How to convert 3D Polylines to 2D Polylines

[GreyHippo]

I first tried Lion's but it seamed like autocad locked up on me, then I tried Cab's suggestion and it worked perfectly.

Thanks, you saved me a bunch of time!!!

[peter]

Here is a 3dto2d function using activeX

After flattening the 3dpoly's you could try using the express tools "overkill" to join them together.

You can also use a pjoin.lsp routine to join them.

(defun C:3DTo2D (/ intCount
                   lstCoordiantes
                   objDocument
                   obj2dPolyline
                   obj3dPolyline
                   ssSelections
                   strProperty
                )
 (if (setq ssSelections (ssget (list (cons 0 "polyline"))))
  (vlax-for obj3dPolyline (vla-get-activeselectionset 
                         (setq objDocument (vla-get-activedocument
                                            (vlax-get-acad-object))))
   (if (= (vla-get-objectname obj3dPolyline) "AcDb3dPolyline")
    (progn
     (setq intCount       0
           lstCoordinates (mapcar 
                          '(lambda (sngCoordinate)
                            (if (= (/ (setq intCount (1+ intCount)) 3.0)
                                   (/ intCount 3)
                                )                             
                             nil
                             sngCoordinate
                            ) 
                           )
                           (vlax-get obj3dPolyline "coordinates")
                          )
          lstCoordinates (vl-remove nil lstCoordinates)
          obj2dPolyline  (vla-addlightweightpolyline 
                          (vla-get-block 
                           (vla-get-activelayout objDocument))
                          (listtosafearray 5 lstCoordinates))
     )
     (foreach strProperty (list "truecolor" "layer" "linetype" "closed")
      (vlax-put obj2dPolyline strProperty (vlax-get obj3dPolyline strProperty))
     )
     (vla-delete obj3dPolyline)
    )
   )
  )
 )
 (princ)
)


; This function creates a safearray from a list and the safearray type symbol
; for example: (listtosafearray vlax-vbinteger (list 0) )

(defun ListToSafeArray (symSafeArrayType lstItems / safArray)
 (setq safArray (vlax-make-safearray symSafeArrayType (cons 0 (1- (length lstItems)))))
 (vlax-safearray-fill safArray lstItems)
)

;vlax-vbInteger  (2)  Integer 
;vlax-vbLong     (3)  Long integer 
;vlax-vbSingle   (4)  Single-precision floating-point number 
;vlax-vbDouble   (5)  Double-precision floating-point number 
;vlax-vbString   (8)  String 
;vlax-vbObject   (9)  Object 
;vlax-vbBoolean (11)  Boolean 
;vlax-vbVariant (12)  Variant 
(princ "C:3dTo2d")
(prin1)

[GreyHippo]

I will try your routine once I get back in the office on Tuesday to see which way is faster. Happy New Year.

[aaronic_abacus]

I suggest using the Flatten lisp program, then the pljoin lisp program.

[aaronic_abacus]

Here's one I wrote a long time ago.

(DEFUN C:GPJ (/ PT1 PT2 SSET SSETN PLN LP ENT LA PLN2 TFC CV ENTL EVS SV EVT VE1 VE2 SI1 SI2 SII1 SII2 SI SII PF FB FE FLTR)
  (PROMPT "*GROUP POLYLINE JOIN*")
  (SETQ SSET (SSGET '((0 . "LWPOLYLINE"))))
  (SETQ SSETN (SSLENGTH SSET))
  (SETQ PLN SSETN)
  (PRINT SSETN)
  (PROMPT " POLYLINES SELECTED")
  (SETQ SSETN (- SSETN 1))
  (SETQ LOOP 1)
  (WHILE LOOP
    (SETQ ENT (SSNAME SSET SSETN))
    (SETQ LA (ASSOC 8 (ENTGET ENT)))
    (SETQ ENTL (ENTGET ENT))
    (SETQ VE1 (CDR (ASSOC 10 ENTL)))
    (SETQ EVS VE1)
    (SETQ SV 1)
    (WHILE SV
      (SETQ ENTL (CDR ENTL))
      (SETQ EVT (ASSOC 10 ENTL))
      (IF (/= EVT NIL)
	(SETQ VE2 (CDR EVT))
	(SETQ SV NIL)
      )
    ) ;END WHILE SV 
    (SETQ SI1 (MAPCAR '+ '(0.1 0.1 0.0) VE1))
    (SETQ SI2 (MAPCAR '+ '(-0.1 -0.1 0.0) VE1))
    (SETQ SII1 (MAPCAR '+ '(0.1 0.1 0.0) VE2))
    (SETQ SII2 (MAPCAR '+ '(-0.1 -0.1 0.0) VE2))
    (SETQ PF '(0 . "LWPOLYLINE"))
    (SETQ FB '(-4 . "<AND"))
    (SETQ FE '(-4 . "AND>"))
    (SETQ FLTR (LIST FB PF LA FE))
    (SETQ SI (SSGET "C" SI1 SI2 FLTR))
    (SETQ SII (SSGET "C" SII1 SII2 FLTR))
    (IF	(= SI NIL)
      (SETQ SI ENT)
    )
    (IF	(= SII NIL)
      (SETQ SII ENT)
    )
    (SETQ CV (CDR (ASSOC 70 (ENTGET ENT))))
    (IF	(> CV 0)
      (SETQ TFC 1)
      (SETQ TFC 0)
    )
    (IF	(= TFC 0)
      (COMMAND "PEDIT" ENT "J" SI SII "" "X")
    )
    (SETQ LP 1)
    (WHILE LP
      (SETQ SSETN (- SSETN 1))
      (PROMPT "\nJOIN ATEMPT # ")
      (PRINC SSETN)
      (IF (/= (SSNAME SSET SSETN) NIL)
	(SETQ NT (ENTGET (SSNAME SSET SSETN)))
	(SETQ NT 1)
      )
      (IF (= NT NIL)
	(SETQ LP 1)
	(SETQ LP NIL)
      )
      (IF (< SSETN 0)
	(SETQ LOOP NIL)
      )
    ) ;END WHILE LP
  ) ;END WHILE LOOP
  (SETQ SSET NIL)
  (SETQ SSET NIL)
  (PRINC)
) ;END JPL

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[GreyHippo]

I tried the programs by Peter and CAB and both work very well but Peter's is about twice as fast, I guess its because of Active X commands.

Thanks to all who helped, you saved me a ton of time!

[CAB2k]

Oh, that's not my lisp. I just posted the link.
Glad you got what you needed.