W
ithout a doubt, Doom 3 is the most
technically advanced PC game
ever built. From the revolutionary
graphics engine to the hyper-realistic phys-
ics model, the game surpasses all others in
its real-world mimicry—if you call a demon-
infested base on Mars the real world, that is.
What’s really amazing about id Software’s
tremendous effort isn’t the raw power of the
engine, or the incredible amount of art that
was created for the game, or even the hyper-
realistic shadows. No, what amazes us is the
wide spectrum of hardware that the game
actually runs well on. You can run Doom
3 on hardware that’s positively ancient by
Maximum PC standards and still get decent
frame rates. Granted, you’re not going to
be able to run it with all the whiz-bang fea-
tures turned on. In fact, you won’t be able
to experience many of the most visually
impressive effects. But at least you’ll be able
to play.
Before we jump into our review of Doom
3 the game, let’s deconstruct every single
aspect of the astounding engine powering it.
Follow along and we’ll tell you exactly how
it all works.You Can See Your Doom Coming
The most discussed aspect of Doom 3
is John Carmack’s very next-gen graph-
ics engine. Making full use of the latest in
programmable shader technology, Doom 3stresses the hell out of any vid-
eocard—from ancient, barely
supported GeForce4-era cards
to the latest, greatest Radeon
X800 and GeForce 6800
boards, which can’t even run
the game at its highest possi-
ble detail levels. What requires
all this pixel-processing power?
Shadows and normal maps.
The secret to the game’s
verisimilitude is its hyper-real-
istic lighting model, courtesy of
stencil shadows. Drawing sten-
cil shadows is easy—the hitch
is that it places a tremendousIn this very simple
map, we can
see some basic
shadows. The
invisible shadow
volumes fill the
area between the
white platform
and the floor
(outlined in
yellow). Doom 3
draws shadows
anywhere those
volumes intersect
polygons.The cacodemon’s energy weapon creates a space- (and mind-) bending effect
on impact. The secret? Two words: programmable shaders.Lab Tests: How Will
Doom 3 Run on My
Computer?
Not sure your PC can pass muster
for Doom 3? It’s time to find out—
we ran a battery of Lab tests to
find out which components work,
and which components don’tTo determine what hardware works best
in Doom 3 , we performed three rounds
of tests. First, we tested videocards to
see exactly how fast different generations
of hardware could run Doom 3. To keep
everything even, we tested three GeForcevideocards in our Athlon FX-51 zero-point
rig: an old GeForce4 MX 460, a GeForce4
Ti 4600, and a GeForce 6800 Ultra, as
well as a Radeon 9800 XT. We tested the
6800 and the 9800 XT in high-quality
mode at 1280x1024 with AA disabled, the
4600 board at 800x600 in medium-qual-
ity, and the MX board at a pokey 640x480
in low-quality mode. (If you’re interested
in seeing how Doom 3 looks on different
generations of graphics hardware, turn to
page 62.)
Second, we wanted to find out how
dependant Doom 3 is on CPU speed and
type, so we tested it with three different
CPUs: an Athlon XP, a Pentium 4, and an
Athlon FX. All the CPU tests were run
with a GeForce 6800 Ultra card, to isolate
the variables as much as possible. Theresults surprised us, and they’ll definitely
surprise you, too.
Finally, we dug up three systems from
our vault to see how Doom 3 handles a
variety of hardware. The three test sys-
tems—a Pentium 4 2GHz with 512MB of
RAM and a GeForce3, an Athlon XP 3200
with a 1GB of RAM and a Radeon 9800
Pro 256MB, and an Athlon FX-51 with
1GB of RAM and a GeForce 6800 Ultra—
represent state-of-the-art hardware from
more than two years ago, one year ago,
and the present, respectively.
We measured frame rates by running
the demo1 using the initial release of
Doom 3. To test your own rig, open the
console by pressing Ctrl+Alt+~ and then
type “timedemo demo1.”60 MA XIMUMPC OCTOBER 2004
Shadow Volumes