How to get the viewport scale via lisp?

[Gordon_S]

I am adapting a routine by Alan J Thompson found here for placing an outline of a paperspace viewport in modelspace.

I have added some lines for making a suitable Noplot layer with appropriate linetype, and wanted to make the lwpolyline have a thickness dependent upon the viewport scale.

My paperspace viewport scales are set for printing via Zoom - 1/50XP for example to get a 1:50 scale plot (or 0.02XP)

Having selected the relevant viewport, I wanted to be able to determine the vp scale, but am unsure how to extract this information from the viewport entity itself.

I did receive help some time in the past for a similar matter, but I'm not sure that I can use it in the same way. The routine was as follows:-

(defun xpfact ()
   (- (car (trans '(1 0 0) 2 3))
      (car (trans '(0 0 0) 2 3))
   )
)

--

Gordon

[Gordon_S]

I've just seen in the DXF Group Codes for Viewports the comment at the bottom of the list that says:

Note  The ZOOM XP factor is calculated with the following formula: group_41 / 2nd_group_1040 (or pspace_height / mspace_height).

However, although I understand what has to be accessed and the nature of the calculation, I do not know how to get hold of the '2nd_group_1040' which appears to be xdata.

What code do I need to access the second 1040 group from the list of xdata?

--

Gordon

[phanaem · Accepted solution]

Hi Gordon

The code from your first post is working if you are in PaperSpace. But if there are multiple viewports with different scale, I don't know for which one is returning the correct answer (something related to ActiveVieport or so).

Try this instead

(if
  (setq ss (ssget ":E:S" '((0 . "VIEWPORT"))))
  (vla-get-CustomScale (vlax-ename->vla-object (ssname ss 0)))
  )

[Gordon_S]

Hi phanaem,

Thanks for your code.

I've added this in to my routine and it works perfectly.

--

Gordon

[Edwin.Saez]

@Gordon_S,

maybe you could share the lisp, since I'm needing as it is to select the vieport and zoom it 1000 / 100XP.

Value 100, would be the scale that would change depending on what you need.

thanks

[gordonstephens20]

Hi Edwin,

I have found the lisp that I adapted slightly , originally by Jimmy Bergmark.

I have it as vp-outline.lsp dated 18 Sept 2003 - you are lucky that I am still around and getting feeds/notifications.

[Edwin.Saez]

@gordonstephens20,

Thanks for sharing the lisp. I think the code needs to be updated, because it does not work in autocad 2018. The command does not do anything.

[gordonstephens20]

Sorry, I have been retired for 6 years now so have not used it in quite a while - also, I do not have Acad 2018.

You may have to ask for some help to tweak it - I think that it has been too long for me to unpick it and work out why it doesn't do anything.

[DannyNL]

The command DOES work in AutoCAD 2018, but only to the use as stated in the comment section at the top.

In a Layout (!) you start the command and select a viewport; the routine then draws a polyline boundary in modelspace (!) to indicate the viewport boundary.

So for scaling and other settings this routine needs to be updated to specifically suite your needs.