Rework ECS framework

- Add queue systems when adding/removing components and systems
- Add GlobalData to ECSManager, used to store data that is not specific
  to entities
- Add View class, used to for loop all entities that contains the given
  Components
- Rework how signaling works

CopiumEngine/src/copium/core/SwapChain.cpp

@@ -430,7 +430,7 @@ namespace Copium
     int width, height;
     glfwGetFramebufferSize(window, &width, &height);
 
-    VkExtent2D extent{width, height};
+    VkExtent2D extent{static_cast<uint32_t>(width), static_cast<uint32_t>(height)};
     extent.width = std::clamp(extent.width, capabilities.minImageExtent.width, capabilities.maxImageExtent.width);
     extent.height = std::clamp(extent.height, capabilities.minImageExtent.height, capabilities.maxImageExtent.height);
     return extent;

CopiumEngine/src/copium/ecs/ComponentPool.h

@@ -19,6 +19,16 @@ namespace Copium
     std::vector<Component> components;
     ComponentListener<Component>* listener = nullptr;
 
+    enum class QueueOperation
+    {
+      Add,
+      Remove
+    };
+
+    std::vector<QueueOperation> queueOperationOrder;
+    std::vector<std::pair<EntityId, Component>> addQueue;
+    std::vector<EntityId> removeQueue;
+
   public:
     ComponentPool()
     {
@@ -35,34 +45,61 @@ namespace Copium
       Emplace(entity, component);
     }
 
-    Component& Emplace(EntityId entity, const Component& component)
+    void Emplace(EntityId entity, const Component& component)
     {
-      components.push_back(component);
-      entities.Emplace(entity);
-      if (listener)
-        listener->Added(entity, components.back());
-      return components.back();
+      addQueue.emplace_back(entity, component);
+      queueOperationOrder.emplace_back(QueueOperation::Add);
     }
 
     bool Erase(EntityId entity) override
     {
-      size_t index = entities.Find(entity);
-      if (!entities.Erase(entity))
+      if (entities.Find(entity) == entities.Size())
         return false;
-      if (listener)
-      {
-        auto it = components.begin() + index;
-        Component component = *it;
-        components.erase(it);
-        listener->Removed(entity, component);
-      }
-      else
-      {
-        components.erase(components.begin() + index);
-      }
+
+      removeQueue.emplace_back(entity);
+      queueOperationOrder.emplace_back(QueueOperation::Remove);
+
       return true;
     }
 
+    void CommitUpdates() override
+    {
+      if (queueOperationOrder.empty())
+        return;
+
+      CP_ASSERT(queueOperationOrder.size() == addQueue.size() + removeQueue.size(),
+                "queueOperationOrder size=%zu doesn't match the sum of the addQueue size=%zu and removeQueue size=%zu, "
+                "which is %zu",
+                queueOperationOrder.size(),
+                addQueue.size(),
+                removeQueue.size(),
+                addQueue.size() + removeQueue.size());
+
+      int addQueueIndex = 0;
+      int removeQueueIndex = 0;
+      for (QueueOperation queueOperation : queueOperationOrder)
+      {
+        switch (queueOperation)
+        {
+          case QueueOperation::Add:
+          {
+            CommitAddComponent(addQueueIndex);
+            addQueueIndex++;
+            break;
+          }
+          case QueueOperation::Remove:
+          {
+            CommitRemoveComponent(removeQueueIndex);
+            removeQueueIndex++;
+            break;
+          }
+        }
+      }
+      removeQueue.clear();
+      addQueue.clear();
+      queueOperationOrder.clear();
+    }
+
     Component& At(size_t index)
     {
       return operator[](index);
@@ -111,5 +148,56 @@ namespace Copium
     {
       return components.end();
     }
+
+    void CommitAddComponent(int queueIndex)
+    {
+      CP_ASSERT(
+        queueIndex < addQueue.size(), "queueIndex=%d is greater than the addQueueSize=%d", queueIndex, addQueue.size());
+
+      const auto& [entity, component] = addQueue[queueIndex];
+      // TODO: Debugging errors caused by this assert might be a bit difficult, since there wont be any stacktrace for
+      //       where the component was added. Might want to validate this in AddComponent somehow (like looping through
+      //       the queued changes and work out if the component already exists)
+      CP_ASSERT(Find(entity) == Size(),
+                "Component already exists in entity (entity=%u, Component=%s)",
+                entity,
+                typeid(Component).name());
+
+      components.push_back(component);
+      entities.Emplace(entity);
+      if (listener)
+        listener->Added(entity, components.back());
+    }
+
+    void CommitRemoveComponent(int queueIndex)
+    {
+      CP_ASSERT(queueIndex < removeQueue.size(),
+                "queueIndex=%d is greater than the removeQueueSize=%d",
+                queueIndex,
+                removeQueue.size());
+
+      const auto& entity = removeQueue[queueIndex];
+      size_t index = entities.Find(entity);
+      if (!entities.Erase(entity))
+      {
+        // TODO: Debugging warnings caused by this might be a bit difficult, since there wont be any stacktrace for
+        //       where the component was added. Might want to validate this in AddComponent somehow (like looping
+        //       through the queued changes and work out if the component already exists)
+        CP_WARN("Entity did not contain component (entity=%u, Component=%s)", entity, typeid(Component).name());
+        return;
+      }
+
+      if (listener)
+      {
+        auto it = components.begin() + index;
+        Component component = *it;
+        components.erase(it);
+        listener->Removed(entity, component);
+      }
+      else
+      {
+        components.erase(components.begin() + index);
+      }
+    }
   };
 }

