Merge branch 'master' into loek/scripts

27 files changed, 510 insertions, 250 deletions

diff --git a/src/crepe/CMakeLists.txt b/src/crepe/CMakeLists.txt
index da9d492..6cbb9fe 100644
--- a/src/crepe/CMakeLists.txt
+++ b/src/crepe/CMakeLists.txt
@@ -2,6 +2,7 @@ target_sources(crepe PUBLIC
 	Particle.cpp
 	Component.cpp
 	Collider.cpp
+	Resource.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -9,6 +10,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Collider.h
 	ValueBroker.h
 	ValueBroker.hpp
+	Resource.h
 )
 
 add_subdirectory(api)
diff --git a/src/crepe/Component.h b/src/crepe/Component.h
index c30419d..eff5a58 100644
--- a/src/crepe/Component.h
+++ b/src/crepe/Component.h
@@ -16,7 +16,12 @@ class Component {
 public:
 	//! Whether the component is active
 	bool active = true;
-	//! The id of the GameObject this component belongs to
+	/**
+	 * \brief The id of the GameObject this component belongs to
+	 *
+	 * \note Only systems are supposed to use this member, but since friend
+	 * relations aren't inherited this needs to be public.
+	 */
 	const game_object_id_t game_object_id;
 
 protected:
@@ -24,7 +29,7 @@ protected:
 	 * \param id The id of the GameObject this component belongs to
 	 */
 	Component(game_object_id_t id);
-	//! Only the ComponentManager can create components
+	//! Only ComponentManager can create components
 	friend class ComponentManager;
 
