CGAL users discussion list

[Sherif Ghali <>]

The right way is to write two brief classes for a spherical (circular)
point and a spherical (circular) segment on S^1. A spherical point can
be a standalone class or a wrapper for Direction_2. You would represent
the set of "forbidden" directions (those in a polygon's interior) using
a spherical segment and confirm that two spherical points at both
vertices are outside the two spherical segments before declaring
the vertices mutually visible.

Sherif



On Thu, May 10, 2007 at 01:18:15PM -0400, Dave Ceddia wrote:
> Hello CGAL experts,
> 
> I am trying to compute the visibility graph among a set of polygons, and
> there are a couple things I can't think of how to do nicely using CGAL. For
> now, I'm trying to figure out how to do segment-polygon intersection. Some
> of the lines of the visibility graph need to connect from a polygon back to
> itself (since the polygons are non-convex), but I want to avoid introducing
> lines that are internal to the polygon. I can't seem to think of a way of
> testing for intersection of a segment with a polygon, is there a simple way
> to do this in CGAL?
> 
> Thanks,
> Dave
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