3 files changed, 16 insertions, 7 deletions

diff --git a/src/crepe/manager/SystemManager.cpp b/src/crepe/manager/SystemManager.cpp
index 5ada30f..eabc022 100644
--- a/src/crepe/manager/SystemManager.cpp
+++ b/src/crepe/manager/SystemManager.cpp
@@ -19,12 +19,12 @@ SystemManager::SystemManager(Mediator & mediator) : Manager(mediator) {
 	this->load_system<InputSystem>();
 	this->load_system<EventSystem>();
 	this->load_system<ScriptSystem>();
+	this->load_system<ParticleSystem>();
 	this->load_system<AISystem>();
 	this->load_system<PhysicsSystem>();
 	this->load_system<CollisionSystem>();
 	this->load_system<AudioSystem>();
 	this->load_system<AnimatorSystem>();
-	this->load_system<ParticleSystem>();
 	this->load_system<RenderSystem>();
 	this->load_system<ReplaySystem>();
 
@@ -32,16 +32,16 @@ SystemManager::SystemManager(Mediator & mediator) : Manager(mediator) {
 }
 
 void SystemManager::fixed_update() {
-	for (auto & [type, system] : this->systems) {
-		if (!system->active) continue;
-		system->fixed_update();
+	for (System & system : this->system_order) {
+		if (!system.active) continue;
+		system.fixed_update();
 	}
 }
 
 void SystemManager::frame_update() {
-	for (auto & [type, system] : this->systems) {
-		if (!system->active) continue;
-		system->frame_update();
+	for (System & system : this->system_order) {
+		if (!system.active) continue;
+		system.frame_update();
 	}
 }
 
diff --git a/src/crepe/manager/SystemManager.h b/src/crepe/manager/SystemManager.h
index 50acf77..614d90c 100644
--- a/src/crepe/manager/SystemManager.h
+++ b/src/crepe/manager/SystemManager.h
@@ -3,6 +3,7 @@
 #include <memory>
 #include <typeindex>
 #include <unordered_map>
+#include <vector>
 
 #include "../system/System.h"
 
@@ -43,6 +44,13 @@ private:
 	 */
 	std::unordered_map<std::type_index, std::unique_ptr<System>> systems;
 	/**
+	 * \brief Collection of System instances
+	 *
+	 * This map holds System instances indexed by the system's class typeid. It is filled in the
+	 * constructor of \c SystemManager using SystemManager::load_system.
+	 */
+	std::vector<std::reference_wrapper<System>> system_order;
+	/**
 	 * \brief Initialize a system
 	 * \tparam T System type (must be derivative of \c System)
 	 */
diff --git a/src/crepe/manager/SystemManager.hpp b/src/crepe/manager/SystemManager.hpp
index 3d26e4c..8d06eb1 100644
--- a/src/crepe/manager/SystemManager.hpp
+++ b/src/crepe/manager/SystemManager.hpp
@@ -36,6 +36,7 @@ void SystemManager::load_system() {
 		throw runtime_error(format("SystemManager: {} is already initialized", type.name()));
 	System * system = new T(this->mediator);
 	this->systems[type] = unique_ptr<System>(system);
+	this->system_order.push_back(*this->systems[type]);
 }
 
 } // namespace crepe