[Mesa-dev] [PATCH 02/29] mesa: Set normalized=true for float array formats.

[Iago Toral]

On Thu, 2014-11-20 at 10:40 -0800, Jason Ekstrand wrote:
> 
> 
> On Wed, Nov 19, 2014 at 11:24 PM, Iago Toral <itoral at igalia.com>
> wrote:
>         Hi Jason,
>         
>         we discussed this some weeks ago actually, the detailed
>         explanation is
>         here:
>         https://bugs.freedesktop.org/show_bug.cgi?id=84566#c5
>         
>         the short answer is that this is necessary because there is a
>         normalized
>         parameter to _mesa_swizzle_and_convert, and when we deal with
>         float
>         types we want to set this to true.
> 
> 
> I went back and looked at that and I thought the result of the
> discussion was to fix the assert in mesa_format_convert and compute
> the normalized parameter correctly.  After that, I thought this
> shouldn't be strictly needed.  It may still be a good idea for
> consistency, but I want to make sure we're doing the right thing in
> mesa_format_convert

With this patch, in mesa_format_convert we simply take the "normalized"
value for mesa_swizzle_and_convert from the normalized field of the
array format, since we make sure that all float array formats will have
this set to 1.

Without this patch we would have to do something like this (pseudocode)
in mesa_format_convert:

normalized = array_format.normalized || array_format.type == FLOAT ||  
             array_format.type == HALF_FLOAT;

We can do it either way, I just think that the latter is a bit
inconsistent because:

a) why would we want to generate array formats with a normalized setting
of 0 if we then want to set normalized to true when they are involved?.

b) Other parts of Mesa check if a format is normalized by doing
normalized = !_mesa_is_enum_format_integer(srcFormat), which will make
float types normalized.

Iago

>         Iago
>         
>         On Wed, 2014-11-19 at 11:31 -0800, Jason Ekstrand wrote:
>         > I'm not sure what I think about this.  Does it make a
>         functional
>         > change other than consistancy?
>         >
>         > --Jason
>         >
>         >
>         > On Tue, Nov 18, 2014 at 1:23 AM, Iago Toral Quiroga
>         > <itoral at igalia.com> wrote:
>         >         In order to check if a format is normalized Mesa
>         does
>         >         something like this:
>         >         normalized = !
>         _mesa_is_enum_format_integer(srcFormat);
>         >
>         >         So all float types will set normalized to true.
>         Since our
>         >         mesa_array_format
>         >         includes a normalized flag for each type we want to
>         make it
>         >         consistent with
>         >         this.
>         >         ---
>         >          src/mesa/main/format_info.py | 3 ++-
>         >          src/mesa/main/format_utils.c | 2 +-
>         >          2 files changed, 3 insertions(+), 2 deletions(-)
>         >
>         >         diff --git a/src/mesa/main/format_info.py
>         >         b/src/mesa/main/format_info.py
>         >         index 315767d..d4bc276 100644
>         >         --- a/src/mesa/main/format_info.py
>         >         +++ b/src/mesa/main/format_info.py
>         >         @@ -220,9 +220,10 @@ for fmat in formats:
>         >             print '      {{ {0} }},'.format(',
>         '.join(map(str,
>         >         fmat.swizzle)))
>         >             if fmat.is_array() and fmat.colorspace in
>         ('rgb', 'srgb'):
>         >                chan = fmat.array_element()
>         >         +      norm = chan.norm or chan.type == parser.FLOAT
>         >                print '      {{{{ {0} }}}},'.format(',
>         '.join([
>         >                   get_array_format_datatype(chan),
>         >         -         str(int(chan.norm)),
>         >         +         str(int(norm)),
>         >                   str(len(fmat.channels)),
>         >                   str(fmat.swizzle[0]),
>         >                   str(fmat.swizzle[1]),
>         >         diff --git a/src/mesa/main/format_utils.c
>         >         b/src/mesa/main/format_utils.c
>         >         index c3815cb..1d65f2b 100644
>         >         --- a/src/mesa/main/format_utils.c
>         >         +++ b/src/mesa/main/format_utils.c
>         >         @@ -30,7 +30,7 @@
>         >
>         >          mesa_array_format RGBA8888_FLOAT = {{
>         >             MESA_ARRAY_FORMAT_TYPE_FLOAT,
>         >         -   0,
>         >         +   1,
>         >             4,
>         >             0, 1, 2, 3,
>         >             0, 1
>         >         --
>         >         1.9.1
>         >
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>         >
>         >
>         
>         
>         
> 
>