 	Component(const Component &) = delete;
diff --git a/src/crepe/Resource.cpp b/src/crepe/Resource.cpp
new file mode 100644
index 0000000..27b4c4b
--- /dev/null
+++ b/src/crepe/Resource.cpp
@@ -0,0 +1,5 @@
+#include "Resource.h"
+
+using namespace crepe;
+
+Resource::Resource(const Asset & asset) {}
diff --git a/src/crepe/Resource.h b/src/crepe/Resource.h
new file mode 100644
index 0000000..eceb15b
--- /dev/null
+++ b/src/crepe/Resource.h
@@ -0,0 +1,29 @@
+#pragma once
+
+namespace crepe {
+
+class ResourceManager;
+class Asset;
+
+/**
+ * \brief Resource interface
+ *
+ * Resource is an interface class used to represent a (deserialized) game resource (e.g.
+ * textures, sounds). Resources are always created from \ref Asset "assets" by ResourceManager.
+ *
+ * The game programmer has the ability to use the ResourceManager to keep instances of concrete
+ * resources between scenes, preventing them from being reinstantiated during a scene
+ * transition.
+ */
+class Resource {
+public:
+	Resource(const Asset & src);
+	virtual ~Resource() = default;
+
+	Resource(const Resource &) = delete;
+	Resource(Resource &&) = delete;
+	Resource & operator=(const Resource &) = delete;
+	Resource & operator=(Resource &&) = delete;
+};
+
+} // namespace crepe
diff --git a/src/crepe/api/AssetManager.cpp b/src/crepe/api/AssetManager.cpp
deleted file mode 100644
index 3925758..0000000
--- a/src/crepe/api/AssetManager.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-#include "util/Log.h"
-
-#include "AssetManager.h"
-
-using namespace crepe;
-
-AssetManager & AssetManager::get_instance() {
-	static AssetManager instance;
-	return instance;
-}
-
-AssetManager::~AssetManager() {
-	dbg_trace();
-	this->asset_cache.clear();
-}
-
-AssetManager::AssetManager() { dbg_trace(); }
diff --git a/src/crepe/api/AssetManager.h b/src/crepe/api/AssetManager.h
deleted file mode 100644
index 3b1cc4b..0000000
--- a/src/crepe/api/AssetManager.h
+++ /dev/null
@@ -1,62 +0,0 @@
-#pragma once
-
-#include <any>
-#include <memory>
-#include <string>
-#include <unordered_map>
-
-namespace crepe {
-
-/**
- * \brief The AssetManager is responsible for storing and managing assets over multiple scenes.
- *
- * The AssetManager ensures that assets are loaded once and can be accessed across different
- * scenes. It caches assets to avoid reloading them every time a scene is loaded. Assets are
- * retained in memory until the AssetManager is destroyed, at which point the cached assets are
- * cleared.
- */
-class AssetManager {
-
-private:
-	//! A cache that holds all the assets, accessible by their file path, over multiple scenes.
-	std::unordered_map<std::string, std::any> asset_cache;
-
-private:
-	AssetManager();
-	virtual ~AssetManager();
-
-public:
-	AssetManager(const AssetManager &) = delete;
-	AssetManager(AssetManager &&) = delete;
-	AssetManager & operator=(const AssetManager &) = delete;
-	AssetManager & operator=(AssetManager &&) = delete;
-
-	/**
-	 * \brief Retrieves the singleton instance of the AssetManager.
-	 *
-	 * \return A reference to the single instance of the AssetManager.
-	 */
-	static AssetManager & get_instance();
-
-public:
-	/**
-	 * \brief Caches an asset by loading it from the given file path.
-	 *
-	 * \param file_path The path to the asset file to load.
-	 * \param reload If true, the asset will be reloaded from the file, even if it is already
-	 * cached.
-	 * \tparam T The type of asset to cache (e.g., texture, sound, etc.).
-	 *
-	 * \return A shared pointer to the cached asset.
-	 *
-	 * This template function caches the asset at the given file path. If the asset is already
-	 * cached and `reload` is false, the existing cached version will be returned. Otherwise, the
-	 * asset will be reloaded and added to the cache.
-	 */
-	template <typename T>
-	std::shared_ptr<T> cache(const std::string & file_path, bool reload = false);
-};
-
-} // namespace crepe
-
-#include "AssetManager.hpp"
diff --git a/src/crepe/api/AssetManager.hpp b/src/crepe/api/AssetManager.hpp
deleted file mode 100644
index 1c0e978..0000000
--- a/src/crepe/api/AssetManager.hpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#pragma once
-
-#include "AssetManager.h"
-
-namespace crepe {
-
-template <typename asset>
-std::shared_ptr<asset> AssetManager::cache(const std::string & file_path, bool reload) {
-	auto it = asset_cache.find(file_path);
-
-	if (!reload && it != asset_cache.end()) {
-		return std::any_cast<std::shared_ptr<asset>>(it->second);
-	}
-
-	std::shared_ptr<asset> new_asset = std::make_shared<asset>(file_path.c_str());
-
-	asset_cache[file_path] = new_asset;
-
-	return new_asset;
-}
-
-} // namespace crepe
diff --git a/src/crepe/api/AudioSource.cpp b/src/crepe/api/AudioSource.cpp
new file mode 100644
index 0000000..7b05cb1
--- /dev/null
+++ b/src/crepe/api/AudioSource.cpp
@@ -0,0 +1,15 @@
+#include "AudioSource.h"
+
+using namespace crepe;
+using namespace std;
+
+AudioSource::AudioSource(game_object_id_t id, const Asset & src)
+	: Component(id),
+	  source(src) {}
+
+void AudioSource::play(bool looping) {
+	this->loop = looping;
+	this->oneshot_play = true;
+}
+
+void AudioSource::stop() { this->oneshot_stop = true; }
diff --git a/src/crepe/api/AudioSource.h b/src/crepe/api/AudioSource.h
new file mode 100644
index 0000000..b20e490
--- /dev/null
+++ b/src/crepe/api/AudioSource.h
@@ -0,0 +1,74 @@
+#pragma once
+
+#include "../Component.h"
+#include "../facade/SoundHandle.h"
+#include "../types.h"
+
+#include "Asset.h"
+#include "GameObject.h"
+
+namespace crepe {
+
+class AudioSystem;
+
+//! Audio source component
+class AudioSource : public Component {
+	//! AudioSource components are handled by AudioSystem
+	friend class AudioSystem;
+
+protected:
+	/**
+	 * \param source Sound sample to load
+	 */
+	AudioSource(game_object_id_t id, const Asset & source);
+	//! Only ComponentManager creates components
+	friend class ComponentManager;
+
+public:
+	// std::unique_ptr needs to be able to destoy this component
+	virtual ~AudioSource() = default;
+
+public:
+	//! Start this audio source
+	void play(bool looping = false);
+	//! Stop this audio source
+	void stop();
+
+public:
+	//! Play when this component becomes active
+	bool play_on_awake = false;
+	//! Repeat the current audio clip during playback
+	bool loop = false;
+	//! Normalized volume (0.0 - 1.0)
+	float volume = 1.0;
+
+private:
+	//! This audio source's clip
+	const Asset source;
+
+	/**
+	 * \name One-shot state variables
+	 *
+	 * These variables trigger function calls when set to true, and are unconditionally reset on
+	 * every system update.
+	 *
+	 * \{
+	 */
+	//! Play this sample
+	bool oneshot_play = false;
+	//! Stop this sample
+	bool oneshot_stop = false;
+	//! \}
+	/**
+	 * \name State diffing variables
+	 * \{
+	 */
+	typeof(active) last_active = false;
+	typeof(volume) last_volume = volume;
+	typeof(loop) last_loop = loop;
+	//! \}
+	//! This source's voice handle
+	SoundHandle voice{};
+};
+
+} // namespace crepe
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index 593c4e6..a163faf 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -1,5 +1,5 @@
 target_sources(crepe PUBLIC
-	# AudioSource.cpp
+	AudioSource.cpp
 	BehaviorScript.cpp
 	GameObject.cpp
 	Rigidbody.cpp
@@ -7,7 +7,6 @@ target_sources(crepe PUBLIC
 	Transform.cpp
 	Color.cpp
 	Texture.cpp
-	AssetManager.cpp
 	Sprite.cpp
 	Config.cpp
 	Metadata.cpp
@@ -27,7 +26,7 @@ target_sources(crepe PUBLIC
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
-	# AudioSource.h
+	AudioSource.h
 	BehaviorScript.h
 	Config.h
 	Script.h
@@ -40,8 +39,6 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Vector2.hpp
 	Color.h
 	Texture.h
-	AssetManager.h
-	AssetManager.hpp
 	Scene.h
 	Metadata.h
 	Camera.h
diff --git a/src/crepe/api/Config.h b/src/crepe/api/Config.h
index a9745c3..6472270 100644
--- a/src/crepe/api/Config.h
+++ b/src/crepe/api/Config.h
@@ -15,20 +15,10 @@ namespace crepe {
  * modified *before* execution is handed over from the game programmer to the engine (i.e. the
  * main loop is started).
  */
-class Config final {
-public:
+struct Config final {
 	//! Retrieve handle to global Config instance
 	static Config & get_instance();
 
