ec;
-    fs::remove_all(fs::path(m_projectRoot.CStr()) / artifactDir.CStr(), ec);
+    fs::remove_all(fs::path(m_projectRoot.CStr()) / legacyArtifactDir.CStr(), ec);
     ec.clear();
-    fs::create_directories(fs::path(m_projectRoot.CStr()) / artifactDir.CStr(), ec);
+    fs::create_directories(
+        (fs::path(m_projectRoot.CStr()) / mainArtifactPath.CStr()).parent_path(),
+        ec);
     if (ec) {
         importedModel.Reset();
         return false;
     }
 
+    ArtifactContainerWriter writer;
     bool writeOk = true;
-    std::vector<ModelSubAssetManifestEntry> subAssetManifestEntries;
     std::unordered_map<const Texture*, Containers::String> textureArtifactPaths;
     std::unordered_map<const Texture*, AssetRef> textureAssetRefs;
     for (size_t textureIndex = 0; writeOk && textureIndex < importedModel.textures.size(); ++textureIndex) {
@@ -2580,16 +2623,23 @@ bool AssetDatabase::ImportModelAsset(const SourceAssetRecord& sourceRecord,
             continue;
         }
 
-        const Containers::String textureArtifactPath =
-            NormalizePathString(fs::path(artifactDir.CStr()) / ("texture_" + std::to_string(textureIndex) + ".xctex"));
-        writeOk = WriteTextureArtifactFile(
-            fs::path(m_projectRoot.CStr()) / textureArtifactPath.CStr(),
-            *texture);
+        const Containers::String entryName =
+            Containers::String(("texture_" + std::to_string(textureIndex) + ".xctex").c_str());
+        Containers::Array<Core::uint8> payload;
+        writeOk = SerializeTextureArtifactPayload(*texture, payload);
         if (!writeOk) {
             break;
         }
 
-        textureArtifactPaths.emplace(texture, textureArtifactPath);
+        ArtifactContainerEntry entry;
+        entry.name = entryName;
+        entry.resourceType = ResourceType::Texture;
+        entry.payload = std::move(payload);
+        writer.AddEntry(std::move(entry));
+
+        textureArtifactPaths.emplace(
+            texture,
+            BuildArtifactContainerEntryPath(mainArtifactPath, entryName));
 
         if (!texture->GetPath().Empty()) {
             AssetRef textureAssetRef;
@@ -2606,11 +2656,12 @@ bool AssetDatabase::ImportModelAsset(const SourceAssetRecord& sourceRecord,
             continue;
         }
 
-        const Containers::String materialArtifactPath =
-            NormalizePathString(fs::path(artifactDir.CStr()) / ("material_" + std::to_string(materialIndex) + ".xcmat"));
-        writeOk = WriteMaterialArtifactFile(
-            fs::path(m_projectRoot.CStr()) / materialArtifactPath.CStr(),
+        const Containers::String entryName =
+            Containers::String(("material_" + std::to_string(materialIndex) + ".xcmat").c_str());
+        Containers::Array<Core::uint8> payload;
+        writeOk = SerializeMaterialArtifactPayload(
             *materialEntry.material,
+            payload,
             textureArtifactPaths,
             textureAssetRefs,
             this);
@@ -2618,9 +2669,16 @@ bool AssetDatabase::ImportModelAsset(const SourceAssetRecord& sourceRecord,
             break;
         }
 
-        materialArtifactPathsByLocalID.emplace(materialEntry.localID, materialArtifactPath);
-        subAssetManifestEntries.push_back(
-            ModelSubAssetManifestEntry{ materialEntry.localID, ResourceType::Material, materialArtifactPath });
+        ArtifactContainerEntry entry;
+        entry.name = entryName;
+        entry.resourceType = ResourceType::Material;
+        entry.localID = materialEntry.localID;
+        entry.payload = std::move(payload);
+        writer.AddEntry(std::move(entry));
+
+        materialArtifactPathsByLocalID.emplace(
+            materialEntry.localID,
+            BuildArtifactContainerEntryPath(mainArtifactPath, entryName));
     }
 
     for (size_t meshIndex = 0; writeOk && meshIndex < importedModel.meshes.size(); ++meshIndex) {
@@ -2639,30 +2697,37 @@ bool AssetDatabase::ImportModelAsset(const SourceAssetRecord& sourceRecord,
                     : Containers::String());
         }
 
-        const Containers::String meshArtifactPath =
-            NormalizePathString(fs::path(artifactDir.CStr()) / ("mesh_" + std::to_string(meshIndex) + ".xcmesh"));
-        writeOk = WriteMeshArtifactFile(
-            fs::path(m_projectRoot.CStr()) / meshArtifactPath.CStr(),
-            *meshEntry.mesh,
-            meshMaterialArtifactPaths);
-        if (writeOk) {
-            subAssetManifestEntries.push_back(
-                ModelSubAssetManifestEntry{ meshEntry.localID, ResourceType::Mesh, meshArtifactPath });
+        const Containers::String entryName =
+            Containers::String(("mesh_" + std::to_string(meshIndex) + ".xcmesh").c_str());
+        Containers::Array<Core::uint8> payload;
+        writeOk = SerializeMeshArtifactPayload(*meshEntry.mesh, meshMaterialArtifactPaths, payload);
+        if (!writeOk) {
+            break;
         }
+
+        ArtifactContainerEntry entry;
+        entry.name = entryName;
+        entry.resourceType = ResourceType::Mesh;
+        entry.localID = meshEntry.localID;
+        entry.payload = std::move(payload);
+        writer.AddEntry(std::move(entry));
     }
 
     Containers::String modelWriteErrorMessage;
     if (writeOk) {
-        writeOk = WriteModelArtifactFile(
-            NormalizePathString(fs::path(m_projectRoot.CStr()) / mainArtifactPath.CStr()),
-            *importedModel.model,
-            &modelWriteErrorMessage);
-    }
-
-    if (writeOk) {
-        writeOk = WriteModelSubAssetManifest(
-            fs::path(m_projectRoot.CStr()) / artifactDir.CStr() / kModelSubAssetManifestFileName,
-            subAssetManifestEntries);
+        Containers::Array<Core::uint8> modelPayload;
+        writeOk = SerializeModelArtifactPayload(*importedModel.model, modelPayload, &modelWriteErrorMessage);
+        if (writeOk) {
+            ArtifactContainerEntry mainEntry;
+            mainEntry.name = "main";
+            mainEntry.resourceType = ResourceType::Model;
+            mainEntry.localID = kMainAssetLocalID;
+            mainEntry.payload = std::move(modelPayload);
+            writer.AddEntry(std::move(mainEntry));
+            writeOk = writer.WriteToFile(
+                NormalizePathString(fs::path(m_projectRoot.CStr()) / mainArtifactPath.CStr()),
+                &modelWriteErrorMessage);
+        }
     }
 
     importedModel.Reset();
@@ -2940,14 +3005,19 @@ bool AssetDatabase::ImportUIDocumentAsset(const SourceAssetRecord& sourceRecord,
     }
 
     const Containers::String artifactKey = BuildArtifactKey(sourceRecord, dependencies);
-    const Containers::String artifactDir = BuildArtifactDirectory(artifactKey);
-    const Containers::String mainArtifactPath =
-        NormalizePathString(fs::path(artifactDir.CStr()) / artifactFileName);
+    const Containers::String legacyArtifactDir = BuildArtifactDirectory(artifactKey);
+    const Containers::String extension =
+        Containers::String(fs::path(artifactFileName == nullptr ? "" : artifactFileName).extension().string().c_str());
+    const Containers::String mainArtifactPath = BuildArtifactFilePath(artifactKey, extension.CStr());
+    const Containers::String artifactDir =
+        NormalizePathString(fs::path(mainArtifactPath.CStr()).parent_path());
 
     std::error_code ec;
-    fs::remove_all(fs::path(m_projectRoot.CStr()) / artifactDir.CStr(), ec);
+    fs::remove_all(fs::path(m_projectRoot.CStr()) / legacyArtifactDir.CStr(), ec);
     ec.clear();
-    fs::create_directories(fs::path(m_projectRoot.CStr()) / artifactDir.CStr(), ec);
+    fs::create_directories(
+        (fs::path(m_projectRoot.CStr()) / mainArtifactPath.CStr()).parent_path(),
+        ec);
     if (ec) {
         SetLastErrorMessage(
             Containers::String("Failed to create UI artifact directory: ") + artifactDir);

engine/src/Rendering/Pipelines/BuiltinForwardPipeline.cpp

@@ -106,6 +106,38 @@ RHI::InputLayoutDesc BuiltinForwardPipeline::BuildInputLayout() {
     texcoord.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, uv0));
     inputLayout.elements.push_back(texcoord);
 
+    RHI::InputElementDesc backTexcoord = {};
+    backTexcoord.semanticName = "TEXCOORD";
+    backTexcoord.semanticIndex = 1;
+    backTexcoord.format = static_cast<uint32_t>(RHI::Format::R32G32_Float);
+    backTexcoord.inputSlot = 0;
+    backTexcoord.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, uv1));
+    inputLayout.elements.push_back(backTexcoord);
+
+    RHI::InputElementDesc tangent = {};
+    tangent.semanticName = "TEXCOORD";
+    tangent.semanticIndex = 2;
+    tangent.format = static_cast<uint32_t>(RHI::Format::R32G32B32_Float);
+    tangent.inputSlot = 0;
+    tangent.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, tangent));
+    inputLayout.elements.push_back(tangent);
+
+    RHI::InputElementDesc bitangent = {};
+    bitangent.semanticName = "TEXCOORD";
+    bitangent.semanticIndex = 3;
+    bitangent.format = static_cast<uint32_t>(RHI::Format::R32G32B32_Float);
+    bitangent.inputSlot = 0;
+    bitangent.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, bitangent));
+    inputLayout.elements.push_back(bitangent);
+
+    RHI::InputElementDesc color = {};
+    color.semanticName = "COLOR";
+    color.semanticIndex = 0;
+    color.format = static_cast<uint32_t>(RHI::Format::R32G32B32A32_Float);
+    color.inputSlot = 0;
+    color.alignedByteOffset = static_cast<uint32_t>(offsetof(Resources::StaticMeshVertex, color));
+    inputLayout.elements.push_back(color);
+
     return inputLayout;
 }
 
@@ -132,17 +164,26 @@ bool BuiltinForwardPipeline::Render(
     const RenderSurface& surface,
     const RenderSceneData& sceneData) {
     if (!Initialize(context)) {
+        Debug::Logger::Get().Error(
+            Debug::LogCategory::Rendering,
+            "BuiltinForwardPipeline::Render failed: Initialize returned false");
         return false;
     }
 
     if (m_volumetricPass != nullptr &&
         !sceneData.visibleVolumes.empty() &&
         !m_volumetricPass->PrepareVolumeResources(context, sceneData)) {
+        Debug::Logger::Get().Error(
+            Debug::LogCategory::Rendering,
+            "BuiltinForwardPipeline::Render failed: PrepareVolumeResources returned false");
         return false;
     }
     if (m_gaussianSplatPass != nullptr &&
         !sceneData.visibleGaussianSplats.empty() &&
         !m_gaussianSplatPass->PrepareGaussianSplatResources(context, sceneData)) {
+        Debug::Logger::Get().Error(
+            Debug::LogCategory::Rendering,
+            "BuiltinForwardPipeline::Render failed: PrepareGaussianSplatResources returned false");
         return false;
     }
 
@@ -156,6 +197,9 @@ bool BuiltinForwardPipeline::Render(
     };
 
     if (!BeginForwardScenePass(passContext)) {
+        Debug::Logger::Get().Error(
+            Debug::LogCategory::Rendering,
+            "BuiltinForwardPipeline::Render failed: BeginForwardScenePass returned false");
         return false;
     }
 
@@ -167,15 +211,35 @@ bool BuiltinForwardPipeline::Render(
     bool renderResult = ExecuteForwardOpaquePass(passContext);
     if (renderResult) {
         renderResult = ExecuteForwardSkyboxPass(passContext);
+        if (!renderResult) {
+            Debug::Logger::Get().Error(
+                Debug::LogCategory::Rendering,
+                "BuiltinForwardPipeline::Render failed: ExecuteForwardSkyboxPass returned false");
+        }
     }
     if (renderResult && m_gaussianSplatPass != nullptr) {
         renderResult = m_gaussianSplatPass->Execute(passContext);
+        if (!renderResult) {
+            Debug::Logger::Get().Error(
+                Debug::LogCategory::Rendering,
+                "BuiltinForwardPipeline::Render failed: BuiltinGaussianSplatPass::Execute returned false");
+        }
     }
     if (renderResult && m_volumetricPass != nullptr) {
         renderResult = m_volumetricPass->Execute(passContext);
+        if (!renderResult) {
+            Debug::Logger::Get().Error(
+                Debug::LogCategory::Rendering,
+                "BuiltinForwardPipeline::Render failed: BuiltinVolumetricPass::Execute returned false");
+        }
     }
     if (renderResult) {
         renderResult = ExecuteForwardTransparentPass(passContext);
+        if (!renderResult) {
+            Debug::Logger::Get().Error(
+                Debug::LogCategory::Rendering,
+                "BuiltinForwardPipeline::Render failed: ExecuteForwardTransparentPass returned false");
+        }
     }
 
     if (sampledDirectionalShadow) {

engine/src/Rendering/Pipelines/Internal/BuiltinForwardPipelineResources.cpp

@@ -438,6 +438,37 @@ BuiltinForwardPipeline::CachedDescriptorSet* BuiltinForwardPipeline::GetOrCreate
         }
     }
 
+    if (setLayout.usesMaterialTextures) {
+        if (material == nullptr) {
+            return nullptr;
+        }
+
+        if (cachedDescriptorSet.materialTextureViews.size() != setLayout.materialTextureBindings.size()) {
+            cachedDescriptorSet.materialTextureViews.assign(
+                setLayout.materialTextureBindings.size(),
+                nullptr);
+        }
+
+        for (size_t bindingIndex = 0; bindingIndex < setLayout.materialTextureBindings.size(); ++bindingIndex) {
+            const BuiltinPassResourceBindingDesc& textureBinding =
+                setLayout.materialTextureBindings[bindingIndex];
+            RHI::RHIResourceView* resolvedTextureView =
+                ResolveMaterialTextureView(material, textureBinding);
+            if (resolvedTextureView == nullptr) {
+                return nullptr;
+            }
+
+            if (cachedDescriptorSet.materialTextureViews[bindingIndex] != resolvedTextureView) {
+                cachedDescriptorSet.descriptorSet.set->Update(
+                    textureBinding.location.binding,
+                    resolvedTextureView);
+                cachedDescriptorSet.materialTextureViews[bindingIndex] = resolvedTextureView;
+            }
+        }
+    } else if (!cachedDescriptorSet.materialTextureViews.empty()) {
+        cachedDescriptorSet.materialTextureViews.clear();
+    }
+
     if (setLayout.usesLighting) {
         if (!passLayout.lighting.IsValid() || passLayout.lighting.set != setIndex) {
             return nullptr;
@@ -556,6 +587,33 @@ RHI::RHIResourceView* BuiltinForwardPipeline::ResolveTextureView(
     return textureView != nullptr ? textureView : m_fallbackTexture2DView;
 }
 
