On Wednesday, May 4, 2016 3:30:13 PM PDT Alejandro Piñeiro wrote: > > On 04/05/16 12:31, Kenneth Graunke wrote: > > On Thursday, April 28, 2016 1:40:31 PM PDT Antia Puentes wrote: > >> From: Alejandro Piñeiro <apinhe...@igalia.com> > >> > >> This commit adds support for PASSTHRU format when pushing > >> double-precision attributes. > >> > >> Check glarray->Doubles in order to know if we should choose a format > >> that does a conversion to float, or just passthru the 64-bit double. > >> --- > >> src/mesa/drivers/dri/i965/brw_draw_upload.c | 30 +++++++++++++++++++++++ ++ > > +--- > >> 1 file changed, 27 insertions(+), 3 deletions(-) > > What's the motivation for using the PASSTHRU formats? Is there some > > advantage over just using the R64*FLOAT formats? > > We can't use R64*FLOAT because it does a double to float conversion, as > explained at the bdw PRM (vol 7, section 10.15, page 470, Table "Source > Element Formats Supported in VF Unit"). PASSTHRU ensures that the > 64-bits are passed without any conversion, that is what we want. If it > is not clear reading the commit message, I could expand it.
Ahh...thanks. For some reason, I just assumed that R64_FLOAT meant double precision float, not "reads a 64 bit float and outputs a 32 bit float". Heh :) Thanks for the explanation!
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