Dynamic curve on mesh

Hi all,
i’m currently trying to write a script that allows you to draw a controlpoint curve on a mesh where you can dynamically change the amount of points and see a preview of the resulting curve while drawing.
I’ found some nice examples that work on a surface
http://discourse.mcneel.com/t/curve-on-surface-with-rebuild-how-to-solve-preview-interruption-solved/31313

So i was wondering if this is also possible on a mesh?

Thanks

Tom

Why do you need to do this? What problem are you trying to solve?

The Rhino SDK does not have a function to create a control points curve on a mesh. So the process is to create a control points curve, perhaps snapping to mesh vertices, and then projecting that curve onto the mesh (in which case the original curve data will lost).

Hi Dale,
What i’m trying to do is design some kind of shell based on a 3d scan of an object. This shell is basically an offset of part of the mesh. To define the region of the scan I want to offset I use the method you described (projecting curves on the mesh).

What i’m actually after now is to show some kind of dynamic preview of the interpolated curve (I pull this curve to the mesh in the next step) while I’m selecting the points on the mesh that will make up this curve.

Rhino already has a PolylineOnMesh command. Is this helpful?