Drawing road alignment

[aloy]

I have a routine drawing road alignment which needs relaoding every 100m. due to the line on the text. It is as follows:

 
(setq p1 (cadr (car l)))
(setq ch(car (car l)))
(setq w 8)
(while 
(/= l nil)
  (setq l (cdr l))
  (setq p2 (cadr (car 
l)))
  (setq p1xl (polar p1 (+ (angle p1 p2) (/ pi 2)) 1.5))
  (setq p1xr (polar p1 (- (angle p1 p2) (/ pi 2)) 1.5))
  (setq p1sl 
(polar p1 (+ (angle p1 p2) (/ pi 2)) w))
  (setq p1sr (polar p1 (- 
(angle p1 p2) (/ pi 2)) w))
  (setq p2sl (polar p2 (+ (angle p1 p2) (/ 
pi 2)) w))
  (setq p2sr (polar p2 (- (angle p1 p2) (/ pi 2)) 
w))
  (command "line" "_NON" p1 "_NON" p2 "")
  (if (= (rem ch 
20) 0)   (command "line" "_NON" p1xl "_NON" p1xr ""))
  (if (= 
(rem ch 100) 0) (command "text" p1xr 4 (* (-(angle p1xl p1xr) (* 2 pi)) (/ 180 
pi)) (substr (rtos ch) 1 6) ""))
  (command "line" "_NON" p1sl "_NON" 
p2sl "")
  (command "line" "_NON" p1sr "_NON" p2sr "")
  (setq 
p1 p2)
  (setq ch(car (car l)))
)

If that line is commented off the rest works fine. What seems to be the problem. Grateful for any help.
Aloy

[MSasu]

I believe that you forgot to mark the trouble-maker code line. Which is the one that should be commented for the routine to work properly?

Also, if you post only an excerpt from your code, is better to add some lines to initiate variables - in above code, one must guess what value store the l variable.

[aloy]

Thanks MSasu,
Here is the variable I:

(setq l '((0.0 (-108.124 81.3947 0.0)) (20.0 (-88.6807 86.0816 0.0)) (40.0 
(-69.2377 
90.7684 0.0)) (60.0 (-49.7946 95.4553 0.0)) (80.0 (-30.3515 
100.142 0.0)) 
(100.0 (-10.9085 104.829 0.0)) (120.0 (8.53462 109.516 0.0)) 
(140.0 (27.9777 
114.203 0.0)) (160.0 (47.4208 118.89 0.0)) (180.0 (66.8638 
123.577 0.0)) (200.0 
(86.3069 128.264 0.0)) (220.0 (105.75 132.951 0.0)) 
(240.0 (125.193 137.637 
0.0)) (260.0 (144.636 142.324 0.0)) (280.0 (164.079 
147.011 0.0)) (300.0 
(183.522 151.698 0.0)) (320.0 (202.965 156.385 0.0)) 
(340.0 (222.408 161.072 
0.0)) (360.0 (241.851 165.759 0.0)) (380.0 (261.295 
170.446 0.0)) (400.0 
(280.738 175.133 0.0)) (420.0 (300.181 179.82 0.0)) 
(440.0 (319.624 184.506 
0.0)) (460.0 (339.067 189.193 0.0)) (480.0 (358.51 
193.88 0.0)) (500.0 (377.953 
198.567 0.0)) (520.0 (397.396 203.254 0.0)) 
(540.0 (416.839 207.941 0.0)) 
(560.0 (436.282 212.628 0.0)) (580.0 (455.725 
217.315 0.0)) (600.0 (475.168 
222.002 0.0)) (620.0 (494.611 226.688 0.0)) 
(640.0 (514.054 231.375 0.0)) 
(660.0 (533.498 236.062 0.0)) (680.0 (552.941 
240.749 0.0)) (700.0 (572.384 
245.436 0.0)) (720.0 (591.827 250.123 0.0)) 
(740.0 (611.27 254.81 0.0)) (760.0 
(630.713 259.497 0.0)) (780.0 (650.156 
264.184 0.0)) (800.0 (669.599 268.871 
0.0)) (820.0 (689.042 273.557 0.0)) 
(840.0 (708.485 278.244 0.0)) (860.0 
(727.928 282.931 0.0)) (880.0 (747.371 
287.618 0.0)) (900.0 (766.814 292.305 
0.0)) (920.0 (786.257 296.992 0.0)) 
(940.0 (805.701 301.679 0.0)) (960.0 
(825.144 306.366 0.0)) (980.0 (844.587 
311.053 0.0)) (990.275 (854.575 313.46 
0.0)) (1000.0 (864.029 315.743 0.0)) 
(1020.0 (883.45 320.518 0.0)) (1040.0 
(902.809 325.543 0.0)) (1060.0 
(922.054 330.982 0.0)) (1080.0 (941.127 336.999 
0.0)) (1086.27 (947.062 
339.035 0.0)) (1100.0 (959.986 343.655)) (1120.0 (978.7 
350.715)) (1140.0 
(997.263 358.162)) (1160.0 (1015.67 365.993)) (1180.0 
(1033.91 374.203)) 
(1200.0 (1051.97 382.79)) (1220.0 (1069.85 391.75)) (1240.0 
(1087.54 
401.079)) (1260.0 (1105.04 410.772)) (1280.0 (1122.33 420.827)) 
(1300.0 
(1139.41 431.238)) (1320.0 (1156.27 442.001)) (1340.0 (1172.9 453.111)) 

