[Mesa-dev] [PATCH 3/9] st/mesa: tweak surface format mapping table

[Ilia Mirkin]

On Mon, Aug 24, 2015 at 4:54 PM, Brian Paul <brianp at vmware.com> wrote:
> On 08/24/2015 02:44 PM, Ilia Mirkin wrote:
>>
>> Not that I really care, but... why flip the order of bgra vs rgba?
>
>
> Because if an 8-bit RGBA integer texture is created, we'll use the gallium
> format PIPE_FORMAT_R8G8B8A8_SINT.  If we create another non-integer surface
> with PIPE_FORMAT_B8G8R8A8_UNORM instead of PIPE_FORMAT_R8G8B8A8_UNORM we'll
> get a failure when copying image data because of the component order
> difference.

You'll get that problem anyways, no? Imagine you create 2 RGBA 8-bit
unorm textures -- one with glTexImage(ifmt=GL_RGBA8, fmt=GL_RGBA,
type=GL_UNSIGNED_INT_8_8_8_8) and another with
glTexImage(ifmt=GL_RGBA8, fmt=GL_RGBA,
type=GL_UNSIGNED_INT_8_8_8_8_REV). The two textures will have the same
GL internal format, but different pipe format component orderings...
so when you copy between them you need to swizzle.

But perhaps I should look at the rest of the series when you manage to
send it :)

  -ilia