From 01c31f46f4ced39e6c4a192ec87c95b8b644c521 Mon Sep 17 00:00:00 2001
From: benkyd <benjaminkyd@gmail.com>
Date: Wed, 8 Jun 2022 20:00:52 +0000
Subject: [PATCH] issues with entity allocation

---
 Aeon/Entity/ComponentController.hpp |  7 ++++--
 Aeon/Entity/Entity.hpp              |  5 ++++
 Aeon/Entity/EntityController.cpp    | 36 +++++++++++++++++++----------
 Aeon/Entity/EntityController.hpp    | 14 +++++++----
 Aeon/Includes.hpp                   |  5 ++++
 Game/ExampleGame.cpp                | 25 ++++++++++++++++++++
 6 files changed, 73 insertions(+), 19 deletions(-)

diff --git a/Aeon/Entity/ComponentController.hpp b/Aeon/Entity/ComponentController.hpp
index cb5c84a..d36214d 100644
--- a/Aeon/Entity/ComponentController.hpp
+++ b/Aeon/Entity/ComponentController.hpp
@@ -12,7 +12,6 @@ namespace EC
 // someone fix this ahaha
 struct IComponentContainer
 {
-    virtual ~IComponentContainer() = default;
     virtual void Create(const Entity) = 0;
     virtual void Destroy(const Entity) = 0;
 };
@@ -25,6 +24,10 @@ struct ComponentContainer : public IComponentContainer
 
     }
 
+    void Create(const Entity) override
+    {
+
+    }
 
     void Destroy(const Entity) override
     {
@@ -57,7 +60,7 @@ public:
 
 
 private:
-    std::map<std::string, IComponentContainer> mComponentContainers;
+    // std::map<std::string, IComponentContainer> mComponentContainers;
 
 };
 
diff --git a/Aeon/Entity/Entity.hpp b/Aeon/Entity/Entity.hpp
index 2d6b017..1cafcf3 100644
--- a/Aeon/Entity/Entity.hpp
+++ b/Aeon/Entity/Entity.hpp
@@ -8,6 +8,11 @@ namespace EC
 
 using Entity = uint32_t;
 
+struct EntityDebugMetadata
+{
+    std::string DebugName;
+};
+
 }
 
 #endif
diff --git a/Aeon/Entity/EntityController.cpp b/Aeon/Entity/EntityController.cpp
index 54bc71f..e7c341e 100644
--- a/Aeon/Entity/EntityController.cpp
+++ b/Aeon/Entity/EntityController.cpp
@@ -15,25 +15,37 @@ EntityRegistry::~EntityRegistry()
 
 Entity EntityRegistry::Create()
 {
-    mEntityCeiling++;
-    uint32_t entityId = mEntityCeiling;
- 
-    Entity entity( { entityId } );
-    mEntities.push( entity );
-    return entity;
+    uint32_t entityId;
+    if ( mFreedEntities.empty() )
+    {
+        mEntityCeiling++;
+        entityId = mEntityCeiling;
+    } 
+    else 
+    {
+        mFreedEntities.pop();
+    }
+
+    mEntities[entityId] = std::vector<std::string>();
+    return entityId;
 }
 
-Entity EntityRegistry::Copy( const Entity entity )
+Entity Copy( const Entity& entity )
 {
     // look up everything, create a new entity and populate
     // with the components in the og entity
 
-    return Entity( { 0 } );
+    return static_cast<uint32_t>( 0 );
 }
 
-Entity EntityRegistry::Destroy( Entity entity )
+void EntityRegistry::Destroy( Entity entity )
 {
-    auto id = entity.id;
-    mEntities = std::move(n.back());          // move last element to removal location
-    mEntities.pop_back();
+    if ( !this->Valid( entity ) ) return;
+    mFreedEntities.push(entity);
+    mEntities.erase(entity);
+}
+
+bool EntityRegistry::Valid( const Entity entity )
+{
+    return mEntities.find(entity) != mEntities.end();
 }
diff --git a/Aeon/Entity/EntityController.hpp b/Aeon/Entity/EntityController.hpp
index 05b5f35..bfb0328 100644
--- a/Aeon/Entity/EntityController.hpp
+++ b/Aeon/Entity/EntityController.hpp
@@ -16,10 +16,10 @@ public:
     EntityRegistry();
     ~EntityRegistry();
 
-    Entity Create()
+    Entity Create();
     Entity Copy( const Entity entity );
     void Destroy( Entity entity );
-    bool Valid(const Entity entity);
+    bool Valid( const Entity entity );
 
     // add, replace components
     template <typename TComponent>
@@ -47,12 +47,16 @@ public:
     // std::vector<T&> Sort(std::function<;
 
 private:
+    // Keep track of IDs that were freed for re-allocation
+    std::queue<uint32_t> mFreedEntities;
     uint32_t mEntityCeiling = 0;
 
-    // On destroy, the last entity is moved to the position
-    // of the old entity for cache coherency
-    std::map<Entity, std::vector<std::string>> mEntities
+    // Currently unused
+    std::unordered_map<Entity, EntityDebugMetadata> mEntityDebug;
 
+    // That's not very cache-friendly of you
+    // optimisations coming soon TM
+    std::unordered_map<Entity, std::vector<std::string>> mEntities;
 };
     
 }
diff --git a/Aeon/Includes.hpp b/Aeon/Includes.hpp
index a7c746c..e1807dc 100644
--- a/Aeon/Includes.hpp
+++ b/Aeon/Includes.hpp
@@ -3,7 +3,12 @@
 
 // shut up
 
+#ifdef __WIN32
 #include <SDL.h>
+#else
+#include <SDL2/SDL.h>
+#endif
+
 extern "C" {
 #include <Aeon/ThirdParty/glad.h>
 }
diff --git a/Game/ExampleGame.cpp b/Game/ExampleGame.cpp
index 2ded34c..ae21db2 100644
--- a/Game/ExampleGame.cpp
+++ b/Game/ExampleGame.cpp
@@ -91,6 +91,31 @@ public:
 	ExampleGame()
 		: App( { "Example" },  { "Game with AEON!" } )
 	{
+
+		EC::EntityRegistry registry;
+
+		EC::Entity entity1 = registry.Create();
+
+		std::cout << entity1 << std::endl;
+
+		std::vector<EC::Entity> entities;
+
+		for (int i = 0; i < 100000; i++)
+		{
+			entities.push_back(registry.Create());
+		}
+
+		std::cout << entities[entities.size()] << std::endl;
+
+		for (int i = 0; i < 100000; i++)
+		{
+			registry.Destroy(entities[i]);
+		}
+
+		entity1 = registry.Create();
+
+		std::cout << entity1 << std::endl;
+
 		Level* level = new Level;
 		PushLayer( (Core::GameLayer*)level );
 		DebugLayer* debug = new DebugLayer;