On Tue, Jul 23, 2013 at 8:42 AM, Grigori Goronzy <g...@chown.ath.cx> wrote: > On 23.07.2013 00:30, Dave Airlie wrote: >> >> On Mon, Jul 22, 2013 at 2:06 PM, Grigori Goronzy <g...@chown.ath.cx> >> wrote: >>> >>> Subpixel text rendering is typically done with a solid src and a >>> pixmap mask. Traditionally, this cannot be accelerated in a single >>> pass and requires two passes [1]. However, we can cheat a little >>> with a constant blend color. >> >> >> The hw should be able to do things in one pass with dual source blending >> afaik. >> > > Yes it can do that, and this was actually my first idea. However, dual > source blending requires additional render target state setup, modifications > to the shaders, and so on. It's likely also a bit slower than single source > blending, after all the shader needs to export twice as much data. > > It might be worthwhile to get back to this to accelerate some of the other > PictOps with component alpha, but using the constant blend color was the > easier and faster solution for the common PictOpOver case. I think it's a > nice trick, I wonder if any other driver implements it?
Oh yeah I'm not saying we shouldn't merge this, it looks like a great idea for this case, and is probably faster than dual source. but yeah for the other cases I suspect a single pass is going to be faster than two passes, even with the extra overheads of dual exports. Dave. _______________________________________________ xorg-driver-ati mailing list xorg-driver-ati@lists.x.org http://lists.x.org/mailman/listinfo/xorg-driver-ati
