From 017c02e8d72c994afd1ba63bb5488d585d7a1b51 Mon Sep 17 00:00:00 2001
From: hydrogendeuteride <dumpsterowner@gmail.com>
Date: Thu, 4 Dec 2025 16:19:53 +0900
Subject: [PATCH] ADD: async glTF texture preloading

---
 src/core/engine.cpp    | 33 ++++++++++++++++++++++++++++++++-
 src/core/engine.h      |  4 ++++
 src/core/engine_ui.cpp |  1 +
 src/scene/vk_scene.cpp | 10 ++++++++++
 src/scene/vk_scene.h   |  3 +++
 5 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/core/engine.cpp b/src/core/engine.cpp
index dc10928..e28994f 100644
--- a/src/core/engine.cpp
+++ b/src/core/engine.cpp
@@ -206,7 +206,7 @@ void VulkanEngine::init()
 
     // Async asset loader for background glTF + texture jobs
     _asyncLoader = std::make_unique<AsyncAssetLoader>();
-    _asyncLoader->init(this, _assetManager.get(), _textureCache.get(), 1);
+    _asyncLoader->init(this, _assetManager.get(), _textureCache.get(), 4);
 
     // Optional ray tracing manager if supported and extensions enabled
     if (_deviceManager->supportsRayQuery() && _deviceManager->supportsAccelerationStructure())
@@ -342,6 +342,7 @@ void VulkanEngine::init_default_data()
     }
 
     addGLTFInstance("mirage", "mirage2000/scene.gltf", glm::mat4(1.0f));
+    preloadInstanceTextures("mirage");
 
     _mainDeletionQueue.push_function([&]() {
         _resourceManager->destroy_image(_whiteImage);
@@ -391,6 +392,36 @@ uint32_t VulkanEngine::loadGLTFAsync(const std::string &sceneName,
     return _asyncLoader->load_gltf_async(sceneName, modelRelativePath, transform);
 }
 
+void VulkanEngine::preloadInstanceTextures(const std::string &instanceName)
+{
+    if (!_textureCache || !_sceneManager)
+    {
+        return;
+    }
+
+    auto gltfScene = _sceneManager->getGLTFInstanceScene(instanceName);
+    if (!gltfScene)
+    {
+        return;
+    }
+
+    uint32_t frame = static_cast<uint32_t>(_frameNumber);
+    uint32_t count = 0;
+
+    // Mark all materials in this glTF scene as used so TextureCache will
+    // schedule their textures for upload before the object is visible.
+    for (const auto &[name, material] : gltfScene->materials)
+    {
+        if (material && material->data.materialSet)
+        {
+            _textureCache->markSetUsed(material->data.materialSet, frame);
+            ++count;
+        }
+    }
+
+    fmt::println("[Engine] Preloaded {} material sets for instance '{}'", count, instanceName);
+}
+
 void VulkanEngine::cleanup()
 {
     if (_asyncLoader)
diff --git a/src/core/engine.h b/src/core/engine.h
index fc3078e..ee031a2 100644
--- a/src/core/engine.h
+++ b/src/core/engine.h
@@ -210,6 +210,10 @@ public:
                            const std::string &modelRelativePath,
                            const glm::mat4 &transform = glm::mat4(1.f));
 
+    // Preload textures for an already-loaded scene instance so they are
+    // available before the object becomes visible (visibility-driven loading).
+    void preloadInstanceTextures(const std::string &instanceName);
+
 	bool resize_requested{false};
 	bool freeze_rendering{false};
 
diff --git a/src/core/engine_ui.cpp b/src/core/engine_ui.cpp
index a82b320..10f68c3 100644
--- a/src/core/engine_ui.cpp
+++ b/src/core/engine_ui.cpp
@@ -467,6 +467,7 @@ namespace
             glm::mat4 S = glm::scale(glm::mat4(1.0f), glm::vec3(gltfScale[0], gltfScale[1], gltfScale[2]));
             glm::mat4 M = T * R * S;
             eng->loadGLTFAsync(gltfName, gltfPath, M);
+            eng->preloadInstanceTextures(gltfName);
         }
     }
 
diff --git a/src/scene/vk_scene.cpp b/src/scene/vk_scene.cpp
index 2f70cf3..2fb4019 100644
--- a/src/scene/vk_scene.cpp
+++ b/src/scene/vk_scene.cpp
@@ -518,6 +518,16 @@ bool SceneManager::removeGLTFInstance(const std::string &name)
     return true;
 }
 
+std::shared_ptr<LoadedGLTF> SceneManager::getGLTFInstanceScene(const std::string &instanceName) const
+{
+    auto it = dynamicGLTFInstances.find(instanceName);
+    if (it != dynamicGLTFInstances.end())
+    {
+        return it->second.scene;
+    }
+    return nullptr;
+}
+
 bool SceneManager::getGLTFInstanceTransform(const std::string &name, glm::mat4 &outTransform)
 {
     auto it = dynamicGLTFInstances.find(name);
diff --git a/src/scene/vk_scene.h b/src/scene/vk_scene.h
index 9dc7fda..10a47d0 100644
--- a/src/scene/vk_scene.h
+++ b/src/scene/vk_scene.h
@@ -177,6 +177,9 @@ public:
 
     const PickingDebug &getPickingDebug() const { return pickingDebug; }
 
+    // Returns the LoadedGLTF scene for a named GLTF instance, or nullptr if not found.
+    std::shared_ptr<LoadedGLTF> getGLTFInstanceScene(const std::string &instanceName) const;
+
 private:
     EngineContext *_context = nullptr;