Public Function InsertKnot ( 
	value As Double
) As Boolean

Imports Rhino.DocObjects

Partial Class Examples
  Public Shared Function InsertKnot(ByVal doc As Rhino.RhinoDoc) As Rhino.Commands.Result
    Dim rc As Rhino.Commands.Result
    Const filter As ObjectType = Rhino.DocObjects.ObjectType.Curve
    Dim objref As Rhino.DocObjects.ObjRef = Nothing
    rc = Rhino.Input.RhinoGet.GetOneObject("Select curve for knot insertion", False, filter, objref)
    If rc <> Rhino.Commands.Result.Success Then
      Return rc
    End If
    Dim curve As Rhino.Geometry.Curve = objref.Curve()
    If curve Is Nothing Then
      Return Rhino.Commands.Result.Failure
    End If
    Dim nurb As Rhino.Geometry.NurbsCurve = curve.ToNurbsCurve()
    If nurb Is Nothing Then
      Return Rhino.Commands.Result.Failure
    End If

    Dim gp As New Rhino.Input.Custom.GetPoint()
    gp.SetCommandPrompt("Point on curve to add knot")
    gp.Constrain(nurb, False)
    gp.[Get]()
    If gp.CommandResult() = Rhino.Commands.Result.Success Then
      Dim t As Double
      Dim crv As Rhino.Geometry.Curve = gp.PointOnCurve(t)
      If crv IsNot Nothing AndAlso nurb.Knots.InsertKnot(t) Then
        doc.Objects.Replace(objref, nurb)
        doc.Views.Redraw()
      End If
    End If
    Return Rhino.Commands.Result.Success
  End Function
End Class