Add deferred async scene asset loading

engine/include/XCEngine/Components/MeshRendererComponent.h

@@ -6,6 +6,7 @@
 #include <XCEngine/Resources/Material/Material.h>
 
 #include <cstdint>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -42,12 +43,17 @@ public:
     void Deserialize(std::istream& is) override;
 
 private:
+    struct PendingMaterialLoadState;
+
+    void BeginAsyncMaterialLoad(size_t index, const std::string& materialPath);
+    void ResolvePendingMaterials();
     void EnsureMaterialSlot(size_t index);
     static std::string MaterialPathFromHandle(const Resources::ResourceHandle<Resources::Material>& material);
 
     std::vector<Resources::ResourceHandle<Resources::Material>> m_materials;
     std::vector<std::string> m_materialPaths;
     std::vector<Resources::AssetRef> m_materialRefs;
+    std::vector<std::shared_ptr<PendingMaterialLoadState>> m_pendingMaterialLoads;
     bool m_castShadows = true;
     bool m_receiveShadows = true;
     uint32_t m_renderLayer = 0;