material_cache.hpp

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// This file is part of the Rendering Engine project.
// Author: Alexander Obzherin <alexanderobzherin@gmail.com>
// Copyright (c) 2025 Alexander Obzherin
// Distributed under the terms of the zlib License. See LICENSE.md for details.
 
#pragma once
 
#include "i_renderer_observer.hpp"
#include <string>
#include <unordered_map>
#include <memory>
 
namespace rendering_engine
{
class IRenderer;
class Material;
struct MaterialSettings;
 
/**
 * @class MaterialCache
 * @brief Manages creation, storage, and lifecycle of Material objects within the rendering engine.
 *
 * MaterialCache serves as a centralized system to instantiate, store, and retrieve materials used in the engine.
 * It supports both manually added materials and, in the future, loading materials from JSON definitions.
 * @see Jira EPIC: MAT-101 - Node-Based Material Editor
 *
 * It observes renderer events (such as swapchain recreation) to reinitialize or release GPU resources tied to materials.
 */
class MaterialCache : public IRendererObserver
{
public:
    /**
     * @brief Constructs a MaterialCache and registers it as a renderer observer.
     * @param renderer Pointer to the renderer interface used for creating GPU resources.
     */
    MaterialCache(IRenderer* renderer);
    /**
     * @brief Destructor. Automatically unregisters from the renderer.
     */
    ~MaterialCache();
 
    /**
     * @brief Creates built-in materials for testing or demonstration.
     *
     * This is a temporary function to manually define materials in code.
     * In the future, materials will be created by parsing JSON files from a materials folder.
     */
    void CreateBuildInMaterials();
    
    /**
     * @brief Adds a new Material instance using the provided settings.
     * @param matSettings MaterialSettings struct containing metadata and configuration for the new material.
     *
     * If a material with the same name already exists, it will be replaced.
     */
    void AddMaterial(MaterialSettings matSettings);
 
    /**
     * @brief Retrieves a pointer to a Material instance by name.
     * @param materialName Name of the material to retrieve.
     * @return Pointer to the Material instance, or nullptr if not found.
     */
    Material* GetMaterial(std::string materialName);
 
    /**
     * @brief Removes a material from the cache.
     * @param materialName Name of the material to remove.
     */
    void RemoveMaterial(std::string materialName);
 
    /**
     * @brief Releases all GPU resources associated with cached materials.
     *
     * Iterates through every material in the cache and calls their resource
     * release routines, freeing descriptor set layouts, pipelines, and any other
     * backend allocations. Unlike @ref RemoveMaterial, this does not erase the
     * material records themselves from the cache, only their GPU-side resources.
     *
     * @details
     * - Use when unloading a scene or before destroying the renderer to ensure
     *   all GPU resources are released in a controlled manner.
     * - After calling this, materials remain in the cache but are not renderable
     *   until @ref OnRenderResourcesRebuild (or per-material reinitialization)
     *   is performed.
     * - Safe to call multiple times; redundant calls will have no effect once
     *   resources are released.
     *
     * @see RemoveMaterial()
     * @see OnRenderResourcesRelease()
     * @see OnRenderResourcesRebuild()
     */
    void ReleaseAll();
 
protected:
    /**
     * @copydoc IRendererObserver::OnRenderResourcesRelease
     */
    void OnRenderResourcesRelease() override;
    /**
     * @copydoc IRendererObserver::OnRenderResourcesRebuild
     */
    void OnRenderResourcesRebuild() override;
 
protected:
    IRenderer* mRenderer;
    std::unordered_map<std::string, std::shared_ptr<Material>> mMaterials;
};
 
} // namespace rendering_engine