[mkgmap-dev] shapes with holes

Sat Jan 19 14:57:39 GMT 2013

> So you have to add some costly checks which point is directly
> connectable. There is an algorithm (I don't remember the name) that
> calculates which points are directly visible from a given point. If you
> want to implement it would work. Just search Wikipedia and the polygon
> algorithms. You will find it. I guss it's not very nice to the
> performance...

Performing a quick search I haven't found an algorithm but the problem 
is very similar to the visibility problems described in wikipedia:
http://en.wikipedia.org/wiki/Visibility_%28geometry%29
http://en.wikipedia.org/wiki/Isovist
http://en.wikipedia.org/wiki/Visibility_graph
http://en.wikipedia.org/wiki/Art_gallery_problem


WanMil