CopiumEngine/src/copium/ecs/ComponentPoolBase.h

@@ -17,6 +17,7 @@ namespace Copium
 
     virtual size_t Size() = 0;
     virtual bool Erase(EntityId entity) = 0;
+    virtual void CommitUpdates() = 0;
     std::vector<EntityId>& GetEntities();
     const std::vector<EntityId>& GetEntities() const;
   };

CopiumEngine/src/copium/ecs/ECSManager.cpp

@@ -4,30 +4,37 @@
 
 namespace Copium
 {
+  std::vector<EntityId> ECSManager::emptyEntities = {};
+
   ECSManager::ECSManager()
-    : systemPool{std::make_unique<SystemPool>(this)}
   {
   }
 
   ECSManager::~ECSManager()
   {
-    for (auto&& components : componentPool)
+    for (auto&& components : componentPools)
     {
       delete components.second;
     }
-    componentPool.clear();
+    componentPools.clear();
   }
 
-  void ECSManager::UpdateSystems()
+  void ECSManager::CommitEntityUpdates()
   {
-    systemPool->Update();
+    for (auto& componentPool : componentPools)
+    {
+      componentPool.second->CommitUpdates();
+    }
   }
 
-  void ECSManager::UpdateSystems(const Signal& signal)
+  void ECSManager::UpdateSystems(const Uuid& systemPoolId)
   {
-    // TODO: Maybe we want a different pool for Signal based Systems for performance reasons?
-    // Maybe even a pool for each type of Signal?
-    systemPool->Update(signal);
+    auto it = systemPools.find(systemPoolId);
+    CP_ASSERT(it != systemPools.end(), "SystemPool doesn't exist with Uuid=%s", systemPoolId.ToString().c_str());
+    it->second->CommitSignals();
+    CommitEntityUpdates();
+    it->second->CommitUpdates();
+    it->second->Update();
   }
 
   size_t ECSManager::GetEntityCount() const
@@ -37,6 +44,13 @@ namespace Copium
 
   EntityId ECSManager::CreateEntity()
   {
+    if (!destroyedEntityIds.empty())
+    {
+      EntityId newId = *destroyedEntityIds.begin();
+      destroyedEntityIds.erase(destroyedEntityIds.begin());
+      return newId;
+    }
+
     CP_ASSERT(currentEntityId != MAX_NUM_ENTITIES, "No more entities available");
     entities.emplace(currentEntityId);
     currentEntityId++;
@@ -47,8 +61,21 @@ namespace Copium
   {
     auto it = entities.find(entity);
     CP_ASSERT(it != entities.end(), "Entity does not exist in ECSManager (entity=%u)", entity);
+    if (entity == currentEntityId - 1)
+    {
+      currentEntityId--;
+      while (!destroyedEntityIds.empty() && *destroyedEntityIds.rbegin() == currentEntityId - 1)
+      {
+        destroyedEntityIds.erase(std::prev(destroyedEntityIds.end()));
+      }
+    }
+    else
+    {
+      destroyedEntityIds.emplace(entity);
+    }
+
     entities.erase(it);
-    for (auto&& pool : componentPool)
+    for (auto&& pool : componentPools)
     {
       pool.second->Erase(entity);
     }

CopiumEngine/src/copium/ecs/ECSManager.h

@@ -2,6 +2,7 @@
 
 #include <functional>
 #include <map>
+#include <set>
 #include <typeindex>
 #include <unordered_set>
 
@@ -10,36 +11,68 @@
 #include "copium/ecs/Signal.h"
 #include "copium/ecs/SystemPool.h"
 #include "copium/util/Common.h"
+#include "copium/util/GenericType.h"
+#include "copium/util/Uuid.h"
 
 namespace Copium
 {
   class ECSManager final
   {
+    CP_DELETE_COPY_AND_MOVE_CTOR(ECSManager);
+
   private:
     std::unordered_set<EntityId> entities;
-    std::map<std::type_index, ComponentPoolBase*> componentPool;
+    std::map<std::type_index, ComponentPoolBase*> componentPools;
 
-    std::unique_ptr<SystemPool> systemPool;
-    int currentEntityId = 1;
+    std::map<Uuid, std::unique_ptr<SystemPool>> systemPools;
+    EntityId currentEntityId = 1;
+    std::set<EntityId> destroyedEntityIds;
+
+    std::map<std::type_index, GenericType> globalDatas;
 
   public:
+    static std::vector<EntityId> emptyEntities;
+
     ECSManager();
     ~ECSManager();
 
     template <typename SystemClass, typename... Args>
-    SystemOrderer AddSystem(const Args&... args)
+    SystemOrderer& AddSystem(const Uuid& systemPoolId)
     {
-      return systemPool->AddSystem(typeid(SystemClass), new SystemClass{args...});
+      auto it = systemPools.find(systemPoolId);
+      if (it == systemPools.end())
+        it = systemPools.emplace(systemPoolId, std::make_unique<SystemPool>(this)).first;
+
+      return it->second->AddSystem(typeid(SystemClass), new SystemClass{});
     }
 
     template <typename SystemClass>
-    void RemoveSystem()
+    void RemoveSystem(const Uuid& systemPoolId)
     {
-      systemPool->RemoveSystem(typeid(SystemClass));
+      auto it = systemPools.find(systemPoolId);
+      CP_ASSERT(it != systemPools.end(), "SystemPool doesn't exist with Uuid=%s", systemPoolId.ToString().c_str());
+
+      it->second->RemoveSystem(typeid(SystemClass));
+
+      if (it->second->IsEmpty())
+        systemPools.erase(it);
     }
 
