Re: State of Linux graphics

[Keith Whitwell <keith@tungstengraphics.com>]

Ian Romanick wrote:
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> Brian Paul wrote:
>
>
> > It's other (non-orientation) texture state I had in mind:
> >
> > - the texel format (OpenGL has over 30 possible texture formats).
> > - texture size and borders
> > - the filtering mode (linear, nearest, etc)
> > - coordinate wrap mode (clamp, repeat, etc)
> > - env/combine mode
> > - multi-texture state
>
>
> Which is why it's such a good target for code generation.  You'd
> generate the texel fetch routine, use that to generate the wraped texel
> fetch routine, use that to generate the filtered texel fetch routine,
> use that to generate the env/combine routines.
>
> Once-upon-a-time I had the first part and some of the second part
> written.  Doing just that little bit was slightly faster on a Pentium 3
> and slightly slower on a Pentium 4.  I suspect the problem was that I
> wasn't caching the generated code smart enough, so it was it trashing
> the CPU cache.  The other problem is that, in the absence of an
> assembler in Mesa, it was really painful to change the code stubs.

Note that the last part is now partially addressed at least - Mesa has 
an integrated and simple runtime assembler for x86 and sse.  There are 
some missing pieces and rough edges, but it's working and useful as it 
stands.

Keith
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