To: djgpp AT delorie DOT com
Subject: John Carmack <johnc AT idnewt DOT idsoftware DOT com>: Re: Question about Doom.
Message-ID: <19970319.192716.7391.1.fwec@juno.com>
From: fwec AT juno DOT com (Mark T Logan)
Date: Wed, 19 Mar 1997 19:29:10 EST

Well,
 I said I would ask the big J.C. (john carmack, not Jesus.  and no I'm
not
being irreverent, I just thought it was an interesting coincedince.)

He actually responded!!!  I don't think I will ever erase that message
from
my mail box.  Anyhoo, here it is.  BTW, his short response suggests he is
busy.  Also, he didn't send the mail to the list like I asked, so I am
guessing
that he didn't want tons of stupid responses.  My point is.. DON'T PESTER
HIM.  he didn't respond to the newsgroup because he is too busy to
respond
to all of you.  and if he had specifically asked me not to forward this
to the
newsgroup, I wouldn't have.  Don't send him anything!!!!

--------- Begin forwarded message ----------
From: John Carmack <johnc AT idnewt DOT idsoftware DOT com>
To: fwec AT juno DOT com (Mark T Logan)
Subject: Re: Question about Doom.
Date: Tue, 18 Mar 97 21:45:27 -0600
Message-ID: <9703190345 DOT AA11856 AT idnewt DOT idsoftware DOT com>
References: <19970317 DOT 171229 DOT 7391 DOT 3 DOT fwec AT juno DOT com>

You wrote:
> Greetings.
> 
> I'm writing to you as a regular reader of the DJGPP newsgroup,
> where a recent (and somewhat off topic) debate about Doom has been
> taking place. It all started when somebody asked about how
> perspective correct texture mapping worked in games like Doom and
> Duke3d. The thread eventually went to asking "How does Doom work?"
> Someone said it used BSP trees, someone else said it used
> raycasting. I said it used bsp trees and raycasted each individual
> polygon, instead of the whole screen at once. Could you take a
> minute out of your day and respond? If you do, send the mail to
> djgpp AT delorie DOT com.

Wolfenstein 3D used ray casting.
Doom used BSP trees and a one dimensional completion mask.
Duke3D used sector flowing.
Quake used BSP trees, a PVS, and an edge list.

John Carmack

--------- End forwarded message ----------

Well, those four sentences should settle the debate somewhat.  Anybody
know what a one dimensional completion mask is?  how 'bout sector
flowing?


||                                         Fwec AT juno DOT com
||  The secret of life.
||    -if it looks like a chicken, and walks like a chicken, and sounds
like a chicken,
||     then there is almost no chance whatsoever that it is a chicken.
||