Strange speed differences on composite

Torgeir Veimo torgeir at
Sun Feb 19 21:18:59 PST 2006

On Tue, 2006-02-14 at 12:07 -0500, Adam Jackson wrote:
> When Render is accelerated in hardware, you can simply load the 1 and
> (1-srca) blend factors into the hardware and it runs like a normal
> screen-to-screen blit; you can think of a plain blit as one where the
> source blend factor is 1 but the dest blend factor is 0.  When it's
> not accelerated in hardware, you have to compute each output pixel by
> reading the dst_color pixel from the framebuffer, blending it with the
> src_color pixel in the CPU, and then writing that result back to the
> framebuffer.  

Wouldn't it make sense to do _all_ client based rendering in software
and only hardware accelerate the copy to framebuffer memory operations
that the compositor needs to do in the case when exa isn't sufficient

It would be akin to running an xnest server with a compositing manager
displaying to the real, exa/xaa acelerated x server, like the dual
server setup with X, Xgl and compiz.

Torgeir Veimo <torgeir at>

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