Sweep2

I am trying to integrate Sweep2 function into my scripting procedures. As you can see in the image below, left is the input rails and section curves. the middle is generated by sweep2 component in GH, same as using sweep2 command in Rhino. 

The one on the right is what I got so far (the output smooth our the kink of the original rails). Basically I am just following the methods provided by sdk sample: http://wiki.mcneel.com/developer/sdksamples/sweep2 . 

The following is the function I copy and use directly from the SDK sample. By using this function, I can generate the sweep surface at right. But I want to have is the one in the middle with the kink edges. Can anyone show me how and where to modify he settings? I guess some sweep arguments need to be changed? I have try couples, such  m_simplify, m_bSimpleSweep, m_bSameHeight, m_rebuild_count... but still cannot find a right combination for this function to output the sweep surface I want. Any suggestions or helps are very appreciated. Thanks for your help and time on this.

'Sweep2 function'----------------
Sub Sweep2( ByVal Rail1 As IOnCurve, _

            ByVal Rail2 As IOnCurve, _

            ByVal sCurves As List(Of IOnCurve), _

            ByRef Sweep2_Breps As List(Of OnBrep))

  'Define a new class that contains sweep2 arguments

  Dim args As New MArgsRhinoSweep2

 

  'Set the 2 rails

  Dim Edge1 As New MRhinoPolyEdge

  Dim Edge2 As New MRhinoPolyEdge

  Edge1.Append(Rail1.DuplicateCurve())

  Edge2.Append(Rail2.DuplicateCurve())

 

  'Add rails to sweep arguments

  args.m_rail_curves(0) = Edge1

  args.m_rail_curves(1) = Edge2

  args.m_bClosed = False

 

  Dim section_curves As New List(Of OnCurve)

 

  'Loop through sections to set parameters

  For Each Section As IOnCurve In sCurves

    Dim sCurve As OnCurve = Section.DuplicateCurve()

    section_curves.Add(sCurve)

 

    Dim t0 As Double = 0

    If Not Edge1.GetClosestPoint(sCurve.PointAtStart(), t0) Then

      If Not Edge1.GetClosestPoint(sCurve.PointAtEnd(), t0) Then

        Dim s As Double = 0

        sCurve.GetNormalizedArcLengthPoint(0.5, s)

        Edge1.GetClosestPoint(sCurve.PointAt(s), t0)

      End If

    End If

    args.m_rail_params(0).Append(t0)

 

    Dim t1 As Double = 0

    If Not Edge2.GetClosestPoint(sCurve.PointAtStart(), t1) Then

      If Not Edge2.GetClosestPoint(sCurve.PointAtEnd(), t1) Then

        Dim s As Double = 0

        sCurve.GetNormalizedArcLengthPoint(0.5, s)

        Edge2.GetClosestPoint(sCurve.PointAt(s), t1)

      End If

    End If

    args.m_rail_params(1).Append(t1)

  Next

 

  'Set shapes

  args.m_shape_curves = section_curves.ToArray

 

  'Set the rest of parameters

  args.m_simplify = 0

  args.m_bSimpleSweep = False

  args.m_bSameHeight = False

  args.m_rebuild_count = -1 'Sample point count for rebuilding shapes

  args.m_refit_tolerance = RMA.Rhino.RhUtil.RhinoApp.ActiveDoc.AbsoluteTolerance()

  args.m_sweep_tolerance = RMA.Rhino.RhUtil.RhinoApp.ActiveDoc.AbsoluteTolerance()

  args.m_angle_tolerance = RMA.Rhino.RhUtil.RhinoApp.ActiveDoc.AngleToleranceRadians()

 

  Dim sBreps() As OnBrep = Nothing

  If (RhUtil.RhinoSweep2(args, sBreps)) Then

    For Each b As OnBrep In sBreps

      Sweep2_Breps.Add(b)

    Next

  End If

 

  Return

End Sub