-private:
-	Config() = default;
-	~Config() = default;
-	Config(const Config &) = default;
-	Config(Config &&) = default;
-	Config & operator=(const Config &) = default;
-	Config & operator=(Config &&) = default;
-
-public:
 	//! Logging-related settings
 	struct {
 		/**
@@ -86,6 +76,12 @@ public:
 		 */
 		std::string root_pattern = ".crepe-root";
 	} asset;
+
+	//! Audio system settings
+	struct {
+		//! Max amount of simultanious voices
+		unsigned int voices = 32;
+	} audio;
 };
 
 } // namespace crepe
diff --git a/src/crepe/api/LoopManager.cpp b/src/crepe/api/LoopManager.cpp
index 88243c4..3e9e21c 100644
--- a/src/crepe/api/LoopManager.cpp
+++ b/src/crepe/api/LoopManager.cpp
@@ -1,4 +1,5 @@
 #include "../system/AnimatorSystem.h"
+#include "../system/AudioSystem.h"
 #include "../system/CollisionSystem.h"
 #include "../system/InputSystem.h"
 #include "../system/ParticleSystem.h"
@@ -20,6 +21,7 @@ LoopManager::LoopManager() {
 	this->load_system<RenderSystem>();
 	this->load_system<ScriptSystem>();
 	this->load_system<InputSystem>();
+	this->load_system<AudioSystem>();
 }
 
 void LoopManager::process_input() { this->get_system<InputSystem>().update(); }
@@ -37,6 +39,7 @@ void LoopManager::fixed_update() {
 	this->get_system<ScriptSystem>().update();
 	this->get_system<PhysicsSystem>().update();
 	this->get_system<CollisionSystem>().update();
+	this->get_system<AudioSystem>().update();
 }
 
 void LoopManager::loop() {
diff --git a/src/crepe/api/LoopManager.h b/src/crepe/api/LoopManager.h
index d8910a0..0947f94 100644
--- a/src/crepe/api/LoopManager.h
+++ b/src/crepe/api/LoopManager.h
@@ -4,6 +4,7 @@
 
 #include "../facade/SDLContext.h"
 #include "../manager/ComponentManager.h"
+#include "../manager/ResourceManager.h"
 #include "../manager/SceneManager.h"
 #include "../system/System.h"
 
@@ -95,6 +96,8 @@ private:
 	ComponentManager component_manager{mediator};
 	//! Scene manager instance
 	SceneManager scene_manager{mediator};
+	//! Resource manager instance
+	ResourceManager resource_manager{mediator};
 
