Convert polylines to 3Dpolylines?

Hello there,

I want to convert a load of polylines into 3D polylines, in vanilla autocad.

I have the 2d polylines drawn with xyz co-ordinates and I want to import them into Infoworks to define river cross-sections. However, infoworks doesn't recognise these objects - it only recognises bona-fide 3dpolylines.

Surprisingly, I haven't managed to find a lisp routine that converts polylines (with 3d values) into actual 3dpolylines.

Any help?

In AutoCAD polylines can only ever be 2d, in that the endpoints of each portion of the polyline will always share the exact same z co-ordinate as each other.

So even if you tried to somehow convert a 2d polyline to a 3d polyline, the mere fact that polylines share z values would still mean it is a 2d polyline.

Having said that, different polylines can have different z values.

In the same way that contours on a map all show, in effect, 2d polylines all at different z values.

These polylines were originally drawn in 2d, however, I have 3d rotated them so that they represent the true shape of the cross-section, in the right place in space.

When you list this polyline, it just says it is a polyline, although each vertex has a different z value.

I need to convert them into offical 3dpolylines, without just tracing over each one with a new 3dpoly.

Could you post an example please?

I may be able to write a LISP that will trace over the 2D polylines with a 3D poly, which may work for you?

Aha - good idea!

I attach one of the sections, in its position after I have 3drotated it. The red line is a polyline and this is the one I need to be converted to an actual 3dpolyline.

Thanks for your help!

2dpl demo.dwg

I've got this, it should incorporate the 3D rotation, but I don't think it does for some reason

(defun c:cPoly  (/ lwPoly vLst eLst)
 (vl-load-com)
 (if (and (setq lwPoly (car (entsel "\nSelect LWPolyline: ")))
          (eq "LWPOLYLINE" (cdr (assoc 0 (entget lwPoly)))))
   (progn
     (setq vLst (mapcar
                  '(lambda (x) (append x '(0.0)))
                     (mapcar 'cdr
                       (vl-remove-if-not
                         '(lambda (x) (eq 10 (car x)))
                            (setq eLst (entget lwPoly))))))
     (entmake (list '(0 . "POLYLINE")
                    (cons 8 (cdr (assoc 8 eLst)))
                    '(66 . 1)
                    '(100 . "AcDb3dPolyline")
                    '(70 . 
                    (cons 210 (cdr (assoc 210 eLst)))))
     (while vLst
       (entmake (list (cons 0 "VERTEX")
                      '(100 . "AcDb3dPolylineVertex")
                      '(70 . 32)
                      (cons 10 (car vLst))))
       (setq vLst (cdr vLst)))
     (entmake '((0 . "SEQEND")))
     ;(entdel lwPoly)) ; Remove to Keep Original
     )
   (princ "\n<!> No LWPolyline Selected <!>"))
 (princ))

ooh - nice try! That does work for converting plines that are on the xy plane, but not on the ones I've already 3Drotated.

I should have asked the question before I wenthrough and rotated all these polyline sections - that would have been perfect!

Thanks again for your help here!

I'm not sure why it doesn't put the new 3dpolylines in the right plane though, as I use the extrusion vector (code 210) from the original LW polyline to create the new 3dpolyline - yet when I check the extrusion vector in the new 3dPolyline, it is back to the XY plane.

Try out PEDIT3D.lsp from http://www.black-cad.de

It should do the job.

Good luck!

Jochen

Wow - impressive stuff! That worked perfectly, thank you.

It looks like I may be a bit late; I imagine the PEDIT3D.lsp will give some pointers as to how AutoCAD treats LWPoly coords aligned to UCS’s other than WCS.

I put together this VBA routine (my understanding of lisp is a bit lacking) to accommodate the “other-world-ly” orientations.

Option Explicit

Sub lw23d()
Dim intCode(0) As Integer
Dim varData(0) As Variant
Dim dblNorm() As Double
Dim dblElev As Double
Dim entLW As AcadLWPolyline
Dim ent3d As Acad3DPolyline
Dim blnClosed As Boolean
Dim varCoords As Variant
Dim i As Long
Dim intbound As Long
Dim varTemp As Variant
Dim dblTemp(2) As Double
Dim dbl3DCoords() As Double

intCode(0) = 0: varData(0) = "LWPOLYLINE"
If SoSSS(intCode, varData) > 0 Then
  For Each entLW In ThisDrawing.SelectionSets.Item("TempSSet")
     dblNorm = entLW.Normal
     dblElev = entLW.Elevation
     blnClosed = entLW.Closed
     intbound = ((UBound(entLW.Coordinates) + 1) / 2) - 1
     ReDim dbl3DCoords(((intbound + 1) * 3) - 1)
     For i = 0 To intbound
        varTemp = entLW.Coordinate(i)
        dblTemp(0) = varTemp(0)
        dblTemp(1) = varTemp(1)
        dblTemp(2) = dblElev
        varTemp = ThisDrawing.Utility.TranslateCoordinates(dblTemp, acOCS, acWorld, 0, dblNorm)
        dbl3DCoords(i * 3) = varTemp(0)
        dbl3DCoords(i * 3 + 1) = varTemp(1)
        dbl3DCoords(i * 3 + 2) = varTemp(2)
     Next
     Set ent3d = ThisDrawing.ModelSpace.Add3DPoly(dbl3DCoords)
     ent3d.Closed = blnClosed
     
  Next

End If

End Sub

Sub SSClear()
Dim SSS As AcadSelectionSets
  On Error Resume Next
  Set SSS = ThisDrawing.SelectionSets
     If SSS.Count > 0 Then
        SSS.Item("TempSSet").Delete
     End If
End Sub

Function SoSSS(Optional grpCode As Variant, Optional dataVal As Variant) As Integer
  Dim TempObjSS As AcadSelectionSet
  SSClear
  Set TempObjSS = ThisDrawing.SelectionSets.Add("TempSSet")
        'pick selection set
  If IsMissing(grpCode) Then
     TempObjSS.SelectOnScreen
  Else
     TempObjSS.SelectOnScreen grpCode, dataVal
  End If
  SoSSS = TempObjSS.Count
End Function