+RHI::RHIResourceView* BuiltinForwardPipeline::ResolveMaterialTextureView(
+    const Resources::Material* material,
+    const BuiltinPassResourceBindingDesc& binding) {
+    const bool expectsCubemap = binding.resourceType == Resources::ShaderResourceType::TextureCube;
+    RHI::RHIResourceView* fallbackView = expectsCubemap ? m_fallbackTextureCubeView : m_fallbackTexture2DView;
+    if (material == nullptr) {
+        return fallbackView;
+    }
+
+    const Resources::ResourceHandle<Resources::Texture> textureHandle = material->GetTexture(binding.name);
+    const Resources::Texture* texture = textureHandle.Get();
+    if (texture == nullptr) {
+        return fallbackView;
+    }
+
+    const Resources::TextureType textureType = texture->GetTextureType();
+    const bool isCubemap =
+        textureType == Resources::TextureType::TextureCube ||
+        textureType == Resources::TextureType::TextureCubeArray;
+    if (expectsCubemap != isCubemap) {
+        return fallbackView;
+    }
+
+    RHI::RHIResourceView* textureView = ResolveTextureView(texture);
+    return textureView != nullptr ? textureView : fallbackView;
+}
+
 BuiltinForwardPipeline::LightingConstants BuiltinForwardPipeline::BuildLightingConstants(
     const RenderLightingData& lightingData) {
     LightingConstants lightingConstants = {};
@@ -664,7 +722,7 @@ bool BuiltinForwardPipeline::DrawVisibleItem(
             ? sceneData.lighting.mainDirectionalShadow.shadowParams
             : Math::Vector4::Zero(),
         sceneData.lighting.HasMainDirectionalShadow()
-            ? Math::Vector4(1.0f, 0.0f, 0.0f, 0.0f)
+            ? sceneData.lighting.mainDirectionalShadow.shadowOptions
             : Math::Vector4::Zero()
     };
 
@@ -730,7 +788,8 @@ bool BuiltinForwardPipeline::DrawVisibleItem(
                 const Resources::Material* materialKey =
                     (setLayout.usesMaterial ||
                      setLayout.usesBaseColorTexture ||
-                     setLayout.usesMaterialBuffers)
+                     setLayout.usesMaterialBuffers ||
+                     setLayout.usesMaterialTextures)
                         ? material
                         : nullptr;
 

engine/src/Resources/Mesh/MeshLoader.cpp

@@ -1,4 +1,5 @@
 #include <XCEngine/Resources/Mesh/MeshLoader.h>
+#include <XCEngine/Core/Asset/ArtifactContainer.h>
 #include <XCEngine/Core/Asset/ArtifactFormats.h>
 #include <XCEngine/Resources/BuiltinResources.h>
 #include <XCEngine/Resources/Material/MaterialLoader.h>
@@ -229,12 +230,27 @@ Containers::String ResolveArtifactDependencyPath(const Containers::String& depen
     }
 
     std::filesystem::path dependencyFsPath(dependencyPath.CStr());
+    Containers::String containerPathText;
+    Containers::String entryName;
+    const bool isContainerEntryPath =
+        TryParseArtifactContainerEntryPath(dependencyPath, containerPathText, entryName);
+    if (isContainerEntryPath) {
+        dependencyFsPath = std::filesystem::path(containerPathText.CStr());
+    }
+
+    auto rebuildResolvedPath = [&entryName, isContainerEntryPath](const std::filesystem::path& resolvedPath) {
+        const Containers::String normalizedPath = NormalizePathString(resolvedPath);
+        return isContainerEntryPath
+            ? BuildArtifactContainerEntryPath(normalizedPath, entryName)
+            : normalizedPath;
+    };
+
     if (dependencyFsPath.is_absolute() && std::filesystem::exists(dependencyFsPath)) {
-        return NormalizePathString(dependencyFsPath);
+        return rebuildResolvedPath(dependencyFsPath);
     }
 
     if (std::filesystem::exists(dependencyFsPath)) {
-        return NormalizePathString(dependencyFsPath);
+        return rebuildResolvedPath(dependencyFsPath);
     }
 
     const Containers::String& resourceRoot = ResourceManager::Get().GetResourceRoot();
@@ -242,7 +258,7 @@ Containers::String ResolveArtifactDependencyPath(const Containers::String& depen
         const std::filesystem::path projectRelativeCandidate =
             std::filesystem::path(resourceRoot.CStr()) / dependencyFsPath;
         if (std::filesystem::exists(projectRelativeCandidate)) {
-            return NormalizePathString(projectRelativeCandidate);
+            return rebuildResolvedPath(projectRelativeCandidate);
         }
     }
 
@@ -254,7 +270,7 @@ Containers::String ResolveArtifactDependencyPath(const Containers::String& depen
     const std::filesystem::path ownerRelativeCandidate =
         ownerArtifactFsPath.parent_path() / dependencyFsPath;
     if (std::filesystem::exists(ownerRelativeCandidate)) {
-        return NormalizePathString(ownerRelativeCandidate);
+        return rebuildResolvedPath(ownerRelativeCandidate);
     }
 
     std::filesystem::path current = ownerArtifactFsPath.parent_path();
@@ -264,7 +280,7 @@ Containers::String ResolveArtifactDependencyPath(const Containers::String& depen
             if (!projectRoot.empty()) {
                 const std::filesystem::path projectRelativeCandidate = projectRoot / dependencyFsPath;
                 if (std::filesystem::exists(projectRelativeCandidate)) {
-                    return NormalizePathString(projectRelativeCandidate);
+                    return rebuildResolvedPath(projectRelativeCandidate);
                 }
             }
             break;
@@ -675,42 +691,66 @@ ImportedMeshData ImportSingleMesh(const aiMesh& mesh,
     result.vertices.reserve(mesh.mNumVertices);
     result.indices.reserve(mesh.mNumFaces * 3);
 
+    const bool hasNormals = mesh.HasNormals();
+    const bool hasTangentsAndBitangents = mesh.HasTangentsAndBitangents();
+    const bool hasUv0 = mesh.HasTextureCoords(0);
+    const bool hasUv1 = mesh.HasTextureCoords(1);
+    const bool hasVertexColors = mesh.HasVertexColors(0);
+    const bool useFallbackUv1 = hasUv0 && !hasUv1;
+
     VertexAttribute attributes = VertexAttribute::Position;
-    if (mesh.HasNormals()) {
+    if (hasNormals) {
         attributes = attributes | VertexAttribute::Normal;
     }
-    if (mesh.HasTangentsAndBitangents()) {
+    if (hasTangentsAndBitangents) {
         attributes = attributes | VertexAttribute::Tangent | VertexAttribute::Bitangent;
     }
-    if (mesh.HasTextureCoords(0)) {
+    if (hasUv0) {
         attributes = attributes | VertexAttribute::UV0;
     }
+    if (hasUv1 || useFallbackUv1) {
+        attributes = attributes | VertexAttribute::UV1;
+    }
+    if (hasVertexColors) {
+        attributes = attributes | VertexAttribute::Color;
+    }
 
     const Math::Matrix4 normalTransform = worldTransform.Inverse().Transpose();
     const float appliedScale = globalScale;
 
     for (Core::uint32 vertexIndex = 0; vertexIndex < mesh.mNumVertices; ++vertexIndex) {
-        StaticMeshVertex vertex;
+        StaticMeshVertex vertex = {};
 
         const aiVector3D& position = mesh.mVertices[vertexIndex];
         const Math::Vector3 transformedPosition = worldTransform.MultiplyPoint(Math::Vector3(position.x, position.y, position.z));
         vertex.position = transformedPosition * appliedScale + offset;
 
-        if (mesh.HasNormals()) {
+        if (hasNormals) {
             const aiVector3D& normal = mesh.mNormals[vertexIndex];
             vertex.normal = normalTransform.MultiplyVector(Math::Vector3(normal.x, normal.y, normal.z)).Normalized();
         }
 
-        if (mesh.HasTangentsAndBitangents()) {
+        if (hasTangentsAndBitangents) {
             const aiVector3D& tangent = mesh.mTangents[vertexIndex];
             const aiVector3D& bitangent = mesh.mBitangents[vertexIndex];
             vertex.tangent = normalTransform.MultiplyVector(Math::Vector3(tangent.x, tangent.y, tangent.z)).Normalized();
             vertex.bitangent = normalTransform.MultiplyVector(Math::Vector3(bitangent.x, bitangent.y, bitangent.z)).Normalized();
         }
 
-        if (mesh.HasTextureCoords(0)) {
+        if (hasUv0) {
             const aiVector3D& uv = mesh.mTextureCoords[0][vertexIndex];
             vertex.uv0 = Math::Vector2(uv.x, uv.y);
+            vertex.uv1 = vertex.uv0;
+        }
+
+        if (hasUv1) {
+            const aiVector3D& uv = mesh.mTextureCoords[1][vertexIndex];
+            vertex.uv1 = Math::Vector2(uv.x, uv.y);
+        }
+
+        if (hasVertexColors) {
+            const aiColor4D& color = mesh.mColors[0][vertexIndex];
+            vertex.color = Math::Vector4(color.r, color.g, color.b, color.a);
         }
 
         result.vertices.push_back(vertex);
@@ -831,14 +871,72 @@ void ApplyMaterialProperty(Material& material, const MaterialProperty& property)
 }
 
 LoadResult LoadMeshArtifact(const Containers::String& path) {
-    std::ifstream input(path.CStr(), std::ios::binary);
-    if (!input.is_open()) {
+    Containers::Array<Core::uint8> data;
+
+    auto tryRead = [&data](const std::filesystem::path& filePath, bool& opened) {
+        opened = false;
+        data.Clear();
+
+        Containers::String containerError;
+        if (ReadArtifactContainerPayloadByPath(
+                Containers::String(filePath.generic_string().c_str()),
+                ResourceType::Mesh,
+                data,
+                &containerError)) {
+            opened = true;
+            return;
+        }
+
+        std::ifstream input(filePath, std::ios::binary | std::ios::ate);
+        if (!input.is_open()) {
+            return;
+        }
+
+        opened = true;
+        const std::streamsize size = input.tellg();
+        if (size < 0) {
+            data.Clear();
+            return;
+        }
+
+        input.seekg(0, std::ios::beg);
+        data.Resize(static_cast<size_t>(size));
+        if (size > 0 &&
+            !input.read(reinterpret_cast<char*>(data.Data()), size)) {
+            data.Clear();
+        }
+    };
+
+    bool opened = false;
+    std::filesystem::path resolvedPath(path.CStr());
+    tryRead(resolvedPath, opened);
+    if (!opened && !resolvedPath.is_absolute()) {
+        const Containers::String& resourceRoot = ResourceManager::Get().GetResourceRoot();
+        if (!resourceRoot.Empty()) {
+            resolvedPath = std::filesystem::path(resourceRoot.CStr()) / resolvedPath;
+            tryRead(resolvedPath, opened);
+        }
+    }
+
+    if (!opened || data.Size() < sizeof(MeshArtifactHeader)) {
         return LoadResult(Containers::String("Failed to read mesh artifact: ") + path);
     }
 
+    size_t offset = 0;
+    auto readBytes = [&data, &offset](void* destination, size_t byteCount) -> bool {
+        if (offset + byteCount > data.Size()) {
+            return false;
+        }
+
+        if (byteCount > 0) {
+            std::memcpy(destination, data.Data() + offset, byteCount);
+            offset += byteCount;
+        }
+        return true;
+    };
+
     MeshArtifactHeader header;
-    input.read(reinterpret_cast<char*>(&header), sizeof(header));
-    if (!input) {
+    if (!readBytes(&header, sizeof(header))) {
         return LoadResult(Containers::String("Failed to parse mesh artifact header: ") + path);
     }
 
@@ -859,28 +957,29 @@ LoadResult LoadMeshArtifact(const Containers::String& path) {
     Containers::Array<MeshSection> sections;
     sections.Resize(header.sectionCount);
     for (Core::uint32 index = 0; index < header.sectionCount; ++index) {
-        input.read(reinterpret_cast<char*>(&sections[index]), sizeof(MeshSection));
-        if (!input) {
+        if (!readBytes(&sections[index], sizeof(MeshSection))) {
             return LoadResult(Containers::String("Failed to read mesh sections: ") + path);
         }
     }
 
     Containers::Array<Core::uint8> vertexData;
     vertexData.Resize(static_cast<size_t>(header.vertexDataSize));
-    if (header.vertexDataSize > 0) {
-        input.read(reinterpret_cast<char*>(vertexData.Data()), static_cast<std::streamsize>(header.vertexDataSize));
-        if (!input) {
-            return LoadResult(Containers::String("Failed to read mesh vertex data: ") + path);
-        }
+    if (header.vertexDataSize > static_cast<Core::uint64>(data.Size() - offset)) {
+        return LoadResult(Containers::String("Failed to read mesh vertex data: ") + path);
+    }
+    if (header.vertexDataSize > 0 &&
+        !readBytes(vertexData.Data(), static_cast<size_t>(header.vertexDataSize))) {
+        return LoadResult(Containers::String("Failed to read mesh vertex data: ") + path);
     }
 
     Containers::Array<Core::uint8> indexData;
     indexData.Resize(static_cast<size_t>(header.indexDataSize));
-    if (header.indexDataSize > 0) {
-        input.read(reinterpret_cast<char*>(indexData.Data()), static_cast<std::streamsize>(header.indexDataSize));
-        if (!input) {
-            return LoadResult(Containers::String("Failed to read mesh index data: ") + path);
-        }
+    if (header.indexDataSize > static_cast<Core::uint64>(data.Size() - offset)) {
+        return LoadResult(Containers::String("Failed to read mesh index data: ") + path);
+    }
+    if (header.indexDataSize > 0 &&
+        !readBytes(indexData.Data(), static_cast<size_t>(header.indexDataSize))) {
+        return LoadResult(Containers::String("Failed to read mesh index data: ") + path);
     }
 
     mesh->SetVertexData(vertexData.Data(),
@@ -901,11 +1000,31 @@ LoadResult LoadMeshArtifact(const Containers::String& path) {
     bounds.SetMinMax(header.boundsMin, header.boundsMax);
     mesh->SetBounds(bounds);
 
+    auto readBinaryString = [&data, &offset, &readBytes](Containers::String& outValue) -> bool {
+        Core::uint32 length = 0;
+        if (!readBytes(&length, sizeof(length))) {
+            return false;
+        }
+
+        if (length == 0) {
+            outValue.Clear();
+            return true;
+        }
+
+        if (offset + length > data.Size()) {
+            return false;
+        }
+
+        outValue = Containers::String(reinterpret_cast<const char*>(data.Data() + offset), length);
+        offset += length;
+        return true;
+    };
+
     MaterialLoader materialLoader;
 
     for (Core::uint32 materialIndex = 0; materialIndex < header.materialCount; ++materialIndex) {
-        const Containers::String materialArtifactPath = ReadBinaryString(input);
-        if (!input) {
+        Containers::String materialArtifactPath;
+        if (!readBinaryString(materialArtifactPath)) {
             return LoadResult(Containers::String("Failed to read mesh material artifact path: ") + path);
         }
 

engine/src/Resources/Model/AssimpModelImporter.cpp

@@ -640,37 +640,61 @@ ImportedMeshData ImportSingleMesh(const aiMesh& mesh) {
     result.vertices.reserve(mesh.mNumVertices);
     result.indices.reserve(mesh.mNumFaces * 3);
 
