From: Peter Amstutz <tetron@student.umass.edu>
  To  : ggi-develop@eskimo.com
  Date: Wed, 16 Jun 1999 21:48:58 -0400 (EDT)

Re: libGGI on matroxfb with Mystique

On Thu, 17 Jun 1999, Denis Oliver Kropp wrote:
> Another problem:
> The glide target worked very well and fast without DirectBuffer (using ggiPutBox for system
> backbuffer). But when I use DirectBuffer on it, it is much slower 66->20 fps.
> Maybe the system memory works as a buffer which handles
> the blits of small images better than writing each of them over the bus.

I think frame buffer access from the bus for the voodoo1/2 is generally
very slow because it was optimized to be accessed from the on-card
rendering chips, not directly from the CPU.  On the other hand you have to
do a lot of large texture downloads, so it's probably optimized for burst
performance over the PCI bus.  That would be my guess as to why you'd get
a slowdown with DirectBuffer...

Of course it would be really cool if someone were to write a
glide-specific sprite extension library that downloaded sprits as textures
(with transparency info) to the 3dfx and used the on-card texturemapping
accel to display them :)

Does libggi2d do sprites even in software yet?
 
           ------------------ Peter Amstutz --------------------
           -------------- tetron@student.umass.edu -------------
           ------- http://www-unix.oit.umass.edu/~tetron -------
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