Y
ou’re probably familiar with Moore’s Law,
which holds that the number of transis-
tors on a chip—and by extension, the
computational power of integrated circuits—
doubles approximately every two years. The
graphics-processor designers at ATI and
Nvidia are performing at a rate of Moore’s
Law squared, improving the performance of
their products by a rate of double every year.
Having this power is fantastic for games,
but it’s also inherently useful for such spe-
cialized purposes as video editing, graphics
design, CAD, and many other disciplines.
But because Windows historically hasn’t
demanded all that much GPU power, graph-
ics hasn’t been much of a design priority for
system manufacturers—that’s why Intel has
been able to dominate the graphics market
by selling integrated graphics offering a frac-
tion of the computational power of even low-
end discrete GPUs from ATI and Nvidia.
Windows Vista changes all that, because
it depends on the GPU to deliver a day-to-
day desktop experience—especially if you
buy a version with Aero, Windows’ new
bells-and-whistles interface. Even without
Aero, the new Windows video playback
infrastructure relies on the GPU to deliver
high-defi nition video playback. The new
Windows Photo Gallery taps GPU power,
too. Microsoft created the DirectX 10 collec-
tion of application program interfaces—of
which Direct3D is the most important—to
leverage this processing power.MEET DIRECTX 10
Microsoft is nothing if not conservative; but
every once in a while, the hidebound soft-
ware giant exposes itself to more than the
usual amount of risk in order to embark on
a new and strategically important endeavor.
DirectX 10 is one such example. Microsoft
has completely re-engineered this crucially
important collection of APIs in order to strip
away every impediment necessitated by
maintaining backward compatibility.
There is a downside to this, but there’s
a tremendous upside for those of us who
want to see the state of the art of graph-
ics advance. Let’s talk about the downside
fi rst—and briefl y: You’re going to need a
new videocard to take full advantage of
DirectX 10. For the time being, only two
GPUs can lay claim to being DirectX 10
compatible. They’re both from Nvidia, and
they’re both expensive. So while there might
be plenty of competition between board
vendors selling DirectX 10 videocards, prices
will likely remain high because Nvidia has no
need to discount the main component that
goes into these cards.
DirectX 10 also incorporates some of
the advanced tools and application program
interfaces from Microsoft’s Xbox and Xbox
360, which should simplify the efforts of
game developers interested in porting their
software from one platform to the other.
These will include XACT (Cross-platform
Audio Creation Tool), which simplifi es theprocess of producing audio capable of run-
ning on a range of sound hardware; and
XInput, so the same game controllers can
be used on both the Xbox and a Windows
PC. Other legacy DirectX APIs, including
DirectPlay, DirectInput, and DirectMusic,
have been streamlined and absorbed.BYE-BYE CAPS BITS
One of Microsoft’s most important changes
does away with what are known as capa-
bilities (caps) bits. In previous versions of
DirectX, software developers couldn’t rely
on hardware—videocards, most impor-
tantly—supporting all the features that
DirectX had to offer. In the DirectX 9 era, for
example, ATI’s Radeon 800-series cards
qualifi ed as being DirectX 9-compliant even
though they didn’t support Shader Model
3.0; by the same token, Nvidia’s GeForce 6-
and 7-series cards were considered DirectX
9-compliant even though they couldn’t per-
form high dynamic-range lighting and anti-
aliasing at the same time. In such instances,
capabilities bits within the card informed
DirectX which features it could support.
There are no caps bits in DirectX 10:
In order to be considered compliant, hard-
ware must support all the new API’s fea-
ture set (with a handful of relatively minor
exceptions). For the most part, this means
support for all aspects of Shader Model
4.0. For game developers, the elimination
of caps bits make the job of programmingDirectX 10 Backgrounder
Might this be the only reason anyone will buy Windows Vista?
The screenshot above, taken from
Funcom’s upcoming MMO Age of Conan:
Hyborian Adventures, is replete with
detailed textures and terrific shadows.
This is about as good as it gets with
DirectX 9.DIRECTX 9 VS. DIRECTX 10: THE DIFFERENCE IS GRAPHIC
This screenshot depicting the same
scene from the same game shows what
DirectX 10 can deliver: Richer color, tex-
tures with more detail, and better realism.
Notice the shadows, and how smoothly the
curves in the arches are rendered.Game developers have squeezed
just about everything they can from
DirectX 9, but games that take
advantage of DirectX 10 and run on
DX10 hardware make DX9 games
look positively primitive. DX
games will have a much higher level
of detail, better lighting, brighter col-
ors, and much more.2 MAXIMUMPC JANUARY 2007
DIRECTX 9 DIRECTX 10
NEXT-GEN GAMING