+    const bool hasNormals = mesh.HasNormals();
+    const bool hasTangentsAndBitangents = mesh.HasTangentsAndBitangents();
+    const bool hasUv0 = mesh.HasTextureCoords(0);
+    const bool hasUv1 = mesh.HasTextureCoords(1);
+    const bool hasVertexColors = mesh.HasVertexColors(0);
+    const bool useFallbackUv1 = hasUv0 && !hasUv1;
+
     VertexAttribute attributes = VertexAttribute::Position;
-    if (mesh.HasNormals()) {
+    if (hasNormals) {
         attributes = attributes | VertexAttribute::Normal;
     }
-    if (mesh.HasTangentsAndBitangents()) {
+    if (hasTangentsAndBitangents) {
         attributes = attributes | VertexAttribute::Tangent | VertexAttribute::Bitangent;
     }
-    if (mesh.HasTextureCoords(0)) {
+    if (hasUv0) {
         attributes = attributes | VertexAttribute::UV0;
     }
+    if (hasUv1 || useFallbackUv1) {
+        attributes = attributes | VertexAttribute::UV1;
+    }
+    if (hasVertexColors) {
+        attributes = attributes | VertexAttribute::Color;
+    }
 
     for (Core::uint32 vertexIndex = 0; vertexIndex < mesh.mNumVertices; ++vertexIndex) {
-        StaticMeshVertex vertex;
+        StaticMeshVertex vertex = {};
         const aiVector3D& position = mesh.mVertices[vertexIndex];
         vertex.position = Math::Vector3(position.x, position.y, position.z);
 
-        if (mesh.HasNormals()) {
+        if (hasNormals) {
             const aiVector3D& normal = mesh.mNormals[vertexIndex];
             vertex.normal = Math::Vector3(normal.x, normal.y, normal.z).Normalized();
         }
 
-        if (mesh.HasTangentsAndBitangents()) {
+        if (hasTangentsAndBitangents) {
             const aiVector3D& tangent = mesh.mTangents[vertexIndex];
             const aiVector3D& bitangent = mesh.mBitangents[vertexIndex];
             vertex.tangent = Math::Vector3(tangent.x, tangent.y, tangent.z).Normalized();
             vertex.bitangent = Math::Vector3(bitangent.x, bitangent.y, bitangent.z).Normalized();
         }
 
-        if (mesh.HasTextureCoords(0)) {
+        if (hasUv0) {
             const aiVector3D& uv = mesh.mTextureCoords[0][vertexIndex];
             vertex.uv0 = Math::Vector2(uv.x, uv.y);
+            vertex.uv1 = vertex.uv0;
+        }
+
+        if (hasUv1) {
+            const aiVector3D& uv = mesh.mTextureCoords[1][vertexIndex];
+            vertex.uv1 = Math::Vector2(uv.x, uv.y);
+        }
+
+        if (hasVertexColors) {
+            const aiColor4D& color = mesh.mColors[0][vertexIndex];
+            vertex.color = Math::Vector4(color.r, color.g, color.b, color.a);
         }
 
         result.vertices.push_back(vertex);

engine/src/Scene/ModelSceneInstantiation.cpp

@@ -0,0 +1,228 @@
+#include <XCEngine/Scene/ModelSceneInstantiation.h>
+
+#include <XCEngine/Components/GameObject.h>
+#include <XCEngine/Components/MeshFilterComponent.h>
+#include <XCEngine/Components/MeshRendererComponent.h>
+#include <XCEngine/Core/Asset/ResourceManager.h>
+#include <XCEngine/Scene/Scene.h>
+
+namespace XCEngine {
+
+namespace {
+
+using namespace Components;
+using namespace Resources;
+
+Containers::String MakeNodeName(const ModelNode& node, Core::uint32 nodeIndex) {
+    if (!node.name.Empty()) {
+        return node.name;
+    }
+
+    return Containers::String(("ModelNode_" + std::to_string(nodeIndex)).c_str());
+}
+
+Containers::String MakeMeshObjectName(const Containers::String& nodeName, Core::uint32 meshBindingOffset) {
+    return Containers::String(
+        (std::string(nodeName.CStr()) + "_Mesh" + std::to_string(meshBindingOffset)).c_str());
+}
+
+AssetRef MakeSubAssetRef(const AssetRef& modelAssetRef, LocalID localID, ResourceType resourceType) {
+    AssetRef ref;
+    ref.assetGuid = modelAssetRef.assetGuid;
+    ref.localID = localID;
+    ref.resourceType = resourceType;
+    return ref;
+}
+
+void SetErrorMessage(Containers::String* outErrorMessage, const Containers::String& message) {
+    if (outErrorMessage != nullptr) {
+        *outErrorMessage = message;
+    }
+}
+
+bool AttachMeshBinding(
+    GameObject& targetObject,
+    const Model& model,
+    const AssetRef& modelAssetRef,
+    const ModelMeshBinding& meshBinding,
+    Containers::String* outErrorMessage,
+    std::vector<GameObject*>* outMeshObjects) {
+    if (!modelAssetRef.IsValid()) {
+        SetErrorMessage(outErrorMessage, "Model asset ref is required when instantiating mesh bindings.");
+        return false;
+    }
+
+    auto* meshFilter = targetObject.GetComponent<MeshFilterComponent>();
+    if (meshFilter == nullptr) {
+        meshFilter = targetObject.AddComponent<MeshFilterComponent>();
+    }
+
+    auto* meshRenderer = targetObject.GetComponent<MeshRendererComponent>();
+    if (meshRenderer == nullptr) {
+        meshRenderer = targetObject.AddComponent<MeshRendererComponent>();
+    }
+
+    meshFilter->SetMeshAssetRef(MakeSubAssetRef(modelAssetRef, meshBinding.meshLocalID, ResourceType::Mesh));
+
+    const auto& materialBindings = model.GetMaterialBindings();
+    const Core::uint32 materialBindingEnd = meshBinding.materialBindingStart + meshBinding.materialBindingCount;
+    if (materialBindingEnd > materialBindings.Size()) {
+        SetErrorMessage(outErrorMessage, "Model mesh binding references material bindings outside the model range.");
+        return false;
+    }
+
+    for (Core::uint32 materialBindingIndex = meshBinding.materialBindingStart;
+         materialBindingIndex < materialBindingEnd;
+         ++materialBindingIndex) {
+        const ModelMaterialBinding& materialBinding = materialBindings[materialBindingIndex];
+        meshRenderer->SetMaterialAssetRef(
+            static_cast<size_t>(materialBinding.slotIndex),
+            MakeSubAssetRef(modelAssetRef, materialBinding.materialLocalID, ResourceType::Material));
+    }
+
+    if (outMeshObjects != nullptr) {
+        outMeshObjects->push_back(&targetObject);
+    }
+    return true;
+}
+
+} // namespace
+
+bool InstantiateModelHierarchy(
+    Components::Scene& scene,
+    const Resources::Model& model,
+    const Resources::AssetRef& modelAssetRef,
+    Components::GameObject* parent,
+    ModelSceneInstantiationResult* outResult,
+    Containers::String* outErrorMessage) {
+    if (!model.IsValid()) {
+        SetErrorMessage(outErrorMessage, "Model is invalid.");
+        return false;
+    }
+
+    if (!model.HasRootNode()) {
+        SetErrorMessage(outErrorMessage, "Model does not have a root node.");
+        return false;
+    }
+
+    const auto& nodes = model.GetNodes();
+    const auto& meshBindings = model.GetMeshBindings();
+    if (model.GetRootNodeIndex() >= nodes.Size()) {
+        SetErrorMessage(outErrorMessage, "Model root node index is outside the node range.");
+        return false;
+    }
+
+    ModelSceneInstantiationResult localResult;
+    localResult.nodeObjects.resize(nodes.Size(), nullptr);
+    for (Core::uint32 nodeIndex = 0; nodeIndex < nodes.Size(); ++nodeIndex) {
+        const ModelNode& node = nodes[nodeIndex];
+        localResult.nodeObjects[nodeIndex] = scene.CreateGameObject(MakeNodeName(node, nodeIndex).CStr(), nullptr);
+        if (localResult.nodeObjects[nodeIndex] == nullptr) {
+            SetErrorMessage(outErrorMessage, "Failed to create a model node game object.");
+            return false;
+        }
+
+        auto* transform = localResult.nodeObjects[nodeIndex]->GetTransform();
+        transform->SetLocalPosition(node.localPosition);
+        transform->SetLocalRotation(node.localRotation);
+        transform->SetLocalScale(node.localScale);
+    }
+
+    for (Core::uint32 nodeIndex = 0; nodeIndex < nodes.Size(); ++nodeIndex) {
+        const ModelNode& node = nodes[nodeIndex];
+        GameObject* nodeObject = localResult.nodeObjects[nodeIndex];
+        if (nodeObject == nullptr) {
+            continue;
+        }
+
+        if (node.parentIndex >= 0) {
+            const Core::uint32 parentIndex = static_cast<Core::uint32>(node.parentIndex);
+            if (parentIndex >= localResult.nodeObjects.size() || localResult.nodeObjects[parentIndex] == nullptr) {
+                SetErrorMessage(outErrorMessage, "Model node references an invalid parent index.");
+                return false;
+            }
+
+            nodeObject->SetParent(localResult.nodeObjects[parentIndex], false);
+        } else if (parent != nullptr) {
+            nodeObject->SetParent(parent, false);
+        }
+    }
+
+    for (Core::uint32 nodeIndex = 0; nodeIndex < nodes.Size(); ++nodeIndex) {
+        const ModelNode& node = nodes[nodeIndex];
+        GameObject* nodeObject = localResult.nodeObjects[nodeIndex];
+        if (nodeObject == nullptr || node.meshBindingCount == 0u) {
+            continue;
+        }
+
+        const Core::uint32 meshBindingEnd = node.meshBindingStart + node.meshBindingCount;
+        if (meshBindingEnd > meshBindings.Size()) {
+            SetErrorMessage(outErrorMessage, "Model node references mesh bindings outside the model range.");
+            return false;
+        }
+
+        if (node.meshBindingCount == 1u) {
+            if (!AttachMeshBinding(
+                    *nodeObject,
+                    model,
+                    modelAssetRef,
+                    meshBindings[node.meshBindingStart],
+                    outErrorMessage,
+                    &localResult.meshObjects)) {
+                return false;
+            }
+            continue;
+        }
+
+        const Containers::String nodeName = MakeNodeName(node, nodeIndex);
+        for (Core::uint32 meshBindingIndex = node.meshBindingStart; meshBindingIndex < meshBindingEnd; ++meshBindingIndex) {
+            GameObject* meshObject = scene.CreateGameObject(
+                MakeMeshObjectName(nodeName, meshBindingIndex - node.meshBindingStart).CStr(),
+                nodeObject);
+            if (meshObject == nullptr) {
+                SetErrorMessage(outErrorMessage, "Failed to create an auxiliary mesh binding game object.");
+                return false;
+            }
+
+            if (!AttachMeshBinding(
+                    *meshObject,
+                    model,
+                    modelAssetRef,
+                    meshBindings[meshBindingIndex],
+                    outErrorMessage,
+                    &localResult.meshObjects)) {
+                return false;
+            }
+        }
+    }
+
+    localResult.rootObject = localResult.nodeObjects[model.GetRootNodeIndex()];
+    if (outResult != nullptr) {
+        *outResult = std::move(localResult);
+    }
+    return true;
+}
+
+bool InstantiateModelHierarchy(
+    Components::Scene& scene,
+    const Containers::String& modelPath,
+    Components::GameObject* parent,
+    ModelSceneInstantiationResult* outResult,
+    Containers::String* outErrorMessage) {
+    ResourceManager& resourceManager = ResourceManager::Get();
+    const ResourceHandle<Resources::Model> modelHandle = resourceManager.Load<Resources::Model>(modelPath);
+    if (!modelHandle.IsValid()) {
+        SetErrorMessage(outErrorMessage, Containers::String("Failed to load model asset: ") + modelPath);
+        return false;
+    }
+
+    AssetRef modelAssetRef;
+    if (!resourceManager.TryGetAssetRef(modelPath, ResourceType::Model, modelAssetRef)) {
+        SetErrorMessage(outErrorMessage, Containers::String("Failed to resolve model asset ref: ") + modelPath);
+        return false;
+    }
+
+    return InstantiateModelHierarchy(scene, *modelHandle, modelAssetRef, parent, outResult, outErrorMessage);
+}
+
+} // namespace XCEngine

project/Assets/Characters.meta

@@ -0,0 +1,5 @@
+fileFormatVersion: 1
+guid: b728e58114669fc3dd9e6521bd22933a
+folderAsset: true
+importer: FolderImporter
+importerVersion: 7

