"Unroll" a Curve and markers?

Rhino Rhino for Windows
1

Is there a command to “unroll” a profile with markers on it, or do I have to split it at the points and use “Length” on each section?

C__Users_cmgui_CAD_Musical Instrument_Guitar_335-345_ES-335 Side Bending form II.3dm (271 KB) - Rhino 7 Commercial - Top 7_5_2025 1_59_22 PM
C__Users_cmgui_CAD_Musical Instrument_Guitar_335-345_ES-335 Side Bending form II.3dm (271 KB) - Rhino 7 Commercial - Top 7_5_2025 1_59_22 PM2048×1109 155 KB

2

You can use the Length command to measure the curve, then draw a straight line with that length. After that, use the Flow command to map the markers from the original curve onto the straight line.

3

I do not know where the markers are , in relation to the length of the curve.

I ended up splitting it using the markers, then did “Length” on each section, and drew a straight line from that information.

C__Users_cmgui_CAD_Musical Instrument_Guitar_335-345_ES-335 Side Bending form II.3dm (271 KB) - Rhino 7 Commercial - Top 7_5_2025 2_33_10 PM
C__Users_cmgui_CAD_Musical Instrument_Guitar_335-345_ES-335 Side Bending form II.3dm (271 KB) - Rhino 7 Commercial - Top 7_5_2025 2_33_10 PM2048×1109 166 KB

Actually “flow” worked, after some fumbling around - Thanks!

4

You don’t need to know where the markers are—Flow keeps their relative position along the curve when mapping to the straight line with the same length.

5

You can also use this updated script — it’s a newer version of the one I shared earlier in this thread:

import Rhino
import scriptcontext as sc

def UnrollCurve():
    # Get the base curve
    result, curve_ref = Rhino.Input.RhinoGet.GetOneObject("Select curve", False, Rhino.DocObjects.ObjectType.Curve)
    if result != Rhino.Commands.Result.Success: return result

    base_curve = curve_ref.Curve()
    if not base_curve: return Rhino.Commands.Result.Failure

    # Create a straight line with the same length as the curve
    straight_line = Rhino.Geometry.Line(
        Rhino.Geometry.Point3d.Origin,
        Rhino.Geometry.Vector3d.XAxis,
        base_curve.GetLength()
    )
    sc.doc.Objects.AddLine(straight_line)

    # Get the objects to unroll along the curve
    result, object_refs = Rhino.Input.RhinoGet.GetMultipleObjects(
        "Select objects to unroll along curve",
        False,
        Rhino.DocObjects.ObjectType.AnyObject
    )
    if result == Rhino.Commands.Result.Success:
        flow_morph = Rhino.Geometry.Morphs.FlowSpaceMorph(base_curve, straight_line.ToNurbsCurve(), False)

        for obj_ref in object_refs:
            original_geometry = obj_ref.Geometry()
            if original_geometry:
                morphed_geometry = original_geometry.Duplicate()
                flow_morph.Morph(morphed_geometry)
                sc.doc.Objects.Add(morphed_geometry)

    sc.doc.Views.Redraw()
    return Rhino.Commands.Result.Success

if __name__ == "__main__":
    UnrollCurve()
6

That’s cool. I had to use roadlike=yes, the markers were being drawn as if the new line was not straight?

I got what I need for now, but will further explore the script and it’s uses.

Thanks again!