On 8/21/06, Dieter <[EMAIL PROTECTED]> wrote:
This all seems very backwards.
Why does a "3D" window frame need to have special hardware? You create
a window and it sits there for minutes, hours, days. A button? How often
do you click a button? Let the CPU do that, and give hardware assist to
video, which has to decode the input and change the display 60 times a
second.
Without acceleration, you can visibly see the drawing that occurs when
something is painted in the first place. More bothersome, lots of
people like opaque window moves, so bitblt must be accelerated.
Scrolling is also common, so more bitblt. Window backgrounds are
often painted to a solid color before other things are drawn, so solid
fill is important. Those are really the most critical 2D effects.
With 3D, your screen (or window) is completely redrawn for every
event, making acceleration critical.
Another reason for hardware-assist is to reduce CPU overhead for these
things, making your whole system more responsive.
The difference between 3D graphics and video is that the video image
has to come from the host all of the time. With 3D rendering, a lot
of textures and stuff are loaded into graphics memory and reused a
lot, with the major bus traffic there being rendering commands.
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