From 4f85999a628477c2029e72aed49e8be49befaa54 Mon Sep 17 00:00:00 2001
From: heinezen <heinezen@hotmail.de>
Date: Wed, 16 Aug 2023 17:30:07 +0200
Subject: [PATCH] gamestate: Add players.

---
 .../component/internal/ownership.cpp          |  6 +--
 .../gamestate/component/internal/ownership.h  | 11 ++--
 libopenage/gamestate/entity_factory.cpp       | 45 +++++++++++++----
 libopenage/gamestate/entity_factory.h         | 39 +++++++++++++--
 libopenage/gamestate/event/spawn_entity.cpp   |  7 +--
 libopenage/gamestate/game.cpp                 | 10 +++-
 libopenage/gamestate/game.h                   |  6 ++-
 libopenage/gamestate/game_state.cpp           | 17 ++++++-
 libopenage/gamestate/game_state.h             | 39 ++++++++++++---
 libopenage/gamestate/player.cpp               | 20 +++++++-
 libopenage/gamestate/player.h                 | 50 ++++++++++++++++++-
 libopenage/gamestate/simulation.cpp           |  4 +-
 libopenage/gamestate/types.h                  |  5 ++
 13 files changed, 217 insertions(+), 42 deletions(-)

diff --git a/libopenage/gamestate/component/internal/ownership.cpp b/libopenage/gamestate/component/internal/ownership.cpp
index 5fcfd3c007f..d4d5151e5de 100644
--- a/libopenage/gamestate/component/internal/ownership.cpp
+++ b/libopenage/gamestate/component/internal/ownership.cpp
@@ -8,7 +8,7 @@
 namespace openage::gamestate::component {
 
 Ownership::Ownership(const std::shared_ptr<openage::event::EventLoop> &loop,
-                     const ownership_id_t owner_id,
+                     const player_id_t owner_id,
                      const time::time_t &creation_time) :
 	owner(loop, 0) {
 	this->owner.set_last(creation_time, owner_id);
@@ -22,11 +22,11 @@ inline component_t Ownership::get_type() const {
 	return component_t::OWNERSHIP;
 }
 
-void Ownership::set_owner(const time::time_t &time, const ownership_id_t owner_id) {
+void Ownership::set_owner(const time::time_t &time, const player_id_t owner_id) {
 	this->owner.set_last(time, owner_id);
 }
 
-const curve::Discrete<ownership_id_t> &Ownership::get_owners() const {
+const curve::Discrete<player_id_t> &Ownership::get_owners() const {
 	return this->owner;
 }
 
diff --git a/libopenage/gamestate/component/internal/ownership.h b/libopenage/gamestate/component/internal/ownership.h
index b28448a557e..cc0f2752499 100644
--- a/libopenage/gamestate/component/internal/ownership.h
+++ b/libopenage/gamestate/component/internal/ownership.h
@@ -8,6 +8,7 @@
 #include "curve/discrete.h"
 #include "gamestate/component/internal_component.h"
 #include "gamestate/component/types.h"
+#include "gamestate/types.h"
 #include "time/time.h"
 
 
@@ -18,8 +19,6 @@ class EventLoop;
 
 namespace gamestate::component {
 
-using ownership_id_t = uint64_t;
-
 class Ownership : public InternalComponent {
 public:
 	/**
@@ -30,7 +29,7 @@ class Ownership : public InternalComponent {
 	 * @param creation_time Ingame creation time of the component.
 	 */
 	Ownership(const std::shared_ptr<openage::event::EventLoop> &loop,
-	          const ownership_id_t owner_id,
+	          const player_id_t owner_id,
 	          const time::time_t &creation_time);
 
 	/**
@@ -48,20 +47,20 @@ class Ownership : public InternalComponent {
 	 * @param time Time at which the owner ID is set.
 	 * @param owner_id New owner ID.
 	 */
-	void set_owner(const time::time_t &time, const ownership_id_t owner_id);
+	void set_owner(const time::time_t &time, const player_id_t owner_id);
 
 	/**
      * Get the owner IDs over time.
      *
      * @return Owner ID curve.
      */
-	const curve::Discrete<ownership_id_t> &get_owners() const;
+	const curve::Discrete<player_id_t> &get_owners() const;
 
 private:
 	/**
      * Owner ID storage over time.
      */
-	curve::Discrete<ownership_id_t> owner;
+	curve::Discrete<player_id_t> owner;
 };
 
