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• 2. Johannes (Apr 07, 2010 16.28):

  hi,
  here is a way to work without rhino commands... you can pick every point on a surface and you will get a line in normal direction with a specified length.
  this script works on every surface (in normal direction):

  Option Explicit
  
  Call SrfNormal()
  Sub SrfNormal()
         
  ' input paramter
  Dim strSrf      : strSrf = Rhino.GetObject("pick srf", 8+16)
  Dim strPt       : strPt = Rhino.GetPointOnSurface(strSrf, "pick point on surface")
  Dim dblLeng     : dblLeng = Rhino.GetReal("length of normal curve", 15)
         
  ' change 3dPoint to UVCoordinates
  Dim dblPar      : dblPar = Rhino.SurfaceClosestPoint(strSrf, strPt)  
  ' zero based normal vector at UVCoordinates
  Dim vNormal     : vNormal = Rhino.SurfaceNormal(strSrf, dblPar)
  ' scaled vector
  vNormal = Rhino.VectorScale(vNormal, dblLeng)
  ' 2nd point
  Dim strPt2      : strPt2 = Rhino.VectorAdd(strPt, vNormal)
         
  ' line between 1st and 2nd point
  Dim strLine     : strLine = Rhino.AddLine(strPt, strPt2)
  
  End Sub

• 1. mrgordon (Apr 07, 2010 03.37):

  I am trying to find a normal line. It seems like the easiest way is to use the _Line command line method. I managed to get the following snippet to work:

  Dim strCommand : strCommand="_Line _Normal -_SelSrf " & strSurface & " -_SelPt " & pt2str(Rhino.SurfaceAreaCentroid(strSurface)(0)) & " -_SelPt 500,500,500 _Enter"
  Rhino.Command strCommand, 0

  I know that the _Line function can take either an end point or a distance for the last value. How could I modify my code to specify a distance instead of a point where I say "-_SelPt 500,500,500". I've tried just putting a number but then the function doesn't appear to work at all.