[Mesa-dev] [RFC PATCH 3/4] mesa: Prefer non-swizzled formats when prefer_no_swizzle set

[Chris Forbes]

Yeah, you're right -- that looks bogus. There's been piles of
confusion recently in formats.h about which end things are laid out
from; the truth though is obviously in the pack/unpack code and the
hardware format documentation.

On Wed, Mar 12, 2014 at 9:12 AM, Francisco Jerez <currojerez at riseup.net> wrote:
> Chris Forbes <chrisf at ijw.co.nz> writes:
>
>> If prefer_no_swizzle is set, try:
>> - The exact matching format
>> - Formats with the required components in the correct order, plus a junk
>>   component
>> - finally, swizzled formats (BGRA etc)
>>
>> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
>> ---
>>  src/mesa/main/texformat.c | 35 +++++++++++++++++++++++++++++++----
>>  1 file changed, 31 insertions(+), 4 deletions(-)
>>
>> diff --git a/src/mesa/main/texformat.c b/src/mesa/main/texformat.c
>> index 33725dc..7cb42bc 100644
>> --- a/src/mesa/main/texformat.c
>> +++ b/src/mesa/main/texformat.c
>> @@ -79,11 +79,13 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
>>        } else if (type == GL_UNSIGNED_INT_2_10_10_10_REV) {
>>           RETURN_IF_SUPPORTED(MESA_FORMAT_B10G10R10A2_UNORM);
>>        }
>> -      RETURN_IF_SUPPORTED(MESA_FORMAT_A8B8G8R8_UNORM);
>> -      RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_UNORM);
>> -      break;
>> +      /* fallthrough */
>>
>>     case GL_RGBA8:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_UNORM);
>> +         break;
>> +      }
>
> Are you sure this is correct on little endian machines?  According to
> the docs, MESA_FORMAT_R8G8B8A8_UNORM would end up with the R component
> in the most significant byte (highest array index) and the A component
> in the least significant byte (lowest array index), which seems like the
> opposite of what GL_RGBA8 is specified to be by
> ARB_shader_image_load_store.
>
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_A8B8G8R8_UNORM);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_UNORM);
>>        break;
>> @@ -100,6 +102,9 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
>>
>>     /* deep RGBA formats */
>>     case GL_RGB10_A2:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R10G10B10A2_UNORM);
>> +      }
>
> This looks correct for any endianness.
>
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B10G10R10A2_UNORM);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_UNORM);
>>        break;
>> @@ -119,6 +124,11 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
>>        }
>>        /* fallthrough */
>>     case GL_RGB8:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_RGB_UNORM8);
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8X8_UNORM);
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_UNORM);
>
> The last two seem wrong for LE too.
>
>> +      }
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_BGR_UNORM8);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8X8_UNORM);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_UNORM);
>> @@ -454,10 +464,19 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
>>        break;
>>     case GL_RGB_SNORM:
>>     case GL_RGB8_SNORM:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8X8_SNORM);
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SNORM);
>> +      }
>
> Same here.
>
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_X8B8G8R8_SNORM);
>> -      /* FALLTHROUGH */
>> +      RETURN_IF_SUPPORTED(MESA_FORMAT_A8B8G8R8_SNORM);
>> +      RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SNORM);
>> +      break;
>>     case GL_RGBA_SNORM:
>>     case GL_RGBA8_SNORM:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SNORM);
>> +      }
>
> And here.
>
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_A8B8G8R8_SNORM);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SNORM);
>>        break;
>> @@ -525,11 +544,19 @@ _mesa_choose_tex_format(struct gl_context *ctx, GLenum target,
>>
>>     case GL_SRGB_EXT:
>>     case GL_SRGB8_EXT:
>> +      if (prefer_no_swizzle) {
>> +         /* there is no MESA_FORMAT_RGB_SRGB8 */
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8X8_SRGB);
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SRGB);
>
> And here.
>
>> +      }
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_BGR_SRGB8);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_SRGB);
>>        break;
>>     case GL_SRGB_ALPHA_EXT:
>>     case GL_SRGB8_ALPHA8_EXT:
>> +      if (prefer_no_swizzle) {
>> +         RETURN_IF_SUPPORTED(MESA_FORMAT_R8G8B8A8_SRGB);
>> +      }
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_A8B8G8R8_SRGB);
>>        RETURN_IF_SUPPORTED(MESA_FORMAT_B8G8R8A8_SRGB);
>>        break;
>> --
>> 1.9.0
>>
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