project/Assets/Characters/Nahida/DependencyMap.md

@@ -0,0 +1,195 @@
+# Nahida Dependency Map
+
+This document captures the Unity sample semantics that must survive the port.
+
+Source roots:
+- Unity reference project: `mvs/NahidaRender`
+- Engine project staging area: `project/Assets/Characters/Nahida`
+
+## Texture groups
+
+Body and Dress1:
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Diffuse.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Lightmap.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Normalmap.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Shadow_Ramp.png`
+
+Hair and Dress2:
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Hair_Diffuse.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Hair_Lightmap.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Hair_Normalmap.png`
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Hair_Shadow_Ramp.png`
+
+Face and shared:
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Face_Diffuse.png`
+- `Textures/Shared/Avatar_Loli_Tex_FaceLightmap.png`
+- `Textures/Shared/Avatar_Tex_Face_Shadow.png`
+- `Textures/Shared/Avatar_Tex_MetalMap.png`
+
+Reference-only extra:
+- `Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Specular_Ramp.png`
+  - Present in the sample resources.
+  - Not directly referenced by the seven Unity Nahida materials that were copied into `docs/reference/NahidaUnity/Materials`.
+
+## Material graph
+
+Shared base material:
+- `docs/reference/NahidaUnity/Materials/Nahida_Base.mat`
+  - Uses `docs/reference/NahidaUnity/Shaders/Genshin.shader`
+  - Binds shared `_MetalMap = Textures/Shared/Avatar_Tex_MetalMap.png`
+  - Carries shared shadow, rim, outline, and specular defaults
+
+Body branch:
+- `docs/reference/NahidaUnity/Materials/Nahida_Body.mat`
+  - `_BaseMap = Body_Diffuse`
+  - `_LightMap = Body_Lightmap`
+  - `_NormalMap = Body_Normalmap`
+  - `_ShadowRamp = Body_Shadow_Ramp`
+  - Enables emission, normal map, rim, specular, and smooth normal
+
+- `docs/reference/NahidaUnity/Materials/Nahida_Dress1.mat`
+  - Reuses the same body texture group
+  - Double-sided
+  - Uses smooth normal
+
+Hair branch:
+- `docs/reference/NahidaUnity/Materials/Nahida_Hair.mat`
+  - `_BaseMap = Hair_Diffuse`
+  - `_LightMap = Hair_Lightmap`
+  - `_NormalMap = Hair_Normalmap`
+  - `_ShadowRamp = Hair_Shadow_Ramp`
+  - Enables emission, normal map, rim, specular, and smooth normal
+
+- `docs/reference/NahidaUnity/Materials/Nahida_Dress2.mat`
+  - Reuses the same hair texture group
+  - Double-sided
+
+Face branch:
+- `docs/reference/NahidaUnity/Materials/Nahida_Face.mat`
+  - `_BaseMap = Face_Diffuse`
+  - `_FaceLightMap = Avatar_Loli_Tex_FaceLightmap`
+  - `_FaceShadow = Avatar_Tex_Face_Shadow`
+  - `_ShadowRamp = Body_Shadow_Ramp`
+  - Marks `_IsFace = 1`
+  - Depends on runtime `_FaceDirection`
+
+- `docs/reference/NahidaUnity/Materials/Nahida_Brow.mat`
+  - Reuses the same face texture group
+  - Uses a tint override through `_BaseColor`
+  - Sets outline width to `0`
+
+## Shader semantics
+
+Core shader files:
+- `docs/reference/NahidaUnity/Shaders/Genshin.shader`
+- `docs/reference/NahidaUnity/Shaders/GenshinInput.hlsl`
+- `docs/reference/NahidaUnity/Shaders/GenshinForwardPass.hlsl`
+- `docs/reference/NahidaUnity/Shaders/GenshinOutlinePass.hlsl`
+
+Important shader features to preserve:
+- `_LightMap` driven shadow partitioning
+- `_FaceLightMap + _FaceShadow + _FaceDirection` face shading path
+- `_MetalMap` driven specular/metal response
+- Rim light
+- Separate outline pass
+- `_UseSmoothNormal` switch for outline data path
+
+## Scene semantics from Unity sample
+
+Reference scene:
+- `docs/reference/NahidaUnity/Scenes/SampleScene.unity`
+
+Observed setup:
+- Instantiates `Avatar_Loli_Catalyst_Nahida.fbx` as a prefab instance
+- Renames the root object to `NahidaUnityModel`
+- Uses `SkinnedMeshRenderer`, not a static `MeshFilter + MeshRenderer` setup
+- Overrides one renderer mesh with `Meshes/Nahida_Body_Smooth.mesh`
+- Assigns body renderer material slots in this order:
+  - slot 0: `Nahida_Hair.mat`
+  - slot 1: `Nahida_Body.mat`
+  - slot 2: `Nahida_Dress1.mat`
+  - slot 3: `Nahida_Dress2.mat`
+- Additional renderers use:
+  - `Nahida_Face.mat`
+  - `Nahida_Brow.mat`
+- One face-related renderer writes `BlendShapeWeights[0] = 100`
+
+## Current static assembly baseline in XCEngine
+
+Preview scene:
+- `Assets/Scenes/NahidaPreview.xc`
+
+Current static assembly uses the existing imported FBX sub-meshes from:
+- `Assets/Models/nahida/Avatar_Loli_Catalyst_Nahida.fbx`
+
+Scene-side material path mapping in `Assets/Scenes/NahidaPreview.xc`:
+- `Nahida_Hair`
+  - mesh localID: `5268898388415806497`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Hair.mat`
+- `Nahida_Body`
+  - mesh localID: `5268897288904178286`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Body.mat`
+- `Nahida_Dress1`
+  - mesh localID: `5268896189392550075`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Dress1.mat`
+- `Nahida_Dress2`
+  - mesh localID: `5268895089880921864`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Dress2.mat`
+- `Nahida_Brow`
+  - mesh localID: `15841426242793151682`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Brow.mat`
+- `Nahida_EffectMesh`
+  - mesh localID: `692846506840157104`
+  - temporary fallback material: `builtin://materials/default-primitive`
+- `Nahida_EyeStar`
+  - mesh localID: `8234240765526303311`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Face.mat`
+- `Nahida_Face`
+  - mesh localID: `1306782875462705981`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Face.mat`
+- `Nahida_FaceEye`
+  - mesh localID: `977130118610429631`
+  - engine material: `Assets/Characters/Nahida/Materials/Nahida_Face.mat`
+
+Current engine-native shader and materials:
+- Shader: `Assets/Shaders/XCCharacterToon.shader`
+- Materials:
+  - `Assets/Characters/Nahida/Materials/Nahida_Hair.mat`
+  - `Assets/Characters/Nahida/Materials/Nahida_Body.mat`
+  - `Assets/Characters/Nahida/Materials/Nahida_Dress1.mat`
+  - `Assets/Characters/Nahida/Materials/Nahida_Dress2.mat`
+  - `Assets/Characters/Nahida/Materials/Nahida_Face.mat`
+  - `Assets/Characters/Nahida/Materials/Nahida_Brow.mat`
+
+Current model material remap sidecars:
+- `Assets/Models/nahida/Avatar_Loli_Catalyst_Nahida.fbx.materialmap`
+- `Assets/Characters/Nahida/Model/Avatar_Loli_Catalyst_Nahida.fbx.materialmap`
+
+Format:
+- `meshLocalID=Assets/.../Material.mat`
+- Multiple material slots can be provided with `|`
+
+Current gaps:
+- No dedicated outline pass yet.
+- Face shading logic now matches the Unity-style forward path more closely, but `_FaceDirection` is still not driven at runtime.
+
+## Runtime driver semantics
+
+Runtime driver:
+- `docs/reference/NahidaUnity/Scripts/MaterialUpdater.cs`
+
+Behavior:
+- Reads the head bone transform every frame
+- Rotates the configured local head direction
+- Writes `_FaceDirection` into every material on the configured face renderers
+
+This means face shading is not static material data. The engine port needs a runtime material-parameter driver.
+
+## Post-process reference
+
+Reference files:
+- `docs/reference/NahidaUnity/Shaders/URPGenshinPostProcess.shader`
+- `docs/reference/NahidaUnity/Scripts/Rendering/`
+- `docs/reference/NahidaUnity/URPSettings/`
+
+These are kept only as semantic reference for a later phase. They should not be treated as engine-native runtime assets.

project/Assets/Characters/Nahida/DependencyMap.md.meta

@@ -0,0 +1,5 @@
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+guid: 28da23fea182596ac7927a1f42a87cd8
+folderAsset: false
+importer: DefaultImporter
+importerVersion: 7

project/Assets/Characters/Nahida/Materials.meta

@@ -0,0 +1,5 @@
+fileFormatVersion: 1
+guid: 725c8d70965b4172e982c891fbc0f6e6
+folderAsset: true
+importer: FolderImporter
+importerVersion: 7

project/Assets/Characters/Nahida/Materials/Nahida_Body.mat

@@ -0,0 +1,19 @@
+{
+  "shader": "Assets/Shaders/XCCharacterToon.shader",
+  "renderQueue": "geometry",
+  "keywords": ["_EMISSION", "_NORMAL_MAP", "_RIM", "_SPECULAR"],
+  "properties": {
+    "_UseEmission": 1.0,
+    "_UseNormalMap": 1.0,
+    "_UseRim": 1.0,
+    "_UseSmoothNormal": 1.0,
+    "_UseSpecular": 1.0
+  },
+  "textures": {
+    "_BaseMap": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Diffuse.png",
+    "_LightMap": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Lightmap.png",
+    "_NormalMap": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Normalmap.png",
+    "_ShadowRamp": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Shadow_Ramp.png",
+    "_MetalMap": "Assets/Characters/Nahida/Textures/Shared/Avatar_Tex_MetalMap.png"
+  }
+}

project/Assets/Characters/Nahida/Materials/Nahida_Body.mat.meta

@@ -0,0 +1,5 @@
+fileFormatVersion: 1
+guid: 4e3f0d5ffce7442ab339368d71155d11
+folderAsset: false
+importer: MaterialImporter
+importerVersion: 8

project/Assets/Characters/Nahida/Materials/Nahida_Brow.mat

@@ -0,0 +1,19 @@
+{
+  "shader": "Assets/Shaders/XCCharacterToon.shader",
+  "renderQueue": "geometry",
+  "keywords": ["_IS_FACE", "_RIM"],
+  "properties": {
+    "_BaseColor": [0.9764706, 0.80103135, 0.76164705, 1.0],
+    "_FaceDirection": [-0.0051237254, -0.11509954, -0.99334073, 0.0],
+    "_IsFace": 1.0,
+    "_OutlineWidth": 0.0,
+    "_UseCustomMaterialType": 1.0,
+    "_UseRim": 1.0
+  },
+  "textures": {
+    "_BaseMap": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Face_Diffuse.png",
+    "_FaceLightMap": "Assets/Characters/Nahida/Textures/Shared/Avatar_Loli_Tex_FaceLightmap.png",
+    "_FaceShadow": "Assets/Characters/Nahida/Textures/Shared/Avatar_Tex_Face_Shadow.png",
+    "_ShadowRamp": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Shadow_Ramp.png"
+  }
+}

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+  "renderQueue": "geometry",
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+    "_MetalMap": "Assets/Characters/Nahida/Textures/Shared/Avatar_Tex_MetalMap.png"
+  }
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+    "_MetalMap": "Assets/Characters/Nahida/Textures/Shared/Avatar_Tex_MetalMap.png"
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+    "_ShadowRamp": "Assets/Characters/Nahida/Textures/Nahida/Avatar_Loli_Catalyst_Nahida_Tex_Body_Shadow_Ramp.png"
+  }
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+  },
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+    "_MetalMap": "Assets/Characters/Nahida/Textures/Shared/Avatar_Tex_MetalMap.png"
+  }
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+5268898388415806497=Assets/Characters/Nahida/Materials/Nahida_Hair.mat
+5268897288904178286=Assets/Characters/Nahida/Materials/Nahida_Body.mat
+5268896189392550075=Assets/Characters/Nahida/Materials/Nahida_Dress1.mat
+5268895089880921864=Assets/Characters/Nahida/Materials/Nahida_Dress2.mat
+15841426242793151682=Assets/Characters/Nahida/Materials/Nahida_Brow.mat
+692846506840157104=builtin://materials/default-primitive
+8234240765526303311=Assets/Characters/Nahida/Materials/Nahida_Face.mat
+1306782875462705981=Assets/Characters/Nahida/Materials/Nahida_Face.mat
+977130118610429631=Assets/Characters/Nahida/Materials/Nahida_Face.mat

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project/Assets/Characters/Nahida/README.md

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+# Nahida Staging Assets
+
+This folder is the non-breaking staging area for migrating the Unity Nahida sample into the engine-native project structure.
+
+Current safety rule:
+- Keep `project/Assets/Models/nahida` in place for now.
+- `project/Assets/Scenes/Main.xc` still references the old imported FBX asset GUID from `Assets/Models/nahida/Avatar_Loli_Catalyst_Nahida.fbx`.
+- Do not rename or delete the old Nahida folder until a `Model`-driven scene path is ready.
+
+Directory layout:
+- `Model/`
+  - Canonical FBX source that should become the future `Model` entry asset.
+- `Textures/Nahida/`
+  - Character-local body, hair, and face textures copied from the Unity sample.
+- `Textures/Shared/`
+  - Shared textures used by the shader and face shading path.
+- `Meshes/`
+  - Extra mesh data needed by the outline path.
+- `docs/reference/NahidaUnity/`
+  - Unity-side semantic reference only.
+  - Stored outside `project/Assets` on purpose so the asset pipeline does not try to import Unity `.mat` and `.shader` files as engine-native assets.
+
+What has been staged in this phase:
+- Full Nahida FBX source.
+- Full body, hair, face, and shared texture set.
+- `Nahida_Body_Smooth.mesh` outline dependency.
+- Unity reference materials, shader files, runtime scripts, sample scene, and URP settings under `docs/reference/NahidaUnity/`.
+
+What has not been done yet:
+- No skinned runtime path, animator path, or blend-shape port.
+- No dedicated outline pass port yet.
+- Face shading now follows the Unity-style `_FaceLightMap + _FaceShadow + _FaceDirection` path in the forward shader, but it still does not have Unity's runtime `_FaceDirection` driver.
+- The preview scene still uses imported FBX sub-meshes, but the main character materials now point at engine-native `.mat` assets.
+- The main character materials now use Unity-aligned property names, keywords, and normal-map bindings, but they still render through a single forward pass in the current engine pipeline.
+
+Current FBX material remap bridge:
+- `Model` instantiation now looks for a sidecar file named `<model>.materialmap`.
+- Each line maps an imported mesh localID to one or more material paths:
+  - `meshLocalID=Assets/.../Material.mat`
+  - Multiple slots can be provided with `|`
+- Nahida remap files are staged at:
+  - `Assets/Models/nahida/Avatar_Loli_Catalyst_Nahida.fbx.materialmap`
+  - `Assets/Characters/Nahida/Model/Avatar_Loli_Catalyst_Nahida.fbx.materialmap`
+
+Recommended next implementation order:
+1. Visually validate `Assets/Scenes/NahidaPreview.xc` and tune framing/light balance against the Unity reference scene.
+2. Add a proper outline solution without introducing skinning work.
+3. Add a lightweight runtime `_FaceDirection` material driver for static preview scenes.
+4. Decide whether the static preview should keep the full instantiated FBX node tree or collapse helper/bone-only nodes for readability.

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project/Assets/Shaders/XCCharacterToon.shader

