Sdk/PhysicsSystem: Fix GetWorld() not initializing the internal world

SDK/include/NDK/Systems/PhysicsSystem.hpp

@@ -27,12 +27,13 @@ namespace Ndk
 			static SystemIndex systemIndex;
 
 		private:
+			void CreatePhysWorld() const;
 			void OnEntityValidation(Entity* entity, bool justAdded) override;
 			void OnUpdate(float elapsedTime) override;
 
 			EntityList m_dynamicObjects;
 			EntityList m_staticObjects;
-			std::unique_ptr<Nz::PhysWorld> m_world; ///TODO: std::optional (Should I make a Nz::Optional class?)
+			mutable std::unique_ptr<Nz::PhysWorld> m_world; ///TODO: std::optional (Should I make a Nz::Optional class?)
 	};
 }
 

SDK/include/NDK/Systems/PhysicsSystem.inl

@@ -11,6 +11,9 @@ namespace Ndk
 
 	inline Nz::PhysWorld& PhysicsSystem::GetWorld()
 	{
+		if (!m_world)
+			CreatePhysWorld();
+
 		return *m_world;
 	}
 
@@ -21,6 +24,9 @@ namespace Ndk
 
 	inline const Nz::PhysWorld& PhysicsSystem::GetWorld() const
 	{
+		if (!m_world)
+			CreatePhysWorld();
+
 		return *m_world;
 	}
 }

SDK/src/NDK/Systems/PhysicsSystem.cpp

@@ -41,6 +41,13 @@ namespace Ndk
 	{
 	}
 
+	void PhysicsSystem::CreatePhysWorld() const
+	{
+		NazaraAssert(!m_world, "Physics world should not be created twice");
+
+		m_world = std::make_unique<Nz::PhysWorld>();
+	}
+
 	/*!
 	* \brief Operation to perform when entity is validated for the system
 	*
@@ -62,7 +69,7 @@ namespace Ndk
 		entities.Insert(entity);
 
 		if (!m_world)
-			m_world = std::make_unique<Nz::PhysWorld>();
+			CreatePhysWorld();
 	}
 
 	/*!