2 files changed, 35 insertions, 3 deletions

diff --git a/src/crepe/system/AudioSystem.cpp b/src/crepe/system/AudioSystem.cpp
index 97cf966..0f943be 100644
--- a/src/crepe/system/AudioSystem.cpp
+++ b/src/crepe/system/AudioSystem.cpp
@@ -1,6 +1,5 @@
 #include "AudioSystem.h"
 
-#include "../api/AudioSource.h"
 #include "../manager/ComponentManager.h"
 #include "../manager/ResourceManager.h"
 #include "../types.h"
@@ -13,12 +12,24 @@ void AudioSystem::update() {
 	ResourceManager & resource_manager = this->mediator.resource_manager;
 	RefVector<AudioSource> components = component_manager.get_components_by_type<AudioSource>();
 
-	for (auto component_ref : components) {
-		AudioSource & component = component_ref.get();
+	for (AudioSource & component : components) {
 		if (!component.active) continue;
 
 		Sound & sound = resource_manager.get<Sound>(component.source);
+		if (component.private_data.empty())
+			component.private_data.set<ComponentPrivate>();
+		auto & data = component.private_data.get<ComponentPrivate>();
 		// TODO: lots of state diffing
+
+
+		this->update_private(component, data);
 	}
 }
 
+void AudioSystem::update_private(const AudioSource & component, ComponentPrivate & data) {
+	data.last_active = component.active;
+	data.last_loop = component.loop;
+	data.last_playing = component.playing;
+	data.last_volume = component.volume;
+}
+
diff --git a/src/crepe/system/AudioSystem.h b/src/crepe/system/AudioSystem.h
index e037f51..7f41fda 100644
--- a/src/crepe/system/AudioSystem.h
+++ b/src/crepe/system/AudioSystem.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "../facade/SoundContext.h"
+#include "../api/AudioSource.h"
 
 #include "System.h"
 
@@ -12,6 +13,26 @@ public:
 	void update() override;
 
 private:
+	/**
+	 * \brief Private data stored by AudioSystem on AudioSource component
+	 */
+	struct ComponentPrivate {
+		//! This sample's voice handle
+		SoLoud::handle handle;
+
+		//! Value of \c active after last system update
+		bool last_active = false;
+		//! Value of \c playing after last system update
+		bool last_playing = false;
+		//! Value of \c volume after last system update
+		float last_volume = 1.0;
+		//! Value of \c loop after last system update
+		bool last_loop = false;
+	};
+
+	void update_private(const AudioSource & component, ComponentPrivate & data);
+
+private:
 	SoundContext context {};
 };