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+Shader "XC Character Toon"
+{
+    Properties
+    {
+        _BaseMap ("Base Map", 2D) = "white" [Semantic(BaseColorTexture)]
+        _BaseColor ("Base Color", Color) = (1,1,1,1) [Semantic(BaseColor)]
+        _Cutoff ("Alpha Cutoff", Range) = 0.5 [Semantic(AlphaCutoff)]
+        _IsDay ("Is Day", Float) = 1
+        _DoubleSided ("Double Sided", Float) = 0
+        _LightMap ("Light Map", 2D) = "white"
+        _LightDirectionMultiplier ("Light Direction Multiplier", Vector) = (1,0.5,1,0)
+        _ShadowOffset ("Shadow Offset", Float) = 0.1
+        _ShadowSmoothness ("Shadow Smoothness", Float) = 0.4
+        _ShadowColor ("Shadow Color", Color) = (1.1,1.1,1.1,1)
+        _ShadowRamp ("Shadow Ramp", 2D) = "white"
+        _UseCustomMaterialType ("Use Custom Material Type", Float) = 0
+        _CustomMaterialType ("Custom Material Type", Float) = 1
+        _UseEmission ("Use Emission", Float) = 0
+        _EmissionIntensity ("Emission Intensity", Float) = 0.2
+        _UseNormalMap ("Use Normal Map", Float) = 0
+        _NormalMap ("Normal Map", 2D) = "bump"
+        _IsFace ("Is Face", Float) = 0
+        _FaceDirection ("Face Direction", Vector) = (0,0,1,0)
+        _FaceShadowOffset ("Face Shadow Offset", Float) = 0
+        _FaceBlushColor ("Face Blush Color", Color) = (1,0.72156864,0.69803923,1)
+        _FaceBlushStrength ("Face Blush Strength", Float) = 0
+        _FaceLightMap ("Face Light Map", 2D) = "white"
+        _FaceShadow ("Face Shadow", 2D) = "white"
+        _UseSpecular ("Use Specular", Float) = 0
+        _SpecularSmoothness ("Specular Smoothness", Float) = 5
+        _NonmetallicIntensity ("Nonmetallic Intensity", Float) = 0.3
+        _MetallicIntensity ("Metallic Intensity", Float) = 8
+        _MetalMap ("Metal Map", 2D) = "white"
+        _UseRim ("Use Rim", Float) = 0
+        _RimOffset ("Rim Offset", Float) = 5
+        _RimThreshold ("Rim Threshold", Float) = 0.5
+        _RimIntensity ("Rim Intensity", Float) = 0.5
+        _UseSmoothNormal ("Use Smooth Normal", Float) = 0
+        _OutlineWidth ("Outline Width", Float) = 1.6
+        _OutlineWidthParams ("Outline Width Params", Vector) = (0,6,0.1,0.6)
+        _OutlineZOffset ("Outline Z Offset", Float) = 0.1
+        _ScreenOffset ("Screen Offset", Vector) = (0,0,0,0)
+        _OutlineColor ("Outline Color", Color) = (0.5176471,0.35686275,0.34117648,1)
+        _OutlineColor2 ("Outline Color 2", Color) = (0.3529412,0.3529412,0.3529412,1)
+        _OutlineColor3 ("Outline Color 3", Color) = (0.47058824,0.47058824,0.5647059,1)
+        _OutlineColor4 ("Outline Color 4", Color) = (0.5176471,0.35686275,0.34117648,1)
+        _OutlineColor5 ("Outline Color 5", Color) = (0.35,0.35,0.35,1)
+    }
+    HLSLINCLUDE
+    cbuffer PerObjectConstants
+    {
+        float4x4 gProjectionMatrix;
+        float4x4 gViewMatrix;
+        float4x4 gModelMatrix;
+        float4x4 gNormalMatrix;
+    };
+
+    static const int XC_MAX_ADDITIONAL_LIGHTS = 8;
+
+    struct AdditionalLightData
+    {
+        float4 colorAndIntensity;
+        float4 positionAndRange;
+        float4 directionAndType;
+        float4 spotAnglesAndFlags;
+    };
+
+    cbuffer LightingConstants
+    {
+        float4 gMainLightDirectionAndIntensity;
+        float4 gMainLightColorAndFlags;
+        float4 gLightingParams;
+        AdditionalLightData gAdditionalLights[XC_MAX_ADDITIONAL_LIGHTS];
+    };
+
+    cbuffer MaterialConstants
+    {
+        float4 _BaseColor;
+        float4 _Cutoff;
+        float4 _IsDay;
+        float4 _DoubleSided;
+        float4 _LightDirectionMultiplier;
+        float4 _ShadowOffset;
+        float4 _ShadowSmoothness;
+        float4 _ShadowColor;
+        float4 _UseCustomMaterialType;
+        float4 _CustomMaterialType;
+        float4 _UseEmission;
+        float4 _EmissionIntensity;
+        float4 _UseNormalMap;
+        float4 _IsFace;
+        float4 _FaceDirection;
+        float4 _FaceShadowOffset;
+        float4 _FaceBlushColor;
+        float4 _FaceBlushStrength;
+        float4 _UseSpecular;
+        float4 _SpecularSmoothness;
+        float4 _NonmetallicIntensity;
+        float4 _MetallicIntensity;
+        float4 _UseRim;
+        float4 _RimOffset;
+        float4 _RimThreshold;
+        float4 _RimIntensity;
+        float4 _UseSmoothNormal;
+        float4 _OutlineWidth;
+        float4 _OutlineWidthParams;
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+        float4 _ScreenOffset;
+        float4 _OutlineColor;
+        float4 _OutlineColor2;
+        float4 _OutlineColor3;
+        float4 _OutlineColor4;
+        float4 _OutlineColor5;
+    };
+
+    cbuffer ShadowReceiverConstants
+    {
+        float4x4 gWorldToShadowMatrix;
+        float4 gShadowBiasAndTexelSize;
+        float4 gShadowOptions;
+    };
+
+    Texture2D BaseColorTexture;
+    Texture2D _LightMap;
+    Texture2D _ShadowRamp;
+    Texture2D _NormalMap;
+    Texture2D _FaceLightMap;
+    Texture2D _FaceShadow;
+    Texture2D _MetalMap;
+    SamplerState LinearClampSampler;
+    Texture2D ShadowMapTexture;
+    SamplerState ShadowMapSampler;
+
+    struct VSInput
+    {
+        float3 position : POSITION;
+        float3 normal : NORMAL;
+        float4 color : COLOR;
+        float2 texcoord : TEXCOORD0;
+        float2 backTexcoord : TEXCOORD1;
+        float3 tangent : TEXCOORD2;
+        float3 bitangent : TEXCOORD3;
+    };
+
+    struct PSInput
+    {
+        float4 position : SV_POSITION;
+        float2 texcoord : TEXCOORD0;
+        float2 backTexcoord : TEXCOORD1;
+        float3 positionWS : TEXCOORD2;
+        float3 positionVS : TEXCOORD3;
+        float3 normalWS : TEXCOORD4;
+        float3 tangentWS : TEXCOORD5;
+        float3 bitangentWS : TEXCOORD6;
+        float4 color : COLOR;
+    };
+
+    float3 NormalizeSafe(float3 value, float3 fallbackValue)
+    {
+        const float lengthSq = dot(value, value);
+        if (lengthSq <= 1e-6f) {
+            return fallbackValue;
+        }
+
+        return value * rsqrt(lengthSq);
+    }
+
+    bool UseEmissionFeature()
+    {
+    #ifdef _EMISSION
+        return true;
+    #else
+        return _UseEmission.x > 0.5f;
+    #endif
+    }
+
+    bool UseNormalMapFeature()
+    {
+    #ifdef _NORMAL_MAP
+        return true;
+    #else
+        return _UseNormalMap.x > 0.5f;
+    #endif
+    }
+
+    bool UseFaceFeature()
+    {
+    #ifdef _IS_FACE
+        return true;
+    #else
+        return _IsFace.x > 0.5f;
+    #endif
+    }
+
+    bool UseSpecularFeature()
+    {
+    #ifdef _SPECULAR
+        return true;
+    #else
+        return _UseSpecular.x > 0.5f;
+    #endif
+    }
+
+    bool UseRimFeature()
+    {
+    #ifdef _RIM
+        return true;
+    #else
+        return _UseRim.x > 0.5f;
+    #endif
+    }
+
+    bool UseDoubleSidedFeature()
+    {
+    #ifdef _DOUBLE_SIDED
+        return true;
+    #else
+        return _DoubleSided.x > 0.5f;
+    #endif
+    }
+
+    float2 ResolveMaterialTexcoord(PSInput input, bool isFrontFace)
+    {
+        if (!UseDoubleSidedFeature()) {
+            return input.texcoord;
+        }
+
+        return lerp(input.texcoord, input.backTexcoord, isFrontFace ? 0.0f : 1.0f);
+    }
+
+    PSInput MainVS(VSInput input)
+    {
+        PSInput output;
+        const float4 positionWS = mul(gModelMatrix, float4(input.position, 1.0f));
+        const float4 positionVS = mul(gViewMatrix, positionWS);
+        output.position = mul(gProjectionMatrix, positionVS);
+        output.texcoord = input.texcoord;
+        output.backTexcoord = input.backTexcoord;
+        output.positionWS = positionWS.xyz;
+        output.positionVS = positionVS.xyz;
+        output.normalWS = normalize(mul((float3x3)gNormalMatrix, input.normal));
+        output.tangentWS = normalize(mul((float3x3)gNormalMatrix, input.tangent));
+        output.bitangentWS = normalize(mul((float3x3)gNormalMatrix, input.bitangent));
+        output.color = input.color;
+        return output;
+    }
+
+    float ComputeShadowAttenuation(float3 positionWS, float3 normalWS, float3 lightDirectionWS)
+    {
+    #ifndef XC_MAIN_LIGHT_SHADOWS
+        return 1.0f;
+    #else
+        if (gShadowOptions.x < 0.5f) {
+            return 1.0f;
+        }
+
+        const float3 resolvedNormalWS = NormalizeSafe(normalWS, float3(0.0f, 1.0f, 0.0f));
+        const float3 resolvedLightDirectionWS =
+            NormalizeSafe(lightDirectionWS, float3(0.0f, -1.0f, 0.0f));
+        const float nDotL = saturate(dot(resolvedNormalWS, resolvedLightDirectionWS));
+        const float normalBiasWorld = gShadowOptions.y * gShadowOptions.z * (1.0f - nDotL);
+        const float3 shadowPositionWS = positionWS + resolvedNormalWS * normalBiasWorld;
+        const float4 shadowClip = mul(gWorldToShadowMatrix, float4(shadowPositionWS, 1.0f));
+        if (shadowClip.w <= 0.0f) {
+            return 1.0f;
+        }
+
+        const float3 shadowNdc = shadowClip.xyz / shadowClip.w;
+    #if UNITY_UV_STARTS_AT_TOP
+        const float shadowUvY = shadowNdc.y * -0.5f + 0.5f;
+    #else
+        const float shadowUvY = shadowNdc.y * 0.5f + 0.5f;
+    #endif
+        const float2 shadowUv = float2(shadowNdc.x * 0.5f + 0.5f, shadowUvY);
+    #if UNITY_NEAR_CLIP_VALUE < 0
+        if (shadowUv.x < 0.0f || shadowUv.x > 1.0f ||
+            shadowUv.y < 0.0f || shadowUv.y > 1.0f ||
+            shadowNdc.z < -1.0f || shadowNdc.z > 1.0f) {
+            return 1.0f;
+        }
+
+        const float receiverDepth = shadowNdc.z * 0.5f + 0.5f - gShadowBiasAndTexelSize.x;
+    #else
+        if (shadowUv.x < 0.0f || shadowUv.x > 1.0f ||
+            shadowUv.y < 0.0f || shadowUv.y > 1.0f ||
+            shadowNdc.z < 0.0f || shadowNdc.z > 1.0f) {
+            return 1.0f;
+        }
+
+        const float receiverDepth = shadowNdc.z - gShadowBiasAndTexelSize.x;
+    #endif
+        const float2 shadowTexelSize = gShadowBiasAndTexelSize.yz;
+        float visibility = 0.0f;
+        [unroll]
+        for (int offsetY = -1; offsetY <= 1; ++offsetY) {
+            [unroll]
+            for (int offsetX = -1; offsetX <= 1; ++offsetX) {
+                const float2 sampleUv =
+                    shadowUv + float2((float)offsetX, (float)offsetY) * shadowTexelSize;
+                if (sampleUv.x < 0.0f || sampleUv.x > 1.0f ||
+                    sampleUv.y < 0.0f || sampleUv.y > 1.0f) {
+                    visibility += 1.0f;
+                    continue;
+                }
+
+                const float shadowDepth = ShadowMapTexture.Sample(ShadowMapSampler, sampleUv).r;
+                visibility += receiverDepth <= shadowDepth ? 1.0f : 0.0f;
+            }
+        }
+
+        visibility *= (1.0f / 9.0f);
+        const float shadowStrength = saturate(gShadowBiasAndTexelSize.w);
+        return lerp(1.0f - shadowStrength, 1.0f, visibility);
+    #endif
+    }
+
+    float ComputeRangeAttenuation(float distanceSq, float range)
+    {
+        if (range <= 0.0f) {
+            return 0.0f;
+        }
+
+        const float clampedRange = max(range, 0.0001f);
+        const float rangeSq = clampedRange * clampedRange;
+        if (distanceSq >= rangeSq) {
+            return 0.0f;
+        }
+
+        const float distance = sqrt(max(distanceSq, 0.0f));
+        const float normalized = saturate(1.0f - distance / clampedRange);
+        return normalized * normalized;
+    }
+
+    float ComputeSpotAttenuation(AdditionalLightData light, float3 directionToLightWS)
+    {
+        const float cosOuter = light.spotAnglesAndFlags.x;
+        const float cosInner = light.spotAnglesAndFlags.y;
+        const float3 spotAxisToLightWS = NormalizeSafe(light.directionAndType.xyz, float3(0.0f, -1.0f, 0.0f));
+        const float cosTheta = dot(spotAxisToLightWS, directionToLightWS);
+        return saturate((cosTheta - cosOuter) / max(cosInner - cosOuter, 1e-4f));
+    }
+
+    float3 EvaluateAdditionalLight(AdditionalLightData light, float3 normalWS, float3 positionWS)
+    {
+        const float lightType = light.directionAndType.w;
+        const float3 lightColor = light.colorAndIntensity.rgb;
+        const float lightIntensity = light.colorAndIntensity.w;
+
+        float3 directionToLightWS = float3(0.0f, 0.0f, 0.0f);
+        float attenuation = 1.0f;
+
+        if (lightType < 0.5f) {
+            directionToLightWS = NormalizeSafe(light.directionAndType.xyz, float3(0.0f, -1.0f, 0.0f));
+        } else {
+            const float3 lightVectorWS = light.positionAndRange.xyz - positionWS;
+            const float distanceSq = dot(lightVectorWS, lightVectorWS);
+            if (distanceSq <= 1e-6f) {
+                return float3(0.0f, 0.0f, 0.0f);
+            }
+
+            directionToLightWS = lightVectorWS * rsqrt(distanceSq);
+            attenuation = ComputeRangeAttenuation(distanceSq, light.positionAndRange.w);
+            if (attenuation <= 0.0f) {
+                return float3(0.0f, 0.0f, 0.0f);
+            }
+
+            if (lightType > 1.5f) {
+                attenuation *= ComputeSpotAttenuation(light, directionToLightWS);
+                if (attenuation <= 0.0f) {
+                    return float3(0.0f, 0.0f, 0.0f);
+                }
+            }
+        }
+
+        const float diffuse = saturate(dot(normalWS, directionToLightWS));
+        if (diffuse <= 0.0f) {
+            return float3(0.0f, 0.0f, 0.0f);
+        }
+
+        return lightColor * (diffuse * lightIntensity * attenuation);
+    }
+
+    float3 ComputeSurfaceNormalWS(PSInput input, float2 texcoord)
+    {
+        float3 normalWS = NormalizeSafe(input.normalWS, float3(0.0f, 1.0f, 0.0f));
+        if (!UseNormalMapFeature()) {
+            return normalWS;
+        }
+
+        const float3 tangentWS = NormalizeSafe(input.tangentWS, float3(1.0f, 0.0f, 0.0f));
+        const float3 bitangentWS = NormalizeSafe(input.bitangentWS, float3(0.0f, 0.0f, 1.0f));
+        const float3 normalTS = _NormalMap.Sample(LinearClampSampler, texcoord).xyz * 2.0f - 1.0f;
+        const float3 mappedNormalWS =
+            tangentWS * normalTS.x +
+            bitangentWS * normalTS.y +
+            normalWS * normalTS.z;
+        return NormalizeSafe(mappedNormalWS, normalWS);
+    }
+
+    float3 GetAdjustedMainLightDirection()
+    {
+        const float3 scaledDirection =
+            gMainLightDirectionAndIntensity.xyz * _LightDirectionMultiplier.xyz;
+        return NormalizeSafe(
+            scaledDirection,
+            NormalizeSafe(gMainLightDirectionAndIntensity.xyz, float3(0.0f, -1.0f, 0.0f)));
+    }
+
+    float ResolveMaterialSelector(float lightMapAlpha)
+    {
+        const float useCustomMaterialType = _UseCustomMaterialType.x > 0.5f ? 1.0f : 0.0f;
+        return lerp(lightMapAlpha, _CustomMaterialType.x, useCustomMaterialType);
+    }
+
+    float GetGenericShadow(float3 normalWS, float3 lightDirectionWS, float aoFactor)
+    {
+        const float ndotl = dot(normalWS, lightDirectionWS);
+        const float halfLambert = ndotl * 0.5f + 0.5f;
+        const float shadow = saturate(2.0f * halfLambert * aoFactor);
+        return lerp(shadow, 1.0f, step(0.9f, aoFactor));
+    }
+
+    float GetFaceShadow(PSInput input, float2 texcoord, float3 lightDirectionWS)
+    {
+        const float3 faceDirection = NormalizeSafe(
+            float3(_FaceDirection.x, 0.0f, _FaceDirection.z),
+            float3(0.0f, 0.0f, 1.0f));
+        const float3 flatLightDirection = NormalizeSafe(
+            float3(lightDirectionWS.x, 0.0f, lightDirectionWS.z),
+            float3(0.0f, 0.0f, 1.0f));
+        const float faceDotLight = dot(faceDirection, flatLightDirection);
+        const float faceCrossLight = cross(faceDirection, flatLightDirection).y;
+
+        float2 shadowUv = texcoord;
+        shadowUv.x = lerp(shadowUv.x, 1.0f - shadowUv.x, step(0.0f, faceCrossLight));
+
+        const float faceShadowMap = _FaceLightMap.Sample(LinearClampSampler, shadowUv).r;
+        const float faceShadow = step(-0.5f * faceDotLight + 0.5f + _FaceShadowOffset.x, faceShadowMap);
+        const float faceMask = _FaceShadow.Sample(LinearClampSampler, texcoord).a;
+        return lerp(faceShadow, 1.0f, faceMask);
+    }
+
+    float3 GetShadowColor(float shadow, float materialSelector)
+    {
+        float rampIndex = 4.0f;
+        rampIndex = lerp(rampIndex, 1.0f, step(0.2f, materialSelector));
+        rampIndex = lerp(rampIndex, 2.0f, step(0.4f, materialSelector));
+        rampIndex = lerp(rampIndex, 0.0f, step(0.6f, materialSelector));
+        rampIndex = lerp(rampIndex, 3.0f, step(0.8f, materialSelector));
+
+        const float rangeMin = 0.5f + _ShadowOffset.x - _ShadowSmoothness.x;
+        const float rangeMax = 0.5f + _ShadowOffset.x;
+        const float2 rampUv = float2(
+            smoothstep(rangeMin, rangeMax, shadow),
+            rampIndex / 10.0f + 0.5f * saturate(_IsDay.x) + 0.05f);
+        const float3 shadowRamp = _ShadowRamp.Sample(LinearClampSampler, rampUv).rgb;
+
+        float3 shadowColor =
+            shadowRamp * lerp(_ShadowColor.rgb, float3(1.0f, 1.0f, 1.0f), smoothstep(0.9f, 1.0f, rampUv.x));
+        shadowColor = lerp(shadowColor, float3(1.0f, 1.0f, 1.0f), step(rangeMax, shadow));
+        return shadowColor;
+    }
+
+    float3 GetSpecular(
+        PSInput input,
+        float3 normalWS,
+        float3 lightDirectionWS,
+        float3 albedo,
+        float3 lightMap)
+    {
+        const float3 viewDirectionVS = NormalizeSafe(-input.positionVS, float3(0.0f, 0.0f, 1.0f));
+        const float3 lightDirectionVS = NormalizeSafe(
+            mul((float3x3)gViewMatrix, lightDirectionWS),
+            float3(0.0f, 0.0f, 1.0f));
+        const float3 normalVS = NormalizeSafe(mul((float3x3)gViewMatrix, normalWS), float3(0.0f, 0.0f, 1.0f));
+        const float3 halfDirectionVS = NormalizeSafe(lightDirectionVS + viewDirectionVS, lightDirectionVS);
+        const float nDotH = dot(normalVS, halfDirectionVS);
+        const float blinnPhong = pow(saturate(nDotH), max(_SpecularSmoothness.x, 1.0f));
+
+        const float2 matcapUv = normalVS.xy * 0.5f + 0.5f;
+        const float3 metalMap = _MetalMap.Sample(LinearClampSampler, matcapUv).rgb;
+
+        const float3 nonMetallic =
+            step(1.1f, lightMap.b + blinnPhong) * lightMap.r * _NonmetallicIntensity.x;
+        const float3 metallic =
+            blinnPhong * lightMap.b * albedo * metalMap * _MetallicIntensity.x;
+        return lerp(nonMetallic, metallic, step(0.9f, lightMap.r));
+    }
+
+    float GetRim(PSInput input, float3 normalWS)
+    {
+        const float3 viewDirectionVS = NormalizeSafe(-input.positionVS, float3(0.0f, 0.0f, 1.0f));
+        const float3 normalVS = NormalizeSafe(mul((float3x3)gViewMatrix, normalWS), float3(0.0f, 0.0f, 1.0f));
+        const float nDotV = dot(normalVS, viewDirectionVS);
+        const float fresnel = pow(saturate(1.0f - nDotV), max(_RimOffset.x, 0.001f));
+        return smoothstep(0.0f, max(_RimThreshold.x, 0.001f), fresnel) * _RimIntensity.x;
+    }
+
+    float4 MainPS(PSInput input, bool isFrontFace : SV_IsFrontFace) : SV_TARGET
+    {
+        const float2 texcoord = ResolveMaterialTexcoord(input, isFrontFace);
+        float4 baseMap = BaseColorTexture.Sample(LinearClampSampler, texcoord);
+        float3 albedo = baseMap.rgb * _BaseColor.rgb;
+        const float alphaMask = baseMap.a;
+
+        if (UseFaceFeature()) {
+            albedo = lerp(albedo, _FaceBlushColor.rgb, _FaceBlushStrength.x * alphaMask);
+        }
+
+        const float3 normalWS = ComputeSurfaceNormalWS(input, texcoord);
+
+        float3 color = albedo;
+        if (gMainLightColorAndFlags.a >= 0.5f) {
+            const float3 lightDirectionWS = GetAdjustedMainLightDirection();
+            const float4 lightMap = _LightMap.Sample(LinearClampSampler, texcoord);
+            const float materialSelector = ResolveMaterialSelector(lightMap.a);
+            float shadow = UseFaceFeature()
+                ? GetFaceShadow(input, texcoord, lightDirectionWS)
+                : GetGenericShadow(normalWS, lightDirectionWS, lightMap.g * input.color.x);
+            shadow *= ComputeShadowAttenuation(input.positionWS, normalWS, lightDirectionWS);
+
+            const float3 shadowColor = GetShadowColor(shadow, materialSelector);
+
+            float3 specular = float3(0.0f, 0.0f, 0.0f);
+            if (UseSpecularFeature()) {
+                specular = GetSpecular(input, normalWS, lightDirectionWS, albedo, lightMap.rgb);
+            }
+
+            float3 emission = float3(0.0f, 0.0f, 0.0f);
+            if (UseEmissionFeature()) {
+                emission = albedo * _EmissionIntensity.x * alphaMask;
+            }
+
+            float3 rim = float3(0.0f, 0.0f, 0.0f);
+            if (UseRimFeature()) {
+                rim = albedo * GetRim(input, normalWS);
+            }
+
+            color = albedo * shadowColor + specular + emission + rim;
+        }
+
+        const int additionalLightCount = min((int)gLightingParams.x, XC_MAX_ADDITIONAL_LIGHTS);
+        [unroll]
+        for (int lightIndex = 0; lightIndex < XC_MAX_ADDITIONAL_LIGHTS; ++lightIndex) {
+            if (lightIndex >= additionalLightCount) {
+                break;
+            }
+
+            color +=
+                albedo *
+                EvaluateAdditionalLight(gAdditionalLights[lightIndex], normalWS, input.positionWS) *
+                0.15f;
+        }
+
+        return float4(saturate(color), 1.0f);
+    }
+    ENDHLSL
+    SubShader
+    {
+        Cull Back
+        ZWrite On
+        ZTest LEqual
+        Pass
+        {
+            Name "ForwardLit"
+            Tags { "LightMode" = "ForwardLit" }
+            HLSLPROGRAM
+            #pragma target 4.5
+            #pragma vertex MainVS
+            #pragma fragment MainPS
+            #pragma multi_compile _ XC_MAIN_LIGHT_SHADOWS
+            #pragma shader_feature_local _ XC_ALPHA_TEST
+            #pragma shader_feature_local _ _EMISSION
+            #pragma shader_feature_local _ _NORMAL_MAP
+            #pragma shader_feature_local _ _IS_FACE
+            #pragma shader_feature_local _ _SPECULAR
+            #pragma shader_feature_local _ _RIM
+            ENDHLSL
+        }
+        UsePass "Builtin Depth Only/DepthOnly"
+        UsePass "Builtin Shadow Caster/ShadowCaster"
+    }
+}

