implemented functions from NativeFunctions.cs

src/modules/MonoGameObjectSystem.cpp

@@ -15,6 +15,28 @@ MonoGameObjectSystem::MonoGameObjectSystem(Engine& engine, u32 max_game_objects)
     gameObjectCtor = Mono::Method<void(u64, u32)>(gameObjectClass, ".ctor");
     gameObjectInvokeUpdate = Mono::Method<void(f64)>(gameObjectClass, "InvokeUpdate");
     gameObjectTryCreateComponent = Mono::Method<Mono::Bool(Mono::String)>(gameObjectClass, "TryCreateComponent_internal");
+    registerNativeCallbacks();
+}
+
+// sets implementations for extern functions from src-csharp/NativeFunctions.cs
+void MonoGameObjectSystem::registerNativeCallbacks(){
+    static MonoGameObjectSystem* this_static = this;
+    if(this_static != this)
+        throw new UsefulException("creation of more than one instance of MonoGameObjectSystem is not allowed");
+
+    auto createGameObject_callback = static_cast<void(*)(u64*, u32*)> (
+        [](u64* id_out, u32* index_out) -> void {
+            this_static->createGameObjectInPool(id_out, index_out);
+        }
+    );
+    mono_add_internal_call("createGameObject", (void*)createGameObject_callback);
+    
+    auto freeGameObject_callback = static_cast<bool(*)(u32)>(
+        [](u32 index) -> bool {
+            return this_static->gameObjectPool.erase(index);
+        }
+    );
+    mono_add_internal_call("freeGameObject", (void*)freeGameObject_callback);
 }
 
 void MonoGameObjectSystem::beginFrame(){
@@ -23,10 +45,20 @@ void MonoGameObjectSystem::beginFrame(){
     }
 }
 
-game::GameObject& MonoGameObjectSystem::createGameObject(){
+// is used in NativeFunctions.cs
+game::GameObject& MonoGameObjectSystem::createGameObjectInPool(u64* id_out, u32* index_out){
     auto pair = gameObjectPool.emplace(game::GameObject(mono.createObject(gameObjectClass)));
+    *id_out = ++obj_id;
+    *index_out = pair.first;
     game::GameObject& obj = pair.second;
-    gameObjectCtor(obj.getObjectHandle().getObject(), ++obj_id, pair.first);
+    return obj;
+}
+
+game::GameObject& MonoGameObjectSystem::createAndConstructGameObject(){
+    u64 obj_id;
+    u32 obj_index;
+    game::GameObject& obj = createGameObjectInPool(&obj_id, &obj_index);
+    gameObjectCtor(obj.getObjectHandle().getObject(), obj_id, obj_index);
     return obj;
 }