Well, posted a routine not long ago that lets you convert Splines to Polylines. I just found a better routine than the one I posted made by Lee-Mac that lets you convert many types of objects to polylines. It even lets you select a polyline and add more segments to it (as seen with the rectangle in the animated pic)

Here’s how:

• SEGS <enter> to start
• Select objects – Line, Arc, Circle, Ellipse, Rectangle, Polyline, Spline…
• <enter> when finished selecting objects
• Specify # of segments (the more segments the smoother curved objects will look)

;;---------------------=={ Segment Curve }==------------------;;

;; ;;

;; Divides selected objects into an LWPolyline with a ;;

;; specified number of segments of equal length. ;;

;;------------------------------------------------------------;;

;; Author: Lee Mac, Copyright © 2011 - www.lee-mac.com ;;

;;------------------------------------------------------------;;

(defun c:Segs ( / *error* _StartUndo _EndUndo acdoc ss j ) (vl-load-com)

(defun *error* ( msg ) (and acdoc (_EndUndo acdoc))

(or (wcmatch (strcase msg) "*BREAK,*CANCEL*,*EXIT*")

(princ (strcat "\n** Error: " msg " **")))

(princ)

)

(defun _StartUndo ( doc ) (_EndUndo doc)

(vla-StartUndoMark doc)

)

(defun _EndUndo ( doc )

(if (= 8 (logand 8 (getvar 'UNDOCTL)))

(vla-EndUndoMark doc)

)

)

(setq acdoc (vla-get-ActiveDocument (vlax-get-acad-object)) *segs (cond ( *segs ) ( 10 )))

(if

(and (setq ss (ssget "_:L" '((0 . "ARC,CIRCLE,LWPOLYLINE,SPLINE,LINE,ELLIPSE"))))

(progn (initget 6)

(setq *segs (cond ( (getint (strcat "\nSpecify Number of Segments <" (itoa *segs) "> : ")) ) ( *segs )))

)

)

(progn (_StartUndo acdoc)

(repeat (setq j (sslength ss))

(

(lambda ( e / k l i p )

(setq k (/ (vlax-curve-getDistatParam e (vlax-curve-getEndParam e)) (float *segs))

l (entget e)

i -1

)

(repeat (1+ *segs)

(setq p (cons (cons 10 (trans (vlax-curve-getPointatDist e (* (setq i (1+ i)) k)) 0 e)) p))

)

(if

(entmake

(append

(list

(cons 0 "LWPOLYLINE")

(cons 100 "AcDbEntity")

(cons 100 "AcDbPolyline")

(cons 90 (length p))

(cons 38 (last (car p)))

(cons 70 (if (vlax-curve-isClosed e) 1 0))

)

(apply 'append

(mapcar '(lambda ( a ) (if (assoc a l) (list (assoc a l)))) '(6 8 39 48 62 210))

)

p

)

)

(entdel e)

)

)

(ssname ss (setq j (1- j)))

)

)

(_EndUndo acdoc)

)

)

(princ)

)