 	//! SDL context \todo no more singletons!
 	SDLContext & sdl_context = SDLContext::get_instance();
diff --git a/src/crepe/facade/Sound.cpp b/src/crepe/facade/Sound.cpp
index 4d3abf5..ad50637 100644
--- a/src/crepe/facade/Sound.cpp
+++ b/src/crepe/facade/Sound.cpp
@@ -1,59 +1,13 @@
+#include "../api/Asset.h"
 #include "../util/Log.h"
 
 #include "Sound.h"
-#include "SoundContext.h"
 
 using namespace crepe;
 using namespace std;
 
-Sound::Sound(unique_ptr<Asset> res) {
+Sound::Sound(const Asset & src) : Resource(src) {
+	this->sample.load(src.get_path().c_str());
 	dbg_trace();
-	this->load(std::move(res));
-}
-
-Sound::Sound(const char * src) {
-	dbg_trace();
-	this->load(make_unique<Asset>(src));
-}
-
-void Sound::load(unique_ptr<Asset> res) { this->sample.load(res->get_path().c_str()); }
-
-void Sound::play() {
-	SoundContext & ctx = SoundContext::get_instance();
-	if (ctx.engine.getPause(this->handle)) {
-		// resume if paused
-		ctx.engine.setPause(this->handle, false);
-	} else {
-		// or start new sound
-		this->handle = ctx.engine.play(this->sample, this->volume);
-		ctx.engine.setLooping(this->handle, this->looping);
-	}
-}
-
-void Sound::pause() {
-	SoundContext & ctx = SoundContext::get_instance();
-	if (ctx.engine.getPause(this->handle)) return;
-	ctx.engine.setPause(this->handle, true);
-}
-
-void Sound::rewind() {
-	SoundContext & ctx = SoundContext::get_instance();
-	if (!ctx.engine.isValidVoiceHandle(this->handle)) return;
-	ctx.engine.seek(this->handle, 0);
-}
-
-void Sound::set_volume(float volume) {
-	this->volume = volume;
-
-	SoundContext & ctx = SoundContext::get_instance();
-	if (!ctx.engine.isValidVoiceHandle(this->handle)) return;
-	ctx.engine.setVolume(this->handle, this->volume);
-}
-
-void Sound::set_looping(bool looping) {
-	this->looping = looping;
-
-	SoundContext & ctx = SoundContext::get_instance();
-	if (!ctx.engine.isValidVoiceHandle(this->handle)) return;
-	ctx.engine.setLooping(this->handle, this->looping);
 }
+Sound::~Sound() { dbg_trace(); }
diff --git a/src/crepe/facade/Sound.h b/src/crepe/facade/Sound.h
index ee43d94..85d141b 100644
--- a/src/crepe/facade/Sound.h
+++ b/src/crepe/facade/Sound.h
@@ -1,84 +1,30 @@
 #pragma once
 
-#include <memory>
 #include <soloud/soloud.h>
 #include <soloud/soloud_wav.h>
 
-#include "../api/Asset.h"
+#include "../Resource.h"
 
 namespace crepe {
 
+class SoundContext;
+
 /**
  * \brief Sound resource facade
  *
- * This class is a wrapper around a \c SoLoud::Wav instance, which holds a
- * single sample. It is part of the sound facade.
+ * This class is a wrapper around a \c SoLoud::Wav instance, which holds a single sample. It is
+ * part of the sound facade.
  */
-class Sound {
-public:
-	/**
-	 * \brief Pause this sample
-	 *
-	 * Pauses this sound if it is playing, or does nothing if it is already paused. The playhead
-	 * position is saved, such that calling \c play() after this function makes the sound resume.
-	 */
-	void pause();
-	/**
-	 * \brief Play this sample
-	 *
-	 * Resume playback if this sound is paused, or start from the beginning of the sample.
-	 *
-	 * \note This class only saves a reference to the most recent 'voice' of this sound. Calling
-	 * \c play() while the sound is already playing causes multiple instances of the sample to
-	 * play simultaniously. The sample started last is the one that is controlled afterwards.
-	 */
-	void play();
-	/**
-	 * \brief Reset playhead position
-	 *
-	 * Resets the playhead position so that calling \c play() after this function makes it play
-	 * from the start of the sample. If the sound is not paused before calling this function,
-	 * this function will stop playback.
-	 */
-	void rewind();
-	/**
-	 * \brief Set playback volume / gain
-	 *
-	 * \param volume  Volume (0 = muted, 1 = full volume)
-	 */
-	void set_volume(float volume);
-	/**
-	 * \brief Get playback volume / gain
-	 *
-	 * \return Volume
-	 */
-	float get_volume() const { return this->volume; }
-	/**
-	 * \brief Set looping behavior for this sample
-	 *
-	 * \param looping  Looping behavior (false = one-shot, true = loop)
-	 */
-	void set_looping(bool looping);
-	/**
-	 * \brief Get looping behavior
-	 *
-	 * \return true if looping, false if one-shot
-	 */
-	bool get_looping() const { return this->looping; }
-
+class Sound : public Resource {
 public:
-	Sound(const char * src);
-	Sound(std::unique_ptr<Asset> res);
-
-private:
-	void load(std::unique_ptr<Asset> res);
+	Sound(const Asset & src);
+	~Sound(); // dbg_trace
 
