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From: | Paul Furber <paul AT sprintlink DOT co DOT za> |
Newsgroups: | comp.os.msdos.djgpp |
Subject: | Re: John Carmack <johnc AT idnewt DOT idsoftware DOT com>: Re: Question about Doom. |
Date: | Thu, 27 Mar 1997 10:42:55 +0200 |
Organization: | Global One South Africa (Pty) Ltd. |
Lines: | 20 |
Message-ID: | <333A330F.5D22@sprintlink.co.za> |
References: | <199703211735 DOT JAA29516 AT netcom9 DOT netcom DOT com> <3332FA0B DOT 3418 AT shoreland DOT com DOT nospam> <3333707A DOT 3D06 AT erols DOT com> <5h6olj$qgr AT news DOT southeast DOT net> |
Reply-To: | paul AT sprintlink DOT co DOT za |
NNTP-Posting-Host: | ppp21.sprintlink.co.za |
Mime-Version: | 1.0 |
To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
M. Edward Kiser wrote: > Oh, and PVS stands for _Potentially_ Visible Set, not Partial. Michael Abrash defines it as such in his Quake discussions on the Dr Dobbs site. > Those are my guesses. Now the dumb question. What is ray casting? Is > it a form of ray tracing? Yes, but simplified. From the eye or camera you just fire out a number of rays from -1/2 the field of view to +1/2 the field of view. When a ray intersects a wall (as calculated on a 2d map) you compute the distance from the eye to the wall and draw a line segment vertically. Do it for all rays in the field of view and you have a 3d representation of a 2D map. Tricks of the Game Programming Gurus, SAMS, has an excellent dicussion of ray-casting. Paul.
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