Message-Id: <199703261706.LAA15333@mail.sockets.net>
Reply-To: <cwhizard AT sockets DOT net>
From: "Anthony Q. Bachler, BAS" <cwhizard AT sockets DOT net>
To: <tob AT world DOT std DOT com>, <djgpp AT delorie DOT com>
Subject: Re: John Carmack <johnc AT idnewt DOT idsoftware DOT com>: Question about Doom.
Date: Wed, 26 Mar 1997 10:40:10 -0600
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I'll admit that it was an oversimplification.  Ray tracing and ray casting
are different breeds of the same animal.  If I recall correctly, ray
casting was developed from ray tracing because of the speed difficulties. 
I also understand that ray tracing produces a much higher quality image
being based on physics the way it is.  Maybe when the Gargoyle comes down
to a price we can all afford, then we will be able to use ray tracing to
produce some really great games.

P.S.  For those of you that haven't heard of the Gargoyule, it's a
multiprocessing PC.  The minimum configuration is 4 Pentium 100's, 64MB's
of DRAM (minimum for the custom OS to run efficiently, although I have
heard that NT will run on it), 4MB of level 2 cache SRAM, and 10GB of HDD
storage.  It also comes with a 3-Com 100-Base-T Combo card.  The Price for
the bare bones unit is $24,999.  That doesn't include a keyboard, monitor,
VGA adapter, COM ports, Printer ports, or a CD-ROM.  Maybe If I win the
Lottery (well actually, definitely if I win the lottery).  
::-)

----------------------------------------------------------------------------
---
C code is like assholes, everyone's stinks but your own.
Looking at C code is like looking at your bedroom, a 
  complete mess to everone else, but you can tell them 
  where every little thing is.
C code is like Ex-Lax, easy going when it works but a
  pain in the ass when it doesn't.
Explaining why C is better than Pascal is like explaining 
  why peanut butter is better than toe jam.
Explaining why Assembler is better than anything is like 
  explaining why being deaf is better than listening to 
  'The artist formerly known as Prince'.

----------
> From: tob AT world DOT std DOT com
> To: djgpp AT delorie DOT com
> Subject: Re: John Carmack <johnc AT idnewt DOT idsoftware DOT com>: Question about
Doom.
> Date: Tuesday, March 25, 1997 17:11
> 
> "Anthony Q. Bachler, BAS" <cwhizard AT sockets DOT net> writes:
> > (Ray Tracing == Ray Casting) = True.  Just a different way of saying
the
> > same thing.  I use the term casting because it makes me think of
fishing
> > and the code is fishing for a structure.  Sounds stupid, but hey, we
all
> > need our little crutches.
> 
> Ooh, we're gonna hear this one being corrected forever.
> 
> Not the same. Ray casting shoots out generally once per vertical line,
> and stops as soon as it gets something it can draw. With ray *casting*,
> objects are "lit" in and of themselves.
> 
> Ray tracing generally shoots out once per pixel and bounces to hit more
> stuff beyond the first object. With ray *tracing*, nothing is "lit" till
> you trace it back to a light source.
> 
> This is why ray casting has been good enough for real time games for
> some time, whereas ray casting still makes you wait for a single frame.
> 
> I am simplifying a lot here, of course. There are endless
> qualifications, variations, and optimizations that make what I said not
> precisely true. Like "raycasting can hit two things with
> semi-transparency and explicit mirrors." or "if you combine raytracing
> with radiosity, objects are lit."
> 
> PS: I like your .sig. Ain't it the truth.
> 
>         Tom