List not being reset when scene is unloaded

Unity Engine
1

I’m making an RPG where the Battle scene is loaded in additively in the game, and in the Awake method of the BattleManager script that gets loaded in as well I set a List of enemies to a new list. This works fine for one battle, but when a second battle gets loaded the lists count is set to zero.

This is where the list is set, line 7.

private void Awake()
    {
        eventManager = EventManager.Instance;
        gameManager = GameManager.Instance;
        overWorldManager = OverWorldManager.Instance;

        enemies = new List<Enemy>();
        commandBuffer = new List<ICommand>();

        SetUpParty();
        GetRandomEncounter();
        SetUpEnemies();

        EnableCursor();
        EnableMenu(startMenu);

        SetActingCharacter(0);
    }

This is where the list is checked. In the first battle the count is one since there’s only one enemy, but in the second battle where there is still one enemy the count is zero for some reason.

public void UpdateEnemies()
    {
        for(int i = 0; i < enemies.Count; i++)
        {
            if (enemies[i].isDead)
                enemies.RemoveAt(i);

            if (enemies.Count == 0)
            {
                BattleWon();
                return;
            }
        }

        enemyNamesPanel.SetActive(true);
        SetEnemyNames();
    }
2

What code actually adds enemies to that list you allocated in Awake()?

3

I instantiate new enemy prefabs then add them to the list

GameObject clone = Instantiate(enemyEncounter.enemyPrefabs[0], smallBattleSpawns[i]);
                    enemies.Add(clone.GetComponent<Enemy>());
4

Excellent… then something funny is happening.

You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also put in Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://discussions.unity.com/t/839300/3

5

I found out what it was. The method UpdateEnemies is called using an event and is subscribed to it in OnEnable, but I forgot to unsubscribe it in OnDisable for when the Battle scene and is unloaded, so when it was called for the second time that was when I would get an error. Rookie mistake on my part.

1 Like
6

Not really Rookie mistake… events are like that. They can trivially hide order of execution stuff like this all the time.

Seen it, done it, debugged it… plenty of times.