Sdk/PhysicsSystem: Create PhysWorld only if required by entities

SDK/include/NDK/Systems/PhysicsSystem.hpp

@@ -10,6 +10,7 @@
 #include <Nazara/Physics/PhysWorld.hpp>
 #include <NDK/EntityList.hpp>
 #include <NDK/System.hpp>
+#include <memory>
 
 namespace Ndk
 {
@@ -31,7 +32,7 @@ namespace Ndk
 
 			EntityList m_dynamicObjects;
 			EntityList m_staticObjects;
-			Nz::PhysWorld m_world;
+			std::unique_ptr<Nz::PhysWorld> m_world; ///TODO: std::optional (Should I make a Nz::Optional class?)
 	};
 }
 

SDK/include/NDK/Systems/PhysicsSystem.inl

@@ -11,7 +11,7 @@ namespace Ndk
 
 	inline Nz::PhysWorld& PhysicsSystem::GetWorld()
 	{
-		return m_world;
+		return *m_world;
 	}
 
 	/*!
@@ -21,6 +21,6 @@ namespace Ndk
 
 	inline const Nz::PhysWorld& PhysicsSystem::GetWorld() const
 	{
-		return m_world;
+		return *m_world;
 	}
 }