private void Start()
 {
     if (target_simulation != null)
     {
         collision_interactor = target_simulation.GetComponent <FluidCollisionInteractor>();
     }
 }
        public override void OnInspectorGUI()
        {
            collision_interactor = (FluidCollisionInteractor)target;
            simulation           = collision_interactor.GetComponent <FluidSimulation3D>();

            EditorGUI.BeginDisabledGroup(true);// Default script ref
            EditorGUILayout.ObjectField("Script:",
                                        MonoScript.FromMonoBehaviour(collision_interactor), typeof(FluidCollisionInteractor), false);
            EditorGUI.EndDisabledGroup();

            if (simulation == null)// Only allow transform setting if not on a fluid sim
            {
                EditorGUILayout.PropertyField(serializedObject.FindProperty("fluid_simulation"), false);
            }
        }