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Question by shatley123 · Nov 30, 2013 at 10:16 AM · errorarrayarraystower-defense

Error when trying to set variable with array

I'm trying to make a tower defense game. I've never used array's before, so i figured now would be a good time. I'm making a enemy, were the goal is to move from waypoint to waypoint. I'm using smoothdamp, so i need target positions, but when i try to set the target positions using the array, i get an error saying "NullReferenceException: Object reference not set to an instance of an object Boo.Lang.Runtime.RuntimeServices.CheckNumericPromotion (IConvertible convertible) Boo.Lang.Runtime.RuntimeServices.CheckNumericPromotion (System.Object value) Boo.Lang.Runtime.RuntimeServices.UnboxSingle (System.Object value) enemy.Update () (at Assets/scripts/enemy.js:16)" If anybody can help me figure out why this is happening, i'd very much appreciate it. Here is my script...

 var waypoint : Transform[];
 var currentWaypoint : int;
 
 //moving smoothdamp vars
 var targetX : float;
 var targetZ : float;
 var time : float;
 private var velocity : float;
 
 function Update()
 {
     targetX = waypoint[currentWaypoint].x;
     targetZ = waypoint[currentWaypoint].z;
     
     transform.position.x = Mathf.SmoothDamp(transform.position.x, targetX, velocity, time * Time.deltaTime);
     transform.position.z = Mathf.SmoothDamp(transform.position.z, targetZ, velocity, time * Time.deltaTime);
 }
 
 function Awake()
 {
     waypoint = Camera.main.GetComponent(waypointsInit).waypoints;
     currentWaypoint = 0;
     targetX = transform.position.x;
     targetZ = transform.position.z;
 }
 
 function OnTriggerEnter(hit : Collider)
 {
     if(hit.gameObject.tag == "waypoint")
     {
         currentWaypoint += 1;
         print(currentWaypoint);
     }
 }
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Best Answer

Answer by bompi88 · Nov 30, 2013 at 03:12 PM

Your waypoint variable contains an array of Transforms, so it's waypoint[currentWaypoint].position.x not waypoint[currentWaypoint].x. So

 targetX = waypoint[currentWaypoint].position.x;
 targetZ = waypoint[currentWaypoint].position.z;

And make sure you have initialized the array in the script that is attached to the camera with some transforms in the inspector, before you run the script.

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