koobas.hobune.stream
List search gives null
Hello, i've got an issue here and might need some help with it. First my code: using UnityEngine; using System.Collections;
public class AttackTowerAimAndShoot : MonoBehaviour {
public float reload = 1F;
public float firePause = 0.25F;
public GameObject effect;
public float amount = 0.001F;
Transform target;
Transform[] muzzlePositions;
Transform turretTurnPoint;
float newFireTime;
float newMoveTime;
private Quaternion rotation;
private float aimError;
GameObject projectile;
public float range = 500F;
// Use this for initialization
void Start () {
Transform muzzle1 = transform.FindChild("MuzzlePos1");
Transform muzzle2 = transform.FindChild("MuzzlePos2");
turretTurnPoint = transform.FindChild("Turret");
}
// Update is called once per frame
void Update () {
if (target == null)
return;
if (target != null)
{
transform.LookAt(target);
newFireTime = Time.time + (reload * 0.5F);
if (Time.time >= newFireTime)
{
Fire ();
}
}
GetTargetEnemy();
}
void Fire ()
{
newFireTime = Time.time + reload;
newMoveTime = Time.time + firePause;
//CalculateAimError();
for (int i = 0; i < muzzlePositions.Length; i++)
{
projectile = Instantiate (Resources.Load("Bullet"), muzzlePositions[i].position, muzzlePositions[i].rotation) as GameObject;
effect = Instantiate (Resources.Load("FireMuzzle"), muzzlePositions[i].position, muzzlePositions[i].rotation) as GameObject;
}
}
void GetTargetEnemy()
{
for (int i = 0; i < StaticVariables.enemies.Count; i++)
{
if(StaticVariables.enemies[i].transform == null)
{
StaticVariables.enemies.Remove(StaticVariables.enemies[i]);
continue;
}
if(Vector3.Distance (StaticVariables.enemies[i].position, transform.position) < range)
{
//Debug.Log(Vector3.Distance (StaticVariables.enemies[i].position, transform.position));
target = StaticVariables.enemies[i];
break;
}
}
The problem is with the last part: The void GetTargetEnemy(). I want my towers to search through a list for a target. Though, the enemies[i] always returns 'null', so my towers don't get a new target. I don't understand any of it and I get a NullReferenceException at the Vector3.Distance check all the time. Any help or word of advice is welcome. Thanks in advance!
Oh, sorry, that's in another code... $$anonymous$$y list: public static List enemies = new List();
And the line of code in which I fill the List:
void Spawn() { for (int i = 0; i < spawnPoints.Length; i++) { enemy = Instantiate (Resources.Load("Enemy"), spawnPoints[i].position, spawnPoints[i].rotation) as Transform;
StaticVariables.enemies.Add(enemy);
Debug.Log("Enemies " + StaticVariables.enemies.Count);
}
}
Spawning the enemy and adding it directly in the list (I think it does that, at least)
Sorry for the messy script part and in the enemy = Instantiate part enemy is defined as a Transform
I don't see any List in unity, but there is ArrayList (which I think functions the same). Is that what your are using?
@dorpeleg List is a generic list available in Unity and should always be used ins$$anonymous$$d of ArrayList
My guess is that you enemies are getting nulled as they are destroyed.
Given you didn't format your code quite right it's hard to see if your enemy list is
List<Transform> enemies = new List<Transform>();
Presuming it is then I would suggest that you change you loop to look like this:
for(int i = StaticVariables.enemies.Count-1; i>= 0; i--)
{
if(StaticVariables.enemies[i] == null) //Not .transform
{
enemies.RemoveAt(i);
continue;
}
//distance check etcetera
Yes, this does make sense, it's still not working propperly, though... $$anonymous$$y NullReferenceException is gone (and I think I also get the logic behind this For loop) but my 'towers' still don't get a target through... I don't know if this is because I tell the script to look at the distance of the [i] ins$$anonymous$$d of pointing to a Transform object in the first place, but i don't know how to fix this... Is there any way to fix this, or can you give me a hint for another option? Or should i ask this in another question? Anyway: thank you for letting me know the secret behind the NullReference mystery! :D
Fixed the problem: I spawned the enemies as Transforms and (I don't know why this happened) they where made null as soon as they entered the list. All i had to do was modify this part:
public Transform enemy;
enemy = Instantiate (Resources.Load("FastEnemy"), spawnPoints[i].position, spawnPoints[i].rotation)
To this:
GameObject newEnemy = Instantiate (Resources.Load("FastEnemy"), spawnPoints[i].position, spawnPoints[i].rotation) as GameObject;
enemy = newEnemy.transform;
And then add it to the list :)
