How to line up torus with disc?

I have a disc that I position on a sphere, and I’m able to orient it to face out correctly by using the lookAt function.

Now I want to place a torus around it, for use with an animation effect. I originally thought parenting the torus to the disc would rotate it the same way, and it hasn’t worked out like I expected.

I have a way of working for now, where I don’t parent, and I rotate the X and it seems to work. However, I feel like there’s a simpler, more trustworthy way to achieve what I’m looking for.

PG starts out in “first attempt, not working” mode. then there are two booleans to show my other attempts.

(lines 64 and 72).

In my app, i move from the sphere to a projected flat plane, and I need to position the torus correctly there as well. I am able to keep the disc oriented with the lookAt command, but I don’t know if rotating around X is the way to go when this happens.

i’d prefer to somehow use the Parent to help me orient it the torus in the correction direction.

Any suggestions?


Hi @Keeger

Can you give a link to your PG? I’ll take a look

boy i feel dumb. i thought i had put it in!

when the parenting is set, any change on orientation/position/scaling is also applied to the children. So, you have to build the couple disc/torus before adding any change like the lookat.
That’s what I did in this PR:

I also added a rotation on X axis for the torus so the torus is around the disc (line 36). And then, you can apply any change on the disc and the torus will follow.

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Oh i feel dumb.

I never tried setting the torus rotation before assigning parent. I saw that when I assigned the parent to the torus, it changed the rotation and the position, so I assumed it would do what it does for position: override it.

Didn’t realize it would add to it and basically proportionately maintain the rotation.

Cedric, big thanks. I spent so many hours and the answer was simple! I knew there was a way to make it work with parent, cuz i’m moving the parent around and just want the animation go stay with it.


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in case you are curious, I was able to set a cone on to the disc, make the disc parent for everything, and keep stuff lined up just using disc. pretty happy!

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