19 files changed, 238 insertions, 83 deletions
diff --git a/src/crepe/CMakeLists.txt b/src/crepe/CMakeLists.txt
index 867329f..8830e05 100644
--- a/src/crepe/CMakeLists.txt
+++ b/src/crepe/CMakeLists.txt
@@ -4,7 +4,6 @@ target_sources(crepe PUBLIC
 	ComponentManager.cpp
 	Component.cpp
 	Collider.cpp
-	Metadata.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -13,7 +12,6 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	ComponentManager.hpp
 	Component.h
 	Collider.h
-	Metadata.h
 )
 
 add_subdirectory(api)
diff --git a/src/crepe/Component.cpp b/src/crepe/Component.cpp
index 358ce31..230bb70 100644
--- a/src/crepe/Component.cpp
+++ b/src/crepe/Component.cpp
@@ -2,4 +2,4 @@
 
 using namespace crepe;
 
-Component::Component(uint32_t id) : game_object_id(id), active(true) {}
+Component::Component(uint32_t id) : game_object_id(id) {}
diff --git a/src/crepe/Component.h b/src/crepe/Component.h
index 8db9b2a..02a4e7e 100644
--- a/src/crepe/Component.h
+++ b/src/crepe/Component.h
@@ -6,18 +6,39 @@ namespace crepe {
 
 class ComponentManager;
 
+/**
+ * \brief Base class for all components
+ * 
+ * This class is the base class for all components. It provides a common
+ * interface for all components.
+ */
 class Component {
 protected:
+	//! Only the ComponentManager can create components
 	friend class crepe::ComponentManager;
+	/**
+	 * \param id The id of the GameObject this component belongs to
+	 */
 	Component(uint32_t id);
 
 public:
 	virtual ~Component() = default;
+	/**
+	 * \brief Get the maximum number of instances for this component
+	 *
+	 * This method returns -1 by default, which means that there is no limit
+	 * for the number of instances. Concrete components can override this method
+	 * to set a limit.
+	 *
+	 * \return The maximum number of instances for this component
+	 */
 	virtual int get_instances_max() const { return -1; }
 
 public:
+	//! The id of the GameObject this component belongs to
 	uint32_t game_object_id;
-	bool active;
+	//! Whether the component is active
+	bool active = true;
 };
 
 } // namespace crepe
diff --git a/src/crepe/ComponentManager.cpp b/src/crepe/ComponentManager.cpp
index 8bde33a..55bd82f 100644
--- a/src/crepe/ComponentManager.cpp
+++ b/src/crepe/ComponentManager.cpp
@@ -1,6 +1,7 @@
-#include "ComponentManager.h"
 #include "util/log.h"
 
+#include "ComponentManager.h"
+
 using namespace crepe;
 
 ComponentManager & ComponentManager::get_instance() {
diff --git a/src/crepe/ComponentManager.h b/src/crepe/ComponentManager.h
index 2b5e1df..f3b0ace 100644
--- a/src/crepe/ComponentManager.h
+++ b/src/crepe/ComponentManager.h
@@ -10,47 +10,110 @@
 
 namespace crepe {
 
+/**
+ * \brief Manages all components
+ * 
+ * This class manages all components. It provides methods to add, delete and get
+ * components.
+ */
 class ComponentManager {
 public:
-	// Singleton
+	/**
+	 * \brief Get the instance of the ComponentManager
+	 * 
+	 * \return The instance of the ComponentManager
+	 */
 	static ComponentManager & get_instance();
 	ComponentManager(const ComponentManager &) = delete;
 	ComponentManager(ComponentManager &&) = delete;
 	ComponentManager & operator=(const ComponentManager &) = delete;
 	ComponentManager & operator=(ComponentManager &&) = delete;
+	~ComponentManager();
 
