From:	ellman AT xs4all DOT nl ()
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro 3D : Sorting Polygons
Date:	3 Apr 1997 20:49:05 GMT
Organization:	XS4ALL
Lines:	22
Message-ID:	<5i1541$h1q$1@news0.xs4all.nl>
References:	<E7rD4t DOT 9zL AT news DOT uwindsor DOT ca> <5hmmtt$5bg$1 AT news0 DOT xs4all DOT nl> <3341AAEF DOT 52E5 AT cam DOT org> <33419DA2 DOT 544FE8A1 AT caldera DOT com>
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In article <33419DA2 DOT 544FE8A1 AT caldera DOT com>, Tim Bird  <tbird AT caldera DOT com> wrote:
>Tudor wrote:
>>ellman AT xs4all DOT nl wrote:
>>> Alternative approaches are to use the Painter's algorithm or Z buffering.
>>What is the Painter's algorithm, if you don't mind?
>
>Painting the items back-to-front.  All you have to do is order
>the things to be drawn by distance and draw everything.  If
>there are lots of overlaps, this gets wasteful, since you end
>up drawing lots of pixels multiple times.  But it's easy to
>code.

Actually, that's depth sorting. The painter's algorithm is to convert all the
polygons into a set of polygons that consist of only what is to be displayed.
It eliminates any hidden polygons, and breaks up any partially-hidden polygons.

Several books tell you how to do this (such as Tricks of the Game Programming
Gurus, Zen of Computer graphics), and the Zed3D tutorial on x2ftp.oulu.fi
tells you about it as well.

AE.

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