Something like Awake that runs even if disabled?

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The documentation for Start says:

Like the Awake function, Start is called exactly once in the lifetime of the script. However, Awake is called when the script object is initialised, regardless of whether or not the script is enabled. Start may not be called on the same frame as Awake if the script is not enabled at initialisation time. http://docs.unity3d.com/ScriptReference/MonoBehaviour.Start.html

It always seemed to me like Awake would be called regardless of whether an object were enabled or not, whereas Start would be called only when the object became active. And that this would apply to app startup. But that does not appear to be the case.

http://forum.unity3d.com/threads/unityevent-disabled-objects-awake-failure.267241/

My question is whether there is anything like Awake that is called even on disabled objects when the app is started. Because that would be terribly handy. (Or am I misunderstanding Awake, maybe it does somehow run on disabled objects at startup?)

So I think I do understand the difference between Awake and Start. If you Instantiate an object then disable it, Awake will run but Start will not. So you should initialize the object itself in Awake and its connections in Start.

What I'm asking is why can't there be another callback, like Init, which runs only at app startup, for all disabled objects in the scene, if it exists. Unity could make a list of which ones to call when it builds the scene, so it doesn't have to traverse the scene hierarchy at startup. (This is basically how static initialization functions are compiled in some languages.)

At the very least I think the docs should be clearer that Awake is not called at startup if the object is not enabled, because it really seems like it would be, as the docs currently describe.

Answer 1

Answer by Lumpazy · May 04, 2019 at 04:43 PM

Oh yeah Earth to unity : Anyone there who would think of mentioning, that a disabled scripts Awake function is executed in the actual documentation of Awake ?

Oh no. It makes Soooo much mooore seeense to mention it in the documentation for 'Start'

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Answer 2

Answer by Xtro · Jan 10, 2017 at 07:50 PM

I released this asset for free quite some time before you asked this question.

"We Need Created Message"

https://www.assetstore.unity3d.com/en/#!/content/23453

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Answer 3

Answer by Schnodahipfe · Jul 24, 2017 at 12:15 PM

Another option, which I use is the following:

Have the gameobject active in the hierarchy
Do all initializations in Awake()
Then deactivate the gameobject in Awake() after the initializations

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Answer 4

This might not help your scenario, but I was running into similar problems with wanting Awake to be called on deactivated GameObjects and children.

My situation was: I needed to deactivate my HUD GameObject at the very beginning of the game (because my game starts at the title screen, where the HUD should not be shown). But this caused Awake() to not be called on all the children of the HUD GameObject!

In Awake() in my HUD script (attached to the root GameObject of the HUD), I was using: gameObject.SetActive(false);

And consequently, all of the children scripts were not having their Awake()s being called at all. However, I found out that one possible way to help this is to deactivate the GameObject on Start() instead. Start() is still called early enough that, if I deactivate the object then, we won't see the HUD flash on the screen at all for a frame -- but it happens after all the Awake()s are called!

 using UnityEngine;
 
 public class HUD : MonoBehaviour {
     public void Start() {
         gameObject.SetActive(false);
     }
 }

I hope this helps! :)

Answer 5

Answer by vfxjex · Sep 30, 2020 at 10:11 PM

Just in case someone bumps into this problem 1st - I made a gameobject called Initializer with this simple script attached, using UnityEngine;

 public class Initializer : MonoBehaviour
 {
     public delegate void Initialize();
     public static Initialize initialize;
 
     void Awake()
     {
         initialize();
     }
 }

2nd - in your script that you want to initialize, add a Constructor and Initialize Method like this,

       using UnityEngine;
         public class MyScript: MonoBehaviour
         {
         bool isInitialized;
             MyScript()
             {
                 Initializer.initialize += Initialize;
             }
         
             void Initialize()
             {
                 if(this == null)
                 {
                     Initializer.initialize -= Initialize;
                     return; 
                 }
                 if (isInitialized)
                 {
                    Initializer.initialize -= Initialize;
                    return;
                 }
                 isInitialized = true;
                 Debug.Log("I WAS INITILIZE");
             }
         }

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Bunny83 · Sep 30, 2020 at 10:47 PM 0

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While this does solve any issues with the loading thread (since you delegate the initialization to another Awake method) this comes with several other issues. First of all in the Unity editor the objects might be created / recreated more often than you may think. So this could still be an issue. Likewise you introduce a memory leak because since you register an instance method to that delegate, that delegate will keep those objects alive forever. This could result in all sorts of hidden issues. At least clear the initialize delegate after you called it.

Similarly if this script ends up on a prefab, since your Initializer awake method is only called once any object instantiation after the Awake method has been called will still register the delegate but it will never be called or cleaned up.

Xtro · Sep 30, 2020 at 11:00 PM 0

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Doesn't work when the gameobject is disabled.

Something like Awake that runs even if disabled?

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