VideoCommon: separate the concept of a 'resource' from an 'asset'. A resource is potentially multiple assets that are chained together but represent one type of data to the rest of the system. An example is a 'material'. A 'material' is a collection of textures, a custom shader, and some metadata that all comes together to form what the concept of the material is. There will be a 'material' resource. For now, start small by introducing the interface and change our texture loading which used assets from the old resource manager, to an actual resource.

Source/Core/VideoCommon/Resources/Resource.h

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+// Copyright 2025 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "VideoCommon/Assets/AssetListener.h"
+#include "VideoCommon/Assets/CustomAssetLibrary.h"
+
+#include <memory>
+#include <unordered_set>
+
+class AbstractTexture;
+namespace VideoCommon
+{
+class CustomAssetCache;
+class CustomResourceManager;
+
+// A resource is an abstract object that maintains
+// relationships between assets (ex: a material that references a texture),
+// as well as a standard way of calculating the final data (ex: a material's AbstractPipeline)
+class Resource : public AssetListener
+{
+public:
+  // Everything the resource needs to manage itself
+  struct ResourceContext
+  {
+    CustomAssetLibrary::AssetID primary_asset_id;
+    std::shared_ptr<CustomAssetLibrary> asset_library;
+    CustomAssetCache* asset_cache;
+    CustomResourceManager* resource_manager;
+  };
+  explicit Resource(ResourceContext resource_context);
+
+  enum class TaskComplete
+  {
+    Yes,
+    No,
+    Error,
+  };
+
+  enum class State
+  {
+    ReloadData,
+    CollectingPrimaryData,
+    CollectingDependencyData,
+    ProcessingData,
+    DataAvailable,
+  };
+
+  TaskComplete IsDataProcessed() const { return m_data_processed; }
+  State GetState() const { return m_state; }
+
+  void AddReference(Resource* reference);
+  void RemoveReference(Resource* reference);
+
+  virtual void MarkAsActive() = 0;
+  virtual void MarkAsPending() = 0;
+
+protected:
+  ResourceContext m_resource_context;
+
+private:
+  void NotifyAssetChanged(bool has_error);
+  void NotifyAssetUnloaded();
+
+  void NotifyAssetLoadSuccess() final;
+  void NotifyAssetLoadFailed() final;
+  void AssetUnloaded() final;
+  virtual void OnUnloadRequested();
+
+  friend class CustomResourceManager;
+  virtual void ResetData();
+  virtual TaskComplete CollectPrimaryData();
+  virtual TaskComplete CollectDependencyData();
+  virtual TaskComplete ProcessData();
+
+  TaskComplete m_data_processed = TaskComplete::No;
+  State m_state = State::ReloadData;
+
+  std::unordered_set<Resource*> m_references;
+};
+}  // namespace VideoCommon