ArcPointDistribution.rvb

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' ArcPointDistribution.rvb -- February 2009
' If this code works, it was written by Dale Fugier.
' If not, I don't know who wrote it.
' Works with Rhino 4.0.
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Option Explicit

Sub ArcPointDistribution
  
  ' Local variables
  Dim arc, cnt, rads
  Dim n_t(), n, i, a0, a1
  Dim line, dom, t

  ' Select arc curve  
  arc = Rhino.GetObject("Select arc", 4)
  If IsNull(arc) Then Exit Sub
  If Not Rhino.IsArc(arc) Then Exit Sub

  ' Get number of points to calculate
  cnt = Rhino.GetInteger("Number of points", 2)
  If IsNull(cnt) Then Exit Sub   
  
  rads = Rhino.ToRadians(Rhino.ArcAngle(arc))
  n = cnt - 1
  ReDim n_t(n)
  
  ' Calculate normalized parameters
  For i = 0 To n
    a0 = Sin(rads/2)
    a1 = Sin(i*rads/n - rads/2)
    n_t(i) = (a0+a1)/(2*a0)
  Next
  
  Rhino.EnableRedraw False
  
  line = Rhino.AddLine(Rhino.CurveStartPoint(arc), Rhino.CurveEndPoint(arc))
  dom = Rhino.CurveDomain(line)
  
  For i = 0 To n
    ' Convert normalized parameter to domain value
    t = (1.0 - n_t(i)) * dom(0) + n_t(i) * dom(1)
    Rhino.AddPoint Rhino.EvaluateCurve(line, t)
  Next
  
  'Rhino.DeleteObject line

  Rhino.EnableRedraw True

End Sub