[Mesa-dev] ARB_copy_image support in Gallium

[Ilia Mirkin]

On Mon, Jul 20, 2015 at 3:53 PM, Brian Paul <brianp at vmware.com> wrote:
> On 07/20/2015 01:19 PM, Ilia Mirkin wrote:
>
>> On Mon, Jul 20, 2015 at 2:44 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>>
>>> Hi Brian,
>>>
>>> You marked off ARB_copy_image (and ARB_clear_texture) as in-progress
>>> by VMware some months ago -- has there been any movement on that? It
>>> appears that Bioshock Infinite requires ARB_copy_image so might be
>>> nice to get that added in.
>>>
>>> The complication in implementing ARB_copy_image was that st/mesa will
>>> pick potentially different PIPE_FORMAT enums for the same internal
>>> format, depending on the parameters to the glTexImage call. A
>>> developer (irc handle Leftmost, I forget his real name, sorry) tried
>>> to wrestle with the issues this presents, but as I recall ended up
>>> coming up short.
>>>
>>> The final implementation probably needs some combination of
>>> resource_copy_region and blit. I think resource_copy_region currently
>>> is spec'd to require identical formats in src and dst, but that could
>>> be relaxed.
>>>
>>> Anyways, would be interested in hearing whether you guys have made any
>>> progress, or if you had thoughts on proper implementation.
>>>
>>> Cheers,
>>>
>>>    -ilia
>>
>>
>> As an aside, here's a very naive implementation of the ext, which
>> fails for lots of reasons not the least of which is that we default to
>> BGRA instead of RGBA. Perhaps we could create a resource_copy_region
>> version that also takes (or knows about) swizzles... that should also
>> cover many (all?) of the situations I think.
>
>
> One of our interns did the implementation (with some contributions from me).
> I need to do a lot of clean-up before posting the patches here though.  I
> was hoping to do that in the next month or two.  If you need it sooner, I'll
> can see what I can do.

As there's a decent chance that tessellation and subroutine support
will land in the next release (thus exposing GL 4.1 in several
drivers), and there is an actual released game that requires
ARB_copy_image, it would definitely be nice to see support land before
the next mesa release is branched off, which should happen in about a
month's time I guess.

Cheers,

  -ilia