(1360.0 (1189.29 464.563)) (1380.0 (1205.45 476.354)) (1400.0 (1221.36 

488.477)) (1420.0 (1237.01 500.927)) (1440.0 (1252.4 513.699)) (1460.0 
(1267.53 
526.788)) (1480.0 (1282.38 540.188)) (1500.0 (1296.95 553.893)) 
(1502.84 
(1298.99 555.867)) (1520.0 (1311.02 567.884 0.0)) (1540.0 (1324.72 
582.453 
0.0)) (1560.0 (1338.05 597.367 0.0)) (1580.0 (1351.12 612.502 0.0)) 
(1598.84 
(1363.33 626.861 0.0))))

You can run it within limits of 0,0 and 1200,1000 in Acad 2011.
Please load two files and see.
The trouble maker is the one that starts with (if (= (rem ch 100) 0)........
Regards,
Aloy

[MSasu]

The error is from the way you attempt to access the items in list - when list had only one item left you try to retrieve the second one, which is nil, thus the error. I have modified your code to avoid this. I added also some small modifications to it - marked in red. You may want to check the labels, too - not sure what you want to achieve.

(setq p1 (cadr (car l)))
(setq ch(car (car l)))
(setq w 8)
(foreach pair (cdr l)
 (setq p2 (cadr pair))
 (setq p1xl (polar p1 (+ (angle p1 p2) (/ pi 2)) 1.5))
 (setq p1xr (polar p1 (- (angle p1 p2) (/ pi 2)) 1.5))
 (setq p1sl (polar p1 (+ (angle p1 p2) (/ pi 2)) w))
 (setq p1sr (polar p1 (- (angle p1 p2) (/ pi 2)) w))
 (setq p2sl (polar p2 (+ (angle p1 p2) (/ pi 2)) w))
 (setq p2sr (polar p2 (- (angle p1 p2) (/ pi 2)) w))
 (command "_line" "_NON" p1 "_NON" p2 "")
 (if (= (rem ch  20) 0)
  (command "_line" "_NON" p1xl "_NON" p1xr ""))
 (if (= (rem ch 100) 0)
  (command "_text" p1xr 4 (* (-(angle p1xl p1xr) (* 2 pi)) (/ 180 pi)) (substr (rtos ch) 1 6)))   ;""))
 (command "_line" "_NON" p1sl "_NON" p2sl "")
 (command "_line" "_NON" p1sr "_NON" p2sr "")
 (setq p1 p2)
 (setq ch (car pair))
)

[aloy]

Sorry, Mircea
The code did not work. However commenting off the end in the trouble maker on my code as sggested by you worked. Please try it. What I am trying to do is to draw the centre line and the road with chainages marked at every 20m. Similarly centre median also could be added for a dual carriagway. The list, l, contains the chainages with respective coordinates of a tangent, spiral (clothoid), circular curve and another spiral section at the end.
Thanks for the help.
Aloy

[MSasu]

Aloy, when posted my changes to your code, have omitted intentionally the first lines from your excerpt since I didn't touched them. Maybe this had confused you. Sorry. I have added them now in post #4.
For me if I load the l variable and next the modified code I got it draw a curved path with some labels; did you tried the new code in a new, clean drawing or there are other items in drawing or ther was other code run previously?
If you get an error, can you please post it here?

[aloy]

Mircea,
Yes, it works fine; no errors. Thank you very much for the method. I will study how to use 'Foreach pair'.
Regards,
Aloy

[MSasu]

Good to hear that, Aloy. You're entirely welcome!