Area for any object

I have a lisp file that calculates the area and perimeter of an object in m2 and m. It only works for closed polylines at the moment, can anyone help me to amend it to work for picked points as well as polylines as the Acad area command does.

Cheers

(defun c:aaaa ()
(setq obj (car (entsel)))
(command "area" "o" obj)
(setq A1 (/ (getvar "area") 1000000))
(setq P1 (/ (getvar "perimeter") 1000))
(terpri)
(prompt "Area = ")(princ A1)(prompt "m2")
(terpri)
(prompt "Peri = ")(princ P1)(prompt "m")
(princ)
)

 

I have a lisp file that calculates the area and perimeter of an object in
m2 and m.

Not really. It reports area and perimeter in whatever units Acad happens to
be using at the time, after dividing them by a million and a thousand
respectively. You're assuming that the drawing units are mm, but there's
nothing in Acad or your routine to validate this assumption. The units could
be microns or parsecs.

 

To calculate the area enclosed by the picked points, put a temporary polyline through the picked points, then get the area of last object (the temp. polyline), then delete the temporary polyline. I think you can do the amendment now yourself!

Hope this idea helps.

Rajesh Patnaik

 

Ok I’ll re-phrase the question!

I have a lisp file that reports area and perimeter in whatever units Acad happens to
be using at the time, after dividing them by a million and a thousand respectively, if the units happen to be mm it calculates the area and perimeter of an object in m2 and m. It only works for closed polylines at the moment, can anyone help me to amend it to work for picked points as well as polylines as the Acad area command does.

 

Try this...
Added the stuff to do points/objects, leaving the rest as you had it.
-doug

(defun c:aaaa ()
(princ "\nArea finder - select type:<Points,Object>")
(setq atype (strcase (getstring)))
(cond
((= atype "P")
(princ "\nPick first point for perimeter:")
(setq pt1 (getpoint))
(command "area" pt1)
(while
(setq pt2 (getpoint pt1 "\nNext Point.."))
(setq ptlist (append ptlist (list pt1)))
(setq pt1 pt2)
(command pt2)
);end while
(command "")
)
((= atype "O")(command "area" "o" pause))
)
(setq A1 (/ (getvar "area") 1000000))
(setq P1 (/ (getvar "perimeter") 1000))
(terpri)
(prompt "Area = ")(princ A1)(prompt "m2")
(terpri)
(prompt "Peri = ")(princ P1)(prompt "m")
(princ)
)

and m. It only works for closed polylines at the moment, can anyone help me to
amend it to work for picked points as well as polylines as the Acad area command
does.

 

Cheers doug,
thanks very much.

 

One way:
(defun c:aaaa ()
(setvar "cmdecho" 1)
(command "area")
(while (= (getvar "cmdactive") 1)
(command pause))
(setvar "cmdecho" 0)
(setq A1 (/ (getvar "area") 1000000))
(setq P1 (/ (getvar "perimeter") 1000))
(terpri)
(prompt "Area = ")(princ A1)(prompt "m2")
(terpri)
(prompt "Peri = ")(princ P1)(prompt "m")
(princ)
)

area and perimeter of an object in m2 and m. It only works for closed polylines at the moment, can anyone help me to amend it to
work for picked points as well as polylines as the Acad area command does.

 

One subtractional thing...<g>
Take this out:
(setq ptlist (append ptlist (list pt1)))
At first I thought I'd need a list of points, but it isn't required.

btw, the 'other Doug B' has a better handle on some of this, f'rinstance
"cmdactive", and his is ultimately cleaner than mine. Though I do like the
rubber bands that mine offers.
-doug

 

the problem is in your command line, where you select o, so only closed
polylines are messured

have a look at cmdactive systemvariable to create a temp polyline
then
(command "_area" "_o" (lastent))

good luck

mfg
gert

 

Thanks for all of that, most useful,
Cheers

 

Thanks Doug. I took the easy way, since
he wanted it to act just like the area command.

 

So can 'cmdactive' be used to burst into any command and
do other 'surreptitious stuff' while the command is still running?

 

Hi Doug,
I'm not sure I understand the question. (getvar "Cmdactive") can
be used to detect whether a built in command is running.
(getvar "Cmdnames") can be used to determine which commands
are running.

Many things can be done between (command...) statements
while a command is active. Since there is no way to check the
value of the command prompts, however, there is no way to
use it to predict what would be the correct answer to a prompt.

Here I was just using it to allow the area command to run to
its conclusion with whatever input the user wanted and then
calculating the areas. A commandended reactor could also
be used but, in this case, it would have been overkill.

Regards,
Doug

 

But if that's how you're going to do it, you don't need the polyline. All
you need is to feed those points to the Area command, which also gives you
the area and perimeter. If you want to get that information for use in a
lisp routine, I'm not sure how you would extract it (either from the Area
result OR from a polyline, since neither of these is in the assoc/dxf code
list for the polyline), but I vaguely recall that there might have been a
similar question raised maybe a few months ago that you could search for on
the website edition.

Kent Cooper, AIA

polyline through the picked points, then get the area of last object (the
temp. polyline), then delete the temporary polyline. I think you can do the
amendment now yourself!

 

Doug's explanation is pretty good. Generally this trick is used when you
need to do something after a command is concluded, such as reporting the
information after running the area command. There's no way to predict how
many points might be picked, but you can check to see if that command is
still in progress, and keep pausing for input as long as it's running.

It's not so much a case of doing stuff while the command is running, it's
more a matter of needing to know when the command is finished.