Re: radeon 2d engine and alpha blending

On Thu, 2003-11-20 at 23:33, Alex Deucher wrote:
> According to marketing literature from ati, radeon hardware seems to
> support alpha and transparent BLTs.  from the literature under 2D
> graphics:
> 
> Support for Windows XP GDI extensions:
> Alpha BLT
> Transparent BLT
> Gradient Fill

I don't suppose that kind of literature explicitly states that the 2D
engine does all this though, does it? :)

> The databooks and DDKs also have several sections on doing transparent
> BLTs.  is there any reason that this can't be used to accelerate alpha
> blending in the xserver?

Yes, AIUI they really mean 'colour-keyed' when they say 'transparent'.

> I'd try to implement it myself, but I'm not familiar enough if XAA to 
> understand how it should be done.

By looking at another driver which does it?

> In the long run using the 3D engine is probably the way to go, but if it 
> could be hacked up quickly using the 2D engine it might give a nice boost 
> in the short term.

Even Hui Yu once told me along the lines of 'the 3D engine needs to be
used for alpha blending'.


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Software libre enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer