Joints on a curve on surface


#1

Hello everyone!

I would like to understand the reason behind this behaviour.

So I create a nurbs sphere, make it live and draw a curve on it. I’m trying to attach joints to the curve with the pointOnCurveInfo node. With “common” curves it works fine, but with curves on surfaces it creates the joints in a totally arbitrary place. I’m sure there’s a reason for it, but what is it?


#2

Hello ! I’ve just tried this and from what it looks like the joints are following the curve, but projected on a plane instead of the sphere ? Maybe a local space issue ?

Good news is I also found a fix ! If you use the duplicate surface curve tool, you can use the duplicated curve to drive the pointOnCurve node and the position will be correct :slight_smile:


#3

hey, elenatchi

thanks for the reply.

the issue with duplicating is that if you grab a cv and move it, you’re moving it in the world space while in my case the curve is on the surface and the cvs move in the uv space of the surface.


#4

But when you use the duplicate curve on surface command, you can still move the cvs along the surface of the original and the duplicate will follow right ?


#5

yes, the curve follows the surface , but if you grab a cv of the curve it won’t follow the curvature of the surface.

anyway, I just figured out why the joints were being created in an “arbitrary” position.
because our curve is in the surface (or uv) space the result of our pointOnCurveInfo will be uv information not world space information. so we just need to convert it back to world space. For now i’m using pointOnSurfaceInfo for this.


#6

Oh great ! Good to know what was causing the problem though, this kind of setup could be very useful, now I want to test it out for myself :blush: