3D Cards - a 'Simple' Explanation

                      From John Ferris

In SynTax, Thomo from Middlesborough asked about 2D and 3D
graphics cards for PCs.  I'm no expert, but this is what I
understand to be the case.

All PCs have a 2D graphics card as standard as a blank monitor is
not very useful. These are fine for normal word-processing /
spreadsheet and Windows stuff as the display is doing very little.
They are also quite adequate for a lot of games. The more memory
these cards have, the higher the resolution and the greater the
number of colours displayed. Most of these cards have few if any
additional 3D capabilities.

The ViRGE S3 cards are such an example, you can get 4MB versions
for under œ20 if you don't need to play the latest 3D games. They
are available in both PCI and AGP formats.

Next are the combined 2D and 3D cards, such as the Matrox Mystique
3D (not the G200) and others which offer a combination. The first
thing to realise is that such cards are not able to run the latest
3Dfx games, because 3Dfx is something different. These 2/3D cards
are basically 2D cards with a few extra bits added in which
improve 3D performance, which was fine for early 3D games but now
they are left trailing behind in a cloud of opaque dust (see
later.)

The 3Dfx Voodoo and now VoodooII cards are dedicated 3D cards but
with a whole range of special effects and texture mapping tricks
which produce wonderful images. These effects allow translucent
fog/mist/clouds of dust, lens flare, lighting effects than are
best seen rather than described and a lot more. In a Subculture
demo, the translucent fog trick is used to simulate the murky
depths of the sea, with objects (usually very sharp cliffs)
appearing out of the murk very realistically.

These cards use the PCI interface and combine with your existing
2D card.  There is a cable which runs from your existing 2D card's
monitor connection to the Voodoo card. The monitor is then
attached to the Voodoo card. For example, you could have a bog
standard 4MB ViRGE card and 12 MB Voodoo II card, which would be
great for playing the latest games.

Texture mapping is the name given to the process whereby surfaces
are given a layer of patterned wallpaper to make them look better.
A texture is simply a pattern which is pasted (mapped) to a
surface to improve the look.  Instead of flat smooth walls,
texture mapping can give brickwork, stone, metallic and many other
such effects. This applies to all surfaces, be they walls, ground,
sky or ten foot lizard monsters of Zarg. Voodoo cards have memory
set aside to deal with these textures which improves speed and
quality.

Another ability is called SLI, or Scan Line Interleave.
Basically this means you can plug in a second, identical
Voodoo card, connect it to the first, and double the power. The
monitor builds up the picture line by line, just as in a
normal TV. With SLI activated, the Voodoo cards work on
alternate lines so halving their workload. I've never seen this in
action.

Voodoo cards can usually support Glide, Direct3D (TM) and OpenGL
(R). If a game supports one or more of these standards, the Voodoo
will work its magic.

As an aside, many 3Dfx games allow something called "Software
Render" or similar. This means that the game will try to produce
the graphic effects using a software program and the CPU. This is
only useful if you do not have a 3Dfx or other (see later) card.
However, even with a very fast CPU, the game runs slowly and can
look at best dull, at worst rather odd and even unplayable.
Playing Incoming with a 4MB ViRGE DX card was surreal, with a 3Dfx
card it was sublime.

A recent addition is the Voodoo II Banshee combined 2D/3Dfx cards.
These combine all the wondrous effects of 3Dfx with a 2D facility
on one card, usually with a stonking 16MB of RAM. I have used a
Creative Labs version and have no complaints. This is a PCI card,
but comes without the SLI option which is no big deal as far as
I'm concerned. There are other makes of Banshee card, I doubt
there is that much difference between them except price.

Note. Such combined cards can also go by the name of Voodoo
Rush.  Some games may need patches to run with such cards. Unreal
needs an upgrade patch to 2.19 before it will work with a
Banshee.

I did find that the Gigabyte GA5AA motherboard would not boot with
a Creative Labs Banshee on board, cause unresolved.

There are other brands of 3D accelerator cards other than 3Dfx of
which these are some:

PowerVR is not very popular so can be discounted.

The G200 Matrox Mystique AGP card has a number, but not all, of
the 3Dfx effects.

The Savage3D and the RivaTNT chipsets are fast newcomers, but both
are AGP only. Due to the fact that 3Dfx will now be making
VoodooIII cards itself, Creative Labs is moving to produce the
RivaTNT chipset.

As far as I'm aware, it is not possible to use AGP and PCI graphic
cards at the same time. AGP is twice the speed of PCI (66MHz vs
33Mhz) and can transmit data at 533MB/sec as opposed to 132MB/sec
on the PCI.  This means users should seriously consider an AGP
graphics card.  There is one possible problem with AGP in that
some older versions of Windows95 have no or limited support for
it. I believe OSR2.1 or higher is required.  Windows98 has no
problems. You should check this out for yourselves and with the
card manufacturers.

As far as recommendations go, I can only judge by experience and a
VoodooII Banshee 16MB would get my vote especially in an AGP
socket.

However, it might not be the best card money could buy.

My advice is to decide how much you want to spend and then check
out everything in that price range, reviews are especially useful.
If you are on the Internet, a search with Yahoo should yield a lot
of information.














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