Option Explicit
'script "wireframe triangulation" - triangulates surfaces by their wireframes including direction preview
'script written by quirin krumbholz
'script copyrighted by quirin krumbholz
'script link - www.ovion.de
'script version 1.0, date 080213

Call main()

Sub main()

Dim surface, arrWires, bound, brepCurve, cmd, cutter, field, part
Dim uv0, uv1, uvDirection, uvValues, uvResult
Dim tr0Point, tr1Point, tr2Point, tr3Point
Dim trtest0Point, trtest1Point, uvtest0, uvtest1
Dim prev0Point, prev1Point, prev2Point, prev3Point, prevPoints
Dim input, inputResult

'-> prompts for a surface to triangulate' 

surface = Rhino.GetObject ("select surface to triangulate", 8)
input = Array("toggle", "yes", "no") 
inputResult = Rhino.GetBoolean ("delete input?", input, Array(True))

Call Rhino.enableRedraw(False)

If inputResult(0) = True Then
  
  Rhino.CopyObject surface

Else

End If

'-> generates preview curve for triangulation direction' 

Rhino.SelectObject (surface)

Dim u, v, i, uvPoint 
Dim arrParam() 
Dim pointArr()
Dim testCurve

u = Rhino.SurfaceDomain(surface, 0)
v = Rhino.SurfaceDomain(surface, 1)

For i = 0 To 20
  
ReDim Preserve arrParam(1)

  arrParam(0) = u(0) + (((u(1) - u(0)) /20)*i)
  arrParam(1) = v(0) + (((v(1) - v(0)) /20)*i)

  uvPoint = Rhino.EvaluateSurface(surface, arrParam)

  ReDim Preserve pointArr(i)
  pointArr(i) = uvPoint

Next

  If IsArray(pointArr) Then 
  
    testCurve = Rhino.AddCurve (pointArr, 3)

  End If
  
   Rhino.UnselectAllObjects
   Rhino.SelectObject (testCurve)

  '-> prompts for selection of tiling direction' 
  
  Call Rhino.enableRedraw(True)
  
  uvValues = Array("toggle", "current", "flip") 
  uvResult = Rhino.GetBoolean ("tiling direction preview", uvValues, Array(True))

  Call Rhino.enableRedraw(False) 

  '-> surface preparation for triangulation'

  Rhino.DeleteObject (testCurve)
  Rhino.SelectObject (surface)
  Rhino.command "_ExtractWireframe"
  arrWires = Rhino.SelectedObjects 

  If IsArray(arrWires) Then
  
    Rhino.SelectObjects (arrWires)
    Rhino.UnselectAllObjects
  
    Rhino.SelectObject (surface)
    Rhino.Command "_Split _SelLast _Enter" 

    field = Rhino.SelectedObjects
    Rhino.DeleteObjects (arrWires)

    '-> triangulation'
    
    If IsArray(field) Then
  
        bound = UBound(field)
        For part = 0 To bound
  
        Rhino.ShrinkTrimmedSurface (field(part))
        Rhino.Command "_Reparameterize 0 1 0 1"
 
        uv0 = 0
        uv1 = 1
                                
        tr0Point = Rhino.EvaluateSurface(field(part), Array(uv0, uv0))
        tr1Point = Rhino.EvaluateSurface(field(part), Array(uv1, uv0))
	tr2Point = Rhino.EvaluateSurface(field(part), Array(uv0, uv1))
        tr3Point = Rhino.EvaluateSurface(field(part), Array(uv1, uv1))
        
        If uvResult(0) = True Then
                  
          Rhino.AddSrfPt Array(tr3Point, tr0Point, tr1Point)
          Rhino.AddSrfPt Array(tr0Point, tr2Point, tr3Point)
        
        Else
        
          Rhino.AddSrfPt Array(tr0Point, tr1Point, tr2Point)
          Rhino.AddSrfPt Array(tr1Point, tr2Point, tr3Point)        
        
        End If
        
        Rhino.DeleteObject (field(part))
        
  Next
  
  Call Rhino.enableRedraw(True)  
  
  End If

  End If
  
End Sub