View direction of vectors

Arno

Hi,

Is it possible to see in what direction a vector goes?

For instance, if I draw a polyline based shape in a counter clockwise direction, I obviously know the direction. But if I draw a shape which is built up out of different shapes, exploded, trimmed, and joined again, I have no idea of the direction of the vectors. For cnc tool radius correction, it's important to know in what direction it goes.

Roy Klein Gebbinck

You can use a linetype with arrows.

*ARROWS,Arrows -> -> ->
A,1,[ZIG,ltypeshp.shx,r=-90,x=-0.25,y=0.25,s=0.25],-1

Tom Foster

Also when changing Length in Properties - which end will change?

Arno

@Roy Klein Gebbinck said:
You can use a linetype with arrows.

*ARROWS,Arrows -> -> ->
A,1,[ZIG,ltypeshp.shx,r=-90,x=-0.25,y=0.25,s=0.25],-1

Roy, thank you!

Feels a bit like a workaround, but in my workflow it actually works fine.

Arno

@Tom Foster said:
Also when changing Length in Properties - which end will change?

Will this work with closed polylines?

ALANH

There are a few is anticlockwise lisps for plines then can do Pedit R.

;; get closed polygon's area

(defun ss-pts2area (l)
(/ (apply (function +)
(mapcar (function (lambda (x y)
(- (* (car x) (cadr y)) (* (car y) (cadr x)))))
(cons (last l) l)
l))
2.)
)

;_force pointset CCW
(setq plent (entsel "\nPick pline"))
(setq co-ord (mapcar 'cdr (vl-remove-if-not '(lambda (x) (= (car x) 10)) (entget (car plent)))))

(if (< (ss-pts2area co-ord) 0)
(command "pedit" plent "R" "")
)

Arno

The arrow line type works great!

I have a somewhat related question.
Cad seems to register in what order one draws shapes. If I draw some straightforward shapes, ie first a circle, then a rectangle, the cnc router will first cut out the circle, then the rectangle.

Is there a way to view in what order the shapes have been drawn, and even change this order?

ALANH

The issue of drawn order has been asked before, I think some code was put forward to remake the entities in a new pick order Google. Re view order try a plain ssget pretty sure selects in drawn order. If you want a fancy zoom to object etc a lot more code.

(defun c:qkdirty ( / ss x)
(setq ss (ssget))
(repeat (setq x (sslength ss))
(command "CHPROP" (ssname ss (setq x (1- x))) "" "C" 1 "")
(alert "Look move this alert out of way")
)
(princ)
)
(c:qkdirty)