Shift closed polyline start point method in grasshopper?

[hayden]

Hi,

How do you change the start point of a closed polyline in GH.

I came across @Helvetosaur query but unfortunately I couldn’t follow as I cant script.

Shift closed polyline start point method?

If I have a Rhino.Geometry.Polyline object which is closed and I want to shift the start point a certain number of indices along the curve, is there a simple method? Not finding anything like a “Change seam” or “Shift list” method in the Polyline class, I improvised this - which is more than a bit of a kludge: #orig_polyline is already a polyline and I want to shift the start point, say 2 #new blank polyline plx=Rhino.Geometry.Polyline() new_start index=2 #add from index to end of list-1 (but…

TIA
H

[0904]

_CrvSeam ?

(Seam in Gh)

[Joseph_Oster]

You don’t need Python for this.

With a polyline, you have two choices:

1. ignore vertices (white point)
2. move start/end point to a different vertex (blue point)

seam_2024Jan21a.gh (9.9 KB)

[Helvetosaur]

Well, if it’s a closed polyline, you can also just shift the point list and create a new polyline - which is what the script does IIRC.

Of course this will produce weird results with open polylines, but you can filter for that if necessary.

[hayden]

Thanks guys. H