 private:
+	//! Deserialized resource (soloud)
 	SoLoud::Wav sample;
-	SoLoud::handle handle;
-
-	float volume = 1.0f;
-	bool looping = false;
+	//! SoundContext uses \c sample
+	friend class SoundContext;
 };
 
 } // namespace crepe
diff --git a/src/crepe/facade/SoundContext.cpp b/src/crepe/facade/SoundContext.cpp
index deb2b62..b1f8cb3 100644
--- a/src/crepe/facade/SoundContext.cpp
+++ b/src/crepe/facade/SoundContext.cpp
@@ -4,17 +4,33 @@
 
 using namespace crepe;
 
-SoundContext & SoundContext::get_instance() {
-	static SoundContext instance;
-	return instance;
-}
-
 SoundContext::SoundContext() {
 	dbg_trace();
-	engine.init();
+	this->engine.init();
+	this->engine.setMaxActiveVoiceCount(this->config.audio.voices);
 }
 
 SoundContext::~SoundContext() {
 	dbg_trace();
-	engine.deinit();
+	this->engine.deinit();
+}
+
+SoundHandle SoundContext::play(Sound & resource) {
+	SoLoud::handle real_handle = this->engine.play(resource.sample, 1.0f);
+	SoundHandle handle = this->next_handle;
+	this->registry[handle] = real_handle;
+	this->next_handle++;
+	return handle;
+}
+
+void SoundContext::stop(const SoundHandle & handle) {
+	this->engine.stop(this->registry[handle]);
+}
+
+void SoundContext::set_volume(const SoundHandle & handle, float volume) {
+	this->engine.setVolume(this->registry[handle], volume);
+}
+
+void SoundContext::set_loop(const SoundHandle & handle, bool loop) {
+	this->engine.setLooping(this->registry[handle], loop);
 }
diff --git a/src/crepe/facade/SoundContext.h b/src/crepe/facade/SoundContext.h
index d703c16..d986c59 100644
--- a/src/crepe/facade/SoundContext.h
+++ b/src/crepe/facade/SoundContext.h
@@ -2,30 +2,80 @@
 
 #include <soloud/soloud.h>
 
+#include "../api/Config.h"
+
 #include "Sound.h"
+#include "SoundHandle.h"
 
 namespace crepe {
 
 /**
  * \brief Sound engine facade
  *
- * This class is a wrapper around a \c SoLoud::Soloud instance, which provides
- * the methods for playing \c Sound instances. It is part of the sound facade.
+ * This class is a wrapper around a \c SoLoud::Soloud instance, which provides the methods for
+ * playing \c Sound instances. It is part of the sound facade.
  */
 class SoundContext {
-private:
-	// singleton
+public:
 	SoundContext();
 	virtual ~SoundContext();
+
 	SoundContext(const SoundContext &) = delete;
 	SoundContext(SoundContext &&) = delete;
 	SoundContext & operator=(const SoundContext &) = delete;
 	SoundContext & operator=(SoundContext &&) = delete;
 