-    void UpdateSystems();
-    void UpdateSystems(const Signal& signal);
+    void CommitEntityUpdates();
+
+    void UpdateSystems(const Uuid& systemPoolId);
+
+    template <typename S, typename... Args>
+    void SendSignal(const Args&... args)
+    {
+      Signal::ValidateSignal<S>();
+      for (auto& systemPool : systemPools)
+      {
+        S* newSignal = new S{args...};
+        newSignal->uuid = S::UUID;
+        systemPool.second->SendSignal(newSignal);
+      }
+    }
 
     EntityId CreateEntity();
     void DestroyEntity(EntityId entity);
@@ -61,41 +94,36 @@ namespace Copium
       else
       {
         ComponentPool<Component>* pool{new ComponentPool<Component>{}};
-        componentPool.emplace(GetComponentId<Component>(), pool);
+        componentPools.emplace(GetComponentId<Component>(), pool);
         pool->SetComponentListener(listener);
       }
     }
 
     template <typename... Components>
-    std::tuple<Components&...> AddComponents(EntityId entity, Components&&... components)
+    void AddComponents(EntityId entity, Components&&... components)
     {
-      return std::forward_as_tuple(AddComponent(entity, Components(components))...);
+      (AddComponent(entity, components), ...);
     }
 
     template <typename Component, typename... Args>
-    Component& AddComponent(EntityId entity, Args&&... args)
+    void AddComponent(EntityId entity, Args&&... args)
     {
-      return AddComponent(entity, Component{args...});
+      AddComponent(entity, Component{args...});
     }
 
     template <typename Component>
-    Component& AddComponent(EntityId entity, const Component& component)
+    void AddComponent(EntityId entity, const Component& component)
     {
       auto pool = GetComponentPool<Component>();
 
       if (pool)
       {
-        CP_ASSERT(!HasComponent<Component>(entity),
-                  "Component already exists in entity (entity=%u, Component=%s)",
-                  entity,
-                  typeid(Component).name());
-        return pool->Emplace(entity, component);
+        pool->Emplace(entity, component);
       }
       else
       {
         ComponentPool<Component>* pool{new ComponentPool{entity, component}};
-        auto ret = componentPool.emplace(GetComponentId<Component>(), pool);
-        return pool->At(0);
+        auto ret = componentPools.emplace(GetComponentId<Component>(), pool);
       }
     }
 
@@ -103,10 +131,7 @@ namespace Copium
     void RemoveComponent(EntityId entity)
     {
       auto pool = GetComponentPoolAssure<Component>();
-      CP_ASSERT(pool->Erase(entity),
-                "Entity did not contain component (entity=%u, Component=%s)",
-                entity,
-                typeid(Component).name());
+      pool->Erase(entity);
     }
 
     template <typename... Components>
@@ -229,22 +254,54 @@ namespace Copium
       return std::type_index(typeid(T));
     }
 
-  private:
-    template <typename Component>
-    ComponentPool<Component>* GetComponentPool()
+    template <typename T, typename... Args>
+    void AddGlobalData(const Args&... args)
     {
-      auto it = componentPool.find(GetComponentId<Component>());
-      return it == componentPool.end() ? nullptr : static_cast<ComponentPool<Component>*>(it->second);
+      auto it = globalDatas.find(typeid(T));
+      CP_ASSERT(!HasGlobalData<T>(), "Global with typeid=%s already exists. Do nothing", typeid(T).name());
+
+      globalDatas.emplace(typeid(T), GenericType::Create<T>(args...));
+    }
+
+    template <typename T>
+    T& GetGlobalData()
+    {
+      auto it = globalDatas.find(typeid(T));
+      CP_ASSERT(it != globalDatas.end(), "Global with typeid=%s doesn't exist");
+
+      return it->second.Get<T>();
+    }
+
+    template <typename T>
+    bool HasGlobalData()
+    {
+      return globalDatas.find(typeid(T)) != globalDatas.end();
+    }
+
+    template <typename T>
+    void RemoveGlobalData()
+    {
+      auto it = globalDatas.find(typeid(T));
+      CP_ASSERT("Global with typeid=%s doesn't exist. Do nothing", typeid(T).name());
+      globalDatas.erase(it);
     }
 
     template <typename Component>
-    ComponentPool<Component>* GetComponentPoolAssure()
+    ComponentPool<std::remove_const_t<Component>>* GetComponentPool()
     {
-      auto it = componentPool.find(GetComponentId<Component>());
-      CP_ASSERT(it != componentPool.end(),
+      auto it = componentPools.find(GetComponentId<Component>());
+      return it == componentPools.end() ? nullptr
+                                        : static_cast<ComponentPool<std::remove_const_t<Component>>*>(it->second);
+    }
+
+    template <typename Component>
+    ComponentPool<std::remove_const_t<Component>>* GetComponentPoolAssure()
+    {
+      auto it = componentPools.find(GetComponentId<Component>());
+      CP_ASSERT(it != componentPools.end(),
                 "Component has not been added to an entity (Component=%s)",
                 typeid(Component).name());
-      return static_cast<ComponentPool<Component>*>(it->second);
+      return static_cast<ComponentPool<std::remove_const_t<Component>>*>(it->second);
     }
   };
 }

