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fair enough. But i still would like a (better) LISP function that returns the
elevation (or nil if out of bounds) for a point on a surface. Ive loaded the
vl com and reactors, and tried the vlisp help. Using Roberts suggestion as a
how do i set the cur_surf object - something similar to (setq cur_surf
With help, developed a function to extract an elevation from a surface (or selected surfaces from a list). It's worked fine until C3D2012 and now with the change in format I need to get it working again.
I'm getting error: "Civil 3D API: Triangle is deleted" for points outside the extent of the surface in my sub-function
(vlax-invoke cur_surf 'FindElevationAtXY (car pt) (cadr pt)) )
It used to simply return nil without crashing and I could handle the nil value in a number of ways and continue to the next point. I use the function in a number of routines attached directly to Access databases for modelling grids and correcting elevations of fields in a number of large database sets.
Any advice on working around or other vlax function needed to check the xy coordinate to the surface is much appreciated.