From: becka@rz.uni-duesseldorf.de
  To  : Ruben <ryu@mundivia.es>
  Date: Sun, 7 Mar 1999 14:24:13 +0100 (MET)

Re: Sprites in video memory (finally)

> > Yes. S3 964 were able to do it, so it would be a shame, if newer ones don't.
> My card is 975, not 964 :))

I'm pretty sure it will do as well. You need to set the color-compare
register and the fg- and bg-mixing registers accordingly.
IIRC in color-compare mode, a copy will use the fg/bg mixing settings
depending on whether the current pixel matches the compare-color or not.
So you set one of them to copy and one to do-nothing.

> > You have memvisuals, and you have the subtarget, so where is the problem ?
> > Except for the little problem, that you can't specifically allocate just
> > one "offscreen area" if you have multiple frames.

> Hmmm, interesting, I will add some kind of support of sub-targets 
> in GGL as soon as I can. But a question, the sub-targets are always 
> on main memory or can be in the VRAM if the target is?

Sub-visuals are on the visual they are created on. They were designed to
support windowing, but if you place the windows offscreen, you get some 
kind of pixmap cache.

Another nice point about them is, that they are complete visuals with
all properties, so you can draw on them like on everything else.

And you don't need to create them on the main visual. If you run out of
space, you open a memvisual and continue to create them there.

Have a look at libggidemos/subdemo.c on how to use them. This demo is
kind of a design study for DirectGGI for X.

Cu,Andy

-- 
= Andreas Beck                    |  Email :  <andreas.beck@ggi-project.org> =