-public:
-	//! Add a component of a specific type
+	/**
+	 * \brief Add a component to the ComponentManager
+	 * 
+	 * This method adds a component to the ComponentManager. The component is
+	 * created with the given arguments and added to the ComponentManager.
+	 * 
+	 * \tparam T The type of the component
+	 * \tparam Args The types of the arguments
+	 * \param id The id of the GameObject this component belongs to
+	 * \param args The arguments to create the component
+	 * \return The created component
+	 */
 	template <typename T, typename... Args>
 	T & add_component(uint32_t id, Args &&... args);
-	//! Deletes all components of a specific type and id
+	/**
+	 * \brief Delete all components of a specific type and id
+	 * 
+	 * This method deletes all components of a specific type and id.
+	 * 
+	 * \tparam T The type of the component
+	 * \param id The id of the GameObject this component belongs to
+	 */
 	template <typename T>
 	void delete_components_by_id(uint32_t id);
-	//! Deletes all components of a specific type
+	/**
+	 * \brief Delete all components of a specific type
+	 * 
+	 * This method deletes all components of a specific type.
+	 * 
+	 * \tparam T The type of the component
+	 */
 	template <typename T>
 	void delete_components();
-	//! Deletes all components of a specific id
+	/**
+	 * \brief Delete all components of a specific id
+	 * 
+	 * This method deletes all components of a specific id.
+	 * 
+	 * \param id The id of the GameObject this component belongs to
+	 */
 	void delete_all_components_of_id(uint32_t id);
-	//! Deletes all components
+	/**
+	 * \brief Delete all components
+	 * 
+	 * This method deletes all components.
+	 */
 	void delete_all_components();
-
-	//! Get a vector<> of all components at specific type and id
+	/**
+	 * \brief Get all components of a specific type and id
+	 * 
+	 * This method gets all components of a specific type and id.
+	 * 
+	 * \tparam T The type of the component
+	 * \param id The id of the GameObject this component belongs to
+	 * \return A vector of all components of the specific type and id
+	 */
 	template <typename T>
 	std::vector<std::reference_wrapper<T>>
 	get_components_by_id(uint32_t id) const;
-	//! Get a vector<> of all components of a specific type
+	/**
+	 * \brief Get all components of a specific type
+	 * 
+	 * This method gets all components of a specific type.
+	 * 
+	 * \tparam T The type of the component
+	 * \return A vector of all components of the specific type
+	 */
 	template <typename T>
 	std::vector<std::reference_wrapper<T>> get_components_by_type() const;
 
 private:
 	ComponentManager();
-	virtual ~ComponentManager();
 
-	/*
-	 * The std::unordered_map<std::type_index, std::vector<std::vector<std::unique_ptr<Component>>>> below might seem a bit strange, let me explain this structure:
-	 * The std::unordered_map<> has a key and value. The key is a std::type_index and the value is a std::vector. So, a new std::vector will be created for each new std::type_index.
-	 * The first std::vector<> stores another vector<>. This first vector<> is to bind the entity's id to a component.
-	 * The second std::vector<> stores unique_ptrs. Each component can be gathered via an unique_ptr. This second vector<> allows multiple components of the same std::type_index for one entity (id).
+private:
+	/**
+	 * \brief The components
+	 * 
+	 * This unordered_map stores all components. The key is the type of the
+	 * component and the value is a vector of vectors of unique pointers to the
+	 * components.
+	 * Every component type has its own vector of vectors of unique pointers to
+	 * the components. The first vector is for the ids of the GameObjects and the
+	 * second vector is for the components (because a GameObject might have multiple
+	 * components).
 	 */
 	std::unordered_map<std::type_index,
 					   std::vector<std::vector<std::unique_ptr<Component>>>>
diff --git a/src/crepe/ComponentManager.hpp b/src/crepe/ComponentManager.hpp
index e74f2e9..11c4d15 100644
--- a/src/crepe/ComponentManager.hpp
+++ b/src/crepe/ComponentManager.hpp
@@ -122,8 +122,6 @@ ComponentManager::get_components_by_type() const {
 
 	// Create an empty vector<>
 	vector<reference_wrapper<T>> component_vector;
-	// Set the id to 0 (the id will also be stored in the returned vector<>)
-	// uint32_t id = 0;
 
 	// Find the type (in the unordered_map<>)
 	if (components.find(type) == components.end()) return component_vector;
@@ -142,12 +140,9 @@ ComponentManager::get_components_by_type() const {
 			// Ensure that the cast was successful
 			if (casted_component == nullptr) continue;
 
-			// Pair the dereferenced raw pointer and the id and add it to the vector<>
+			// Add the dereferenced raw pointer to the vector<>
 			component_vector.emplace_back(ref(*casted_component));
 		}
-
-		// Increase the id (the id will also be stored in the returned vector<>)
-		//++id;
 	}
 
