sequence redefine leadership and direction of a polyline composed of lines and arcs

[blubossa]

you can redefine the squenza points, and their line of a polyline?

In practice I have many polylines which I want to change the start and then the sequence of the other, or the direction.

basically I want to export the heads and try to pass the txt file to a CNC machine.

thanks

[RobertB]

In AutoCAD 2011 the PEdit command has an option to reverse the PLine.

[alanjt]

In AutoCAD 2011 the PEdit command has an option to reverse the PLine.

Wow, is that what he meant?

[blubossa]

I want to change the initial vertex and direction of a polyline made up of lines and arcs.....

I hope I was clear

thank you

[marko_ribar]

If you change initial vertex of a polyline, the whole polyline would look different... In CAD it is essential important the order of procedure of witch the entities are created... This order is kept in its memory and entity data... You can only modify entity in new manner, but everything previously made will be the same... Just think of it, you have polyline; and if your first vertex becomes someone else, entity data would be moved from initial first (assoc 10 edata of a polyline) to some else (assoc 10 edata) and what would be with other (assoc 10 edata) ? - one part of the list of entity data would remain the same - from that some (assoc 10 edata) to the end, but first part - to that some (assoc 10 edata) would go to the end... The whole look of polyline would be different...

Direction of entity you can change in ACAD 2011 by reversing order of points through PEDIT -> edit vertex -> reverse ... Then the polyline would look the same and only procedure of its creation would be inverted...

[marko_ribar]

Anyway, if the polyline is closed - for other I don't guarantee that you'll get result you want, you can apply this routine :

(defun c:ChInitVert ()
(prompt "\nPick closed polyline with arcs")
(setq e (car (entsel)))
(setq ed (entget e))
(setq edd nil)
(setq q -1)
(while (< q 0)
(progn
(setq ec (car ed))
(setq ed (cdr ed))
(if (eq (car ec) 10) (progn (setq ed (cons ec ed)) (setq edd (reverse edd)) (setq q 1)) (setq edd (cons ec edd)))
))
(setq eddd nil)
(setq eddd1 nil)
(setq eddd2 nil)
(setq eddd ed)
(setq m (getreal "\nInput number of witch vertex do you want to become initial counting original as 0 : "))
(setq n (* m 5))
(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 eddd2 (cdr eddd2))
(setq eddd2 (reverse eddd2))
(setq eddd3 '((210 0.0 0.0 1.0)))
(setq newed (append edd eddd2 eddd1 eddd3))
(entmod newed)
(entupd e)
(princ "\nAfter ChInitVert, run PEDIT->Edit Vertex to see change")
(textscr)
(princ)
)

M.R.

[blubossa]

it's not good routine for pline with many arcs........because change the look of the polyline

[marko_ribar]

I've made corrections...

test it now...

M.R.

To see another solution view :
https://forums.augi.com/showthread.php?p=1105551

[alanjt]

I wrote this for reversing the direction of LWPolylines, Lines and Splines.