The battle between 3D chipmakers and Intel is similar to the battle between hardware DVD and software DVD. Is the "system" price/performance better when you do 3D graphics or DVD on a dedicated chip, or when you rely on the CPU to help carry the load?
pubs.cmpnet.com
<<A simmering conflict between Intel
Corp. and graphics-accelerator companies over how the 3-D
graphics pipeline should be partitioned bubbled up at the recent
Computer Game Developers Conference. The debate centers on
the geometry front end of the 3-D pipeline, where transforms and
lighting are calculated.
Except in workstations, geometry and lighting (a component of
primitive triangle calculation) are the exclusive domain of the CPU.
But graphics-chip vendors say that the CPU has topped out its
ability to churn out more triangles at a rate that can keep up with
the latest 3-D processors.>>
<<SNIP>>
<<"Our expectation is that [geometry] will be an on-chip feature in
1999, and to a small degree this year companies will offer off-chip
geometry engines," said Dean McCarron, a principal of Mercury
Research (Scottsdale, Ariz.). "In a lot of instances, the CPU is the
bottleneck, and when it isn't, [the CPU in question] is usually a
$500 or $700 CPU. When you want good game performance and
a $1,000 box, you'll need a geometry engine.">>
<<SNIP>>
<<At best, Katmai will offer a 60 percent improvement in the front
end of the geometry stage. That's only a marginal gain, considering
that today's most-advanced 3-D processor chips can handle about
four times as many triangles as the processor can send, said Neil
Trevett, vice president of marketing for 3Dlabs (San Jose, Calif.).
The gap has less to do with a failure on Intel's part to keep up than
with the inherent weakness of a general-purpose CPU - even one
with the vector-processing capabilities of Katmai - in processing
more triangles.
"Vector processors are effective for deep pipelining of operation
units," Trevett said. "It hits a snag with geometry because it's full of
exceptions. You can process vertices and discover one of the
vertices in the middle of the array needs to be clipped. There are
lots of exceptions that you have that prevent you from getting peak
theoretical processing in a vector processor."
A hardware geometry engine, by contrast, is more adept at
handling those exceptions because it has dedicated transistors
assigned for the task.>> |
