[Mesa-dev] [RFC] [BRANCH] Floating point textures and rendering for Mesa, softpipe and llvmpipe

[keith whitwell]

On Wed, Sep 1, 2010 at 8:34 PM, tom fogal <tfogal at sci.utah.edu> wrote:
> Luca Barbieri <luca at luca-barbieri.com> writes:
>> > It's an impressive amount of work you did here. I'll comment only
>> > on the llvmpipe of the changes for now.
>>
>> Thanks for your feedback!
>
> While we're on the topic: yes, this is great to see Luca.  Thank you!
>
>> > So instead of going through a lot of work to support multiple
>> > swizzled types I'd prefer to keep the current simplistic (always
>> > 8bit unorm) swizzled type, and simply ignore errors in the
>> > clamping/precision loss when rendering to formats with higher
>> > precision dynamic range.
>> >
>> > In summary, apart of your fragment clamping changes, I'd prefer to
>> > keep the rest of llvmpipe unchanged (and innacurate) for the time
>> > being.
>>
>> Note that this totally destroys the ability to use llvmpipe for high
>> dynamic range rendering, which fundamentally depends on the ability
>> to store unclamped and relatively high precision values.
>
> FWIW, we've got an app that allows one to choose the bit depth we do
> our compositing in, and the difference between 8 and 16 for some data
> is quite striking.  16 and 32 not so much, though sometimes visible.

Is that 8-fixed and 16-float (ie half-float)?  Or does a 16-bit fixed
format also work?

Keith