MaximumPC 2004 10

MA XIMUMPC SEPTEMBER 2004

tex shader programs: small programs that

can modify data at different points in the

3D pipeline. Readers familiar with previous

Maximum PC articles on 3D engines, listen

up: We told you that programmable shad-

ers could result in more than fancy-looking

water and waving grass!

Physics

It’s fairly obvious that realistic physics

modeling is one of the next major frontiers

in game design. Nearly every game avail-

able today—from first-person shooters to

real-time strategy games—uses some form

of physics engine. In making Doom 3 , id

Software chose to create its own, rather

than using a popular off-the-shelf physics

engine like Havoc or MathEngine.

Doom 3’s physics engine doesn’t push

the envelope in a big way—it doesn’t really

distinguish itself from middleware physics

engines—but it at least delivers everything

we’ve come to expect from Havoc-based

games, including ragdoll physics that

produce incredible dynamic death anima-

tions, realistic fire physics, and many of

the weapon effects. Note that the in-game

physics in Doom 3 —like most other games

that claim “real-physics”—are in fact

approximations of real-world physics cal-

culations. Don’t use Doom 3 to model your

senior thesis, physics students.

Can You Hear Me Now?

Doom 3’s sound engine has been the sub-

ject of much controversy. Unlike most

games’ sound systems, Doom 3 shuns the

Windows-only DirectSound API in favor of

a more general, host-based approach.

Performing all the 3D sound calculations

on the CPU offers several benefits: The

game isn’t hindered at all by the limitations

of DirectSound, and the developers can

programmatically modify in-game sounds.

In addition to creating a variety of sounds

for each type of object—some bullet

impacts have seven different sound varia-

tions—the engine can also modify sound

Our pal the spider looks

pretty good with a DirectX

8-level card, such as the

GeForce4 Ti. The only

difference between it and

the DX9-level spider is the

lower-resolution textures

required by the 128MB

card.

The spider produced by

the DX7-level card—a

GeForce4 MX—is not a

pretty sight. His shadow

is very simple, and the

shadows don’t interact.

Note that there are no

shades of gray in his

shadow—the floor is

either entirely black or

its normal color.

Here, using the GeForce4
MX, the weaknesses of a
fixed-function pipeline card
are readily apparent. Look at
how blown-out the light on
the left wall is, and notice the
low-resolution textures on
the zombie’s back. Detail is
sacrificed to accommodate a
mere 64MB of video memory.

Using the GeForce4

Ti card, the zombie

looks almost the

same as with more

powerful DirectX

9 cards. However,

we had to turn

off antialiasing

to improve

performance.

In a laudable move, id programmed Doom 3 to run on

hardware that predates the millennium. We’re talking

GeForce3s here, people! This made us wonder: What’s

the trade-off in visual quality as you step down in GPU

technology? To answer the question, we ran Doom 3

on several different videocards.

But How Does It Look on My GeForce MX?

We show you how Doom 3 looks on a variety of videocards

For the purposes of our tests—to best demonstrate the

difference between videocards—we custom-built a basic

Doom 3 map with a few enemies and some dynamic lights.

This shot was taken at the High Quality setting on a

DirectX9-class nVidia GeForce 6800 Ultra card with 4x AA

turned on. Note the smooth, rounded shadow edges and the

different shades of dark inside the shadows.

DirectX 8

DirectX 7

DirectX 8

DirectX 7

DirectX 9