Random Spawning


can someone, please, tell me how to have two objects can't occupy the same position? or in other words, only one object per spawn. thank's a lot for your help

var timer : float = 0.0;
var spawning : boolean = false;
var prefab : Rigidbody;
var spawn1 : Transform;
var spawn2 : Transform;
var spawn3 : Transform;

function Update () {
 //check if spawning at the moment, if not add to timer
  timer += Time.deltaTime;
 //when timer reaches 2 seconds, call Spawn function
 if(timer >= 2){

function Spawn(){
 //set spawning to true, to stop timer counting in the Update function
 spawning = true;
 //reset the timer to 0 so process can start over
 timer = 0;

 //select a random number, inside a maths function absolute command to ensure it is a whole number
 var randomPick : int = Mathf.Abs(Random.Range(1,4));

 //create a location 'Transform' type variable to store one of 3 possible locations declared at top of script
 var location : Transform;

 //check what randomPick is, and select one of the 3 locations, based on that number
 if(randomPick == 1){
  location = spawn1;
  Debug.Log("Chose pos 1");
 else if(randomPick == 2){
  location = spawn2;
  Debug.Log("Chose pos 2");
 else if(randomPick == 3){
  location = spawn3;
  Debug.Log("Chose pos 3");

 //create the object at point of the location variable
 var thingToMake : Rigidbody = Instantiate(prefab, location.position, location.rotation);

 //halt script for 1 second before returning to the start of the process
 yield WaitForSeconds(1);
 //set spawning back to false so timer may start again
 spawning = false;

For starters, you can save yourself some code by using an array for your spawn points:

var spawn : Transform[];

function Spawn()

spawning = true;
timer = 0;

var randomPick : int = Mathf.Abs(Random.Range(0,3));

var thingToMake : Rigidbody = Instantiate(prefab, spawn[randomPick].position, spawn [randomPick].rotation);

 yield WaitForSeconds(1);
 spawning = false;

As for your question, not quite clear what you're trying to achieve. Do you mean you only want a spawn point to be used once? In other words, are you asking how to make it so that, for example, spawn point 2 isn't used twice in a row?