How to change a surface point elevation with visual lisp

[tcorey]

I am attempting to use lisp to change a TIN Surface point elevation using visual lisp.

I get the surface object with ename->vla-object

I retrieve the points safearray with vlax-get-property and then vlax-variant-value.

I now have a safearray from which I can extract each point's x y z using a counter.

I then thought I could use vlax-safearray-put-element to change the elevation. Debugging responds that the value has been 'put,' but I don't know how I need to figure out how to put it all back into the surface.

I notice that 'Points property of the surface object is read only. Does that mean I am spinning my wheels or is there a way to do this.

;This code evaluates surface points on Groundwater surface and changes them to equal OG surface if groundwater is higher.


(defun c:go ()

  (setq ogsrfv (vlax-ename->vla-object (car (entsel "\nSelect OG surface:")))
	gwsrfv (vlax-ename->vla-object (car (entsel "\nSelect GW surface: ")))
	)

 ; (vlax-dump-object ogsrfv t)
 ; (vlax-dump-object gwsrfv t)

  (setq gwpts (vlax-get-property gwsrfv 'Points))
  (setq gwptsvar (vlax-variant-value gwpts))
  (setq lb (vlax-safearray-get-l-bound gwptsvar 1))
  (setq ub (vlax-safearray-get-u-bound gwptsvar 1))
  (setq ctr lb)

  (while (<= ctr ub)
    (setq p1x (vlax-safearray-get-element gwptsvar ctr))
    (setq p1y (vlax-safearray-get-element gwptsvar (+ ctr 1)))
    (setq p1z (vlax-safearray-get-element gwptsvar (+ ctr 2)))


    ;Get OG elevation
      (setq OGz (vlax-invoke-method ogsrfv 'FindElevationAtXY p1x p1y))

;if gw elevation is higher than og, modify gw to match og
    (if (> p1z ogz)
	(vlax-safearray-put-element gwptsvar (atoi (rtos (+ ctr 2) 2 0)) OGz)
      );end if

    

	

    (setq ctr (+ ctr 3))
    
    );end while


   (princ)
  );end defun

 I am attaching a test drawing with a couple of very simple surfaces.

Please don't tell me to go learn .net. I know it's better and Autodesk doesn't want to support vlisp for Civil 3D, but vlisp is just so convenient for us non-programmers.

Thanks in advance for any sage advice...

Tim

[Jeff_M · Accepted solution]

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@tcorey wrote:

I am attempting to use lisp to change a TIN Surface point elevation using visual lisp.

I am attaching a test drawing with a couple of very simple surfaces.

Please don't tell me to go learn .net. I know it's better and Autodesk doesn't want to support vlisp for Civil 3D, but vlisp is just so convenient for us non-programmers.

Thanks in advance for any sage advice...

Tim

---

Well...... I won't tell you, then, that the EditOperations are not available in the COM API but they are in the managed .NET API....

[tcorey]

I figured that was the case. Dang it.

Thanks, Jeff.

Tim