With LISP, how can I tell how many segments are in a LWPOLYLINE ?

[stephen.coff]

Guys,
I am clear on how to get the start point, end point and to set a specific distance of a LWPOLYLINE.

(setq ET (entlast))
(setq OBJ (vlax-ename->vla-object ET))
(setq STRTPT (vlax-curve-getStartPoint OBJ))
(setq ENDPT (vlax-curve-getendPoint OBJ))
(setq PLPT (vlax-curve-getpointatdist OBJ "MyPolylinePoint"))

This will give me the angle of the first segment, if i am correct. Not clear on how it is doing it. I have read a previous thread though couldn't follow.

(setq ANGL
(* (/ 180 pi)
(angle (list 0.0 0.0 0.0)
(vlax-curve-getFirstDeriv OBJ
(vlax-curve-getparamatdist OBJ 0.0001))
)
)
)

Is it possible with code to determin how many actual segments a polyline has ?
How do I cycle through and get the angle and direction for multiple segments of the LWPOLYLINE ?

Could someone please try an explain the small code above that determins the angle and what it is doing ? The "K.I.S.S." (keep it simple stupid) method is much preffered as i am simple.

Any assistance is much appreciated.


Stephen

[CADmium]

try this:
(setq ET (entlast))
(setq OBJ (vlax-ename->vla-object ET))

(setq SEG-COUNT (vlax-curve-getendparam OBJ))

[CAB2k]

See the second post.
http://forums.augi.com/showthread.php?t=32645

Also see kennet's post below that one.

[stephen.coff]

Thank you CADmium, that gets me the mumber of segments.

Cab2k,
I have been over that thread already and now again though not understanding it all. I wan't to be able to get the angles and lengths of all the segments if possible ? The answer is most likely in my face but just not understanding Kennet. Is there another thread that covers this topic in any simpler detail.

Stephen

[CAB2k]

See if this helps explain it.

(defun C:TEST (/ curve idx ang)
  (vl-load-com)
  (command "_.pline"
           "_non" '(0 0)
           "_non" '(10 0)
           "_non" '(0 10)
           "_non" '(0 20)
           "_non" '(-10 20)
           "_non" '(-10 10)
           "")
  (setq curve (entlast))
  (setq idx 0)
  (repeat (fix (1- (vlax-curve-getendparam curve)))
    (setq ang (angle '(0 0) (vlax-curve-getFirstDeriv curve idx))) ; (+ idx 0.005)
    (print "Angle of segment #")
    (princ idx)
    (princ " is ")
    (princ ang)
    (princ " radians.")
    (setq idx (1+ idx))
  )
  (princ)
)