Topic: Helix problem

[LogicTools]

Please load the code on a blank dwg.
There are 2 commands on the code:

Code - Auto/Visual Lisp: [Select]

1. c:helix_on_world_ucs

  On World UCS creates 2 helix the second a perfect continuation of the other.

Code - Auto/Visual Lisp: [Select]

1. c:helix_on_custom_ucs

Same code as before but on a custom UCS. The second helix is not drawn as a continuation of the first one.
Can somebody help me understand this.

Code - Auto/Visual Lisp: [Select]

1. (vl-load-com)
2. (defun set_act_ucs (/ ucsorg ucsxdir ucsydir xvec yvec act_ucs)
3.  (setq
4.   AcadObject     (vlax-get-acad-object)
5.   AcadApp        (vla-get-Application AcadObject)
6.   ActiveDocument (vla-get-ActiveDocument AcadApp)
7.   UCSs           (vla-get-UserCoordinateSystems ActiveDocument)
8.   ucsorg         '(35.5021 10.9139 -1.27168)
9.   ucsxdir        '(-0.997401 -0.0720439 0.0)
10.   ucsydir        '(0.0 0.0 1.0)
11.   xvec           '()
12.   yvec           '()
13.  )
14.  (mapcar '(lambda (o v) (setq xvec (append xvec (list (+ o v))))) ucsorg ucsxdir)
15.  (mapcar '(lambda (o v) (setq yvec (append yvec (list (+ o v))))) ucsorg ucsydir)
16.  (setq
17.   act_ucs (vla-Add UCSs
18.                    (vlax-3d-point ucsorg)
19.                    (vlax-3d-point xvec)
20.                    (vlax-3d-point yvec)
21.                    "TEMP"
22.           )
23.  )  
24.  (vla-put-ActiveUCS ActiveDocument act_ucs)  
25. )
26.  
27. (defun helix_test (/ starts s_rad e_rad pitch ends step in_ang)
28.  (setq
29.   starts '(9 0 0)
30.   s_rad  '(9 2 0)
31.   e_rad  '(9 3 0)
32.   pitch   1
33.   ends   '(-1 0 0)
34.   step   0.75
35.   in_ang (angle ends starts)
36.  )
37.  (vl-cmdf "._helix" "_non" starts "_non" s_rad "_non" e_rad "_H" pitch "_A" "_non" ends)
38.  (setq
39.   e_rad   (list (car s_rad) (- (cadr s_rad) step) 0)
40.   ends    (polar starts in_ang pitch)
41.  )
42.  (vl-cmdf "._helix" "_non" starts "_non" s_rad "_non" e_rad "_H" pitch "_A" "_non" ends)
43.  (vl-cmdf "._zoom" "_e" "")
44. )
45.  
46. (defun c:helix_on_world_ucs ()
47.  (vl-cmdf "._ucs" "w" "")
48.  (helix_test)
49.  )
50.  
51. (defun c:helix_on_custom_ucs ()
52.  (set_act_ucs)
53.  (helix_test)
54.  )
55.