how to call something just once from an update function

You'd be better off not using Update, but rather a coroutine, since the point of Update is that it runs every frame. With a coroutine you can just wait until the event is done and run the code afterward once.

Here's an exampe on how to use a coroutine: In this (really simple) example the coroutine gets started in the Start() function.

 void Start()
 {
     StartCoroutine(DoSomeStuff());
 }
 
 IEnumerator DoSomeStuff()
 {
 
     //"Ready" gets logged
     Debug.Log("Ready");
     
     //Coroutine will wait 1 second to continue
     yield return new WaitForSeconds(1.0f);
     
     //"Set" gets logged
     Debug.Log("Set");
     
     //Coroutine will wait 1 second to continue         
     yield return new WaitForSeconds(1.0f);
 
     //"Go" gets logged
     Debug.log("Go");
 
     ...
 }

You can do anything you like within a coroutine, the "yield" statement simply sets the function on "hold" for how long you choose.

You can also use "yield return new WaitForEndOfFrame()" and other functions. When you get the hang of coroutines, you can do some really cool stuff with it.

Cheers.

Hi,

It took me awhile, but I finally figured out I could do what I wanted with a simple Boolean variable, doorPresent, which I set false in the Start() function. Then I set that to true after making only one door. Seems to be working so far. Coroutines and yield look really interesting -- will study them more. Thanks. Zaffer

 function Update() { 
     if(Application.GetStreamProgressForLevel(levelToLoad) == 1) { 
        Progress.message = "Level at index 1 has been fully streamed!";
        //StartCoroutine(MakeDoor()); 
        MakeDoor();
        level1Ready = true; 
     }
     else {
         percentageLoaded = Application.GetStreamProgressForLevel(levelToLoad) * 100;
         Progress.message = percentageLoaded.ToString();
         level1Ready = false;
     }
 } 
 
 function MakeDoor(){
     //yield;
     if(doorPresent == false){
         Instantiate(door, Vector3(154, 1.8, 166), Quaternion.identity);
         doorPresent = true;
     }
    
 }

Hi Eric5h5 and Tim,

I wanted to take your advice about coroutines being better, and after some work, I was able to set up a loading sequence using a while loop, yield and coroutines instead Update(). I needed a little help from regular forum, but everything works. Here's the code. Zaffer

P.S. You are right, Tim, couroutines are very cool!

function Start(){ ManageLoadingElements(); }

 function ManageLoadingElements(){
     yield StartCoroutine("SetUpLoadingElements");
     TakeDownLoadingElements();
 }
  
 function SetUpLoadingElements(){
     while(Application.GetStreamProgressForLevel(levelToLoad) < 1){
         percentageLoaded = Application.GetStreamProgressForLevel(levelToLoad) * 100;
         progressCylinder.transform.localScale.x = percentageLoaded * 0.1;
         progressCylinder.transform.position = progressCylinderPosition;
         progressText3D.text = Mathf.RoundToInt(percentageLoaded) + "%"; 
         yield;
     }
 }
  
 function TakeDownLoadingElements(){
     Destroy(progressCylinder);
     Destroy(progressText3D);  
     MakeDoor();
 }
  
 function MakeDoor(){
     var door : GameObject;
     if(doorPresent == false){
         door = Instantiate(doorPrefab, Vector3(157, 2.65, 169.59), Quaternion.identity);
         doorPresent = true;
         door.name = "Iron Door";
     }
 }

I would use a boolean variable, that is true only for the first run.

 var firstCall:Boolean;
 void Start()
 {
     firstCall = true;
 }
 function Update() { 
     if(Application.GetStreamProgressForLevel(levelToLoad) == 1) { 
        Progress.message = "Level at index 1 has been fully streamed!";
        //StartCoroutine(MakeDoor());
        if(firstCall)
        {
           MakeDoor();
           firstCall = false;
        }
        level1Ready = true; 
     }
     else {
         percentageLoaded = Application.GetStreamProgressForLevel(levelToLoad) * 100;
         Progress.message = percentageLoaded.ToString();
         level1Ready = false;
     }
 }