CopiumEngine/src/copium/ecs/Entity.cpp

@@ -40,7 +40,7 @@ namespace Copium
     return id != entity.id;
   }
 
-  Entity::operator bool() const
+  bool Entity::IsValid() const
   {
     if (id == INVALID_ENTITY)
       return false;
@@ -49,6 +49,11 @@ namespace Copium
     return false;
   }
 
+  Entity::operator bool() const
+  {
+    return IsValid();
+  }
+
   void Entity::Invalidate()
   {
     id = INVALID_ENTITY;
@@ -79,4 +84,4 @@ namespace Copium
   {
     return {manager, manager->CreateEntity()};
   }
-}
+}

CopiumEngine/src/copium/ecs/Entity.h

@@ -24,6 +24,7 @@ namespace Copium
     bool operator!=(const Entity& entity);
     operator bool() const;
 
+    bool IsValid() const;
     void Invalidate();
     void Destroy();
     void SetId(EntityId entityId);
@@ -33,15 +34,15 @@ namespace Copium
     static Entity Create(ECSManager* manager);
 
     template <typename Component, typename... Args>
-    inline Component& AddComponent(Args... args)
+    inline void AddComponent(Args... args)
     {
-      return manager->AddComponent<Component>(id, args...);
+      manager->AddComponent<Component>(id, args...);
     }
 
     template <typename... Components>
-    std::tuple<Components&...> AddComponents(Components&&... components)
+    void AddComponents(Components&&... components)
     {
-      return manager->AddComponents(id, components...);
+      manager->AddComponents(id, components...);
     }
 
     template <typename Component>

CopiumEngine/src/copium/ecs/Signal.cpp

@@ -1,10 +0,0 @@
-#include "copium/ecs/Signal.h"
-
-namespace Copium
-{
-  int Signal::GetAllocatedId()
-  {
-    allocatedIds++;
-    return allocatedIds;
-  }
-}

CopiumEngine/src/copium/ecs/Signal.h

@@ -1,48 +1,42 @@
 #pragma once
 
-#define CP_SIGNAL_DECLERATION_DEFINITION() \
-  static int GetIdStatic()                 \
-  {                                        \
-    static int id = GetAllocatedId();      \
-    return id;                             \
-  }                                        \
-                                           \
-  int GetId() const                        \
-  {                                        \
-    return GetIdStatic();                  \
-  }
+#include "copium/util/Uuid.h"
 
-#define CP_SIGNAL_DECLERATION(SignalClass) \
-  static int GetIdStatic();                \
-  int GetId() const override
-
-#define CP_SIGNAL_DEFINITION(SignalClass) \
-  int SignalClass::GetIdStatic()          \
-  {                                       \
-    static int id = GetAllocatedId();     \
-    return id;                            \
-  }                                       \
-                                          \
-  int SignalClass::GetId() const          \
-  {                                       \
-    return GetIdStatic();                 \
-  }
+#define CP_REGISTER_SIGNAL static inline Copium::Uuid UUID = Copium::Uuid()
 
 namespace Copium
 {
   class Signal
   {
-  private:
-    static inline int allocatedIds = 0;
-
   public:
     Signal() = default;
-    virtual ~Signal() = default;
 
-    virtual int GetId() const = 0;
+    const Uuid& GetUuid() const
+    {
+      return uuid;
+    }
 
-  protected:
-    static int GetAllocatedId();
+    template <typename T>
+    static void ValidateSignal()
+    {
+      static_assert(std::is_base_of_v<Signal, T>, "ValidateSignal : Given T is does not have Signal as base class");
+      static_assert(
+        has_static_uuid<T>(),
+        "ValidateSignal : Given T has not defined a UUID. Did you add CP_REGISTER_SIGNAL to your Signal class?");
+    }
+
+  private:
+    friend class ECSManager;
+    Uuid uuid;
+
+    template <typename, typename = void>
+    struct has_static_uuid : std::false_type
+    {
+    };
+
+    template <typename T>
+    struct has_static_uuid<T, std::void_t<decltype(T::UUID)>> : std::true_type
+    {
+    };
   };
-
 }

CopiumEngine/src/copium/ecs/System.h

@@ -3,44 +3,54 @@
 #include <set>
 
 #include "copium/ecs/ECSManager.h"
-#include "copium/ecs/Entity.h"
-#include "copium/ecs/SystemBase.h"
+#include "copium/ecs/Signal.h"
 
 namespace Copium
 {
-  template <typename... Components>
-  class System : public SystemBase
+  class System
   {
   public:
-    void Run() override
+    virtual ~System() = default;
+    virtual void Run() = 0;
+
+    virtual void HandleSignal(const Signal& signal)
     {
-      manager->Each<Components...>([&](EntityId entityId, Components&... components)
-                                   { RunEntity(Entity{manager, entityId}, components...); });
     }
 
-    void Run(const Signal& signal) override
+    const bool IsSignalSubscribed(const Uuid& uuid) const
     {
-      manager->Each<Components...>([&](EntityId entityId, Components&... components)
-                                   { RunEntity(signal, Entity{manager, entityId}, components...); });
+      return subscribedSignals.count(uuid) != 0;
     }
 