project/Assets/Shaders/XCCharacterToon.shader.meta

@@ -0,0 +1,5 @@
+fileFormatVersion: 1
+guid: 5a51f782e3c149bd8bf65c8b0e25d3a1
+folderAsset: false
+importer: ShaderImporter
+importerVersion: 8

tests/Components/test_mesh_render_components.cpp

@@ -147,6 +147,48 @@ TEST(MeshFilterComponent_Test, SetMeshPathPreservesPathWithoutLoadedResource) {
     EXPECT_EQ(component.GetMesh(), nullptr);
 }
 
+TEST(MeshFilterComponent_Test, SetMeshAssetRefPreservesProjectSubAssetReference) {
+    namespace fs = std::filesystem;
+
+    ResourceManager& manager = ResourceManager::Get();
+    manager.Initialize();
+
+    const fs::path projectRoot = fs::temp_directory_path() / "xc_mesh_filter_asset_ref_test";
+    const fs::path assetsDir = projectRoot / "Assets";
+    const fs::path meshPath = assetsDir / "runtime.mesh";
+
+    fs::remove_all(projectRoot);
+    fs::create_directories(assetsDir);
+    {
+        std::ofstream meshFile(meshPath);
+        ASSERT_TRUE(meshFile.is_open());
+        meshFile << "placeholder";
+    }
+
+    manager.SetResourceRoot(projectRoot.string().c_str());
+
+    AssetRef meshRef;
+    ASSERT_TRUE(manager.TryGetAssetRef("Assets/runtime.mesh", ResourceType::Mesh, meshRef));
+
+    MeshFilterComponent component;
+    component.SetMeshAssetRef(meshRef);
+
+    EXPECT_TRUE(component.GetMeshAssetRef().IsValid());
+    EXPECT_EQ(component.GetMeshAssetRef().assetGuid, meshRef.assetGuid);
+    EXPECT_EQ(component.GetMeshAssetRef().localID, meshRef.localID);
+    EXPECT_EQ(component.GetMeshAssetRef().resourceType, meshRef.resourceType);
+    EXPECT_EQ(component.GetMeshPath(), "Assets/runtime.mesh");
+
+    std::stringstream stream;
+    component.Serialize(stream);
+    EXPECT_NE(stream.str().find("meshRef="), std::string::npos);
+    EXPECT_EQ(stream.str().find("meshRef=;"), std::string::npos);
+
+    manager.SetResourceRoot("");
+    manager.Shutdown();
+    fs::remove_all(projectRoot);
+}
+
 TEST(MeshFilterComponent_Test, DeferredSceneDeserializeLoadsMeshAsyncByPath) {
     ResourceManager& manager = ResourceManager::Get();
     manager.Initialize();
@@ -276,6 +318,56 @@ TEST(MeshRendererComponent_Test, SetMaterialPathPreservesPathWithoutLoadedResour
     EXPECT_EQ(component.GetMaterial(1), nullptr);
 }
 
+TEST(MeshRendererComponent_Test, SetMaterialAssetRefPreservesProjectSubAssetReference) {
+    namespace fs = std::filesystem;
+
+    ResourceManager& manager = ResourceManager::Get();
+    manager.Initialize();
+
+    const fs::path projectRoot = fs::temp_directory_path() / "xc_mesh_renderer_sub_asset_ref_test";
+    const fs::path assetsDir = projectRoot / "Assets";
+    const fs::path materialPath = assetsDir / "runtime.material";
+
+    fs::remove_all(projectRoot);
+    fs::create_directories(assetsDir);
+
+    {
+        std::ofstream materialFile(materialPath);
+        ASSERT_TRUE(materialFile.is_open());
+        materialFile << "{\n";
+        materialFile << "  \"renderQueue\": \"geometry\",\n";
+        materialFile << "  \"renderState\": {\n";
+        materialFile << "    \"cull\": \"back\"\n";
+        materialFile << "  }\n";
+        materialFile << "}";
+    }
+
+    manager.SetResourceRoot(projectRoot.string().c_str());
+
+    AssetRef materialRef;
+    ASSERT_TRUE(manager.TryGetAssetRef("Assets/runtime.material", ResourceType::Material, materialRef));
+
+    MeshRendererComponent component;
+    component.SetMaterialAssetRef(0, materialRef);
+
+    ASSERT_EQ(component.GetMaterialCount(), 1u);
+    EXPECT_TRUE(component.GetMaterialAssetRefs()[0].IsValid());
+    EXPECT_EQ(component.GetMaterialAssetRefs()[0].assetGuid, materialRef.assetGuid);
+    EXPECT_EQ(component.GetMaterialAssetRefs()[0].localID, materialRef.localID);
+    EXPECT_EQ(component.GetMaterialAssetRefs()[0].resourceType, materialRef.resourceType);
+    EXPECT_EQ(component.GetMaterialPath(0), "Assets/runtime.material");
+    ASSERT_NE(component.GetMaterial(0), nullptr);
+
+    std::stringstream stream;
+    component.Serialize(stream);
+    EXPECT_NE(stream.str().find("materialRefs="), std::string::npos);
+    EXPECT_EQ(stream.str().find("materialRefs=;"), std::string::npos);
+
+    manager.SetResourceRoot("");
+    manager.Shutdown();
+    fs::remove_all(projectRoot);
+}
+
 TEST(MeshRendererComponent_Test, DeserializeIgnoresPlainMaterialPathsWithoutAssetRefs) {
     MeshRendererComponent target;
 

tests/Rendering/CMakeLists.txt

@@ -26,6 +26,7 @@ add_custom_target(rendering_integration_tests
         rendering_integration_offscreen_scene
         rendering_integration_skybox_scene
         rendering_integration_post_process_scene
+        rendering_integration_nahida_preview_scene
 )
 
 add_custom_target(rendering_all_tests

tests/Rendering/integration/CMakeLists.txt

@@ -25,3 +25,4 @@ add_subdirectory(volume_scene)
 add_subdirectory(volume_occlusion_scene)
 add_subdirectory(volume_transform_scene)
 add_subdirectory(gaussian_splat_scene)
+add_subdirectory(nahida_preview_scene)

tests/Rendering/integration/nahida_preview_scene/CMakeLists.txt

@@ -0,0 +1,71 @@
+cmake_minimum_required(VERSION 3.15)
+
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+project(rendering_integration_nahida_preview_scene)
+
+set(ENGINE_ROOT_DIR ${CMAKE_SOURCE_DIR}/engine)
+set(PACKAGE_DIR ${CMAKE_SOURCE_DIR}/mvs/OpenGL/package)
+
+get_filename_component(PROJECT_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../../.. ABSOLUTE)
+
+find_package(Vulkan QUIET)
+
+add_executable(rendering_integration_nahida_preview_scene
+    main.cpp
+    ${CMAKE_SOURCE_DIR}/tests/RHI/integration/fixtures/RHIIntegrationFixture.cpp
+    ${PACKAGE_DIR}/src/glad.c
+)
+
+target_include_directories(rendering_integration_nahida_preview_scene PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_SOURCE_DIR}/tests/RHI/integration/fixtures
+    ${ENGINE_ROOT_DIR}/include
+    ${PACKAGE_DIR}/include
+    ${PROJECT_ROOT_DIR}/engine/src
+)
+
+target_link_libraries(rendering_integration_nahida_preview_scene PRIVATE
+    d3d12
+    dxgi
+    d3dcompiler
+    winmm
+    opengl32
+    XCEngine
+    GTest::gtest
+)
+
+if(TARGET Vulkan::Vulkan)
+    target_link_libraries(rendering_integration_nahida_preview_scene PRIVATE Vulkan::Vulkan)
+    target_compile_definitions(rendering_integration_nahida_preview_scene PRIVATE XCENGINE_SUPPORT_VULKAN)
+endif()
+
+target_compile_definitions(rendering_integration_nahida_preview_scene PRIVATE
+    UNICODE
+    _UNICODE
+    XCENGINE_SUPPORT_OPENGL
+    XCENGINE_SUPPORT_D3D12
+)
+
+add_custom_command(TARGET rendering_integration_nahida_preview_scene POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+        ${CMAKE_SOURCE_DIR}/tests/RHI/integration/compare_ppm.py
+        $<TARGET_FILE_DIR:rendering_integration_nahida_preview_scene>/
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+        ${ENGINE_ROOT_DIR}/third_party/renderdoc/renderdoc.dll
+        $<TARGET_FILE_DIR:rendering_integration_nahida_preview_scene>/
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+        ${ENGINE_ROOT_DIR}/third_party/assimp/bin/assimp-vc143-mt.dll
+        $<TARGET_FILE_DIR:rendering_integration_nahida_preview_scene>/
+)
+
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/GT.ppm)
+    add_custom_command(TARGET rendering_integration_nahida_preview_scene POST_BUILD
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different
+            ${CMAKE_CURRENT_SOURCE_DIR}/GT.ppm
+            $<TARGET_FILE_DIR:rendering_integration_nahida_preview_scene>/GT.ppm
+    )
+endif()
+
+include(GoogleTest)
+gtest_discover_tests(rendering_integration_nahida_preview_scene)

