Geodesic and Plank Lines on Surface Help

Grasshopper
1

This is a relatively simple, yet hyper-specific question.
Are there any plugins or features in Rhino or Grasshoppper that allow creation of a geodesic line by defining a start point and an angle? I am aware of the current “Short Path” and “Geodesic” commands that already exist, but I’d like to run a command that gives me results like this: Geodesic curve on a torus.
I have found examples of this in the past, that have been available, but none of them work with the current version:
The Geometry of Bending: Geodesics on a Cone
eat-a-bug: Surface Turtle
The Geometry of Bending: ToyCar plug-in for Rhino by David Rutten
The plugin by the David Rutten is what I’m looking for, especially.

I have found a plugin that’s very similar:https://www.food4rhino.com/app/curveonsurface-0,
but it behaves more like a chain of shortpaths, pulled to a surface, and smoothed, which is incredibly buggy.

Any help or assistance is super appreciated, even if we don’t find a working answer.

2

Just to be sure, you need “exact” (curve) or approximated (polyline on mesh) ?
For mesh you could use



3

Oof, I saw those plugins too, but they aren’t quite right.
I’d like a smooth exact curve, so that it can be unrolled flat and can have straight edges.

4

What I understand from David Rutten discussion is that toy car was not exact in the sense it uses discretized calculations.

What do you mean by ?

Toycar.rhp is here (thanks Google), it works here :grinning:

5

Thank you. That is exactly what I was looking for and it does still work like a charm.
Thanks for doing that digging, I had not come across that thread.