Summary: How to set the length of a curve object.
The following example RhinoScript subroutine demonstrates how to set the overall length of a selected curve object. The subroutine prompts the user to pick a curve and to enter a new overall length. From this, the script determines which end of the curve to modify and trims it accordingly.
Option Explicit Sub SetCrvLength Dim crv, lold, lnew, dom, pts, t crv = Rhino.GetCurveObject("Select curve to set length", 4, True) If Not IsArray(crv) Then Exit Sub If Rhino.IsCurveClosed(crv(0)) Then Rhino.Print "Cannot set the length of closed curves." Exit Sub End If lold = Rhino.CurveLength(crv(0)) lnew = Rhino.GetReal("New curve length", lold, 0.0, lold) If Not IsNumeric(lnew) Then Exit Sub If (lnew <= 0) Or (lnew >= lold) Then Exit Sub dom = Rhino.CurveDomain(crv(0)) If (dom(1)-crv(4)) < (crv(4)-dom(0)) Then Rhino.ReverseCurve crv(0) dom = Rhino.CurveDomain(crv(0)) End If pts = Rhino.DivideCurveLength(crv(0), lnew) t = Rhino.CurveClosestPoint(crv(0), pts(1)) Rhino.TrimCurve crv(0), Array(dom(0), t), True End Sub