-    virtual void RunEntity(Entity entity, Components&... components) {};
-    virtual void RunEntity(const Signal& signal, Entity entity, Components&... components) {};
-
-    // TODO: Not sure if this is the way entities should be validated
-    std::set<EntityId> loggedEntities;
-
-    bool ValidateEntity(Entity entity)
+    template <typename S>
+    void SubscribeToSignal()
     {
-      if (entity && entity.HasComponents<Components...>())
-      {
-        loggedEntities.erase(entity);
-        return true;
-      }
-      if (loggedEntities.find(entity) == loggedEntities.end())
-        CP_WARN("Invalid Entity");
-      loggedEntities.emplace(entity);
-      return false;
+      Signal::ValidateSignal<S>();
+      subscribedSignals.emplace(S::UUID);
     }
+
+    template <typename S>
+    void UnsubscribeToSignal()
+    {
+      Signal::ValidateSignal<S>();
+      subscribedSignals.erase(S::UUID);
+    }
+
+    void SetECSManager(ECSManager* manager)
+    {
+      this->manager = manager;
+    }
+
+    template <typename S, typename... Args>
+    void SendSignal(const Args&... args)
+    {
+      manager->SendSignal<S>(args...);
+    }
+
+  protected:
+    ECSManager* manager;
+
+  private:
+    std::set<Uuid> subscribedSignals{};
   };
 }

CopiumEngine/src/copium/ecs/SystemBase.h

@@ -1,22 +0,0 @@
-#pragma once
-
-#include "copium/ecs/Signal.h"
-
-namespace Copium
-{
-  class ECSManager;
-
-  class SystemBase
-  {
-    friend class SystemPool;
-
-  protected:
-    ECSManager* manager;
-
-  public:
-    virtual ~SystemBase() = default;
-
-    virtual void Run() = 0;
-    virtual void Run(const Signal& signal) = 0;
-  };
-}

CopiumEngine/src/copium/ecs/SystemOrderer.cpp

@@ -10,13 +10,34 @@ namespace Copium
   {
   }
 
-  void SystemOrderer::Before(const std::type_index& otherSystemId)
+  void SystemOrderer::CommitOrdering()
+  {
+    for (const auto& [orderOperation, systemId] : orderQueue)
+    {
+      switch (orderOperation)
+      {
+        case OrderOperation::Before:
+        {
+          CommitBefore(systemId);
+          break;
+        }
+        case OrderOperation::After:
+        {
+          CommitAfter(systemId);
+          break;
+        }
+      }
+    }
+    orderQueue.clear();
+  }
+
+  void SystemOrderer::CommitBefore(const std::type_index& otherSystemId)
   {
     systemPool->MoveSystemBefore(systemId, otherSystemId);
   }
 
-  void SystemOrderer::After(const std::type_index& otherSystemId)
+  void SystemOrderer::CommitAfter(const std::type_index& otherSystemId)
   {
     systemPool->MoveSystemAfter(systemId, otherSystemId);
   }
-}
+}

CopiumEngine/src/copium/ecs/SystemOrderer.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <typeindex>
+#include <vector>
 
 namespace Copium
 {
@@ -8,27 +9,37 @@ namespace Copium
 
   class SystemOrderer
   {
-  private:
-    std::type_index systemId;
-    SystemPool* systemPool = nullptr;
-
   public:
     SystemOrderer(std::type_index systemId, SystemPool* systemPool);
 
-    template <typename Other>
+    template <typename System>
     void Before()
     {
-      Before(typeid(Other));
+      orderQueue.emplace_back(OrderOperation::Before, typeid(System));
     }
 
-    template <typename Other>
+    template <typename System>
     void After()
     {
-      After(typeid(Other));
+      orderQueue.emplace_back(OrderOperation::After, typeid(System));
     }
 
   private:
-    void Before(const std::type_index& otherSystemId);
-    void After(const std::type_index& otherSystemId);
+    enum class OrderOperation
+    {
+      Before,
+      After
+    };
+
+    std::type_index systemId;
+    SystemPool* systemPool = nullptr;
+    std::vector<std::pair<OrderOperation, std::type_index>> orderQueue;
+
+  private:
+    friend class SystemPool;
+
+    void CommitOrdering();
+    void CommitBefore(const std::type_index& otherSystemId);
+    void CommitAfter(const std::type_index& otherSystemId);
   };
 }

CopiumEngine/src/copium/ecs/SystemPool.cpp

@@ -2,6 +2,8 @@
 
 #include <algorithm>
 
+#include "copium/ecs/System.h"
+
 namespace Copium
 {
   SystemPool::SystemPool(ECSManager* manager)
@@ -19,28 +21,56 @@ namespace Copium
     systems.clear();
   }
 
-  SystemOrderer SystemPool::AddSystem(const std::type_index& systemId, SystemBase* system)
+  SystemOrderer& SystemPool::AddSystem(const std::type_index& systemId, System* system)
   {
-    system->manager = manager;
-    CP_ASSERT(systems.find(systemId) == systems.end(), "System already exist in Ecs");
-    systems.emplace(systemId, system);
-    systemOrder.emplace_back(system);
-    return SystemOrderer{systemId, this};
+    system->SetECSManager(manager);
+    addQueue.emplace_back(systemId, system, SystemOrderer{systemId, this});
+    queueOperationOrder.emplace_back(QueueOperation::Add);
+    return std::get<2>(addQueue.back());
   }
 
   void SystemPool::RemoveSystem(const std::type_index& systemId)
   {
-    auto it = systems.find(systemId);
-    if (it == systems.end())
-    {
-      CP_WARN("System does not exist in Ecs");
-      return;
-    }
+    removeQueue.emplace_back(systemId);
+    queueOperationOrder.emplace_back(QueueOperation::Remove);
+  }
 
