8 files changed, 45 insertions, 13 deletions

diff --git a/src/crepe/api/BehaviorScript.h b/src/crepe/api/BehaviorScript.h
index 02d588a..3909b96 100644
--- a/src/crepe/api/BehaviorScript.h
+++ b/src/crepe/api/BehaviorScript.h
@@ -9,7 +9,6 @@
 namespace crepe {
 
 class ScriptSystem;
-class Mediator;
 class ComponentManager;
 class Script;
 
diff --git a/src/crepe/api/Engine.cpp b/src/crepe/api/Engine.cpp
index 7ae89b9..e8b7fd6 100644
--- a/src/crepe/api/Engine.cpp
+++ b/src/crepe/api/Engine.cpp
@@ -5,12 +5,12 @@
 using namespace crepe;
 using namespace std;
 
-void Engine::start() {
+int Engine::main() noexcept {
 	try {
 		this->setup();
 	} catch (const exception & e) {
 		Log::logf(Log::Level::ERROR, "Uncaught exception in setup: {}\n", e.what());
-		return;
+		return EXIT_FAILURE;
 	}
 
 	try {
@@ -19,10 +19,11 @@ void Engine::start() {
 		Log::logf(Log::Level::ERROR, "Uncaught exception in main loop: {}\n", e.what());
 		this->event_manager.trigger_event<ShutDownEvent>();
 	}
+
+	return EXIT_SUCCESS;
 }
 
 void Engine::setup() {
-	this->game_running = true;
 	this->loop_timer.start();
 	this->scene_manager.load_next_scene();
 
diff --git a/src/crepe/api/Engine.h b/src/crepe/api/Engine.h
index 5421d60..efe7853 100644
--- a/src/crepe/api/Engine.h
+++ b/src/crepe/api/Engine.h
@@ -20,13 +20,16 @@ namespace crepe {
  */
 class Engine {
 public:
-	void start();
-
 	/**
-	 * \brief Add a new concrete scene to the scene manager
+	 * \brief Engine entrypoint
+	 *
+	 * This function is called by the game programmer after registering all scenes
 	 *
-	 * \tparam T  Type of concrete scene
+	 * \returns process exit code
 	 */
+	int main() noexcept;
+
+	//! \copydoc SceneManager::add_scene
 	template <typename T>
 	void add_scene();
 
@@ -44,7 +47,8 @@ private:
 	 */
 	void loop();
 
-	bool game_running = false;
+	//! Game loop condition
+	bool game_running = true;
 
 private:
 	//! Global context
diff --git a/src/crepe/api/GameObject.h b/src/crepe/api/GameObject.h
index 6203f81..0dabed1 100644
--- a/src/crepe/api/GameObject.h
+++ b/src/crepe/api/GameObject.h
@@ -39,8 +39,9 @@ private:
 public:
 	//! The id of the GameObject
 	const game_object_id_t id;
-
+	//! This entity's transform
 	Transform & transform;
+	//! This entity's metadata
 	Metadata & metadata;
 
 public:
diff --git a/src/crepe/api/ParticleEmitter.cpp b/src/crepe/api/ParticleEmitter.cpp
index 90b77a0..fd69e26 100644
--- a/src/crepe/api/ParticleEmitter.cpp
+++ b/src/crepe/api/ParticleEmitter.cpp
@@ -1,6 +1,7 @@
 #include "ParticleEmitter.h"
 
 using namespace crepe;
+using namespace std;
 
 ParticleEmitter::ParticleEmitter(game_object_id_t game_object_id, const Data & data)
 	: Component(game_object_id),
@@ -9,3 +10,17 @@ ParticleEmitter::ParticleEmitter(game_object_id_t game_object_id, const Data & d
 		this->data.particles.emplace_back();
 	}
 }
+
+unique_ptr<Component> ParticleEmitter::save() const {
+	return unique_ptr<Component>{new ParticleEmitter(*this)};
+}
+
+void ParticleEmitter::restore(const Component & snapshot) {
+	*this = static_cast<const ParticleEmitter &>(snapshot);
+}
+
+ParticleEmitter & ParticleEmitter::operator=(const ParticleEmitter & other) {
+	data.particles = other.data.particles;
+	return *this;
+}
+
diff --git a/src/crepe/api/ParticleEmitter.h b/src/crepe/api/ParticleEmitter.h
index b83fd61..5f563de 100644
--- a/src/crepe/api/ParticleEmitter.h
+++ b/src/crepe/api/ParticleEmitter.h
@@ -80,6 +80,12 @@ public:
 public:
 	//! Configuration data for particle emission settings.
 	Data data;
+
+protected:
+	virtual std::unique_ptr<Component> save() const;
+	ParticleEmitter(const ParticleEmitter &) = default;
+	virtual void restore(const Component & snapshot);
+	virtual ParticleEmitter & operator=(const ParticleEmitter &);
 };
 
 } // namespace crepe
diff --git a/src/crepe/api/Script.hpp b/src/crepe/api/Script.hpp
index 2553fd1..b42a6df 100644
--- a/src/crepe/api/Script.hpp
+++ b/src/crepe/api/Script.hpp
@@ -40,10 +40,17 @@ void Script::subscribe_internal(const EventHandler<EventType> & callback,
 	EventManager & mgr = this->mediator->event_manager;
 	subscription_t listener = mgr.subscribe<EventType>(
 		[this, callback](const EventType & data) -> bool {
+			// check if (parent) BehaviorScript component is active
 			bool & active = this->active;
 			if (!active) return false;
-			ReplayManager & replay = this->mediator->replay_manager;
-			if (replay.get_state() == ReplayManager::PLAYING) return false;
+
+			// check if replay manager is playing (if initialized)
+			try {
+				ReplayManager & replay = this->mediator->replay_manager;
+				if (replay.get_state() == ReplayManager::PLAYING) return false;
+			} catch (const std::runtime_error &) {}
+
+			// call user-provided callback
 			return callback(data);
 		},
 		channel);
diff --git a/src/crepe/api/Transform.h b/src/crepe/api/Transform.h
index bbd23e0..a6f3486 100644
--- a/src/crepe/api/Transform.h
+++ b/src/crepe/api/Transform.h
@@ -41,7 +41,6 @@ protected:
 	Transform(const Transform &) = default;
 	virtual void restore(const Component & snapshot);
 	virtual Transform & operator=(const Transform &) = default;
-
 };
 
 } // namespace crepe