Strange speed differences on composite

[Alan Cox]

On Llu, 2006-02-20 at 10:24 -0500, Adam Jackson wrote:
> This is basically the shadowfb model, which kinda works.  Currently, using 
> shadowfb means giving up DRI and Xv, and most people aren't willing to give 
> that up.  

Thats also not very hard to fix and fix efficiently on cards that can
handle DRI or for Xv in general as its just an extra cliprect to
subtract the rectangle of the Xv image out of the shadow update list or
do the Xv work into the shadowfb. If you want alpha in your Xv image
then its not much different.

AFAIK only one DRI capable card would require shadowfb + DRI and that
would be the Voodoo1 which isn't supported for DRI anyway. If I ever do
get around to Voodoo 1/2 DRI it'll also need the mouse handling by
keeping the mouse at nearest depth in the Z plane and clipping the Z
range of the 3D just short of it so you've got a clipping plane of
sorts.

Alan