Topic: GetParamAtPoint Problem

[civil.eng]

Hello everyone,
There is a problem with vlax-curve functions with 3Dpolyline, the attached file I wanted to use GetParamAtPoint function but it gives nil for some points while there is no problem with polyline and it occurs only with 3Dpolyline :

Code: [Select]

(defun c:ff ()
  (setq obj (vlax-ename->vla-object (car (entsel))))
  (setq pt (getpoint))
  (vlax-curve-getparamatpoint obj pt)
)


[ribarm]

Code: [Select]

(defun c:ff ()
  (setq obj (vlax-ename->vla-object (car (entsel))))
  (setq pt (getpoint))
  (vlax-curve-getparamatpoint obj (vlax-curve-getclosestpointto obj (trans pt 1 0)))
)

HTH., M.R.

[civil.eng]

Thanks, but your codes didn't work. Did you try it on the file?

[ribarm]

Indeed, sometimes CAD just won't work as expected... I moved 3dpoly, point at middle of segment, tried several times and at the end it worked... Sometime you just have to nudge things a bit to make it work - that's CAD (it happens from time to time, for ex. intersectwith method doesn't work if entity is far away from origin 0,0,0 - this isn't such a case, you just have to do something on entity that behaves buggy...)

[Tharwat]

Also here returns nil
Work around it via retrieving the coordinates of that targeted polyline then sort them to nearest distance to pt with x and y only without Z.

[Lee Mac]

This is a known bug with the vlax-curve-* functions when the target entity is far from the origin - the below presents a possible workaround for you to consider:

Code - Auto/Visual Lisp: [Select]

1. (defun c:test ( / b e o p v x )
2.     (if
3.         (and
4.             (setq e (car (entsel)))
5.             (setq p (getpoint "\nSpecify point to obtain param: "))
6.         )
7.         (progn
8.             (setq v (vlax-ename->vla-object e)
9.                   b (vlax-curve-getstartpoint e)
10.                   p (mapcar '- (trans p 1 0) b)
11.                   b (vlax-3D-point b)
12.                   o (vlax-3D-point 0 0)
13.             )
14.             (vla-move v b o)
15.             (setq x (vlax-curve-getparamatpoint e (vlax-curve-getclosestpointto e p)))
16.             (vla-move v o b)
17.             (princ "\nParameter: ")
18.             (prin1 x)
19.         )
20.     )
21.     (princ)
22. )