RETRO TECH / ANALYSIS
- a bank of 2MB of high-bandwidth (for the time) EDO RAM,
and the resulting scanlines were fed out to a DAC, which
output to a good, old-fashioned analogue VGA output.
THE FIRST CARDS
The fact that the Voodoo Graphics chipset was 3D-only
helped to keep down the price, but it did make using the card
a little strange. While the card itself could talk to the CPU
and system RAM through the PCI bus, it worked in tandem
with an existing 2D graphics card for 2D DOS and Windows
acceleration, only taking over when there were 3D graphics
to be rendered.
This happened through a D-Sub pass-through cable
running from the output of the 2D card to an input on the
Voodoo Graphics card. While some 3Dfx cards handled the
switching electronically, others actually had a mechanical
switch. On these, you could literally hear when the Voodoo
Graphics card kicked into action.
3Dfx never manufactured its own 1st-generation cards.
Instead, the designs and chips were sold and licensed to
third-party manufacturers, with Diamond and Orchid first
out of the gate with the Monster 3D and Righteous 3D in late- These first cards sold for approximately £300, which
was a lot but not exorbitant for a PC graphics card at the time.
What’s more, these beauties could perform amazing
feats with even fairly modest PC configurations. At a time
when even Intel’s Pentium 133 processors were struggling
to deliver consistently good frame rates with the standard
software renderer in some demanding games, you could
slot a Monster 3D into your Pentium 90 system and see
great-looking, silky-smooth visuals.
Yet 3Dfx’s work went beyond designing the architecture to
creating an API that enables game developers to support the
card. At the time, there were no 3D engines that supported
3D hardware and no standard APIs for developing 3D games.
OpenGL was focused mainly on CAD and workstation
graphics, while Intel was unwilling to release its new 3DR
rendering library for use on hardware that would run DOS
games. Microsoft had yet to develop what became Direct3D.
As a result, 3Dfx developed its own API, GLide. This was
based on OpenGL, so it wasn’t unfamiliar to experienced
3D developers, but it pared back the calls and instructions to
focus on those used in real-time 3D games.
To show off Glide’s capabilities, 3Dfx didn’t just have its
own internal demos, but a range of Atari and Midway arcade
games, including the racer, San Francisco Rush, and the beat-
’em-up, Mace: The Dark Age. These ably demonstrated what
the new hardware could do. All that was needed were some
suitably awesome PC games.With Sellers working on the hardware and Tarolli on the
core algorithms, the 3Dfx team came up with the idea of an
add-in card that only accelerated 3D, and left 2D graphics
and Windows acceleration to a separate graphics card. At
first, all they had working was a software simulation built in C
and running on a Pentium 90 processor, but this evolved into
a card based on two heavily optimised processors.
The first, the Frame Buffer Interface, took polygon
scene data from the CPU and applied Z-buffering and
Gouraud shading, tracking which polygons were visible,
and ensuring that only those were drawn and filled, then
applying shading to provide an impression of simulated light
and colour.
Each frame of the image would then be converted into
scan lines from top to bottom, then sent on to the second
chip. The Texture Mapping Unit, or T-Rex as it was known,
applied perspective-correct textures, complete with
mipmapping (the process of using smaller, less-detailed
textures as an object gets further away) and bilinear or
trilinear filtering (smoothing out blocky textures when
displayed at their largest size close to the viewpoint).
What’s more, the T-Rex supported alpha blending, for
convincing transparency effects. No other consumer-grade
graphics hardware was able to handle this at the time. Each
chip worked with its own frame buffer or texture memoryYou could now run Quake at
640 x 480 in glorious 16-bit
colour and still hit 30fps
Tomb Raider was
a 3Dfx showcase,
smoothing out the
blocky textures,
improving frame
rates and adding
transparent water
to the mix
By the time Unreal
hit the market, 3Dfx
was established as
the best tech to run
it. Check out those
shiny surfaces and
lavish textures