Re: [Dri-devel] Please help answering these newbie questions

[Michel <mi...@da...>]

On Sat, 2002-08-03 at 22:11, Ed Yu wrote:

> I was reading stuff online and I came upon terms like
> directFB and DGA . I understand so far directfb
> bypasses X whereas DGA is an extension to X.

DirectFB is independent of X.

> However that's where I get confused. Does DRI use DGA?

No.

> What is their relationship and/or difference?

The only thing they have in common is that they have something to do
with X extensions. :)

> I tried search online but somehow there is a lack of information on
> DGA.=20

Basically, DGA is a relict from times when circumventing the X server
was the only way to get decent performance for games and the likes. Even
the author of DGA 2.0 says it shouldn't be used and should go away ASAP.


> In addition, does anyone actually use directFB or
> similar technology? Would directly accessing the frame
> buffer be faster? How would directly accessing frame
> buffer allow hardware acceleratio. It seems to be that
> by accessing the framebuffer, you would bypass all the
> 3D card pipelines. Is that true?

Yes, but DirectFB isn't simply about direct framebuffer access - you can
access the framebuffer device directly for that, no need for a library.
See http://directfb.org/.


> Another question is that I came upon SDL. They don't
> seem to use DRI (they use x + dga). Is it because DRI
> is based upon OpenGL acceleration so it is not able to
> support it?

SDL does use OpenGL, which can be provided by the DRI.


Hope this helps,


--=20
Earthling Michel D=E4nzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member   /  CS student, Free Software enthusiast