[Mesa-dev] [PATCH] mesa: do more teximage error checking for generic compressed formats

[Kenneth Graunke]

On 08/17/2012 09:34 AM, Roland Scheidegger wrote:
> Am 16.08.2012 23:29, schrieb Anuj Phogat:
>> On Thu, Aug 16, 2012 at 10:23 AM, Brian Paul <brianp at vmware.com> wrote:
>>> On 08/15/2012 02:31 PM, Anuj Phogat wrote:
>>>>
>>>> On Tue, May 1, 2012 at 2:07 PM, Brian Paul <brianp at vmware.com
>>>> <mailto:brianp at vmware.com>> wrote:
>>>>
>>>>     When glTexImage or glCopyTexImage is called with internalFormat
>>>>     being a
>>>>     generic compressed format (like GL_COMPRESSED_RGB) we need to do
>>>>     the same
>>>>     error checks as for specific compressed formats.  In particular,
>>>>     check if
>>>>     the texture target is compatible with the format.  None of the texture
>>>>     compression formats we support so far work with GL_TEXTURE_1D, for
>>>>     example.
>>>>
>>>>     See also https://bugs.freedesktop.org/show_bug.cgi?id=49124
>>>>
>>>>
>>>> Brian, generic texture compression formats with GL_TEXTURE_1D seem to
>>>> work fine
>>>> on i965 drivers.
>>>
>>>
>>> Does that wind up using one of the DXT formats?
>> It uses RGTC for GL_COMPRESSED_RED & GL_COMPRESSED_RG
>> FXT for GL_COMPRESSED_RGB & GL_COMPRESSED_RGBA
> Those are also 4x4 based.

I'm surprised we do that.  I would have expected uncompressed.

> That said, I think you are right. An implementation must not fail
> teximage[123]d calls with generic compressed formats. If there's no
> suitable format available, it is however free to use some suitable
> uncompressed format (for the specific case, using rgtc here really
> doesn't make much sense as that's going to be twice as big as
> uncompressed, unless the hw needs some block-alignment anyway, but I
> could see why you'd chose that with the code being the same for 1d and
> 2d textures - it's not like you'd want to optimize that case).

Yeah.  The idea is that a GL_COMPRESSED_WHATEVER internal format means
"feel free to pick a compressed format, if you want".  So we need to
allow those internal formats for 1D/3D, but we should probably always
pick an uncompressed format.