Hardware Reference
In-Depth Information
A modern video adapter that includes a chipset capable of 3D video acceleration has special built-in
hardware that can perform the rasterization process much more quickly than if it were done by
software (using the system processor) alone. Most chipsets with 3D acceleration perform the
following rasterization functions right on the adapter:
•
Scan conversion
—The determination of which onscreen pixels fall into the space delineated
by each primitive
•
Shading
—The process of filling pixels with smoothly flowing color using the flat or Gouraud
shading technique
•
Texture mapping
—The process of filling pixels with images derived from a 2D sample
picture or surface image
•
Visible surface determination
—The identification of which pixels in a scene are obscured by
other objects closer to the viewer in three-dimensional space
•
Animation
—The process of switching rapidly and cleanly to successive frames of motion
sequences
•
Antialiasing
—The process of adjusting color boundaries to smooth edges on rendered objects
Note
To learn more about 3D techniques such as fogging, Z-buffering, T-buffering, programmable
shading, and rendering methods, see the sections, “Typical 3D Techniques,” “Advanced 3D
Filtering and Rendering,” and “Single- Versus Multi-Pass Rendering,” in Chapter 12, “Video
Hardware,” in
Upgrading and Repairing PCs,
19th Edition.
Software Optimization
It's important to realize that the presence of an advanced 3D-rendering feature on any given video
card is meaningless unless game and application software designers optimize their software to take
advantage of the feature. Although various 3D standards exist (OpenGL and DirectX), video card
makers provide drivers that make their games play with the leading standards. Because some cards
do play better with certain games, you should read the reviews in publications and websites to see
how your favorite graphics card performs with them. Typically, it can take several months or longer
after a new version of DirectX or OpenGL is introduced before 3D games take full advantage of the
3D rendering features provided by the new application programming interface (API).
Some video cards allow you to perform additional optimization by adjusting settings for OpenGL,
Direct 3D, RAMDAC, and bus clock speeds, as well as other options. Note that the bare-bones 3D
graphics card drivers provided as part of Microsoft Windows usually don't provide these dialog
boxes. Be sure to use the drivers provided with the graphics card or download updated versions from
the graphics card or GPU vendor's website.
APIs
APIs provide hardware and software vendors a means to create drivers and programs that can work
quickly and reliably across a variety of platforms. When APIs exist, drivers can be written to
interface with the API rather than directly with the OS and its underlying hardware.
Currently, the leading game APIs include SGI's OpenGL and Microsoft's Direct3D (part of DirectX).