-    auto itOrder = std::find(systemOrder.begin(), systemOrder.end(), it->second);
-    delete it->second;
-    systems.erase(it);
-    systemOrder.erase(itOrder);
+  void SystemPool::CommitUpdates()
+  {
+    if (queueOperationOrder.empty())
+      return;
+
+    CP_ASSERT(queueOperationOrder.size() == addQueue.size() + removeQueue.size(),
+              "queueOperationOrder size=%zu doesn't match the sum of the addQueue size=%zu and removeQueue size=%zu, "
+              "which is %zu",
+              queueOperationOrder.size(),
+              addQueue.size(),
+              removeQueue.size(),
+              addQueue.size() + removeQueue.size());
+
+    int addQueueIndex = 0;
+    int removeQueueIndex = 0;
+    for (QueueOperation queueOperation : queueOperationOrder)
+    {
+      switch (queueOperation)
+      {
+        case QueueOperation::Add:
+        {
+          CommitAddSystem(addQueueIndex);
+          addQueueIndex++;
+          break;
+        }
+        case QueueOperation::Remove:
+        {
+          CommitRemoveSystem(removeQueueIndex);
+          removeQueueIndex++;
+          break;
+        }
+      }
+    }
+    removeQueue.clear();
+    addQueue.clear();
+    queueOperationOrder.clear();
   }
 
   void SystemPool::Update()
@@ -51,20 +81,44 @@ namespace Copium
     }
   }
 
-  void SystemPool::Update(const Signal& signal)
+  void SystemPool::SendSignal(Signal* signal)
   {
-    for (auto& system : systemOrder)
+    signalQueue.emplace(signal);
+  }
+
+  void SystemPool::CommitSignals()
+  {
+    while (!signalQueue.empty())
     {
-      system->Run(signal);
+      auto& signal = signalQueue.front();
+      for (auto& system : systemOrder)
+      {
+        if (system->IsSignalSubscribed(signal->GetUuid()))
+        {
+          system->HandleSignal(*signal);
+        }
+      }
+      delete signal;
+      signalQueue.pop();
     }
   }
 
+  size_t SystemPool::Size() const
+  {
+    return systemOrder.size();
+  }
+
+  bool SystemPool::IsEmpty() const
+  {
+    return systemOrder.empty();
+  }
+
   void SystemPool::MoveSystemAfter(const std::type_index& systemId, const std::type_index& afterSystemId)
   {
     auto it1 = systems.find(systemId);
-    CP_ASSERT(it1 != systems.end(), "System does not exist in SystemPool");
+    CP_ASSERT(it1 != systems.end(), "System with typeid=%s does not exist in SystemPool", systemId.name());
     auto it2 = systems.find(afterSystemId);
-    CP_ASSERT(it2 != systems.end(), "System does not exist in SystemPool");
+    CP_ASSERT(it2 != systems.end(), "System with typeid=%s does not exist in SystemPool", afterSystemId.name());
 
     auto itSystemId = std::find(systemOrder.rbegin(), systemOrder.rend(), it1->second);
     auto itAfterSystemId = std::find(systemOrder.rbegin(), systemOrder.rend(), it2->second);
@@ -74,13 +128,45 @@ namespace Copium
   void SystemPool::MoveSystemBefore(const std::type_index& systemId, const std::type_index& beforeSystemId)
   {
     auto it1 = systems.find(systemId);
-    CP_ASSERT(it1 != systems.end(), "System does not exist in SystemPool");
+    CP_ASSERT(it1 != systems.end(), "System with typeid=%s does not exist in SystemPool", systemId.name());
     auto it2 = systems.find(beforeSystemId);
-    CP_ASSERT(it2 != systems.end(), "System does not exist in SystemPool");
+    CP_ASSERT(it2 != systems.end(), "System with typeid=%s does not exist in SystemPool", beforeSystemId.name());
 
     auto itSystemId = std::find(systemOrder.rbegin(), systemOrder.rend(), it1->second);
     auto itBeforeSystemId = std::find(systemOrder.rbegin(), systemOrder.rend(), it2->second);
 
     std::rotate(itSystemId, itSystemId + 1, itBeforeSystemId + 1);
   }
+
+  void SystemPool::CommitAddSystem(int queueIndex)
+  {
+    CP_ASSERT(
+      queueIndex < addQueue.size(), "queueIndex=%d is greater than the addQueueSize=%d", queueIndex, addQueue.size());
+
+    auto& [systemId, system, ordering] = addQueue[queueIndex];
+    CP_ASSERT(systems.find(systemId) == systems.end(), "System with typeid=%s already exists in SystemPool");
+
+    systems.emplace(systemId, system);
+    systemOrder.emplace_back(system);
+    ordering.CommitOrdering();
+  }
+
+  void SystemPool::CommitRemoveSystem(int queueIndex)
+  {
+    CP_ASSERT(queueIndex < removeQueue.size(),
+              "queueIndex=%d is greater than the removeQueueSize=%d",
+              queueIndex,
+              removeQueue.size());
+
+    const auto& systemId = removeQueue[queueIndex];
+    auto it = systems.find(systemId);
+    CP_ASSERT(it != systems.end(), "System with typeid=%s does not exist in SystemPool", systemId.name());
+
+    auto itOrder = std::find(systemOrder.begin(), systemOrder.end(), it->second);
+    CP_ASSERT(itOrder != systemOrder.end(), "System with typeid=%s does not exist in systemOrder", systemId.name());
+
+    delete it->second;
+    systems.erase(it);
+    systemOrder.erase(itOrder);
+  }
 }