 } // namespace gamestate::component
diff --git a/libopenage/gamestate/entity_factory.cpp b/libopenage/gamestate/entity_factory.cpp
index f6aa7f4fc96..f6c3d6f6608 100644
--- a/libopenage/gamestate/entity_factory.cpp
+++ b/libopenage/gamestate/entity_factory.cpp
@@ -31,6 +31,7 @@
 #include "gamestate/game_entity.h"
 #include "gamestate/game_state.h"
 #include "gamestate/manager.h"
+#include "gamestate/player.h"
 #include "gamestate/system/types.h"
 #include "log/message.h"
 #include "renderer/render_factory.h"
@@ -152,17 +153,22 @@ std::shared_ptr<activity::Activity> create_test_activity() {
 }
 
 EntityFactory::EntityFactory() :
-	next_id{0},
+	next_entity_id{0},
+	next_player_id{0},
 	render_factory{nullptr} {
 }
 
 std::shared_ptr<GameEntity> EntityFactory::add_game_entity(const std::shared_ptr<openage::event::EventLoop> &loop,
                                                            const std::shared_ptr<GameState> &state,
+                                                           player_id_t owner_id,
                                                            const nyan::fqon_t &nyan_entity) {
-	auto entity = std::make_shared<GameEntity>(this->get_next_id());
+	auto entity = std::make_shared<GameEntity>(this->get_next_entity_id());
 	entity->set_manager(std::make_shared<GameEntityManager>(loop, state, entity));
 
-	init_components(loop, state, entity, nyan_entity);
+	// use the owner's data to initialize the entity
+	// this ensures that only the owner's tech upgrades apply
+	auto db_view = state->get_player(owner_id)->get_db_view();
+	init_components(loop, db_view, entity, nyan_entity);
 
 	if (this->render_factory) {
 		entity->set_render_entity(this->render_factory->add_world_render_entity());
@@ -171,6 +177,17 @@ std::shared_ptr<GameEntity> EntityFactory::add_game_entity(const std::shared_ptr
 	return entity;
 }
 
+std::shared_ptr<Player> EntityFactory::add_player(const std::shared_ptr<openage::event::EventLoop> & /* loop */,
+                                                  const std::shared_ptr<GameState> &state,
+                                                  const nyan::fqon_t & /* player_setup */) {
+	auto player = std::make_shared<Player>(this->get_next_player_id(),
+	                                       state->get_db_view()->new_child());
+
+	// TODO: Components (for resources, diplomacy, etc.)
+
+	return player;
+}
+
 void EntityFactory::attach_renderer(const std::shared_ptr<renderer::RenderFactory> &render_factory) {
 	std::unique_lock lock{this->mutex};
 
@@ -178,7 +195,7 @@ void EntityFactory::attach_renderer(const std::shared_ptr<renderer::RenderFactor
 }
 
 void EntityFactory::init_components(const std::shared_ptr<openage::event::EventLoop> &loop,
-                                    const std::shared_ptr<GameState> &state,
+                                    const std::shared_ptr<nyan::View> &owner_db_view,
                                     const std::shared_ptr<GameEntity> &entity,
                                     const nyan::fqon_t &nyan_entity) {
 	auto position = std::make_shared<component::Position>(loop);
@@ -190,13 +207,12 @@ void EntityFactory::init_components(const std::shared_ptr<openage::event::EventL
 	auto command_queue = std::make_shared<component::CommandQueue>(loop);
 	entity->add_component(command_queue);
 
-	auto db_view = state->get_nyan_db();
-	auto nyan_obj = db_view->get_object(nyan_entity);
+	auto nyan_obj = owner_db_view->get_object(nyan_entity);
 	nyan::set_t abilities = nyan_obj.get_set("GameEntity.abilities");
 
 	for (const auto &ability_val : abilities) {
 		auto ability_fqon = std::dynamic_pointer_cast<nyan::ObjectValue>(ability_val.get_ptr())->get_name();
-		auto ability_obj = db_view->get_object(ability_fqon);
+		auto ability_obj = owner_db_view->get_object(ability_fqon);
 
 		auto ability_parent = ability_obj.get_parents()[0];
 		if (ability_parent == "engine.ability.type.Move") {
@@ -218,7 +234,7 @@ void EntityFactory::init_components(const std::shared_ptr<openage::event::EventL
 			auto attr_settings = ability_obj.get_set("Live.attributes");
 			for (auto &setting : attr_settings) {
 				auto setting_obj_val = std::dynamic_pointer_cast<nyan::ObjectValue>(setting.get_ptr());
-				auto setting_obj = db_view->get_object(setting_obj_val->get_name());
+				auto setting_obj = owner_db_view->get_object(setting_obj_val->get_name());
 				auto attribute = setting_obj.get_object("AttributeSetting.attribute");
 				auto start_value = setting_obj.get_int("AttributeSetting.starting_value");
 