+	/**
+	 * \brief Play a sample
+	 *
+	 * Plays a Sound from the beginning of the sample and returns a handle to control it later.
+	 *
+	 * \param resource Sound instance to play
+	 *
+	 * \returns Handle to control this voice
+	 */
+	virtual SoundHandle play(Sound & resource);
+	/**
+	 * \brief Stop a voice immediately if it is still playing
+	 *
+	 * \note This function does nothing if the handle is invalid or if the sound is already
+	 * stopped / finished playing.
+	 *
+	 * \param handle Voice handle returned by SoundContext::play
+	 */
+	virtual void stop(const SoundHandle & handle);
+	/**
+	 * \brief Change the volume of a voice
+	 *
+	 * \note This function does nothing if the handle is invalid or if the sound is already
+	 * stopped / finished playing.
+	 *
+	 * \param handle Voice handle returned by SoundContext::play
+	 * \param volume New gain value (0=silent, 1=default)
+	 */
+	virtual void set_volume(const SoundHandle & handle, float volume);
+	/**
+	 * \brief Set the looping behavior of a voice
+	 *
+	 * \note This function does nothing if the handle is invalid or if the sound is already
+	 * stopped / finished playing.
+	 *
+	 * \param handle Voice handle returned by SoundContext::play
+	 * \param loop Looping behavior (false=oneshot, true=loop)
+	 */
+	virtual void set_loop(const SoundHandle & handle, bool loop);
+
 private:
-	static SoundContext & get_instance();
+	//! Abstracted class
 	SoLoud::Soloud engine;
-	friend class Sound;
+
+	//! Config reference
+	Config & config = Config::get_instance();
+
+	//! Sound handle registry
+	std::unordered_map<SoundHandle, SoLoud::handle> registry;
+	//! Unique handle counter
+	SoundHandle next_handle = 0;
 };
 
 } // namespace crepe
diff --git a/src/crepe/facade/SoundHandle.h b/src/crepe/facade/SoundHandle.h
new file mode 100644
index 0000000..b7925fc
--- /dev/null
+++ b/src/crepe/facade/SoundHandle.h
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <cstddef>
+
+namespace crepe {
+
+/**
+ * \brief Voice handle returned by
+ */
+typedef size_t SoundHandle;
+
+} // namespace crepe
diff --git a/src/crepe/manager/CMakeLists.txt b/src/crepe/manager/CMakeLists.txt
index 517b8a2..480c8ee 100644
--- a/src/crepe/manager/CMakeLists.txt
+++ b/src/crepe/manager/CMakeLists.txt
@@ -4,6 +4,7 @@ target_sources(crepe PUBLIC
 	Manager.cpp
 	SaveManager.cpp
 	SceneManager.cpp
+	ResourceManager.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -16,5 +17,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	SaveManager.h
 	SceneManager.h
 	SceneManager.hpp
+	ResourceManager.h
+	ResourceManager.hpp
 )
 
diff --git a/src/crepe/manager/Mediator.h b/src/crepe/manager/Mediator.h
index 8094d80..ba0b41f 100644
--- a/src/crepe/manager/Mediator.h
+++ b/src/crepe/manager/Mediator.h
@@ -12,6 +12,7 @@ namespace crepe {
 
 class ComponentManager;
 class SceneManager;
+class ResourceManager;
 