 	// Return the vector<>
diff --git a/src/crepe/Metadata.h b/src/crepe/Metadata.h
deleted file mode 100644
index 1577987..0000000
--- a/src/crepe/Metadata.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#pragma once
-
-#include <string>
-#include <vector>
-
-#include "Component.h"
-
-namespace crepe {
-
-class Metadata : public Component {
-public:
-	Metadata(uint32_t game_object_id, const std::string & name,
-			 const std::string & tag);
-	virtual int get_instances_max() const { return 1; }
-
-public:
-	std::string name;
-	std::string tag;
-	uint32_t parent = -1;
-	std::vector<uint32_t> children;
-};
-
-} // namespace crepe
diff --git a/src/crepe/api/AudioSource.h b/src/crepe/api/AudioSource.h
index 42add50..1e24ae8 100644
--- a/src/crepe/api/AudioSource.h
+++ b/src/crepe/api/AudioSource.h
@@ -10,7 +10,7 @@ namespace crepe {
 class Sound;
 
 //! Audio source component
-class AudioSource : Component {
+class AudioSource : public Component {
 public:
 	AudioSource(std::unique_ptr<Asset> audio_clip);
 	virtual ~AudioSource() = default;
diff --git a/src/crepe/api/CMakeLists.txt b/src/crepe/api/CMakeLists.txt
index 0bb1263..3e0c044 100644
--- a/src/crepe/api/CMakeLists.txt
+++ b/src/crepe/api/CMakeLists.txt
@@ -11,6 +11,7 @@ target_sources(crepe PUBLIC
 	Texture.cpp
 	AssetManager.cpp
 	Sprite.cpp
+	Metadata.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -28,4 +29,5 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Texture.h 
 	AssetManager.h 
 	AssetManager.hpp
+	Metadata.h
 )
diff --git a/src/crepe/api/GameObject.cpp b/src/crepe/api/GameObject.cpp
index 51cd08f..b24b980 100644
--- a/src/crepe/api/GameObject.cpp
+++ b/src/crepe/api/GameObject.cpp
@@ -6,23 +6,25 @@
 using namespace crepe;
 using namespace std;
 
-GameObject::GameObject(uint32_t id, std::string name, std::string tag,
-					   const Point & position, double rotation, double scale)
+GameObject::GameObject(uint32_t id, const std::string & name,
+					   const std::string & tag, const Point & position,
+					   double rotation, double scale)
 	: id(id) {
+	// Add Transform and Metadata components
 	ComponentManager & mgr = ComponentManager::get_instance();
 	mgr.add_component<Transform>(this->id, position, rotation, scale);
 	mgr.add_component<Metadata>(this->id, name, tag);
 }
 
 void GameObject::set_parent(const GameObject & parent) {
-	auto & mgr = ComponentManager::get_instance();
+	ComponentManager & mgr = ComponentManager::get_instance();
 
-	// set parent on own Metadata component
+	// Set parent on own Metadata component
 	vector<reference_wrapper<Metadata>> this_metadata
 		= mgr.get_components_by_id<Metadata>(this->id);
 	this_metadata.at(0).get().parent = parent.id;
 
-	// add own id to children list of parent's Metadata component
+	// Add own id to children list of parent's Metadata component
 	vector<reference_wrapper<Metadata>> parent_metadata
 		= mgr.get_components_by_id<Metadata>(parent.id);
 	parent_metadata.at(0).get().children.push_back(this->id);
diff --git a/src/crepe/api/GameObject.h b/src/crepe/api/GameObject.h
index 602f33c..2a82258 100644
--- a/src/crepe/api/GameObject.h
+++ b/src/crepe/api/GameObject.h
@@ -3,19 +3,58 @@
 #include <cstdint>
 #include <string>
 
-#include "api/Point.h"
-
 namespace crepe {
 
+class Point;
+
+/**
+ * \brief Represents a GameObject
+ * 
+ * This class represents a GameObject. The GameObject class is only used
+ * as an interface for the game programmer. The actual implementation is
+ * done in the ComponentManager.
+ */
 class GameObject {
 public:
-	GameObject(uint32_t id, std::string name, std::string tag,
+	/**
+	 * This constructor creates a new GameObject. It creates a new
+	 * Transform and Metadata component and adds them to the ComponentManager.
+	 * 
+	 * \param id The id of the GameObject
+	 * \param name The name of the GameObject
+	 * \param tag The tag of the GameObject
+	 * \param position The position of the GameObject
+	 * \param rotation The rotation of the GameObject
+	 * \param scale The scale of the GameObject
+	 */
+	GameObject(uint32_t id, const std::string & name, const std::string & tag,
 			   const Point & position, double rotation, double scale);
+	/**
+	 * \brief Set the parent of this GameObject
+	 * 
+	 * This method sets the parent of this GameObject. It sets the parent
+	 * in the Metadata component of this GameObject and adds this GameObject
+	 * to the children list of the parent GameObject.
+	 * 
+	 * \param parent The parent GameObject
+	 */
 	void set_parent(const GameObject & parent);
-
+	/**
+	 * \brief Add a component to the GameObject
+	 * 
+	 * This method adds a component to the GameObject. It forwards the
+	 * arguments to the ComponentManager.
+	 * 
+	 * \tparam T The type of the component
+	 * \tparam Args The types of the arguments
+	 * \param args The arguments to create the component
+	 * \return The created component
+	 */
 	template <typename T, typename... Args>
 	T & add_component(Args &&... args);
 