@@ -238,9 +254,16 @@ void EntityFactory::init_components(const std::shared_ptr<openage::event::EventL
 	entity->add_component(activity);
 }
 
-entity_id_t EntityFactory::get_next_id() {
-	auto new_id = this->next_id;
-	this->next_id++;
+entity_id_t EntityFactory::get_next_entity_id() {
+	auto new_id = this->next_entity_id;
+	this->next_entity_id++;
+
+	return new_id;
+}
+
+player_id_t EntityFactory::get_next_player_id() {
+	auto new_id = this->next_player_id;
+	this->next_player_id++;
 
 	return new_id;
 }
diff --git a/libopenage/gamestate/entity_factory.h b/libopenage/gamestate/entity_factory.h
index 3960a08e530..5a369d995ea 100644
--- a/libopenage/gamestate/entity_factory.h
+++ b/libopenage/gamestate/entity_factory.h
@@ -23,6 +23,7 @@ class RenderFactory;
 namespace gamestate {
 class GameEntity;
 class GameState;
+class Player;
 
 /**
  * Creates game entities that contain data of objects inside the game world.
@@ -43,14 +44,32 @@ class EntityFactory {
      *
 	 * @param loop Event loop for the gamestate.
 	 * @param state State of the game.
+	 * @param owner_id ID of the player owning the entity.
 	 * @param nyan_entity fqon of the GameEntity data in the nyan database.
 	 *
 	 * @return New game entity.
 	 */
 	std::shared_ptr<GameEntity> add_game_entity(const std::shared_ptr<openage::event::EventLoop> &loop,
 	                                            const std::shared_ptr<GameState> &state,
+	                                            player_id_t owner_id,
 	                                            const nyan::fqon_t &nyan_entity);
 
+	/**
+	 * Create a new player.
+	 *
+	 * This just creates the player. The caller is responsible for initializing
+	 * its components and placing it into the game.
+	 *
+	 * @param loop Event loop for the gamestate.
+	 * @param state State of the game.
+	 * @param player_setup fqon of the player setup in the nyan database.
+	 *
+	 * @return New player.
+	 */
+	std::shared_ptr<Player> add_player(const std::shared_ptr<openage::event::EventLoop> &loop,
+	                                   const std::shared_ptr<GameState> &state,
+	                                   const nyan::fqon_t &player_setup);
+
 	/**
 	 * Attach a renderer which enables graphical display options for all ingame entities.
 	 *
@@ -64,12 +83,12 @@ class EntityFactory {
 	 * Initialize components of a game entity.
 	 *
 	 * @param loop Event loop for the gamestate.
-	 * @param state State of the game.
+	 * @param owner_db_view View of the nyan database of the player owning the entity.
 	 * @param entity Game entity.
 	 * @param nyan_entity fqon of the GameEntity data in the nyan database.
 	 */
 	void init_components(const std::shared_ptr<openage::event::EventLoop> &loop,
-	                     const std::shared_ptr<GameState> &state,
+	                     const std::shared_ptr<nyan::View> &owner_db_view,
 	                     const std::shared_ptr<GameEntity> &entity,
 	                     const nyan::fqon_t &nyan_entity);
 
@@ -78,12 +97,24 @@ class EntityFactory {
      *
      * @return Unique ID for a game entity.
      */
-	entity_id_t get_next_id();
+	entity_id_t get_next_entity_id();
+
+	/**
+	 * Get a unique ID for creating a player.
+	 *
+	 * @return Unique ID for a player.
+	 */
+	player_id_t get_next_player_id();
 
 	/**
      * ID of the next game entity to be created.
      */
-	entity_id_t next_id;
+	entity_id_t next_entity_id;
+
+	/**
+	 * ID of the next player to be created.
+	 */
+	player_id_t next_player_id;
 
