[Mesa-dev] [PATCH] r600: fix VERTEX_ATTRIB_STRIDE to be 2048

[Roland Scheidegger]

Am 04.02.2018 um 20:13 schrieb Dave Airlie:
> On 2 February 2018 at 18:02, Roland Scheidegger <sroland at vmware.com> wrote:
>> Are you sure of that? You only get 11 stride bits to program, and they
>> are in bytes. Therefore I can't see how you could program 2048 (unless
>> the hw would interpet 0 as 2048 but I think stride 0 is valid there?).
>>
> 
> Hmm so GL 4.4 defines the minimum for this to be 2048.
> 
> Could be a bit of a blocker :-)
> 
> Dave.
> 

I'm wondering what the blob did?
I suppose you could always just lie - if the tests only care about the
query and never actually test it you could get away with it...
I mean, before GL 4.4, it was not even queryable and was supposed to
always work no matter the stride, but in reality it would just silently
fail...
I was merely pointing out the limit there was probably intentional (so,
if lying is the answer, I'd suggest a comment at least). (And I didn't
verify what the hw really does with stride 0.)
I guess alternatively you could fix it up in the vertex fetch shader
(so, program stride 1024 in this case and lshift the id-to-fetch by 2 -
albeit I do not actually understand how the VTX_FETCH_VERTEX_DATA and
VTX_FETCH_INSTANCE_DATA work, but nevertheless I suppose it should be
fixable to patch it up somehow).

Roland