AutoLISP: Break Polyline at Vertex

You can always explode a Polyline if you need to break your polyline into individual segments. This method will make the polyline into individual lines. But what if you would like these individual segments to remain individual polylines? That’s where this routine comes in handy.

Here’s how:

  • BPV <enter> to start Break Polyline Vertex
  • Select the polyline(s) <enter>


(defun c:BPV (/ _chop ss i e)

;; Break lwPolyline at each Vertex

;; Alan J. Thompson, 09.14.11


(defun _chop (lst e)

(if (vlax-curve-isClosed e)

(cdr lst)

(reverse (cdr (reverse (cdr lst))))



(if (setq ss (ssget "_:L" '((0 . "LWPOLYLINE") (-4 . ">") (90 . 2))))

(repeat (setq i (sslength ss))

(foreach point (_chop (apply 'append

(mapcar '(lambda (x)

(if (eq (car x) 10)

(list (trans (cdr x) 0 1))



(entget (setq e (ssname ss (setq i (1- i)))))





(vl-cmdf "_.break" e "_F" "_non" point "_non" point)

(setq e (entlast))









About AutoCAD Tips

This blog serves as a knowledge base for myself (and anyone else) so that I can reference tips & tricks that I have learned and also refer others to it as well. I hope that this blog helps you learn at least one tip to make your drafting/design experience better.
This entry was posted in AutoLISP, Modifying, Polylines. Bookmark the permalink.

1 Response to AutoLISP: Break Polyline at Vertex

  1. robert says:

    A great perspective, but this does not work in my cad, could there be a bug?

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