vlax-invoke-method "FindElevationAtXY"

[Shinigami_black]

Hi, I try to write a lisp to get elevation from TIN surface in AutoCAD Civil 3D. But coordinate can be not on surface. In this case I get an error and my lisp execution stops. Here are a function

(defun GetElevationAtXY (coordinate surfaceName / )
	(vlax-invoke-method surfaceName "FindElevationAtXY" (car coordinate) (cadr coordinate)))
)

If coordinate are not on surface I would like to return nil, and continue lisp execution. nil would be handled later in another function. Is it possible in lisp?

P.S.

error message I get are

Error. Automation Error. Triangle is deleted

[Shinigami_black]

I found I can use vl-catch-all-apply for this, and added it to my function. But now I get error message like this

Error: bad argument type: symbolp nil

 This is my curent function

(defun GetElevationAtXY (coordinate surfaceName / z)
	(set z
	     (vl-catch-all-apply 'vlax-invoke-method (list surfaceName "FindElevationAtXY" (car coordinate) (cadr coordinate)))
	)
	(if (= (vl-catch-all-error-p z) T)
		(setq z nil)
		(setq z z)
	)
)

 This error is in line

(vl-catch-all-apply 'vlax-invoke-method (list surfaceName "FindElevationAtXY" (car coordinate) (cadr coordinate)))

[bhull1985]

http://www.lee-mac.com/errormessages.html

Here's the page where you can check the different error codes and what they mean, as well as tutorials on how to fix them.

Typically what follows a call to -invoke-method is a method, it appears as if that may not be the case in your line of code but perhaps im wrong

[Shinigami_black]

Here are samething wrong with list I make

To test  (vl-catch-all-apply 'vlax-invoke-method li) I have creaded li in AutoCAD command line

(setq li (list surfaceName "FindElevationAtXY" (car coordinate) (cadr coordinate)))

 And I got back this

(#<VLA-OBJECT IAeccTinSurface 000000002f769c80> "FindElevationAtXY" 419214 6144697)

 look at "FindElevationAtXY".

But if I do this in lisp

(defun GetElevationAtXY (coordinate surfaceName / z li)
	(setq li (list surfaceName "FindElevationAtXY" (car coordinate) (cadr coordinate)))
	(princ li)
	(set z
	    (vl-catch-all-apply 'vlax-invoke-method li)
	)
	(if (= (vl-catch-all-error-p z) T)
		(setq z nil)
		(setq z z)
	)
)

 I get this printed

(#<VLA-OBJECT IAeccTinSurface 000000002f769c80> FindElevationAtXY 419143.0 6.14477e+006)

 "FindElevationAtXY" became FindElevationAtXY. So probably it is treated as variable and not as string. But here are no variable FindElevationAtXY so it is equal to nil.

But how to fix it?

[Shinigami_black · Accepted solution]

It was my mistake.
was not (setq z
but was (set z