Populating NPC's Outside Of Loop

Question

This was my original question: Populating Sprites I used the following code to spawn Enemy Sprites in my game. I have 2 types that I was using and it would display one then remove it and display the other. It did this repeatedly(Imagine someone playing with a light switch and you have what is happening with the NPCs. EnemyType1 is Off and EnemyType2 is On.).Also It does not apply the current level number meaning, it does not spawn the number of enemies for the level. The number of enemies I want to spawn is the exact number of the level. I used other types of random methods( nextBoolean(), nextInt(), nextFloat() ). I showed the code to my friend and he told me that I would need to spawn them outside of my loop, but he did not know how to. So now I am trying to see if anyone on stack could help me. What I am trying to do is this:

NPC's = Enemies

I have 2 types of NPC's that I want to use. The number of Enemies that are spawned are equal to the the current level number. I want to be able to spawn how ever many is needed for that level and have it to where which Enemy that will spawn is random, so you don't know if you will get EnemyType1 or EnemyType2 or a Mix. Ex: Level 1, only 1 Enemy spawns, the type is random. Level 2, only 2 Enemies spawn, the type is random. Level 3, only 3 enemies spawn, the type is random. etc.

Thanks In Advance.

Answer 1

Basically at the start of the level you need to call a function that creates the enemies for the current level, for example you could do :

for(int i=0; i < currentLevel; i++)
    enemyList.Add(new Enemy(nextInt() % 2));

This would populate the list with a number of enemies equal to the current level. This should only be done when you change level, for example :

if(enemyList.Count == 0) {
    currentLevel++;
    CreateNewEnemies();
}

This means you have to unpopulate your list when the enemies die, this will be done in your Update loop.

foreach(Enemy e in enemyList) {
    if(e.IsDead)
        deadEnemies.Add(e);
}

foreach(Enemy e in deadEnemies) {
    enemyList.Remove(e);
}
deadEnemies.Clear();

This is not optimal, but should work.

Answer 2

I am not 100% sure what you are asking, but from this post and the other one here is my guess:

It sounds like you were selecting which type of NPC the NPC should be during the update for the object. This would be why it constantly changes every frame.

What you need to do is find a place where you can set that value where it will only be set one time. This is probably what your friend meant by 'outside of the loop'.

If you can more clearly describe what you are seeing as opposed to trying to explain what you are doing, it might help be able to refine this answer more.

Answer 3

It sounds like you need to learn more about how Object Oriented Programming works.

I think that you are creating an instance of an enemy, and then without storing that instance in an array, just creating a new instance with the same name, effectively destroying the original instance and creating a new instance.

Create an array that will hold all the enemies. When you spawn an enemy add it to next position in the array.

In your update method loop through all the enemies and update 1 per loop.