+public:
+	//! The id of the GameObject
 	uint32_t id;
 };
 
diff --git a/src/crepe/api/GameObject.hpp b/src/crepe/api/GameObject.hpp
index 77cf40e..bfba7fe 100644
--- a/src/crepe/api/GameObject.hpp
+++ b/src/crepe/api/GameObject.hpp
@@ -8,7 +8,7 @@ namespace crepe {
 
 template <typename T, typename... Args>
 T & GameObject::add_component(Args &&... args) {
-	auto & mgr = ComponentManager::get_instance();
+	ComponentManager & mgr = ComponentManager::get_instance();
 	return mgr.add_component<T>(this->id, std::forward<Args>(args)...);
 }
 
diff --git a/src/crepe/Metadata.cpp b/src/crepe/api/Metadata.cpp
index 53d93da..53d93da 100644
--- a/src/crepe/Metadata.cpp
+++ b/src/crepe/api/Metadata.cpp
diff --git a/src/crepe/api/Metadata.h b/src/crepe/api/Metadata.h
new file mode 100644
index 0000000..4d37108
--- /dev/null
+++ b/src/crepe/api/Metadata.h
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "../Component.h"
+
+namespace crepe {
+
+/**
+ * \brief Metadata component
+ * 
+ * This class represents the Metadata component. It stores the name, tag, parent
+ * and children of a GameObject.
+ */
+class Metadata : public Component {
+public:
+	/**
+	 * \param game_object_id The id of the GameObject this component belongs to
+	 * \param name The name of the GameObject
+	 * \param tag The tag of the GameObject
+	 */
+	Metadata(uint32_t game_object_id, const std::string & name,
+			 const std::string & tag);
+	/**
+	 * \brief Get the maximum number of instances for this component
+	 *
+	 * \return The maximum number of instances for this component
+	 */
+	virtual int get_instances_max() const { return 1; }
+
+public:
+	//! The name of the GameObject
+	std::string name;
+	//! The tag of the GameObject
+	std::string tag;
+	//! The id of the parent GameObject (-1 if no parent)
+	uint32_t parent = -1;
+	//! The ids of the children GameObjects
+	std::vector<uint32_t> children;
+};
+
+} // namespace crepe
diff --git a/src/crepe/api/Transform.cpp b/src/crepe/api/Transform.cpp
index 1d8d401..5274b01 100644
--- a/src/crepe/api/Transform.cpp
+++ b/src/crepe/api/Transform.cpp
@@ -1,9 +1,7 @@
 #include <cstdint>
 
-#include "api/Point.h"
 #include "util/log.h"
 
-#include "Component.h"
 #include "Transform.h"
 
 using namespace crepe;
diff --git a/src/crepe/api/Transform.h b/src/crepe/api/Transform.h
index 557061b..02125ef 100644
--- a/src/crepe/api/Transform.h
+++ b/src/crepe/api/Transform.h
@@ -8,15 +8,30 @@
 
 namespace crepe {
 
+/**
+ * \brief Transform component
+ * 
+ * This class represents the Transform component. It stores the position,
+ * rotation and scale of a GameObject.
+ */
 class Transform : public Component {
-	// FIXME: What's the difference between the `Point` and `Position`
-	// classes/structs? How about we replace both with a universal `Vec2` that
-	// works similar (or the same) as those found in GLSL?
-
 public:
-	Transform(uint32_t id, const Point &, double, double);
+	/**
+	 * \param id The id of the GameObject this component belongs to
+	 * \param point The position of the GameObject
+	 * \param rot The rotation of the GameObject
+	 * \param scale The scale of the GameObject
+	 */
+	Transform(uint32_t id, const Point & point, double rot, double scale);
 	~Transform();
+	/**
+	 * \brief Get the maximum number of instances for this component
+	 *
+	 * \return The maximum number of instances for this component
+	 */
 	virtual int get_instances_max() const { return 1; }
+
+public:
 	//! Translation (shift)
 	Point position;
 	//! Rotation, in radians
diff --git a/src/example/ecs.cpp b/src/example/ecs.cpp
index 6f9752e..a8df7e7 100644
--- a/src/example/ecs.cpp
+++ b/src/example/ecs.cpp
@@ -1,8 +1,8 @@
 #include <iostream>
 
