Polyline start point

Change start point on polyline with lisp

(vla-put-coordinate
 (vlax-ename->vla-object (setq enm (car (entsel))))
 0
 (trans (getpoint "\nNew point: ") 1 enm)
)

Change start point on polyline with lisp

Are you looking to change the position of the start vertex (i.e. changing the appearance of the polyline), or relocate the start vertex to one of the other vertices for a closed polyline?

I want to change the entry point of the closed polyline . Thank you

You probably need to use vlax-3d-point (AutoCAD is less forgiving than BricsCAD):

(vla-put-coordinate
 (vlax-ename->vla-object (setq enm (car (entsel))))
 0
 (vlax-3d-point (trans (getpoint "\nNew point: ") 1 enm))
)

francesc said:

I want to change the entry point of the closed polyline . Thank you

Here, try this from my library...

(defun c:CHIV ( / osm ss e f ed edd eddd eddd1 eddd2 eddd3 newed p m n i )

 (vl-load-com)

 (setq osm (getvar 'osmode))
 (setvar 'osmode 1)
 (prompt "\nPick closed 2d polyline with or without arcs")
 (setq ss (ssget "_+.:E:S:L" '((0 . "*POLYLINE") (-4 . "<or") (70 . 1) (70 . 129) (-4 . "or>"))))
 (if ss
   (setq e (ssname ss 0))
   (progn
     (setvar 'osmode osm)
     (alert "Picked wrong entity... Please pick normal closed 2d polyline next time-quitting...")
     (exit)
   )
 )
 (if (eq (cdr (assoc 0 (entget e))) "POLYLINE")
   (progn
     (setq f t)
     (command "_.convertpoly" "_l" e "")
   )
 )
 (setq ed (entget e))
 (setq edd nil)
 (foreach ec ed 
   (if (not 
         (or (eq (car ec) 10) (eq (car ec) 40) (eq (car ec) 41) (eq (car ec) 42) (eq (car ec) 91) (eq (car ec) 210))
       )
       (setq edd (cons ec edd))
   )
 )
 (setq edd (reverse edd))
 (setq eddd nil)
 (setq eddd1 nil)
 (setq eddd2 nil)
 (setq eddd (member (assoc 10 ed) ed))
 (setq p (getpoint "\nPick vertex you want to become initial"))
 (setq m (vlax-curve-getparamatpoint e (vlax-curve-getclosestpointto e p)))
 (if (assoc 91 ed) (setq n (* m 5)) (setq n (* m 4)))
 (setq i 0)
 (foreach ec eddd
   (progn
     (setq i (+ i 1))
     (if (<= i n)
       (setq eddd1 (cons ec eddd1))
     )
     (if (> i n)
       (setq eddd2 (cons ec eddd2))
     )
   )
 )
 (setq eddd1 (reverse eddd1))
 (setq eddd3 (list (assoc 210 eddd2)))
 (setq eddd2 (cdr eddd2))
 (setq eddd2 (reverse eddd2))
 (setq newed (append edd eddd2 eddd1 eddd3))
 (entmod newed)
 (entupd e)
 (setvar 'osmode osm)
 (if f
   (command "_.convertpoly" "_h" e "")
 )
 (alert "After CHIV, run PEDIT->Edit Vertex to see change")
 (princ)
)

HTH, M.R.

[EDIT : Newer version here : https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/get-all-lines-and-trace-them-all/m-p/11329901/highlight/true#M434369 ]