[Mesa-dev] gallium scaled types

[Dave Airlie]

On Tue, Nov 1, 2011 at 2:11 PM, Dave Airlie <airlied at gmail.com> wrote:
>>
>> After wasting so much time on this topic, and conceding on most points, I'm disappointed that the new pure integers formats were added without support for converting to/from floats (my 2nd request above) which ended up causing obscures bugs in llvmpipe (my 1st request).
>>
>> I regret having been so laissez-faire -- I should had made a fuss in the review request when my 2nd request was ignored --, but I learnt my lesson.
>
> I just added a fix to make sure llvmpipe didn't say it supported pure
> integer types so it should be unable to execute any of the problematic
> paths.
>
> The thing is converting pure integers to floats at any point in the
> pipeline is wrong and is a bug and should be treated as such. I left
> scope for translating ints to floats but I can find no reason in any
> API to enable this and unless someone has proof of such I don't feel
> we should, since you cannot represent a 32-bit integers in a 32-bit
> float without loss of precision.
>
> I'll do another llvmpipe run vs 7.11 and see what falls out later
> today and fix it, I did one before merge though I had to do a rebase
> since.
>
> But vlee has been fairly good at pointing me at piglit regressions so
> far and I've tried to fix them as they came in.
>
> Adding GLSL1.30 support to llvmpipe is going to involve doing it
> properly and not adding int->float conversions.

Ah now I see the fix I did for the last regression in the test code
broke stuff, so actually I should have just pushed the test code fix
and not the llvmpipe driver change.

Sorry, will piglit even over the seemingly "trivial" changes next time.

Dave.