 #include "../crepe/ComponentManager.h"
-#include "../crepe/Metadata.h"
 #include "../crepe/api/GameObject.h"
+#include "../crepe/api/Metadata.h"
 #include "../crepe/api/Transform.h"
 
 using namespace crepe;
diff --git a/src/example/particle.cpp b/src/example/particle.cpp
index 69da015..607530d 100644
--- a/src/example/particle.cpp
+++ b/src/example/particle.cpp
@@ -7,6 +7,7 @@
 #include <crepe/Particle.h>
 #include <crepe/api/GameObject.h>
 #include <crepe/api/ParticleEmitter.h>
+#include <crepe/api/Point.h>
 #include <crepe/facade/SDLApp.h>
 #include <crepe/system/ParticleSystem.h>
 
diff --git a/src/makefile b/src/makefile
index 8506a43..be1548c 100644
--- a/src/makefile
+++ b/src/makefile
@@ -19,13 +19,13 @@ LOEK += crepe/Asset.cpp
 LOEK += crepe/Asset.h
 TODO += crepe/Collider.cpp
 TODO += crepe/Collider.h
-TODO += crepe/Component.cpp
-TODO += crepe/Component.h
-TODO += crepe/ComponentManager.cpp
-TODO += crepe/ComponentManager.h
-TODO += crepe/ComponentManager.hpp
-TODO += crepe/Metadata.cpp
-TODO += crepe/Metadata.h
+MAX += crepe/Component.cpp
+MAX += crepe/Component.h
+MAX += crepe/ComponentManager.cpp
+MAX += crepe/ComponentManager.h
+MAX += crepe/ComponentManager.hpp
+MAX += crepe/api/Metadata.cpp
+MAX += crepe/api/Metadata.h
 TODO += crepe/Particle.cpp
 TODO += crepe/Particle.h
 TODO += crepe/Position.h
@@ -43,9 +43,9 @@ TODO += crepe/api/Color.h
 LOEK += crepe/api/Config.h
 TODO += crepe/api/Force.cpp
 TODO += crepe/api/Force.h
-TODO += crepe/api/GameObject.cpp
-TODO += crepe/api/GameObject.h
-TODO += crepe/api/GameObject.hpp
+MAX += crepe/api/GameObject.cpp
+MAX += crepe/api/GameObject.h
+MAX += crepe/api/GameObject.hpp
 TODO += crepe/api/ParticleEmitter.cpp
 TODO += crepe/api/ParticleEmitter.h
 TODO += crepe/api/Point.h
@@ -58,8 +58,8 @@ TODO += crepe/api/Sprite.cpp
 TODO += crepe/api/Sprite.h
 TODO += crepe/api/Texture.cpp
 TODO += crepe/api/Texture.h
-TODO += crepe/api/Transform.cpp
-TODO += crepe/api/Transform.h
+MAX += crepe/api/Transform.cpp
+MAX += crepe/api/Transform.h
 TODO += crepe/facade/SDLApp.cpp
 TODO += crepe/facade/SDLApp.h
 TODO += crepe/facade/SDLContext.cpp
@@ -88,7 +88,7 @@ LOEK += crepe/util/log.h
 TODO += example/asset_manager.cpp
 LOEK += example/audio_internal.cpp
 TODO += example/components_internal.cpp
-TODO += example/ecs.cpp
+MAX += example/ecs.cpp
 LOEK += example/log.cpp
 TODO += example/particle.cpp
 TODO += example/physics.cpp
@@ -97,7 +97,7 @@ LOEK += example/script.cpp
 LOEK += test/audio.cpp
 LOEK += test/dummy.cpp
 
-FMT := $(LOEK) #<<< CHANGE THIS TO YOUR NAME FOR STEP 2
+FMT := $(MAX) #<<< CHANGE THIS TO YOUR NAME FOR STEP 2
 format: FORCE
 	clang-tidy -p build/compile_commands.json --fix-errors $(FMT)