 /**
  * Struct to pass references to classes that would otherwise need to be singletons down to
@@ -30,6 +31,7 @@ struct Mediator {
 	OptionalRef<SceneManager> scene_manager;
 	OptionalRef<SaveManager> save_manager = SaveManager::get_instance();
 	OptionalRef<EventManager> event_manager = EventManager::get_instance();
+	OptionalRef<ResourceManager> resource_manager;
 	OptionalRef<SDLContext> sdl_context = SDLContext::get_instance();
 	OptionalRef<LoopTimer> timer = LoopTimer::get_instance();
 };
diff --git a/src/crepe/manager/ResourceManager.cpp b/src/crepe/manager/ResourceManager.cpp
new file mode 100644
index 0000000..7c01808
--- /dev/null
+++ b/src/crepe/manager/ResourceManager.cpp
@@ -0,0 +1,30 @@
+#include "util/Log.h"
+
+#include "ResourceManager.h"
+
+using namespace crepe;
+using namespace std;
+
+ResourceManager::ResourceManager(Mediator & mediator) : Manager(mediator) {
+	mediator.resource_manager = *this;
+	dbg_trace();
+}
+ResourceManager::~ResourceManager() { dbg_trace(); }
+
+void ResourceManager::clear() {
+	std::erase_if(this->resources, [](const pair<const Asset, CacheEntry> & pair) {
+		const CacheEntry & entry = pair.second;
+		return entry.persistent == false;
+	});
+}
+
+void ResourceManager::clear_all() { this->resources.clear(); }
+
+void ResourceManager::set_persistent(const Asset & asset, bool persistent) {
+	this->get_entry(asset).persistent = persistent;
+}
+
+ResourceManager::CacheEntry & ResourceManager::get_entry(const Asset & asset) {
+	if (!this->resources.contains(asset)) this->resources[asset] = {};
+	return this->resources.at(asset);
+}
diff --git a/src/crepe/manager/ResourceManager.h b/src/crepe/manager/ResourceManager.h
new file mode 100644
index 0000000..84b275d
--- /dev/null
+++ b/src/crepe/manager/ResourceManager.h
@@ -0,0 +1,78 @@
+#pragma once
+
+#include <memory>
+#include <unordered_map>
+
+#include "../Resource.h"
+#include "../api/Asset.h"
+
+#include "Manager.h"
+
+namespace crepe {
+
+/**
+ * \brief Owner of concrete Resource instances
+ * 
+ * ResourceManager caches concrete Resource instances per Asset. Concrete resources are
+ * destroyed at the end of scenes by default, unless the game programmer marks them as
+ * persistent.
+ */
+class ResourceManager : public Manager {
+public:
+	ResourceManager(Mediator & mediator);
+	virtual ~ResourceManager(); // dbg_trace
+
+private:
+	//! Cache entry
+	struct CacheEntry {
+		//! Concrete resource instance
+		std::unique_ptr<Resource> resource = nullptr;
+		//! Prevent ResourceManager::clear from removing this entry
+		bool persistent = false;
+	};
+	//! Internal cache
+	std::unordered_map<const Asset, CacheEntry> resources;
+	/**
+	 * \brief Ensure a cache entry exists for this asset and return a mutable reference to it
+	 *
+	 * \param asset Asset the concrete resource is instantiated from
+	 *
+	 * \returns Mutable reference to cache entry
+	 */
+	CacheEntry & get_entry(const Asset & asset);
+
+public:
+	/**
+	 * \brief Mark a resource as persistent (i.e. used across multiple scenes)
+	 *
+	 * \param asset Asset the concrete resource is instantiated from
+	 * \param persistent Whether this resource is persistent (true=keep, false=destroy)
+	 */
+	void set_persistent(const Asset & asset, bool persistent);
+
+	/**
+	 * \brief Retrieve reference to concrete Resource by Asset
+	 *
+	 * \param asset Asset the concrete resource is instantiated from
+	 * \tparam Resource Concrete derivative of Resource
+	 *
+	 * This class instantiates the concrete resource if it is not yet stored in the internal
+	 * cache, or returns a reference to the cached resource if it already exists.
+	 *
+	 * \returns Reference to concrete resource
+	 *
+	 * \throws std::runtime_error if the \c Resource parameter does not match with the actual
+	 * type of the resource stored in the cache for this Asset
+	 */
+	template <typename Resource>
+	Resource & get(const Asset & asset);
+
+	//! Clear non-persistent resources from cache
+	void clear();
+	//! Clear all resources from cache regardless of persistence
+	void clear_all();
+};
+
+} // namespace crepe
+
+#include "ResourceManager.hpp"
diff --git a/src/crepe/manager/ResourceManager.hpp b/src/crepe/manager/ResourceManager.hpp
new file mode 100644
index 0000000..5167d71
--- /dev/null
+++ b/src/crepe/manager/ResourceManager.hpp
@@ -0,0 +1,27 @@
+#pragma once
+
+#include <format>
+
+#include "ResourceManager.h"
+
+namespace crepe {
+
+template <typename T>
+T & ResourceManager::get(const Asset & asset) {
+	using namespace std;
+	static_assert(is_base_of<Resource, T>::value,
+				  "cache must recieve a derivative class of Resource");
+
+	CacheEntry & entry = this->get_entry(asset);
+	if (entry.resource == nullptr) entry.resource = make_unique<T>(asset);
