Any way to have gravity not act on child but act on its parent?

Archived Forums Questions & Answers
1

Referring to this video- https://streamable.com/6rpues
I’m trying to make it so that the object with the box collider does NOT have gravity on it, but its parent (an empty GameObject with a sphere collider and rigidbody) does have gravity. In that video, see when I extend the box collider, the sphere begins to tilt over to that side. That’s what I’m trying to not make happen. I want to keep it so that the box collider can push the sphere like it does.

I’ve tried using a separate object with its own rigidbody and then linking the two with a Fixed Joint, but that was creating odd issues.

I’ve also tried linking the two (when seperate gameobjects) via code, but then the sphere wouldn’t get pushed away when the box hits a wall.

I feel like I’m at that point where I’ve been thinking about this for too long and need a fresh set of eyes on this issue :slight_smile:

2 Answers

2
2

A child is bound to its parents euclidean space (all the way up to world space). They move relative to their parent. So whilst you could compensate for it… really you probably shouldnt.

Why does it need to be composed that way? cant you just do it the other way round?

I.e. move the child and leave the parent stationary.

Thanks for the reply! I've tried messing around with reversing the child/parent relationship, but I haven't found anything that works since I'm growing the localScale.y of the parent object in order to have the box stretch from one end. So when I apply the sphere collider to the child, the sphere got bigger with the extension of the cube. I feel like I might be missing something really simple. The whole issue stems from the problem that I want that box collider to be effectively weightless, but still have it fixed to that sphere which has weight and gravity.

 –
3

To anyone who might come across this question in the future: I found a solution despite it might not being elegant or best practice. Instead of trying to restructure the object hierarchy and mess with a bunch of empty GameObjects and stuff, the answer was to simply set the rigidbody’s centerOfMass to a point that always stays in the center of the sphere (in my case, that cube). Hm, maybe this was a good solution? I don’t even know anymore. I feel satisfied. Time for dinner.