[OSM-talk] osmxapi/bbox question

[Frederik Ramm]

Hi,

>> Can anyone point me to a good algorithm for selecting points within an
>> arbitrary polygon?

> I don't have it in pseudocode, but one I've heard of casts a ray (horizontal
> is common) out from the point being tested and then checks the intersection
> of that ray against each segment of the polygon. If the total number of
> intersections is odd, then the point lies inside the polygon. If the number
> is even, then it's outside. This works for holes in a polygon, too.

I think I saw an XSLT implementation of that in one of the OSM projects 
somewhere but I tried very hard to forget ;-)

Bye
Frederik