CopiumEngine/src/copium/ecs/SystemPool.h

@@ -1,37 +1,57 @@
 #pragma once
 
 #include <map>
+#include <queue>
 #include <typeindex>
 #include <vector>
 
 #include "copium/ecs/Signal.h"
-#include "copium/ecs/SystemBase.h"
 #include "copium/ecs/SystemOrderer.h"
 #include "copium/util/Common.h"
 
 namespace Copium
 {
   class ECSManager;
+  class System;
 
   class SystemPool final
   {
     CP_DELETE_COPY_AND_MOVE_CTOR(SystemPool);
 
-  private:
-    ECSManager* manager;
-    std::map<std::type_index, SystemBase*> systems;
-    std::vector<SystemBase*> systemOrder;
-
   public:
     SystemPool(ECSManager* manager);
     ~SystemPool();
 
-    SystemOrderer AddSystem(const std::type_index& systemId, SystemBase* system);
+    SystemOrderer& AddSystem(const std::type_index& systemId, System* system);
     void RemoveSystem(const std::type_index& systemId);
     void Update();
-    void Update(const Signal& signal);
+    void SendSignal(Signal* signal);
+    void CommitSignals();
+    void CommitUpdates();
+
+    size_t Size() const;
+    bool IsEmpty() const;
 
     void MoveSystemAfter(const std::type_index& systemId, const std::type_index& afterSystemId);
     void MoveSystemBefore(const std::type_index& systemId, const std::type_index& beforeSystemId);
+
+  private:
+    ECSManager* manager;
+    std::map<std::type_index, System*> systems;
+    std::vector<System*> systemOrder;
+
+    enum class QueueOperation
+    {
+      Add,
+      Remove
+    };
+
+    std::vector<QueueOperation> queueOperationOrder;
+    std::vector<std::tuple<std::type_index, System*, SystemOrderer>> addQueue;
+    std::vector<std::type_index> removeQueue;
+    std::queue<Signal*> signalQueue;
+
+    void CommitAddSystem(int queueIndex);
+    void CommitRemoveSystem(int queueIndex);
   };
 }

CopiumEngine/src/copium/ecs/View.h

@@ -0,0 +1,113 @@
+#pragma once
+
+#include "copium/ecs/ECSManager.h"
+#include "copium/ecs/Entity.h"
+
+namespace Copium
+{
+  template <typename Component, typename... Components>
+  struct View
+  {
+    class Iterator
+    {
+    public:
+      std::tuple<Entity, Component&, Components&...> operator*()
+      {
+        EntityId entityId{entities[index]};
+        CP_ASSERT((manager->HasComponents<Component, Components...>(entityId)),
+                  "entity doesn't contains all components");
+        return std::forward_as_tuple<Entity, Component&, Components&...>(
+          Entity{manager, entityId}, firstPool->At(index), manager->GetComponent<Components>(entityId)...);
+      }
+
+      Iterator& operator++()
+      {
+        ++index;
+        FindNextEntity();
+        return *this;
+      }
+
+      Iterator operator++(int)
+      {
+        Iterator it = *this;
+        ++*this;
+        return it;
+      }
+
+      Iterator operator+(size_t advance)
+      {
+        Iterator it = *this;
+        for (int i = 0; i < advance; i++)
+          ++it;
+        return it;
+      }
+
+      bool operator==(const Iterator& other) const
+      {
+        return index == other.index;
+      }
+
+      bool operator!=(const Iterator& other) const
+      {
+        return !(*this == other);
+      }
+
+    private:
+      friend class View;
+
+      ECSManager* manager;
+      ComponentPool<std::remove_const_t<Component>>* firstPool;
+      const std::vector<EntityId>& entities;
+      int index;
+
+      Iterator(ECSManager* manager, ComponentPool<std::remove_const_t<Component>>* firstPool)
+        : manager{manager},
+          firstPool{firstPool},
+          entities{firstPool ? firstPool->GetEntities() : ECSManager::emptyEntities},
+          index{0}
+      {
+      }
+
+      static Iterator Begin(ECSManager* manager)
+      {
+        Iterator iterator{manager, manager->GetComponentPool<Component>()};
+        iterator.FindNextEntity();
+        return iterator;
+      }
+
+      static Iterator End(ECSManager* manager)
+      {
+        Iterator iterator{manager, manager->GetComponentPool<Component>()};
+        if (iterator.firstPool)
+          iterator.index = iterator.firstPool->GetEntities().size();
+        return iterator;
+      }
+
+      void FindNextEntity()
+      {
+        while (index < entities.size() && !manager->HasComponents<Components...>(entities[index]))
+        {
+          ++index;
+        }
+      }
+    };
+
+    View(ECSManager* manager)
+      : manager{manager}
+    {
+    }
+
+    Iterator begin()
+    {
+      return Iterator::Begin(manager);
+    }
+
+    Iterator end()
+    {
+      return Iterator::End(manager);
+    }
+
+  private:
+    ECSManager* manager;
+  };
+}

CopiumEngine/src/copium/event/EventSignal.cpp

@@ -1,16 +0,0 @@
-#include "copium/event/EventSignal.h"
-
-namespace Copium
-{
-  EventSignal::EventSignal(const Event& event)
-    : event{event}
-  {
-  }
-
-  const Event& EventSignal::GetEvent() const
-  {
-    return event;
-  }
-
-  CP_SIGNAL_DEFINITION(EventSignal);
-}

