Parent rigidbody2D affecting child rigidbody2D

[acherow1]

Godot Version

4.5

Question

I have a very simple project with two 2D rigidbodies. One is a child of the other. When the parent moves, the child jitters a bit, following the movement, before snapping back to where it *should* be, but the jitter is still very noticeable. As far as I'm aware, rigidbody movement should be entirely independent of the parent-child relationship, and the child should NOT be moving with the parent. Does anyone know why this might be happening, and how to fix it?

[Harrison_Sinclair]

is it necessary that the child node is a child node?

[wchc]

You shouldn’t make a rigid body child of another rigid body.

@acherow1

As far as I’m aware, rigidbody movement should be entirely independent of the parent-child relationship, and the child should NOT be moving with the parent.

That’s incorrect.

@acherow1

Does anyone know why this might be happening, and how to fix it?

Reparent your child rigid body to not be a child of a rigid body.

[acherow1]

somewhat? its a packed scene with the topmost node being the parent rigidbody, intended to be instantiated in other scenes. I suppose I could reparent the children in the ready function but that seems like a duct tape solution.

[acherow1]

This never happened with other versions of Godot. It was correct up until this version, why would I have assumed otherwise

[wchc]

I don’t think parenting 2 rigidbodies together were ever correct, that’s against how rigidbodies work in principle.
See this post from 2 years ago, someone gave exactly the same answer.

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Attention Topic was automatically imported from the old Question2Answer platform. Asked By axii My goal for having a Rigidbody parented to another Rigidbody is to create a ‘slime’ block, where once the slime has touched another rigidbody, it sticks to it, and to achieve this I have tried all of the joints (to little success) and have now tried reparenting the piece to stick to the slime rigidbody. However, this causes the rigidbody from t…

Rigidbodies should be controlled by physics directly.
If you don’t want the child to move with the parent, why do you even parent them together? Just separate them from each other and both your problems are solved.

[acherow1]

I see..

Well as explained above its just a matter of the parent rigidbody being a prefab. When one is instantiated I want the other one to be there as well. I suppose I could have an empty node as a parent of both and instantiate that, but then for every instance of it there will be a random node2D floating somewhere… Doesn’t feel very elegant. Neither does reparenting the bodies on the ready function and then deleting the floating node2D, but I suppose some jank has to be accepted for functionality.

[wchc]

What are these parent and child rigidbodies specifically in your game? E.g. is it a player and a ball? Etc.
Knowing that, we can then maybe help you make this decision.