XAA vs. EXA in old hardware support

[Adam Jackson]

On Friday 16 June 2006 19:56, Alan Cox wrote:
> Ar Gwe, 2006-06-16 am 17:20 -0400, ysgrifennodd Michael Lorenz:
> > So EXA dropped hardware line drawing? On both the P9100 and the cg6
> > it's significantly faster than in software, especially on newer cg6
> > where it's quite a huge margin. Probably doesn't have much of an effect
> > on overall X performance I guess.
>
> It has a horrendous effect on xtank, one or two other games like one of
> the battlezone games and not much else I've found so far. X still
> abstracts the line draw so you can certainly extend EXA to allow line
> drawing overrides without breaking anything.

Psht.  Like xtank matters.

EXA now decomposes line draws (and some other stuff) to iterated calls to the 
driver's Solid fill routine.  Performance is comparable to software but since 
it's all accelerated you don't have the stall when switching between software 
and hardware, so in principle it'll be slightly faster overall.  Of course 
drivers can still, with some care, wrap the GC themselves and handle 
operations that EXA doesn't natively accelerate, but it's unlikely to be much 
of a win with modern usage patterns.

- ajax
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