tests/Rendering/integration/nahida_preview_scene/main.cpp

@@ -185,7 +185,7 @@ void DumpMeshDiagnostics(const char* label, const Mesh* mesh) {
 
     const StaticMeshVertex& firstVertex = vertices[0];
     std::printf(
-        "[NahidaDiag] %s firstVertex pos=(%.4f, %.4f, %.4f) normal=(%.4f, %.4f, %.4f) tangent=(%.4f, %.4f, %.4f) bitangent=(%.4f, %.4f, %.4f) uv=(%.4f, %.4f)\n",
+        "[NahidaDiag] %s firstVertex pos=(%.4f, %.4f, %.4f) normal=(%.4f, %.4f, %.4f) tangent=(%.4f, %.4f, %.4f) bitangent=(%.4f, %.4f, %.4f) uv0=(%.4f, %.4f) uv1=(%.4f, %.4f) color=(%.4f, %.4f, %.4f, %.4f)\n",
         label,
         firstVertex.position.x,
         firstVertex.position.y,
@@ -200,7 +200,13 @@ void DumpMeshDiagnostics(const char* label, const Mesh* mesh) {
         firstVertex.bitangent.y,
         firstVertex.bitangent.z,
         firstVertex.uv0.x,
-        firstVertex.uv0.y);
+        firstVertex.uv0.y,
+        firstVertex.uv1.x,
+        firstVertex.uv1.y,
+        firstVertex.color.x,
+        firstVertex.color.y,
+        firstVertex.color.z,
+        firstVertex.color.w);
     std::printf(
         "[NahidaDiag] %s uvRange min=(%.4f, %.4f) max=(%.4f, %.4f)\n",
         label,
@@ -356,6 +362,16 @@ void NahidaPreviewSceneTest::SetUp() {
     ASSERT_NE(m_scene->Find("Face"), nullptr);
 
     PreloadSceneResources();
+
+    auto* bodyMeshObject = m_scene->Find("Body_Mesh0");
+    ASSERT_NE(bodyMeshObject, nullptr);
+    auto* bodyMeshFilter = bodyMeshObject->GetComponent<MeshFilterComponent>();
+    ASSERT_NE(bodyMeshFilter, nullptr);
+    Mesh* bodyMesh = bodyMeshFilter->GetMesh();
+    ASSERT_NE(bodyMesh, nullptr);
+    EXPECT_TRUE(HasVertexAttribute(bodyMesh->GetVertexAttributes(), VertexAttribute::Color));
+    EXPECT_TRUE(HasVertexAttribute(bodyMesh->GetVertexAttributes(), VertexAttribute::UV1));
+
     ApplyIsolationFilter();
     ApplyDiagnosticOverrides();
     DumpTargetDiagnostics();

tests/Rendering/unit/test_builtin_forward_pipeline.cpp

@@ -135,7 +135,7 @@ private:
 TEST(BuiltinForwardPipeline_Test, UsesFloat3PositionInputLayoutForStaticMeshVertices) {
     const InputLayoutDesc inputLayout = BuiltinForwardPipeline::BuildInputLayout();
 
-    ASSERT_EQ(inputLayout.elements.size(), 5u);
+    ASSERT_EQ(inputLayout.elements.size(), 7u);
 
     const InputElementDesc& position = inputLayout.elements[0];
     EXPECT_EQ(position.semanticName, "POSITION");
@@ -158,19 +158,33 @@ TEST(BuiltinForwardPipeline_Test, UsesFloat3PositionInputLayoutForStaticMeshVert
     EXPECT_EQ(texcoord.inputSlot, 0u);
     EXPECT_EQ(texcoord.alignedByteOffset, static_cast<uint32_t>(offsetof(StaticMeshVertex, uv0)));
 
-    const InputElementDesc& tangent = inputLayout.elements[3];
+    const InputElementDesc& backTexcoord = inputLayout.elements[3];
+    EXPECT_EQ(backTexcoord.semanticName, "TEXCOORD");
+    EXPECT_EQ(backTexcoord.semanticIndex, 1u);
+    EXPECT_EQ(backTexcoord.format, static_cast<uint32_t>(Format::R32G32_Float));
+    EXPECT_EQ(backTexcoord.inputSlot, 0u);
+    EXPECT_EQ(backTexcoord.alignedByteOffset, static_cast<uint32_t>(offsetof(StaticMeshVertex, uv1)));
+
+    const InputElementDesc& tangent = inputLayout.elements[4];
     EXPECT_EQ(tangent.semanticName, "TEXCOORD");
-    EXPECT_EQ(tangent.semanticIndex, 1u);
+    EXPECT_EQ(tangent.semanticIndex, 2u);
     EXPECT_EQ(tangent.format, static_cast<uint32_t>(Format::R32G32B32_Float));
     EXPECT_EQ(tangent.inputSlot, 0u);
     EXPECT_EQ(tangent.alignedByteOffset, static_cast<uint32_t>(offsetof(StaticMeshVertex, tangent)));
 
-    const InputElementDesc& bitangent = inputLayout.elements[4];
+    const InputElementDesc& bitangent = inputLayout.elements[5];
     EXPECT_EQ(bitangent.semanticName, "TEXCOORD");
-    EXPECT_EQ(bitangent.semanticIndex, 2u);
+    EXPECT_EQ(bitangent.semanticIndex, 3u);
     EXPECT_EQ(bitangent.format, static_cast<uint32_t>(Format::R32G32B32_Float));
     EXPECT_EQ(bitangent.inputSlot, 0u);
     EXPECT_EQ(bitangent.alignedByteOffset, static_cast<uint32_t>(offsetof(StaticMeshVertex, bitangent)));
+
+    const InputElementDesc& color = inputLayout.elements[6];
+    EXPECT_EQ(color.semanticName, "COLOR");
+    EXPECT_EQ(color.semanticIndex, 0u);
+    EXPECT_EQ(color.format, static_cast<uint32_t>(Format::R32G32B32A32_Float));
+    EXPECT_EQ(color.inputSlot, 0u);
+    EXPECT_EQ(color.alignedByteOffset, static_cast<uint32_t>(offsetof(StaticMeshVertex, color)));
 }
 
 TEST(RenderSurfacePipelineUtils_Test, ResolvesContiguousSurfaceAttachmentFormatsIntoPipelineDesc) {

tests/Resources/Mesh/test_mesh_loader.cpp

@@ -1,5 +1,6 @@
 #include <gtest/gtest.h>
 #include <XCEngine/Core/Asset/AssetDatabase.h>
+#include <XCEngine/Core/Asset/ArtifactContainer.h>
 #include <XCEngine/Core/Asset/ResourceManager.h>
 #include <XCEngine/Resources/BuiltinResources.h>
 #include <XCEngine/Resources/Material/MaterialLoader.h>
@@ -304,13 +305,19 @@ TEST(MeshLoader, ProjectBackpackSampleArtifactRetainsSectionMaterialTextures) {
     AssetDatabase::ResolvedAsset resolvedAsset;
     ASSERT_TRUE(database.EnsureArtifact("Assets/Models/backpack/backpack.obj", ResourceType::Model, resolvedAsset));
     ASSERT_TRUE(resolvedAsset.artifactReady);
-    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).filename().string(), "main.xcmodel");
+    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).extension().string(), ".xcmodel");
 
-    const fs::path meshArtifactPath = fs::path(resolvedAsset.artifactDirectory.CStr()) / "mesh_0.xcmesh";
-    ASSERT_TRUE(fs::exists(meshArtifactPath));
+    const String meshArtifactPath =
+        BuildArtifactContainerEntryPath(resolvedAsset.artifactMainPath, "mesh_0.xcmesh");
+    XCEngine::Containers::Array<XCEngine::Core::uint8> payload;
+    ASSERT_TRUE(ReadArtifactContainerEntryPayload(
+        resolvedAsset.artifactMainPath,
+        "mesh_0.xcmesh",
+        ResourceType::Mesh,
+        payload));
 
     MeshLoader loader;
-    const LoadResult result = loader.Load(meshArtifactPath.string().c_str());
+    const LoadResult result = loader.Load(meshArtifactPath);
     ASSERT_TRUE(result);
     ASSERT_NE(result.resource, nullptr);
 
@@ -331,6 +338,60 @@ TEST(MeshLoader, ProjectBackpackSampleArtifactRetainsSectionMaterialTextures) {
     manager.Shutdown();
 }
 
+TEST(MeshLoader, ProjectNahidaSampleMarksFallbackUv1WhenSecondaryChannelIsAbsent) {
+    namespace fs = std::filesystem;
+
+    const fs::path repositoryRoot = GetRepositoryRoot();
+    const fs::path projectRoot = repositoryRoot / "project";
+    const fs::path nahidaModelPath =
+        projectRoot / "Assets" / "Characters" / "Nahida" / "Model" / "Avatar_Loli_Catalyst_Nahida.fbx";
+    const fs::path assimpDllPath = repositoryRoot / "engine" / "third_party" / "assimp" / "bin" / "assimp-vc143-mt.dll";
+
+    if (!fs::exists(nahidaModelPath)) {
+        GTEST_SKIP() << "Nahida sample model is not available in the local project fixture.";
+    }
+
+    ASSERT_TRUE(fs::exists(assimpDllPath));
+
+#ifdef _WIN32
+    struct DllGuard {
+        HMODULE module = nullptr;
+        ~DllGuard() {
+            if (module != nullptr) {
+                FreeLibrary(module);
+            }
+        }
+    } dllGuard;
+    dllGuard.module = LoadLibraryW(assimpDllPath.wstring().c_str());
+    ASSERT_NE(dllGuard.module, nullptr);
+#endif
+
+    ResourceManager& manager = ResourceManager::Get();
+    manager.Initialize();
+    manager.SetResourceRoot(projectRoot.string().c_str());
+
+    MeshLoader loader;
+    const LoadResult result = loader.Load(nahidaModelPath.string().c_str());
+    ASSERT_TRUE(result);
+    ASSERT_NE(result.resource, nullptr);
+
+    auto* mesh = static_cast<Mesh*>(result.resource);
+    ASSERT_NE(mesh, nullptr);
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV0));
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV1));
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Color));
+
+    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
+    ASSERT_NE(vertices, nullptr);
+    ASSERT_GT(mesh->GetVertexCount(), 0u);
+    EXPECT_FLOAT_EQ(vertices[0].uv0.x, vertices[0].uv1.x);
+    EXPECT_FLOAT_EQ(vertices[0].uv0.y, vertices[0].uv1.y);
+
+    delete mesh;
+    manager.SetResourceRoot("");
+    manager.Shutdown();
+}
+
 TEST(MeshLoader, AssetDatabaseCreatesModelArtifactAndReusesItWithoutReimport) {
     namespace fs = std::filesystem;
     using namespace std::chrono_literals;
@@ -378,22 +439,35 @@ TEST(MeshLoader, AssetDatabaseCreatesModelArtifactAndReusesItWithoutReimport) {
     ASSERT_TRUE(database.EnsureArtifact("Assets/textured_triangle.obj", ResourceType::Model, firstResolve));
     ASSERT_TRUE(firstResolve.exists);
     ASSERT_TRUE(firstResolve.artifactReady);
-    EXPECT_EQ(fs::path(firstResolve.artifactMainPath.CStr()).filename().string(), "main.xcmodel");
+    EXPECT_EQ(fs::path(firstResolve.artifactMainPath.CStr()).extension().string(), ".xcmodel");
     EXPECT_TRUE(fs::exists(projectRoot / "Assets" / "textured_triangle.obj.meta"));
-    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "SourceAssetDB" / "assets.db"));
-    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "ArtifactDB" / "artifacts.db"));
+    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "assets.db"));
+    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "artifacts.db"));
     EXPECT_TRUE(fs::exists(firstResolve.artifactMainPath.CStr()));
-    EXPECT_TRUE(fs::exists(fs::path(firstResolve.artifactDirectory.CStr()) / "mesh_0.xcmesh"));
-    EXPECT_TRUE(fs::exists(
-        fs::path(firstResolve.artifactDirectory.CStr()) /
-        ("material_" + std::to_string(sourceMaterialIndex) + ".xcmat")));
-    EXPECT_TRUE(fs::exists((fs::path(firstResolve.artifactDirectory.CStr()) / "texture_0.xctex")));
+    const String meshArtifactPath =
+        BuildArtifactContainerEntryPath(firstResolve.artifactMainPath, "mesh_0.xcmesh");
+    const String materialArtifactPath = BuildArtifactContainerEntryPath(
+        firstResolve.artifactMainPath,
+        String(("material_" + std::to_string(sourceMaterialIndex) + ".xcmat").c_str()));
+    XCEngine::Containers::Array<XCEngine::Core::uint8> artifactPayload;
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        firstResolve.artifactMainPath,
+        "mesh_0.xcmesh",
+        ResourceType::Mesh,
+        artifactPayload));
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        firstResolve.artifactMainPath,
+        String(("material_" + std::to_string(sourceMaterialIndex) + ".xcmat").c_str()),
+        ResourceType::Material,
+        artifactPayload));
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        firstResolve.artifactMainPath,
+        "texture_0.xctex",
+        ResourceType::Texture,
+        artifactPayload));
 
     MaterialLoader materialLoader;
-    LoadResult materialArtifactResult =
-        materialLoader.Load(
-            (fs::path(firstResolve.artifactDirectory.CStr()) /
-             ("material_" + std::to_string(sourceMaterialIndex) + ".xcmat")).string().c_str());
+    LoadResult materialArtifactResult = materialLoader.Load(materialArtifactPath);
     ASSERT_TRUE(materialArtifactResult);
     ASSERT_NE(materialArtifactResult.resource, nullptr);
     auto* artifactMaterial = static_cast<Material*>(materialArtifactResult.resource);
@@ -414,8 +488,7 @@ TEST(MeshLoader, AssetDatabaseCreatesModelArtifactAndReusesItWithoutReimport) {
     delete artifactMaterial;
 
