Array of GameObjects

Question

Hi All.

I'm having some trouble adding and especially retrieving GameObjects from an array. Here is a code sample:

var balls = new Array();

function Start() {

// Instantiate ball for test-purpose
var newBall : GameObject = GameObject.Instantiate(ballPrefab,Vector3(10.0,0.0,10.0),Quaternion.identity) as GameObject;
balls.Add(newBall);

}

function findClosestBall(ball_x : int, ball_y : int) : GameObject {

for (var i=0; balls.length; i++){ var ball : GameObject = balls[i] as GameObject; // THIS MAKES ERROR var ballVector : Vector3 = (ball.transform.position); }

return null;

}

The error I'm getting is: NullReferenceException: Object reference not set to an instance of an object

What am I doing wrong? What is the correct way to store an array of GameObjects?

Thanks, Jonas

Answer 1

Problem is solved. Answer can be found at http://forum.unity3d.com/viewtopic.php?t=49078

In short, here is the code:

var balls : ArrayList;

function Start() { balls = new ArrayList();

// Instantiate ball for test-purpose var newBall = Instantiate(ballPrefab,Vector3(10.0,0.0,10.0),Quaternion.identity); balls.Add(newBall.gameObject); // Notice .gameObject }

function findClosestBall(ball_x : int, ball_y : int) : GameObject {

var closestBall : GameObject; var shortestDistance : float = 9999; var ballPos : Vector3; var coordinatePos : Vector3; var distanceVector : Vector3;

for(var ball : GameObject in balls){ ballPos = ball.transform.position; coordinatePos = Vector3(ball_x, GameController.y_height, ball_y); distanceVector = ballPos - coordinatePos;

  if (distanceVector.magnitude < shortestDistance){ 
     closestBall = ball; 
     shortestDistance = distanceVector.magnitude; 
  }

} return closestBall; }

Answer 2

Answer by duck · Apr 09, 2010 at 09:55 AM

your for statement has an error. It says:

for (var i=0; balls.length; i++) {

when it should say:

for (var i=0; i < balls.length; i++){

Add comment · Show 1 · Share

Jonas · Apr 09, 2010 at 10:37 AM 0

Share

Yeah of course. That's not the error though.

Answer 3

Answer by Shadamer · Nov 30, 2013 at 03:43 PM

No, he's right. That would cause the error. If balls.length is not zero, that expression evaluates to true, no matter what iteration you're on. You'll eventually hit the end of the array and be out of objects, hence the null reference.

Add comment · Share

Answer 4

Answer by ScottPeal · Jan 25, 2014 at 05:28 PM

I like to use

for (var i=0; i < balls.length - 1; i++)

Add comment · Show 1 · Share

Veith · Jun 01, 2016 at 06:42 PM -1

Share

Are your balls that short?

Array of GameObjects

4 Replies

Your answer

Follow this Question

Related Questions