Making a turret fire another arrow if an enemy survives the hit

Questions & Answers
1

Hey, I made a script which is attached to a turret, 

public class TurretRealScript : MonoBehaviour {

public GameObject arrowPrefab;
public GameObject Target;

void Start () {

}

// Update is called once per frame
void Update () {

}
void OnTriggerEnter(Collider other)
{
    if (other.gameObject.tag == "Enemy")
    {
        Target = other.gameObject;
        Instantiate(arrowPrefab,
        transform.position,transform.rotation);
    }
   }

}

and a script attached to the object which is to be fired at the enemy once the collision is triggered

public class ArrowProjectileScript2 : MonoBehaviour {

      public GameObject Target;
      private Vector3 direction = Vector3.forward;
      public float speed=30.0f;

// Use this for initialization
void Start () {

}

// Update is called once per frame
void Update () {
    Target = GameObject.FindWithTag("Enemy");
    transform.Translate(direction*speed*Time.deltaTime);
    transform.LookAt(Target.transform);
}

}

So far this works fine, when the turret sphere detects a collision the arrow is fired at the enemy and my script attached to the enemy destroys the arrow on collision but must require a further 2 hits before the enemy itself is destroyed,

public class Enemy1DestroyScript : MonoBehaviour {

public int count=0;
// Use this for initialization
void Start () {

}

// Update is called once per frame
void Update () {
if (count>2)
{
    Destroy(gameObject);
}
}
void OnCollisionEnter(Collision hit)
{
    if(hit.gameObject.tag=="Arrow")
    {
        Destroy(hit.gameObject);
        count++;
    }
}

}

What I would like to happen is after the first 2 secs of the arrow being fired, if there is an enemy still alive in the collison area then fire another arrow. currently an arrow is only fired when an a new enemy triggers the onTriggerEnter which is no use if some enemies require more than one arrow to be killed.

Thanks for your time!

2

var Target : GameObject;
var bullet : GameObject;
var fired = 0;

function Start () { 
}

function Update () {
   if (Target){
	  fireagain ();
   }
}
function OnTriggerEnter (other : Collider) {
		if (other.gameObject.tag == "enemy"){
		      Target = other.gameObject;
              Instantiate(bullet,transform.position,transform.rotation);
		      fired = 1;
		}
}
function fireagain (){
	if (fired == 0){
		fired = 1;
		Instantiate(bullet,transform.position,transform.rotation);
        yield WaitForSeconds (1);
		fired = 0;
	}
}
3

Its Java but few changes should make it work.

var Target : GameObject;
var bullet : GameObject;
var fired = 0;
var firerate = 2;

function Start () {
}

function Update () {
  if (Target)
  {
	fireagain ();
  } 
}

function OnTriggerEnter (other : Collider) {
		if (other.gameObject.tag == "enemy"){
		        Target = other.gameObject;
                fireagain ();
		}

}
function fireagain (){
	if (fired == 0)
	{
		fired = 1;
		Instantiate(bullet,transform.position,transform.rotation);
		yield WaitForSeconds (firerate);
		fired = 0;
	}
}
4

OnTriggerEnter only returns true on the frame when the enemy is entering the collider.

If you have new enemies instantiated at runtime, you can launch a function that would check for new enemies with FindGameObjectsWithTag, I would recommend to use every 1 or 2 sec as it is a very expensive function.

If they are all on the map at the beginning, just check for them in the Start function

Once you have those enemies in a list or built-in array of game object, you can check the distance with Vector3.Distance and check if the enemies are in a define distance and attack the closest one. Once the closest one is dead, the turret will check again for closest one and so on.