koobas.hobune.stream
A way to check if an object has DontDestroyOnLoad activated
Is there a way to check if a gameobject (or its parent) has been set to DontDestroyOnLoad?
A good question that I would love to know the answer to...
Assuming that there's no official way to query the property, I've come up with a workaround:
Created a simple MonoBehaviour script that calls Object.DontDestroyOnLoad(gameObject) in Awake(), and named it DontDestroyOnLoad.
function Awake() { DontDestroyOnLoad(gameObject); }
Attached the script to all objects I don't want to be destroyed, instead of doing the call from another component.
This way it's modular and I can see and modify the property in the editor. And more importantly, I can query it like this:
var obj: GameObject;
if (obj.GetComponent.<DontDestroyOnLoad>()) {
print("The object is kept between levels.");
}
unity has "gameObject.scene" for a while now
you can go all like
if (gameObject.scene.buildIndex == -1) //dontdestroy activated
nowdays
According to the docs, -1 means it was loaded by an asset bundle.
https://docs.unity3d.com/ScriptReference/Scene$$anonymous$$anagement.Scene-buildIndex.html
Are we positive that this works as expected?
gameObject.scene.buildIndex will return -1 for addressable, assetbundle in additional to DontDesroyOnLoad scene. Check gameObject.scene.name == "DontDestroyOnLoad" instead.
We worked around this function call with HideFlags. Worked for us. I guess HideFlags.DontSave is almost the same as DontDestroyOnLoad().
gameObject.hideFlags = HideFlags.DontSave;
if (!((gameObject.hideFlags & HideFlags.DontSave) == HideFlags.DontSave)) {
// You may be destroyed.
}
DontSave means that the object is not saved to the scene. Further if you load another scene this object does not get destroyed, because it is not part of the scene. Just in case you're wondering why 'dont save' even you want to 'dont destroy' it.
Ouh and you could also display a enum popup in the inspector to define what flag should be assigned. More common approach?!
From the documentation:
// Instantiates a Plane everytime the game starts and never destroys it
// even if you stop your game preview
// NOTE: Watch out, this can cause LEA$$anonymous$$S
function Start() {
var notDestructable : GameObject = GameObject.CreatePrimitive(PrimitiveType.Plane);
notDestructable.hideFlags = HideFlags.DontSave;
}
It doesn't look exactly safe, does it? It appears to be meant for editor rather than for general usage.
As long as you just check for the flag without assigning it, it shouldn't be any problem.
You can now use gameObject.scene.name == "DontDestroyOnLoad" to check if a scene is flagged with DontDestroyOnLoad.
Note that the above answer of checking gameObject.scene.buildIndex will return -1 for addressable, assetbundle in additional to DontDesroyOnLoad scene, and it likely isn't what you want.
