Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ptsfa!amdahl!drivax!dambrose
From: dambrose@drivax.UUCP (David Ambrose)
Newsgroups: comp.graphics
Subject: Re: polygons and points
Message-ID: <2932@drivax.UUCP>
Date: 13 Jan 88 19:58:57 GMT
References: <506UD138985@NDSUVM1>
Reply-To: dambrose@drivax.UUCP (David Ambrose)
Organization: Digital Research Inc
Lines: 18

In article <506UD138985@NDSUVM1> UD138985@NDSUVM1.BITNET writes:
>     I would like to know if anyone out there has a fool proof method
>(algorithm) for determining whether or not a point is inside of a polygon.

	You could use the tried and true "parity" algorithm.  Draw a
line from the point to "infinity".  Find all the intersections of this
line with the polygon's edges and count them.  If the number is odd,
the point is inside; even,  it's outside.

	I don't have any referrences at hand but may be able to provide
them if badgered.



-- 
______________________________________________________________________________
David L. Ambrose, --  Digital Research, Inc         ...!amdahl!drivax!dambrose
DISCLAIMER: Don't blame DRI.  They wouldn't approve of this anyway. r}ix
NO CARRIER