Actually, you should shorten the maths - makes it a bit more efficient
function getArea pPts
if line 1 of pPts <> line -1 of pPts then return 0
put 0 into tArea
put empty into oldL
repeat for each line L in pPts
if oldL is not empty then
-- put item 1 of L - item 1 of oldL into dx
-- put item 2 of oldL + (item 2 of L - item 2 of oldL)
/ 2 into avgY
-- put dx * avgY into thisArea
-- add thisArea to tArea
add (item 1 of L - item 1 of oldL) * ( item 2 of oldL + item 2
of L) / 2 to tArea
end if
put L into oldL
end repeat
return abs(tArea)
end getArea
-- Alex.
On 08/11/2015 00:09, Alex Tweedly wrote:
Roger,
try this (I've done some minimal testing, so do please check it ...)
it assumes the polygon is closed
function getArea pPts
if line 1 of pPts <> line -1 of pPts then return 0
put 0 into tArea
put empty into oldL
repeat for each line L in pPts
if oldL is not empty then
put item 1 of L - item 1 of oldL into dx
put item 2 of oldL + (item 2 of L - item 2 of oldL) / 2 into
avgY
put dx * avgY into thisArea
add thisArea to tArea
end if
put L into oldL
end repeat
return abs(tArea)
end getArea
NB you could shorten it, but I left each math step separate to make it
easier to debug / check
-- Alex.
On 07/11/2015 22:29, Roger Guay wrote:
Thanks very much, Scott. I do have a long points list that I would
have to manipulate even before apply this technique. I’m not looking
forward to that, but I may have to go this route.
Cheers,
Roger
On Nov 7, 2015, at 12:05 PM, Scott Rossi <sc...@tactilemedia.com>
wrote:
It looks like this could translate to LC if you have the point
locations
of your polygon:
https://www.mathsisfun.com/geometry/area-irregular-polygons.html
Regards,
Scott Rossi
Creative Director
Tactile Media, UX/UI Design
On 11/7/15, 2:01 PM, "use-livecode on behalf of Roger Guay"
<use-livecode-boun...@lists.runrev.com on behalf of i...@mac.com>
wrote:
Can anyone think of an easy way of getting the area of an Irregular
polygon?
Thanks,
Roger
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