How to edit InterpCrvOnSrf on a rounded surface of a ring

Hello everyone
this being my first post here.
I need to create an organic relief on the surface of a ring which is rounded in both directions.
the InterpCrvOnSrf lets me draw the curves directly on the ring, but it’s tricky to control and requires points editing.
is there a way to edit the curve’s control points without leaving the ring surface?
there’s the On-surface Snap option but it is Greyed out
I could draw the curves flat within a CreateUVCrv boundary, then FlowAlongSrf them only this would be a limiting compromise here, and i hope there is a good way to edit the curves directly on the ring’s surface.

many thanks for all this wealth of information here in this great forum

How about using Project or Pull to get your curve an a surface (with Record History)? You can pull your edited InterpcrvOnSrf or other, cleaner curve (with fewer control points than InterpcrvOnSrf usually has).

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yes Project with History works very well. I have managed to draw the curves for the leaves with Project already but enabling Rec. History as you suggested has allowed for the editing freedom needed for creating a [Chased] relief on a ring.
[Pull is a new one for me… I’ll look into it as well]
many thanks


I met the same situation that the curve’s control points with leaving the surface.
Have you solved the problem? I don’t know how to handle it.
I want to edit curve’s control points to modify the curve’s shape on surface.
I will appreciate it for your help.

Maybe best that you post the surface and curves you are having issue with [in .3dm]
and an example [like a drawing] of what you are trying to achieve.

I don’t remember what happened in regard to the issue in this thread, it was 4 years ago.
Now days I usually do organic forms in another software. But most probably you can do what you need in Rhino.
Post the geometry and people here will help you.
best regards

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Thanks to your relpy.
like this,some edit points are on the surface,but some points were not.
I have tried the CurveOnSurface plugins,but it can’t make close curve on surface.
Best wishes!

For a curve on a non-planar surface the control points will not be on the surface. The edit points will be on the surface.

Modify the curve by moving an edit point on the surface and portions of the curve and some of the other edit points will usually move away from the surface. The same will occur if a control point is moved. That is how the math of NURBS curves and surfaces works. As noted in a previous comment Pull or Project can be used to move the curve back on to the surface.