[综合讨论] 沿曲线滑动点

' Option Explicit
  
  Sub OffsetPointOnCurve
  
    ' Select the curve
    Dim crv : crv = Rhino.GetObject("Select curve", 4)
    If IsNull(crv) Then Exit Sub
  
    ' Select a point on the curve to offset from      
    Dim pt : pt = Rhino.GetPointOnCurve(crv, "Select point on curve")
    If IsNull( pt) Then Exit Sub
  
    ' Specify the offset distance    
    Dim dist : dist = Rhino.GetReal("Distance to offset point")
    If IsNull(dist) Then Exit Sub
  
    ' Get the closest point on the curve from the test point      
    Dim t : t = Rhino.CurveClosestPoint(crv, pt)
  
    ' Get the curve's domain
    Dim d : Dom = Rhino.CurveDomain(crv)
  
    ' Get the total length of the curve
    Dim l : l = Rhino.CurveLength(crv)
  
    ' Determine the length from the start of the curve to the test point
    Dim ls : ls = Rhino.CurveLength(crv,,Array(Dom(0),t))
  
    ' Offset a point in each direction    
    Rhino.AddPoint Rhino.CurveArcLengthPoint(crv, ls + dist, True)
    'Rhino.AddPoint Rhino.CurveArcLengthPoint(crv, l - ls + dist, False)
  
    ' Add the test point for reference
    'Rhino.AddPoint pt
  
  End Sub