Polygons & Nodal Points...

cabney cabney at cyberpass.net
Sun Jul 15 21:58:12 CDT 2001

On Sun, 15 Jul 2001 schoon at amgt.com wrote:

> Yes, this is true, using a ray... But it fails when a point is right on
> a boundary, and the polygon is odd shaped which would make an even
> amount of crossings... Still a valid point, but fails the test...

well, no.  Use >= and <= for points on the lower and upper edge of the
polygon, and I if you construct some odd scenarios (even allowing the
'north' and 'south' edges to cross, or using concave (acute) vertices)
you'll find it works.  Just start the count from the minimum point on
the y-axis, and proceed, either to your point or to the maximum y-value.

There was a time
A wind that blew so young
For this could be the biggest sky
And I could have the faintest idea


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