+
+	T * concrete_resource = dynamic_cast<T *>(entry.resource.get());
+	if (concrete_resource == nullptr)
+		throw runtime_error(format("ResourceManager: mismatch between requested type and "
+								   "actual type of resource ({})",
+								   asset.get_path()));
+
+	return *concrete_resource;
+}
+
+} // namespace crepe
diff --git a/src/crepe/system/AudioSystem.cpp b/src/crepe/system/AudioSystem.cpp
new file mode 100644
index 0000000..ddba268
--- /dev/null
+++ b/src/crepe/system/AudioSystem.cpp
@@ -0,0 +1,63 @@
+#include "AudioSystem.h"
+
+#include "../manager/ComponentManager.h"
+#include "../manager/ResourceManager.h"
+#include "../types.h"
+
+using namespace crepe;
+using namespace std;
+
+void AudioSystem::update() {
+	ComponentManager & component_manager = this->mediator.component_manager;
+	ResourceManager & resource_manager = this->mediator.resource_manager;
+	RefVector<AudioSource> components
+		= component_manager.get_components_by_type<AudioSource>();
+
+	for (AudioSource & component : components) {
+		Sound & resource = resource_manager.get<Sound>(component.source);
+
+		this->diff_update(component, resource);
+
+		this->update_last(component);
+	}
+}
+
+void AudioSystem::diff_update(AudioSource & component, Sound & resource) {
+	SoundContext & context = this->get_context();
+
+	if (component.active != component.last_active) {
+		if (!component.active) {
+			context.stop(component.voice);
+			return;
+		}
+		if (component.play_on_awake)
+			component.oneshot_play = true;
+	}
+	if (!component.active) return;
+
+	if (component.oneshot_play) {
+		component.voice = context.play(resource);
+		component.oneshot_play = false;
+	}
+	if (component.oneshot_stop) {
+		context.stop(component.voice);
+		component.oneshot_stop = false;
+	}
+	if (component.volume != component.last_volume) {
+		context.set_volume(component.voice, component.volume);
+	}
+	if (component.loop != component.last_loop) {
+		context.set_loop(component.voice, component.loop);
+	}
+}
+
+void AudioSystem::update_last(AudioSource & component) {
+	component.last_active = component.active;
+	component.last_loop = component.loop;
+	component.last_volume = component.volume;
+}
+
+SoundContext & AudioSystem::get_context() {
+	if (this->context == nullptr) this->context = make_unique<SoundContext>();
+	return *this->context.get();
+}
diff --git a/src/crepe/system/AudioSystem.h b/src/crepe/system/AudioSystem.h
new file mode 100644
index 0000000..2ddc443
--- /dev/null
+++ b/src/crepe/system/AudioSystem.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include "../api/AudioSource.h"
+#include "../facade/Sound.h"
+#include "../facade/SoundContext.h"
+
+#include "System.h"
+
+namespace crepe {
+
+class AudioSystem : public System {
+public:
+	using System::System;
+	void update() override;
+
+private:
+	/**
+	 * \brief Update `last_*` members of \c component
+	 *
+	 * Copies all component properties stored for comparison between AudioSystem::update() calls
+	 *
+	 * \param component AudioSource component to update
+	 */
+	void update_last(AudioSource & component);
+
+	/**
+	 * \brief Compare update component
+	 *
+	 * Compares properties of \c component and \c data, and calls SoundContext functions where
+	 * applicable.
+	 *
+	 * \param component AudioSource component to update
+	 * \param resource Sound instance for AudioSource's Asset
+	 */
+	void diff_update(AudioSource & component, Sound & resource);
+
+protected:
+	/**
+	 * \brief Get SoundContext
+	 *
+	 * SoundContext is retrieved through this function instead of being a direct member of
+	 * AudioSystem to aid with testability.
+	 */
+	virtual SoundContext & get_context();
+
+private:
+	//! SoundContext
+	std::unique_ptr<SoundContext> context = nullptr;
+};
+
+} // namespace crepe
diff --git a/src/crepe/system/CMakeLists.txt b/src/crepe/system/CMakeLists.txt
index 95f6e33..6b2e099 100644
--- a/src/crepe/system/CMakeLists.txt
+++ b/src/crepe/system/CMakeLists.txt
@@ -5,6 +5,7 @@ target_sources(crepe PUBLIC
 	PhysicsSystem.cpp
 	CollisionSystem.cpp
 	RenderSystem.cpp
+	AudioSystem.cpp
 	AnimatorSystem.cpp
 	InputSystem.cpp
 )
@@ -15,6 +16,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	PhysicsSystem.h
 	CollisionSystem.h
 	RenderSystem.h
+	AudioSystem.h
 	AnimatorSystem.h
 	InputSystem.h
 )
diff --git a/src/crepe/system/System.cpp b/src/crepe/system/System.cpp
index f68549b..ecc740d 100644
--- a/src/crepe/system/System.cpp
+++ b/src/crepe/system/System.cpp
@@ -1,7 +1,5 @@
-#include "../util/Log.h"
-
 #include "System.h"
 
 using namespace crepe;
 
-System::System(const Mediator & mediator) : mediator(mediator) { dbg_trace(); }
+System::System(const Mediator & mediator) : mediator(mediator) {}