Verify line ends are not free

[keshishian1]

Hello,
I'm working on a LISP routine to verify that all lines in a drawing are properly connected to adjacent lines. Occasionally, the plans I receive contain very small gaps—often at square chamfers—which can cause issues. While the routine generally functions as expected, it sometimes flags lines that appear to be correctly connected. I'm wondering if this approach to checking connectivity is sound, or if there's a more reliable method I should consider. Any insights or suggestions would be greatly appreciated.

Thank You.

[ВeekeeCZ · Accepted solution]

 I see that it works perfectly fine with LINEs. That is what the lisp is written for. It does not support ARCs at all. All the red lines are connected to ARCs.

[Kent1Cooper]

---

@ВeekeeCZ wrote:

 .... it works perfectly fine with LINEs. That is what the lisp is written for. It does not support ARCs at all. ....

---

If that's needed, these changes ought to work [untested] to also include Arcs, with a way of finding the start and end points of either object type, since that can't be done with entity data entries, because those points are not in the entity data for Arcs:

....

(vl-load-com)

(prompt "\nSelect Lines and Arcs to check for disconnected endpoints...")
(setq ss (ssget '((0 . "LINE,ARC"))))

....

;; Collect endpoints with entity handles
(setq i 0)
(while (< i (sslength ss))

(setq en (ssname ss i))
(setq ent (entget en))
(setq pt1 (vlax-curve-getStartPoint en))
(setq pt2 (vlax-curve-getEndPoint en))
(setq endpoints (cons (list pt1 pt2 en) endpoints))
(setq i (1+ i))
)

....

And the same could easily be expanded to include Polylines and Splines and Ellipses, but would need to be made more restrictive about those, to accept or process only those that are not closed.

[keshishian1]

Thank You. I will add the code to my script.

[ronjonp]

@keshishian1 

Here's another way to look for coincident end/start points. This will mark them with circles if not found.

(defun c:foo (/ a s)
  ;; RJP » 2025-08-25
  (cond
    ((setq s (ssget '((0 . "*LINE,ARC"))))
     (setq s (mapcar '(lambda (x) (list (vlax-curve-getstartpoint x) (vlax-curve-getendpoint x)))
		     (vl-remove-if 'listp (mapcar 'cadr (ssnamex s)))
	     )
     )
     (setq s (vl-sort (apply 'append s) '(lambda (r j) (< (car r) (car j)))))
     (while (cadr s)
       (setq a (car s))
       (setq s (cdr s))
       (if
	 (null (vl-some '(lambda (x) (and (equal a x 1e-4) (progn (setq s (vl-remove x s)) t))) s))
	  (entmakex (list '(0 . "CIRCLE") '(8 . "CHECK") (cons 10 a) '(40 . 4)))
       )
     )
    )
  )
  (princ)
)

[keshishian1]

Thank You but it shows a few false positives.

[ronjonp]

@keshishian1 Code updated above. Give it a try.

Strange though on your test drawing I don't get the result you're seeing.

[keshishian1]

I tried and it gave the same result. It may be a variable setting that is causing this. It is fine: I can check those manually. thanks again.

[ronjonp]

Sounds good ... glad to help! 🍻