Strange and unexpected behaviour with Transform.SetParent

I have noticed that when assigning a parent to a gameobject with the instruction Transform.SetParent, in runtime, the new parent is rotated depending on the child gameobject rotation.
Is it a bug?
In any case it is an absurd and unexpected behaviour, because I expected the child to be affected by the parent transform but not inversely.

 

The new parent should not be affected, no. Are you certain there is no other process acting on the parent? Can you post the code that is causing the issue?

 

If you can provide an isolated example of this happening, it definitely sounds like a bug. Seems unlikely though.

 

I have to admit my game project is quite complex. But I have managed to isolate the issue and it only happens when I use an script to instantiate runtime enemy ai bots and I parent them to the root scenary object area.
So I think the issue can be reproduced using the SetParent instruction runtime with a child moving object newly created, in my case the enemy AI bots. Then the parent transform is affected by that child and strangely the root scenary object is rotated (even although it is marked as static)

 

There's still got to be some other factor. That is one of the most common things done in nearly every Unity game, and literally every game would break if that caused the parent to move.

 

I would like to share my project with you to show this strange issue, but it weights 40 Gb...
Thanks anyway.

 

That is not isolation. Isolation is when you open a new, empty project, drop two gameobjects in it, write a script to simulate your basic premise: moving object parenting to the not moving one and check if the rotation is changing or not. Who knows what the pathfinding/AI system does for example?

 

Sorry, I only wanted to say that when I don't use that script the issue does not happen.
Thanks.

 

Hmm maybe share that particular script then? Maybe we can find an issue that you missed.

 

This is the script simplified, deleting the line :pirate1.SetParent(transform.root) the issue doesn't happen.The script is attached to a gameobject inside the object root (scenary) hierarchy.

(Sorry by the spaghetti code)

void Update()

cam=Camera.main.transform;

dist=Vector3.Distance(cam.position, transform.position);

if ( dist<100){

if (created1==false && Vector3.Distance(cam.position, point1.transform.position)<50){
if (pirate1==null){
pirate1=Instantiate(pirateprefab,point1.transform.position, Quaternion.identity);
pirate1.SetParent(transform.root); // TRANSFORM.ROOT IS THE SCENARY ROOT OBJECT ***
}else{
pirate1.transform.position=point1.transform.position;
pirate1.gameObject.SetActive(true);
}
created1=true;
}
}

if ( dist>200){
if (pirate1)
pirate1.gameObject.SetActive(false);
created1=false;
}
}

 

Please read this: https://forum.unity.com/threads/using-code-tags-properly.143875/

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Well, I guess the problem isn't in this part of the script.