calculating polygons areas using autocad field

[franciscorefosco]

hello guys,
this is my first post here.
i have a doubt and i can find an answear on internet.
i draw my cad files in CENTIMETER.
all texts and dimmensions i insert on the LAYOUT.
i created a FIELD that calculates the area of a closed polygon, which i insert on the LAYOUT and it refers to a polygon on the MODEL.
so far, everything works fine.
the thing is that this field calculates the area in SQUARE CENTIMETER, and i need it to calculate SQUARE METER.
lets say there is a square of 2m x 2m (which i draw 200cm x 200cm), the area should be 4.00m2. instead, it calculates 200cm x 200cm = 40000cm2.
its correct, but i would like to see the result as SQUARE METER, or 4.00m2
So i found out that i could use "SCALE FACTOR" on the field properties, and change the factor from 1 to 0.0001.
then it works fine, it shows as i want.
but.... there is an issue.
when i copy and paste this field, to calculate the area of another closed polygon (which would be another room of the house, lie bathroom, bedroom, kitchen or something else), i need to point the FIELD to the new polygon i want it to calculate. when i do it, the FIELD loses the "SCALE FACTOR" that i had eddited before, so i need to manually change againg the factor of "SCALE FACTOR" from 1 to 0,0001.
as i have to calculate the area of several rooms of the houses i design, it takes a long time to go and edit the factor of "SCALE FACTOR" one by one.
i also tried to change the ambient scale, but could make it work as i need.

what do you guys recommend?

thanks a lot,

[Opie]

Welcome to AUGI!

Use a formula in your field. You can insert multiple fields within your formula.

[rkmcswain]

Use a formula in your field.

Per his comment below, he is already using a formula

So i found out that i could use "SCALE FACTOR" on the field properties, and change the factor from 1 to 0.0001.

The problem seems to be when you copy this field and select a new Object to tie it to, the formula is dropped.

when i copy and paste this field, to calculate the area of another closed polygon (which would be another room of the house, lie bathroom, bedroom, kitchen or something else), i need to point the FIELD to the new polygon i want it to calculate. when i do it, the FIELD loses the "SCALE FACTOR" that i had eddited before, so i need to manually change againg the factor of "SCALE FACTOR" from 1 to 0,0001.

The only solution I can see is to write a lisp routine to place the field and automatically include the formula.

[franciscorefosco]

hello guys,

thanks for the replies.
RKMCSWAIN, could you explain a little more about LISP?
i have no clue what's that, or how to make it work...

=]

[rkmcswain]

RKMCSWAIN, could you explain a little more about LISP?
i have no clue what's that, or how to make it work...

AutoLISP is a programming language for AutoCAD.
Take a look at these posts for some examples of making fields using lisp.

http://forums.augi.com/search.php?searchid=2269633

[Tom Beauford]

Try:

;SqMetersField
;^C^C^P(or C:SqMetersField (load "SqMetersField.lsp"));SqMetersField
(defun c:SqMetersField (/ ufa actDoc tab obid tpt lin plineReactor) 
;|  (defun ufa (notifier-object reactor-object parameter-list) 
    (cond 
      ((vlax-property-available-p notifier-object "Area") 
       (setq actDoc 
       (vla-get-ActiveDocument (vlax-get-acad-object))) 
       (vla-SAVE actDoc) 
      ) 
    ) 
  ) |;
  (setvar"cmdecho" 0) 
 (princ "\nSelect closed Object or Hatch ")
 (setq ss (ssget "+.:E:S" '((0 . "lwpolyline,spline,circle,ellipse,hatch"))))
; :E  Everything in aperture
; :S  Force single object selection only
; The "+." puts (ssget) into "point" mode. It helps the ":S"
; single-mode act just like (entsel) by avoiding implied
; selection windows.
; (if ss
   (setq ent (ssname SS 0)
         EnTyp (cdr (assoc 0 (entget ent)))
         obj (vlax-ename->vla-object ent)
           obid (vla-get-objectid obj)
           tpt (getpoint"\nSelect Area Text Point: ")
   )
   (setq lin (strcat "%<\\AcObjProp Object(%<\\_ObjId " (rtos obid 2 0) ">%).Area \\f \"%lu2%pr3%ps[±, Sq Meters]%ct8[1e-004]%th44\">%"))
  (command "mtext" tpt "w" "0" lin "") 
  (princ) 
)

[franciscorefosco]

Hello TOM,

could you please tell me where should I paste this code?
FIELD -> OTHER -> LISPVARIABLE -> ?

thank you,

[Tom Beauford]

Copy the code and paste into a text editor. Save it as "SqMetersField.lsp" in a support folder. On the Command line enter: (load "SqMetersField.lsp")
Then enter: SqMetersField
Pick the object you wish to have the area of, then pick the text location. It will add the label at the current text size.

[franciscorefosco]

hello again guys,

i followed step by step this website, to learn how to use the LISP code which TOM has provided http://www.cadtutor.net/forum/showthread.php?t=1390
unfortunatelly, i didnt succeed.
when i was trying to use the command on autocad, after selecting a closed object, it would return a message saying that thre was an error, "Select objects: ; error: bad argument type: lselsetp nil"
maybe i should just give up, this issue doesnt seem to be easy to solve.

=]

[Tom Beauford]

hello again guys,

i followed step by step this website, to learn how to use the LISP code which TOM has provided http://www.cadtutor.net/forum/showthread.php?t=1390
unfortunatelly, i didnt succeed.
when i was trying to use the command on autocad, after selecting a closed object, it would return a message saying that thre was an error, "Select objects: ; error: bad argument type: lselsetp nil"
maybe i should just give up, this issue doesnt seem to be easy to solve.

=]

Try adding

(vl-load-com)

as the first line in the routine. What version of Autocad are you running?