;; free lisp from cadviet.com
;;; this lisp was downloaded from https://www.cadviet.com/forum/topic/33919-c%E1%BA%A7n-lisp-chuy%E1%BB%83n-dwgdxf-sang-plaxis/
  (defun dxf(ent code)
   (cdr (assoc code (entget ent)))
)
(defun p2s(p)
   (apply 'strcat (mapcar '(lambda (x) (fullstr (rtos x 2 Accuracydigit) 14)) p))
)
(defun line2param(ent)
   (list (p2s (dxf ent 10)) (p2s (dxf ent 11)))
)

(defun lwpolyline2param(ent / tt z)
   (setq
  z  (dxf ent 38)
  tt (vl-remove-if '(lambda (x) (/= (car x) 10) ) (entget ent))
  tt (mapcar '(lambda (x) (p2s (append (cdr x) (list z)))) tt)
   )
   tt
)

(defun polyline2param(ent / kq)
   (setq ent (entnext ent)
  kq nil)
   (while (and ent (= (dxf ent 0) "VERTEX"))
     (setq kq (append kq (list (p2s (dxf ent 10))))
    ent (entnext ent)
     )

   )
   kq
)


(defun getpointindex(pp / tmp)
   (if (setq tmp (member pp points))
     (1+ (- (length points) (length tmp)))
     (length (setq points (append points (list pp))))
   )
)

(defun fullstr(str num / sl)
   (setq sl (- num (strlen str)))
   (repeat sl
     (setq str (strcat " " str))
   )
)
(defun converttogeometry()
   (setq
  index 0
         sl (if ss (sslength ss) 0)
   )
   (repeat sl
     (setq ent (ssname ss index)

     )
     (cond
((= (dxf ent 0) "LINE") (setq tmp (line2param ent)))
((= (dxf ent 0) "LWPOLYLINE") (setq tmp (lwpolyline2param ent)))
(T (setq tmp (polyline2param ent)))
     )

     (setq pline (strcat (fullstr (itoa (length tmp)) 5) "  - points on layerboundary" (fullstr (itoa index) 6) "\n      ")
    currentnumberinrow 0)

     (foreach point tmp
(setq pline (strcat pline (fullstr (itoa (getpointindex point)) 5))
      currentnumberinrow (1+ currentnumberinrow))
(if (>= currentnumberinrow 10)
  (progn
    (setq currentnumberinrow 0
  pline (strcat pline "\n      "))
  )
)
     )
     (setq plines (append plines (list pline))
    index (1+ index))
   )         
   (princ)
)

(defun getinput()
(princ "\nPlease select LINE, POLYLINE: ")
(setq ss (ssget '((0 . "*LINE")))
Accuracydigit (getint "\nEnter a integer value to choose Accuracy level (1=0.1, 2=0.01, 3=0.001,...)<2>: ")
Accuracydigit (if Accuracydigit Accuracydigit 2)
fname (getfiled "Please specify [.geo] file" (getvar "dwgprefix") "geo" 1)
)
) 

(defun expten(count / kq)
(setq kq 1.0)
(repeat count
   (setq kq (* 10.0 kq))
)
)
(defun writeoutput()
(setq fhnd (open fname "w"))
(if (not fhnd)
   (alert (strcat "error when write to " fname))
   (progn
     (write-line (strcat
         "GEOMETRY FILE FOR THE M-SERIES\n"
         "==============================================================================\n"
         "==========================    BEGINNING OF DATA     ==========================\n"
         "POINTS      Accuracy = " (fullstr (rtos (/ 1.0 (expten Accuracydigit)) 2 4) 12) "\n"
  (fullstr (itoa (length points)) 5) "  - Number of geometry-points -"  
       )
fhnd
     )
     (setq index 1)
     (foreach point points
(write-line (strcat (fullstr (itoa index) 8) point) fhnd)
(setq index (1+ index))
     )
     (write-line "LAYERS" fhnd)
     (write-line (strcat (fullstr (itoa (1- (length plines))) 5) "  - Number of layers -") fhnd)

     (setq index 0)
     (foreach pline plines
(write-line pline fhnd)
(setq index (1+ index))      
     )
     (write-line "" fhnd)
     (write-line "END OF DATA FILE" fhnd)
     (close fhnd)
   )
)
)

(defun c:cad2geo( / ss)
(setq points nil)
(setq plines nil)
(getinput)
(converttogeometry)
(writeoutput)
(alert "Export to [.geo] file successfully!")
(princ)
)