 	/**
 	 * Factory for creating connector objects to the renderer which make game entities displayable.
diff --git a/libopenage/gamestate/event/spawn_entity.cpp b/libopenage/gamestate/event/spawn_entity.cpp
index d618bcd2085..a2274234501 100644
--- a/libopenage/gamestate/event/spawn_entity.cpp
+++ b/libopenage/gamestate/event/spawn_entity.cpp
@@ -101,7 +101,7 @@ void SpawnEntityHandler::invoke(openage::event::EventLoop & /* loop */,
                                 const param_map &params) {
 	auto gstate = std::dynamic_pointer_cast<gamestate::GameState>(state);
 
-	auto nyan_db = gstate->get_nyan_db();
+	auto nyan_db = gstate->get_db_view();
 
 	auto game_entities = nyan_db->get_obj_children_all("engine.util.game_entity.GameEntity");
 
@@ -151,7 +151,8 @@ void SpawnEntityHandler::invoke(openage::event::EventLoop & /* loop */,
 	}
 
 	// Create entity
-	auto entity = this->factory->add_game_entity(this->loop, gstate, nyan_entity);
+	player_id_t owner_id = params.get("owner", 0);
+	auto entity = this->factory->add_game_entity(this->loop, gstate, owner_id, nyan_entity);
 
 	// Setup components
 	auto entity_pos = std::dynamic_pointer_cast<component::Position>(
@@ -163,7 +164,7 @@ void SpawnEntityHandler::invoke(openage::event::EventLoop & /* loop */,
 
 	auto entity_owner = std::dynamic_pointer_cast<component::Ownership>(
 		entity->get_component(component::component_t::OWNERSHIP));
-	entity_owner->set_owner(time, params.get("owner", 0));
+	entity_owner->set_owner(time, owner_id);
 
 	auto activity = std::dynamic_pointer_cast<component::Activity>(
 		entity->get_component(component::component_t::ACTIVITY));
diff --git a/libopenage/gamestate/game.cpp b/libopenage/gamestate/game.cpp
index b496ae7e1e7..90dfe5ede3d 100644
--- a/libopenage/gamestate/game.cpp
+++ b/libopenage/gamestate/game.cpp
@@ -11,6 +11,7 @@
 
 #include "assets/mod_manager.h"
 #include "assets/modpack.h"
+#include "gamestate/entity_factory.h"
 #include "gamestate/game_state.h"
 #include "gamestate/universe.h"
 #include "util/path.h"
@@ -20,12 +21,19 @@
 namespace openage::gamestate {
 
 Game::Game(const std::shared_ptr<openage::event::EventLoop> &event_loop,
-           const std::shared_ptr<assets::ModManager> &mod_manager) :
+           const std::shared_ptr<assets::ModManager> &mod_manager,
+           const std::shared_ptr<EntityFactory> &entity_factory) :
 	db{nyan::Database::create()},
 	state{std::make_shared<GameState>(this->db, event_loop)},
 	universe{std::make_shared<Universe>(state)} {
 	this->load_data(mod_manager);
 
+	// TODO: Testing player creation
+	auto player1 = entity_factory->add_player(event_loop, state, "");
+	auto player2 = entity_factory->add_player(event_loop, state, "");
+	state->add_player(player1);
+	state->add_player(player2);
+
 	// TODO: This lets the spawner event check which modpacks are loaded,
 	//       so that it can decide which entities it can spawn.
 	//       This can be removed when we spawn based on game logic rather than
diff --git a/libopenage/gamestate/game.h b/libopenage/gamestate/game.h
index 9c9eb1def42..aecfd3bd72e 100644
--- a/libopenage/gamestate/game.h
+++ b/libopenage/gamestate/game.h
@@ -29,6 +29,7 @@ class Path;
 
 namespace gamestate {
 class GameState;
+class EntityFactory;
 class Universe;
 
 /**
@@ -46,12 +47,13 @@ class Game {
 	/**
 	 * Create a new game.
 	 *
-	 * @param root_dir openage root directory.
      * @param event_loop Event simulation loop for the gamestate.
      * @param mod_manager Mod manager.
+	 * @param entity_factory Factory for creating entities. Used for creating the players.
 	 */
 	Game(const std::shared_ptr<openage::event::EventLoop> &event_loop,
-	     const std::shared_ptr<assets::ModManager> &mod_manager);
+	     const std::shared_ptr<assets::ModManager> &mod_manager,
+	     const std::shared_ptr<EntityFactory> &entity_factory);
 	~Game() = default;
 