     MeshLoader meshLoader;
-    LoadResult meshArtifactResult =
-        meshLoader.Load((fs::path(firstResolve.artifactDirectory.CStr()) / "mesh_0.xcmesh").string().c_str());
+    LoadResult meshArtifactResult = meshLoader.Load(meshArtifactPath);
     ASSERT_TRUE(meshArtifactResult);
     ASSERT_NE(meshArtifactResult.resource, nullptr);
     auto* artifactMesh = static_cast<Mesh*>(meshArtifactResult.resource);
@@ -566,7 +639,13 @@ TEST(MeshLoader, ResourceManagerLoadsImportedMeshSubAssetByAssetRefFromProjectAs
         ASSERT_TRUE(meshAssetRef.IsValid());
 
         ASSERT_TRUE(manager.TryResolveAssetPath(meshAssetRef, resolvedMeshPath));
-        EXPECT_EQ(fs::path(resolvedMeshPath.CStr()).filename().string(), "mesh_0.xcmesh");
+        String resolvedContainerPath;
+        String resolvedEntryName;
+        ASSERT_TRUE(TryParseArtifactContainerEntryPath(
+            resolvedMeshPath,
+            resolvedContainerPath,
+            resolvedEntryName));
+        EXPECT_EQ(resolvedEntryName, "mesh_0.xcmesh");
     }
 
     manager.UnloadAll();

tests/Resources/Model/CMakeLists.txt

@@ -6,6 +6,7 @@ set(MODEL_TEST_SOURCES
     test_model.cpp
     test_model_loader.cpp
     test_model_import_pipeline.cpp
+    test_model_scene_instantiation.cpp
 )
 
 add_executable(model_tests ${MODEL_TEST_SOURCES})

tests/Resources/Model/test_model_import_pipeline.cpp

@@ -1,6 +1,7 @@
 #include <gtest/gtest.h>
 
 #include <XCEngine/Core/Asset/AssetDatabase.h>
+#include <XCEngine/Core/Asset/ArtifactContainer.h>
 #include <XCEngine/Core/Asset/ResourceManager.h>
 #include <XCEngine/Resources/Mesh/Mesh.h>
 #include <XCEngine/Resources/Mesh/MeshLoader.h>
@@ -85,11 +86,24 @@ TEST(ModelImportPipeline, AssetDatabaseImportsObjAsModelArtifact) {
     AssetDatabase::ResolvedAsset resolvedAsset;
     ASSERT_TRUE(database.EnsureArtifact("Assets/textured_triangle.obj", ResourceType::Model, resolvedAsset));
     ASSERT_TRUE(resolvedAsset.artifactReady);
-    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).filename().string(), "main.xcmodel");
+    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).extension().string(), ".xcmodel");
     EXPECT_TRUE(fs::exists(resolvedAsset.artifactMainPath.CStr()));
-    EXPECT_TRUE(fs::exists(fs::path(resolvedAsset.artifactDirectory.CStr()) / "mesh_0.xcmesh"));
-    EXPECT_TRUE(fs::exists(fs::path(resolvedAsset.artifactDirectory.CStr()) / "material_0.xcmat"));
-    EXPECT_TRUE(fs::exists(fs::path(resolvedAsset.artifactDirectory.CStr()) / "texture_0.xctex"));
+    XCEngine::Containers::Array<XCEngine::Core::uint8> payload;
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        resolvedAsset.artifactMainPath,
+        "mesh_0.xcmesh",
+        ResourceType::Mesh,
+        payload));
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        resolvedAsset.artifactMainPath,
+        "material_0.xcmat",
+        ResourceType::Material,
+        payload));
+    EXPECT_TRUE(ReadArtifactContainerEntryPayload(
+        resolvedAsset.artifactMainPath,
+        "texture_0.xctex",
+        ResourceType::Texture,
+        payload));
 
     ModelLoader modelLoader;
     const LoadResult modelResult = modelLoader.Load(resolvedAsset.artifactMainPath);
@@ -109,7 +123,8 @@ TEST(ModelImportPipeline, AssetDatabaseImportsObjAsModelArtifact) {
 
     MeshLoader meshLoader;
     const LoadResult meshResult =
-        meshLoader.Load((fs::path(resolvedAsset.artifactDirectory.CStr()) / "mesh_0.xcmesh").string().c_str());
+        meshLoader.Load(
+            BuildArtifactContainerEntryPath(resolvedAsset.artifactMainPath, "mesh_0.xcmesh"));
     ASSERT_TRUE(meshResult);
     ASSERT_NE(meshResult.resource, nullptr);
 
@@ -182,4 +197,64 @@ TEST(ModelImportPipeline, ResourceManagerLoadsModelFromProjectAsset) {
     fs::remove_all(projectRoot);
 }
 
+TEST(ModelImportPipeline, ProjectNahidaSampleArtifactPreservesFallbackUv1Semantic) {
+    namespace fs = std::filesystem;
+
+    const fs::path repositoryRoot = GetRepositoryRoot();
+    const fs::path projectRoot = repositoryRoot / "project";
+    const fs::path nahidaModelPath =
+        projectRoot / "Assets" / "Characters" / "Nahida" / "Model" / "Avatar_Loli_Catalyst_Nahida.fbx";
+    const fs::path assimpDllPath = repositoryRoot / "engine" / "third_party" / "assimp" / "bin" / "assimp-vc143-mt.dll";
+
+    if (!fs::exists(nahidaModelPath)) {
+        GTEST_SKIP() << "Nahida sample model is not available in the local project fixture.";
+    }
+
+    ASSERT_TRUE(fs::exists(assimpDllPath));
+
+#ifdef _WIN32
+    AssimpDllGuard dllGuard;
+    dllGuard.module = LoadLibraryW(assimpDllPath.wstring().c_str());
+    ASSERT_NE(dllGuard.module, nullptr);
+#endif
+
+    ResourceManager& manager = ResourceManager::Get();
+    manager.Initialize();
+    manager.SetResourceRoot(projectRoot.string().c_str());
+
+    AssetDatabase database;
+    database.Initialize(projectRoot.string().c_str());
+
+    AssetDatabase::ResolvedAsset resolvedAsset;
+    ASSERT_TRUE(database.EnsureArtifact(
+        "Assets/Characters/Nahida/Model/Avatar_Loli_Catalyst_Nahida.fbx",
+        ResourceType::Model,
+        resolvedAsset));
+    ASSERT_TRUE(resolvedAsset.artifactReady);
+    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).extension().string(), ".xcmodel");
+
+    MeshLoader meshLoader;
+    const LoadResult meshResult =
+        meshLoader.Load(BuildArtifactContainerEntryPath(resolvedAsset.artifactMainPath, "mesh_0.xcmesh"));
+    ASSERT_TRUE(meshResult);
+    ASSERT_NE(meshResult.resource, nullptr);
+
+    auto* mesh = static_cast<Mesh*>(meshResult.resource);
+    ASSERT_NE(mesh, nullptr);
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV0));
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV1));
+    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Color));
+
+    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
+    ASSERT_NE(vertices, nullptr);
+    ASSERT_GT(mesh->GetVertexCount(), 0u);
+    EXPECT_FLOAT_EQ(vertices[0].uv0.x, vertices[0].uv1.x);
+    EXPECT_FLOAT_EQ(vertices[0].uv0.y, vertices[0].uv1.y);
+
+    delete mesh;
+    database.Shutdown();
+    manager.SetResourceRoot("");
+    manager.Shutdown();
+}
+
 } // namespace

tests/Resources/Model/test_model_scene_instantiation.cpp

@@ -0,0 +1,173 @@
+#include <gtest/gtest.h>
+
+#include <XCEngine/Components/MeshFilterComponent.h>
+#include <XCEngine/Components/MeshRendererComponent.h>
+#include <XCEngine/Core/Asset/AssetRef.h>
+#include <XCEngine/Core/Asset/ResourceManager.h>
+#include <XCEngine/Resources/Model/Model.h>
+#include <XCEngine/Scene/ModelSceneInstantiation.h>
+#include <XCEngine/Scene/Scene.h>
+
+#include <filesystem>
+#include <fstream>
+
+#ifdef _WIN32
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+#include <windows.h>
+#endif
+
+using namespace XCEngine;
+using namespace XCEngine::Components;
+using namespace XCEngine::Resources;
+
+namespace {
+
+std::filesystem::path GetRepositoryRoot() {
+    return std::filesystem::path(__FILE__).parent_path().parent_path().parent_path().parent_path();
+}
+
+std::string GetMeshFixturePath(const char* fileName) {
+    return (std::filesystem::path(XCENGINE_TEST_FIXTURES_DIR) / "Resources" / "Mesh" / fileName).string();
+}
+
+void CopyTexturedTriangleFixture(const std::filesystem::path& assetsDir) {
+    namespace fs = std::filesystem;
+
+    fs::copy_file(
+        GetMeshFixturePath("textured_triangle.obj"),
+        assetsDir / "textured_triangle.obj",
+        fs::copy_options::overwrite_existing);
+    fs::copy_file(
+        GetMeshFixturePath("textured_triangle.mtl"),
+        assetsDir / "textured_triangle.mtl",
+        fs::copy_options::overwrite_existing);
+    fs::copy_file(
+        GetMeshFixturePath("checker.bmp"),
+        assetsDir / "checker.bmp",
+        fs::copy_options::overwrite_existing);
+}
+
+#ifdef _WIN32
+struct AssimpDllGuard {
+    HMODULE module = nullptr;
+
+    ~AssimpDllGuard() {
+        if (module != nullptr) {
+            FreeLibrary(module);
+        }
+    }
+};
+#endif
+
+TEST(ModelSceneInstantiation, BuildsHierarchyFromManualModelGraph) {
+    Scene scene("Instantiation Scene");
+    Model model;
+    IResource::ConstructParams params = {};
+    params.name = "ManualModel";
+    params.path = "Assets/manual_model.fbx";
+    params.guid = ResourceGUID::Generate(params.path);
+    model.Initialize(params);
+
+    ModelNode rootNode;
+    rootNode.name = "Root";
+    rootNode.parentIndex = -1;
+    rootNode.localPosition = Math::Vector3(1.0f, 2.0f, 3.0f);
+
+    ModelNode childNode;
+    childNode.name = "Child";
+    childNode.parentIndex = 0;
+    childNode.localPosition = Math::Vector3(4.0f, 5.0f, 6.0f);
+    childNode.localScale = Math::Vector3(2.0f, 2.0f, 2.0f);
+
+    model.AddNode(rootNode);
+    model.AddNode(childNode);
+    model.SetRootNodeIndex(0u);
+
+    ModelSceneInstantiationResult result;
+    Containers::String errorMessage;
+    ASSERT_TRUE(InstantiateModelHierarchy(scene, model, AssetRef(), nullptr, &result, &errorMessage))
+        << errorMessage.CStr();
+
+    ASSERT_NE(result.rootObject, nullptr);
+    EXPECT_EQ(result.rootObject->GetName(), "Root");
+    ASSERT_EQ(result.nodeObjects.size(), 2u);
+    ASSERT_NE(result.nodeObjects[1], nullptr);
+    EXPECT_EQ(result.nodeObjects[1]->GetParent(), result.rootObject);
+    EXPECT_EQ(result.rootObject->GetTransform()->GetLocalPosition(), Math::Vector3(1.0f, 2.0f, 3.0f));
+    EXPECT_EQ(result.nodeObjects[1]->GetTransform()->GetLocalPosition(), Math::Vector3(4.0f, 5.0f, 6.0f));
+    EXPECT_EQ(result.nodeObjects[1]->GetTransform()->GetLocalScale(), Math::Vector3(2.0f, 2.0f, 2.0f));
+}
+
+TEST(ModelSceneInstantiation, RestoresMeshAndMaterialSubAssetRefsFromImportedModel) {
+    namespace fs = std::filesystem;
+
+    const fs::path projectRoot = fs::temp_directory_path() / "xc_model_scene_instantiation";
+    const fs::path assetsDir = projectRoot / "Assets";
+    fs::remove_all(projectRoot);
+    fs::create_directories(assetsDir);
+    CopyTexturedTriangleFixture(assetsDir);
+
+#ifdef _WIN32
+    AssimpDllGuard dllGuard;
+    const fs::path assimpDllPath = GetRepositoryRoot() / "engine" / "third_party" / "assimp" / "bin" / "assimp-vc143-mt.dll";
+    ASSERT_TRUE(fs::exists(assimpDllPath));
+    dllGuard.module = LoadLibraryW(assimpDllPath.wstring().c_str());
+    ASSERT_NE(dllGuard.module, nullptr);
+#endif
+
+    ResourceManager& manager = ResourceManager::Get();
+    manager.Initialize();
+    manager.SetResourceRoot(projectRoot.string().c_str());
+
+    const auto modelHandle = manager.Load<Model>("Assets/textured_triangle.obj");
+    ASSERT_TRUE(modelHandle.IsValid());
+
+    AssetRef modelAssetRef;
+    ASSERT_TRUE(manager.TryGetAssetRef("Assets/textured_triangle.obj", ResourceType::Model, modelAssetRef));
+
+    Scene scene("Instantiation Scene");
+    ModelSceneInstantiationResult result;
+    Containers::String errorMessage;
+    ASSERT_TRUE(InstantiateModelHierarchy(scene, *modelHandle, modelAssetRef, nullptr, &result, &errorMessage))
+        << errorMessage.CStr();
+
+    ASSERT_NE(result.rootObject, nullptr);
+    ASSERT_FALSE(result.meshObjects.empty());
+    auto* meshObject = result.meshObjects.front();
+    ASSERT_NE(meshObject, nullptr);
+
+    auto* meshFilter = meshObject->GetComponent<MeshFilterComponent>();
+    auto* meshRenderer = meshObject->GetComponent<MeshRendererComponent>();
+    ASSERT_NE(meshFilter, nullptr);
+    ASSERT_NE(meshRenderer, nullptr);
+    ASSERT_NE(meshFilter->GetMesh(), nullptr);
+    ASSERT_EQ(meshRenderer->GetMaterialCount(), 1u);
+    ASSERT_NE(meshRenderer->GetMaterial(0), nullptr);
+
+    const AssetRef& meshRef = meshFilter->GetMeshAssetRef();
+    EXPECT_TRUE(meshRef.IsValid());
+    EXPECT_EQ(meshRef.assetGuid, modelAssetRef.assetGuid);
+    EXPECT_EQ(meshRef.localID, modelHandle->GetMeshBindings()[0].meshLocalID);
+    EXPECT_EQ(meshRef.resourceType, ResourceType::Mesh);
+
+    ASSERT_EQ(meshRenderer->GetMaterialAssetRefs().size(), 1u);
+    const AssetRef& materialRef = meshRenderer->GetMaterialAssetRefs()[0];
+    EXPECT_TRUE(materialRef.IsValid());
+    EXPECT_EQ(materialRef.assetGuid, modelAssetRef.assetGuid);
+    EXPECT_EQ(materialRef.localID, modelHandle->GetMaterialBindings()[0].materialLocalID);
+    EXPECT_EQ(materialRef.resourceType, ResourceType::Material);
+
+    const std::string serializedScene = scene.SerializeToString();
+    EXPECT_NE(serializedScene.find("meshRef="), std::string::npos);
+    EXPECT_EQ(serializedScene.find("meshRef=;"), std::string::npos);
+    EXPECT_NE(serializedScene.find("materialRefs="), std::string::npos);
+    EXPECT_EQ(serializedScene.find("materialRefs=;"), std::string::npos);
+
+    manager.SetResourceRoot("");
+    manager.Shutdown();
+    fs::remove_all(projectRoot);
+}
+
+} // namespace