Unity2D 检测多个触发碰撞

Question

I'm trying to make an attack system to my game and for the moment is something like this:

 private void Start()
{
    triggerActive = false;
}

private void Update()
{
    if (triggerActive)
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            enemyOne.Attacked();
        }
    }
}

private void OnTriggerStay2D(Collider2D col)
{

    triggerActive = true;
   enemyOne = col.gameObject.GetComponent<Hittable>();
   
}
private void OnTriggerExit2D(Collider2D collision)
{
    triggerActive = false;
    enemyOne = null;
    
}

For the moment this works good, but now I want to try to detect more than one collider at the same so I can attack two different enemies at the same time. How could I do that?

Answer 1

You could check in OnTriggerStay2D:

if (col.gameobject == enemyone)
...
else if (col.gameobject == enemytwo)
...

For enemyone and enemytwo you could use two public gameobjects that you reference externally in the Unity editor.

There are other examples how you can iterate over many enemies:

void OnTriggerStay2D(Collision collision)
{
        foreach (ContactPoint contact in collision.contacts)
        {
            print(contact.thisCollider.name + " hit " + contact.otherCollider.name);
            // Visualize the contact point
            Debug.DrawRay(contact.point, contact.normal, Color.white);
        }
}

Answer 2

First you need move the trigger flag from this class to the Hittable class.

class Hittable
{
    public bool isHit = false;
}

Then you need to replace enemyOne with a list of Hittable objects.

List<Hittable> enemies = new List<Hittable>();

When the trigger hits the enemy, we add the enemy into the enemy list. OnTriggerExit2D is not necessary, because we clear the list every frame.

private void OnTriggerStay2D(Collider2D col)
{
   var enemy = col.gameObject.GetComponent<Hittable>();
   if (!enemy.isHit)
   {
       enemy.isHit = true;
       enemies.Add(enemy);
   }
}

Finally we attack the enemies in the list every frame.

private void Update()
{
    if (enemies.Count > 0)
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            foreach (var enemy in enemies)
            {
                enemy.isHit = false;
                enemy.Attacked();
            }
        }
        enemies.Clear();
    }
}

Answer 3

You can use Physics2D.OverlapCircleAll to detect all the colliders (enemies) in a certain radius. Or you can also use Physics2D.CircleCastAll to detect all the colliders (enemies) except those are hidden by other ones.

For more information, you should check the Unity Documentation.