 	/**
diff --git a/libopenage/gamestate/game_state.cpp b/libopenage/gamestate/game_state.cpp
index 759b6388408..9cda3633791 100644
--- a/libopenage/gamestate/game_state.cpp
+++ b/libopenage/gamestate/game_state.cpp
@@ -8,6 +8,7 @@
 #include "log/log.h"
 
 #include "gamestate/game_entity.h"
+#include "gamestate/player.h"
 
 
 namespace openage::gamestate {
@@ -18,7 +19,7 @@ GameState::GameState(const std::shared_ptr<nyan::Database> &db,
 	db_view{db->new_view()} {
 }
 
-const std::shared_ptr<nyan::View> &GameState::get_nyan_db() {
+const std::shared_ptr<nyan::View> &GameState::get_db_view() {
 	return this->db_view;
 }
 
@@ -29,6 +30,13 @@ void GameState::add_game_entity(const std::shared_ptr<GameEntity> &entity) {
 	this->game_entities[entity->get_id()] = entity;
 }
 
+void GameState::add_player(const std::shared_ptr<Player> &player) {
+	if (this->players.contains(player->get_id())) [[unlikely]] {
+		throw Error(MSG(err) << "Player with ID " << player->get_id() << " already exists");
+	}
+	this->players[player->get_id()] = player;
+}
+
 const std::shared_ptr<GameEntity> &GameState::get_game_entity(entity_id_t id) const {
 	if (!this->game_entities.contains(id)) [[unlikely]] {
 		throw Error(MSG(err) << "Game entity with ID " << id << " does not exist");
@@ -40,6 +48,13 @@ const std::unordered_map<entity_id_t, std::shared_ptr<GameEntity>> &GameState::g
 	return this->game_entities;
 }
 
+const std::shared_ptr<Player> &GameState::get_player(player_id_t id) const {
+	if (!this->players.contains(id)) [[unlikely]] {
+		throw Error(MSG(err) << "Player with ID " << id << " does not exist");
+	}
+	return this->players.at(id);
+}
+
 const std::shared_ptr<assets::ModManager> &GameState::get_mod_manager() const {
 	return this->mod_manager;
 }
diff --git a/libopenage/gamestate/game_state.h b/libopenage/gamestate/game_state.h
index c091303548c..d252acaadcb 100644
--- a/libopenage/gamestate/game_state.h
+++ b/libopenage/gamestate/game_state.h
@@ -26,6 +26,7 @@ class EventLoop;
 
 namespace gamestate {
 class GameEntity;
+class Player;
 
 /**
  * State of the game.
@@ -45,11 +46,13 @@ class GameState : public openage::event::State {
 	                   const std::shared_ptr<openage::event::EventLoop> &event_loop);
 
 	/**
-      * Get the nyan database view of this state.
-      *
-      * @return nyan database view.
-      */
-	const std::shared_ptr<nyan::View> &get_nyan_db();
+     * Get the nyan database view for the whole game.
+     *
+     * Players have individual views for their own data.
+     *
+     * @return nyan database view.
+     */
+	const std::shared_ptr<nyan::View> &get_db_view();
 
 	/**
      * Add a new game entity to the index.
@@ -58,10 +61,18 @@ class GameState : public openage::event::State {
      */
 	void add_game_entity(const std::shared_ptr<GameEntity> &entity);
 
+	/**
+     * Add a new player to the index.
+     *
+     * @param player New player.
+     */
+	void add_player(const std::shared_ptr<Player> &player);
+
 	/**
      * Get a game entity by its ID.
      *
      * @param id ID of the game entity.
+	 *
      * @return Game entity with the given ID.
      */
 	const std::shared_ptr<GameEntity> &get_game_entity(entity_id_t id) const;
@@ -74,8 +85,17 @@ class GameState : public openage::event::State {
 	const std::unordered_map<entity_id_t, std::shared_ptr<GameEntity>> &get_game_entities() const;
 
 	/**
-      * TODO: Only for testing.
-      */
+	 * Get a player by its ID.
+	 *
+	 * @param id ID of the player.
+	 *
+	 * @return Player with the given ID.
+	 */
+	const std::shared_ptr<Player> &get_player(player_id_t id) const;
+
+	/**
+     * TODO: Only for testing.
+     */
 	const std::shared_ptr<assets::ModManager> &get_mod_manager() const;
 	void set_mod_manager(const std::shared_ptr<assets::ModManager> &mod_manager);
 
