finding points..

how do i find the last two points in a polyline that i has just drawn in
lisp? is there a way to map all the points and recall the last two? do i
use the mapcar command? if so how....

exp.

(command "_.PLINE")
(while (> (getvar "CMDACTIVE") 0)
(getvar lp01 (getvar "nexttolastpoint")
(getvar lp02 (getvar "lastpoint")
(setq lp03 (polar lp02 (angle lp01 lp02) (* scale01 0.2656250)))

Thanks Court

ps..... this is a variation on my last post..

 

A "nextotolastpoint" system variable sure could be handy sometimes. So
could a "next-to-last-entity" option in object selection, or a
"the-last-<x>-entities" option. (I've built myself an
erase-the-last-<x>-entities routine.)

You should be able to save each point as you go, and make your own
next-to-last point by setting the lp01 to the "old" lastpoint before picking
a "new" one with the next point on the Pline.

At first I thought you probably don't need to save that lp03 future
insertion point after every pline segment you draw, just after the last one
(i.e. after the end of the "while" operation):

(command "_.PLINE")
(while (> (getvar "CMDACTIVE") 0)
(setq lp01 lp02
lp02 (getpoint lp01)
(
(
(setq lp03 (polar lp02 (angle lp01 lp02) (* scale01 0.2656250)))

But no, that wouldn't work, because it would go back around and set lp01
equal to lp02 before you got a chance to end the Pline command, so you'd end
up with lp01 and lp02 being the same, which would spoil the setting of lp03.

So maybe you should, after all, set lp03 each time, but you need some setq's
and a getpoint in place of some getvar's. Does this work?

(command "_.PLINE")
(while (> (getvar "CMDACTIVE") 0)
(setq lp01 lp02)
lp02 (getpoint lp01)
lp03 (polar lp02 (angle lp01 lp02) (* scale01 0.2656250))
)
)
<...insert at lp03...>

I'm assuming the still-active Pline command will supply a prompt for the
next point, so you don't need to put one in with the "getpoint" function.

Then, even if it goes back and sets lp01 equal to lp02 again before you end
Pline, it won't matter because you'll already have the lp03 location defined
anyway.

Kent Cooper, AIA


...

 

Hi Court

One solution can be the use of vlax-curve-xxxx functions:

<snip>
(vl-load-com)
....
(command "_.PLINE")
(while...)
(setq TmpObj (vlax-ename->vla-object (entlast))
lp03 (polar
(vlax-curve-getEndPoint TmpObj)
(Vec2Ang
(vlax-curve-getFirstDeriv
TmpObj
(vlax-curve-getEndParam TmpObj)
)
)
(* scale01 0.2656250)
)
)
<snip>

;
; == Function Vec2Ang
; Converts a vector to an angle.
; Arguments [Type]:
; Vec = Vector value

• 
  ; Return [Type]:
  ; > Angle value [REAL]
  ; Notes:
  ; Credits to Luis Esquivel
  ;
  (defun Vec2Ang (Vec / XvcVal YvcVal)
  (setq XvcVal (car Vec)
  YvcVal (cadr Vec)
  )
  (cond
  ((equal XvcVal 0 1E-4) (if (minusp YvcVal) (* pi 1.5) (* pi 0.5)))
  ((equal XvcVal -1 1E-4) pi)
  ((equal YvcVal 0 1E-4) (if (minusp XvcVal) pi 0.0))
  ((atan YvcVal XvcVal))
  )
  )
  
  This will work with all kind of Polylines, Splines, Lines, Arcs etc.
  Because we use the end tangent also no prob with 'bulged' Polylines...
  
  Cheers