An equivalent of "Sample Curve" but in a driver expression?

Question

I would like to utilize a curve tangent or a curve normal in my driver (i.e. in its Scripted expression)
When working with geometry there's the "Sample Curve" node for that. Is it possible to obtain those values in a property driver?

What I am trying to do:

have my vehicle model follow a path object
Done - I used the "Follow path" constraint on the vehicle parent object.
have the wheels rotate according to the distance travelled along this path object
Done - a driver on the "Rotation X" in Delta Transform does that for me. (The driver references the offset of the aforementioned "Follow Path" constraint.)
have the wheels steer/aim according to the tangent (or the normal?) of the curve

You could use this technique: Passing GeoNodes attribute to Shader frame offset to read the data in geonodes and pass it to a driver. — Markus von Broady, Jul 28 '23 at 22:53
The cleanest method might well be case-by-case .. could you give an example of how you want to use the vectors? — Robin Betts, Jul 29 '23 at 07:17
@RobinBetts good point, I am going to update the question elaborate more — Jaroslav Záruba, Jul 29 '23 at 10:48
@MarkusvonBroady Thanks, that's a step in the right direction! I am not very skilled in Blender, so I don't know yet how to bring the tangent at a point on a path object into the "calculation" part of another object... While the point is determined by a constraint: ${constraints["Follow Path"].offset} — Jaroslav Záruba, Jul 29 '23 at 10:56

Jaroslav Záruba · Answer 1 · 2023-07-29T15:22:09.933

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Only now I realized I can add inputs to my Geometry Node group, and such input can have its own driver:

edited Jul 29 '23 at 15:22

answered Jul 29 '23 at 14:04

Jaroslav Záruba

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An equivalent of "Sample Curve" but in a driver expression?

1 Answers1