koobas.hobune.stream
How does Transform.SetParent() worldPositionStays work with null parent?
Hi there,
I have trouble understanding how Transform.SetParent()'s worldPositionStays parameter works, specifically when parent is set to null.
The scripting reference says:
If true, the parent-relative position, scale and rotation are modified such that the object keeps the same world space position, rotation and scale as before.
Naturally, I usually set it to true, because I don't want parenting to change position, rotation, or scale. So I was surprised when trying to "unparent" with transform.SetParent(null, true); the inverse of the parents' scale was applied! Even though if I carefully think about it, localScale relative to null parent (assuming the scale of null is (1, 1, 1)) would mean just localScale, I still expected that it will automatically compensate for the relative differences between the original and new parents' scales. Note that if I "unparent" with worldPositionStays = false it works as I originally expected.
EDIT: Interestingly, this answer says the opposite about how worldPositionStays works...
So, basically, my questions are:
- why does transform.SetParent()'s worldPositionStays work this way when the parent is set to null?
- is the above observed the intended behaviour, or is it a bug? (I was expecting it to compensate for scale differences)
- in general, what is the recommended way of using worldPositionStays?
Also, I seem to remember transform.parent being deprecated in Unity 5 and worldPositionStays defaulting to false... does my memory play tricks on me, or was this changed recently?
I don't know but if I had to guess you'd be the one to find this answer...
I am sorry.. :.(
Good day.
If i had this problem, i should solve the problem "thinking outside the box"... i mean, you can store the values you need, unparent it, and assign the values again (if unparentiung changes it, it doesent care, you wil lchange it after)
Bye!
Of course I can assign it the values I want, but that is not "thinking outside the box", that is a workaround, and I want to understand how it works internally.
To give a bit of background, the whole issue came up while writing an object pool to make instantiating more efficient. When I moved an object to the pool, I parented it to the object pool game object, and when taking it out, I unparented ( SetParent(null)). But it seems setting the parent is really slow, and modifying position and scale slows things down even more.
