Message-ID:	<351AD81E.E9F2939C@wpol.com>
From:	John & Sue Kissell <jdk AT wpol DOT com>
Reply-To:	jdk AT wpol DOT com
MIME-Version:	1.0
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: point inside polygon detection
References:	<6fce42$md4 AT bgtnsc02 DOT worldnet DOT att DOT net>
Lines:	26
Date:	Thu, 26 Mar 1998 19:25:48 GMT
NNTP-Posting-Host:	208.195.214.68
NNTP-Posting-Date:	Thu, 26 Mar 1998 14:25:48 EST
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

This may be total nonsense, but it seems to me that you should be able
to compare the point's coordinates to the *average* location (+ or - 1/2
the size in X and Y) of the object's corner coordinates. This is easy to
see with a plain (all right angle) rectangle, but without testing it
could be absolute rubbish for non-regular objects.


Hope this gives you some ideas,
John Kissell

Steve Patton wrote:
> 
> Hi,
> 
>   Is there a quick easy way to detect whether a point lies within the
> boundaries of a 2d polygon?  Right now I'm dealing with a four sided
> polygon.  This shape could be a rectangle (at any rotation angle, or
> distortion), trapazoid, etc, any 4 sided polygon.  This has to be checked a
> LOT, so I would appreciate an efficient algorithm.  Source code is not
> neccessary, if you can give me an idea, I can run with it.  Thanks!
> 
> --
> -Steve
> Personal : http://home.att.net/~pattonl
> Business : http://home.att.net/~pattonl/digital_resources.htm

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