CopiumEngine/src/copium/event/EventSignal.h

@@ -1,22 +0,0 @@
-#pragma once
-
-#include "copium/ecs/Signal.h"
-#include "copium/event/Event.h"
-
-namespace Copium
-{
-
-  class EventSignal : public Signal
-  {
-  private:
-    const Event& event;
-
-  public:
-    EventSignal(const Event& event);
-
-    const Event& GetEvent() const;
-
-    CP_SIGNAL_DECLERATION(EventSignal);
-  };
-
-}

CopiumEngine/src/copium/renderer/Renderer.cpp

@@ -102,6 +102,58 @@ namespace Copium
     return offset;
   }
 
+  glm::vec2 Renderer::TextUi(
+    const std::string& str, const glm::vec2& position, const Font& font, float size, const glm::vec3& color)
+  {
+    glm::vec2 offset = position;
+    for (char c : str)
+    {
+      if (c == ' ')
+      {
+        const Glyph& glyph = font.GetGlyph(c);
+        offset.x += glyph.advance * size;
+        continue;
+      }
+      else if (c == '\t')
+      {
+        const Glyph& glyph = font.GetGlyph(' ');
+        offset.x += glyph.advance * size * 4;
+        continue;
+      }
+      else if (c == '\n')
+      {
+        offset.y += font.GetLineHeight() * size;
+        offset.x = position.x;
+        continue;
+      }
+      const Glyph& glyph = font.GetGlyph(c);
+      AllocateQuad();
+      int texIndex = AllocateSampler(font);
+      AddVertex(offset + glm::vec2{glyph.boundingBox.l * size, -glyph.boundingBox.t * size},
+                color,
+                texIndex,
+                glm::vec2{glyph.texCoordBoundingBox.l, glyph.texCoordBoundingBox.t},
+                RendererVertex::TYPE_TEXT);
+      AddVertex(offset + glm::vec2{glyph.boundingBox.l * size, -glyph.boundingBox.b * size},
+                color,
+                texIndex,
+                glm::vec2{glyph.texCoordBoundingBox.l, glyph.texCoordBoundingBox.b},
+                RendererVertex::TYPE_TEXT);
+      AddVertex(offset + glm::vec2{glyph.boundingBox.r * size, -glyph.boundingBox.b * size},
+                color,
+                texIndex,
+                glm::vec2{glyph.texCoordBoundingBox.r, glyph.texCoordBoundingBox.b},
+                RendererVertex::TYPE_TEXT);
+      AddVertex(offset + glm::vec2{glyph.boundingBox.r * size, -glyph.boundingBox.t * size},
+                color,
+                texIndex,
+                glm::vec2{glyph.texCoordBoundingBox.r, glyph.texCoordBoundingBox.t},
+                RendererVertex::TYPE_TEXT);
+      offset.x += glyph.advance * size;
+    }
+    return offset;
+  }
+
   void Renderer::AddVertex(
     const glm::vec2& position, const glm::vec3& color, int texindex, const glm::vec2& texCoord, int type)
   {

CopiumEngine/src/copium/renderer/Renderer.h

@@ -46,6 +46,12 @@ namespace Copium
                    const Font& font,
                    float size,
                    const glm::vec3& color = glm::vec3(1, 1, 1));
+    // Returns the position where the text rendering ended
+    glm::vec2 TextUi(const std::string& str,
+                     const glm::vec2& position,
+                     const Font& font,
+                     float size,
+                     const glm::vec3& color = glm::vec3(1, 1, 1));
 
     void Begin(CommandBuffer& commandBuffer);
     void End();

CopiumEngine/src/copium/util/GenericType.h

@@ -0,0 +1,56 @@
+#pragma once
+
+#include <functional>
+
+class GenericType
+{
+public:
+  template <typename T, typename... Args>
+  static GenericType Create(const Args&... args)
+  {
+    GenericType type;
+    type.data = new T{args...};
+    type.deleter = [](void* data) { delete (T*)data; };
+
+    return type;
+  }
+
+  GenericType(GenericType&& type)
+    : data{type.data},
+      deleter{type.deleter}
+  {
+    type.data = nullptr;
+  }
+
+  GenericType& operator=(GenericType&& type)
+  {
+    this->data = type.data;
+    this->deleter = type.deleter;
+    type.data = nullptr;
+    return *this;
+  }
+
+  ~GenericType()
+  {
+    if (data)
+    {
+      deleter(data);
+    }
+    data = nullptr;
+  }
+
+  template <typename T>
+  T& Get()
+  {
+    return *(T*)data;
+  }
+
+private:
+  GenericType() = default;
+
+  GenericType(const GenericType& type) = delete;
+  GenericType& operator=(const GenericType& type) = delete;
+
+  void* data;
+  std::function<void(void*)> deleter;
+};

CopiumEngine/src/copium/util/Timer.cpp

@@ -26,4 +26,9 @@ namespace Copium
 
     return elapsedTime;
   }
+
+  void Timer::OffsetSeconds(int time)
+  {
+    startTime += std::chrono::seconds(time);
+  }
 }

CopiumEngine/src/copium/util/Timer.h

@@ -15,5 +15,6 @@ namespace Copium
     void Start();
     double Elapsed();
     double ElapsedRestart();
+    void OffsetSeconds(int time);
   };
 }