Polygon operations

Thanks Laszlo,
but i was more thinking about the Polyop extension (ch=INITADDONSCOPE ("PolyOperations ", "", "")) which is said by Zsolt to be a more effective way to do such operations.
Although I will look with this macro.
But that would be very very very nice to see just a little example of use of the extension to see how we can use it. The source containers etc.. are a bit difficult to understand from scratch.
Maybe there is an object in the library using it?
Thanks in advance,
olivier

AC v13, winVista

Thanks a lot!
BTW I have been trying to use the polyoperations macro to calculate areas, but it appears to me that the results are bit different than what they should be. (if i draw a polygon and see the area)
Is that a bug?
You can't use the addon to calculate areas, can you?
(in that case it is not documented in the manual)
thanks,
regards,
olivier

Here is the code from the Polygonoperations.gsm macro:

----
area=0

tempNumPnts = nsp/3

areaLX = get(1) ! Last point
areaLY = get(1)
!!ziiz=get(1)
areaFX = areaLX ! First point
areaFY = areaLY

for areaI=1 to tempNumPnts-1
areaX = get(1)
areaY = get(1)
!!ziiz=get(1)
area = area + (areaX + areaLX) * (areaY - areaLY) * 0.5

areaLX = areaX
areaLY = areaY
next areaI
area = area + (areaFX + get(1)) * (areaFY - get(1)) * 0.5


-------

I add this in the beginning to give my polygon:
-------
for i=1 to vardim1(ac_coords)
put ac_coords[2],ac_coords[3],0
next i

------
ac_coords comes from the accessories API

but the resulting area is totally false...

I don't understand this code anyway which should call 3 times "get" per loop but "gets" only 2 times per loop.
Is there something obvious that I missed?

Thanks in advance,
Olivier

Ok, I think I fixed the little bug in the macro:
--
for areaI=1 to tempNumPnts-1
---
should be
--
for areaI=1 to tempNumPnts-2
--
now it seems to work.

However it doesn't work if there are holes in the polygon.
Some more work should fix this second problem.

and added of course this ziiz=get(1) in the loop to get 3 times instead of 2