@@ -90,6 +110,11 @@ class GameState : public openage::event::State {
      */
 	std::unordered_map<entity_id_t, std::shared_ptr<GameEntity>> game_entities;
 
+	/**
+     * Map of all players in the current game by their ID.
+     */
+	std::unordered_map<player_id_t, std::shared_ptr<Player>> players;
+
 	/**
      * TODO: Only for testing
      */
diff --git a/libopenage/gamestate/player.cpp b/libopenage/gamestate/player.cpp
index ab8d0d3d528..e57c4d8a350 100644
--- a/libopenage/gamestate/player.cpp
+++ b/libopenage/gamestate/player.cpp
@@ -1,8 +1,24 @@
-// Copyright 2018-2021 the openage authors. See copying.md for legal info.
+// Copyright 2018-2023 the openage authors. See copying.md for legal info.
 
 #include "player.h"
 
+#include "nyan/nyan.h"
+
+
 namespace openage::gamestate {
 
+Player::Player(player_id_t id,
+               const std::shared_ptr<nyan::View> &db_view) :
+	id{id},
+	db_view{db_view} {
+}
+
+player_id_t Player::get_id() const {
+	return this->id;
+}
+
+const std::shared_ptr<nyan::View> &Player::get_db_view() const {
+	return this->db_view;
+}
 
-} // openage::gamestate
+} // namespace openage::gamestate
diff --git a/libopenage/gamestate/player.h b/libopenage/gamestate/player.h
index b5ad5d0bcd7..db6c53b1283 100644
--- a/libopenage/gamestate/player.h
+++ b/libopenage/gamestate/player.h
@@ -2,6 +2,14 @@
 
 #pragma once
 
+#include <memory>
+
+#include "gamestate/types.h"
+
+
+namespace nyan {
+class View;
+} // namespace nyan
 
 namespace openage::gamestate {
 
@@ -10,8 +18,48 @@ namespace openage::gamestate {
  */
 class Player {
 public:
-	Player() = default;
+	/**
+	 * Create a new player with the given id.
+	 *
+	 * @param id Unique player ID.
+	 * @param db_view View of the nyan database used for the player.
+	 */
+	Player(player_id_t id,
+	       const std::shared_ptr<nyan::View> &db_view);
+
+	// players can't be copied to prevent duplicate IDs
+	Player(const Player &) = delete;
+	Player(Player &&) = default;
+
+	Player &operator=(const Player &) = delete;
+	Player &operator=(Player &&) = default;
+
 	~Player() = default;
+
+	/**
+	 * Get the unique ID of the player.
+	 *
+	 * @return Unique player ID.
+	 */
+	player_id_t get_id() const;
+
+	/**
+	 * Get the nyan game database view for the player.
+	 *
+	 * @return nyan database view.
+	 */
+	const std::shared_ptr<nyan::View> &get_db_view() const;
+
+private:
+	/**
+	 * Player ID. Must be unique.
+	 */
+	const player_id_t id;
+
+	/**
+     * Player view of the nyan game data database.
+     */
+	std::shared_ptr<nyan::View> db_view;
 };
 
 } // namespace openage::gamestate
diff --git a/libopenage/gamestate/simulation.cpp b/libopenage/gamestate/simulation.cpp
index 1c045548bce..c925888815a 100644
--- a/libopenage/gamestate/simulation.cpp
+++ b/libopenage/gamestate/simulation.cpp
@@ -54,7 +54,9 @@ void GameSimulation::start() {
 
 	this->init_event_handlers();
 
-	this->game = std::make_shared<gamestate::Game>(event_loop, this->mod_manager);
+	this->game = std::make_shared<gamestate::Game>(event_loop,
+	                                               this->mod_manager,
+	                                               this->entity_factory);
 
 	this->running = true;
 
diff --git a/libopenage/gamestate/types.h b/libopenage/gamestate/types.h
index 7b90547de62..ad7423853b8 100644
--- a/libopenage/gamestate/types.h
+++ b/libopenage/gamestate/types.h
@@ -11,4 +11,9 @@ namespace openage::gamestate {
  */
 using entity_id_t = uint64_t;
 
+/**
+ * Player IDs.
+ */
+using player_id_t = uint64_t;
+
 } // namespace openage::gamestate