[Mesa-dev] [PATCH 1/2] gallium: remove PIPE_CAP_MAX_COMBINED_SAMPLERS

[Ilia Mirkin]

Hmmm... unclear from a quick read of the code. nv40_verttex.c looks at
nv30->fragprog.textures/samplers (instead of nv30->vertprog) to
disable VTXTEX_ENABLE, but doesn't do anything with them if they're
set. Could just be a copy-pasta situation, or could be that TEX_ENABLE
and VTXTEX_ENABLE can't be set for the same index... The
enables/formats/etc are all in separate registers, but there's nothing
saying that you can use both at the same time. I'll see if there's any
docs on it when I get home.

Separately, the chances of major new features being implemented in
nv30 at this point are relatively low. I'm probably the only person
looking at it, and I'm just trying to make the current functionality
work (or at least be not as wrong). There's sitll quite some work
ahead in that regard --
http://people.freedesktop.org/~imirkin/nv40-comparison/problems.html

On Mon, Feb 3, 2014 at 7:58 PM, Marek Olšák <maraeo at gmail.com> wrote:
> nv40 supports texturing in the vertex shader, but I don't know if the
> number of textures used by the vertex shader doesn't limit the maximum
> number of textures which can be used by the fragment shader. For
> example, if the vertex shaders uses 4 textures, the fragment shader
> can only use 12 instead of 16. I'm asking if nv40 has such a
> limitation.
>
> Thank you.
>
> Marek
>
> On Tue, Feb 4, 2014 at 1:37 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> [+ben, nv30 driver author]
>>
>> On Mon, Feb 3, 2014 at 7:18 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>> Ilia,
>>>
>>> I see you worked on nv30. Are vertex shader texture slots shared with
>>> fragment shader texture slots on nv40? If yes, does the nouveau team
>>> plan to implement vertex shader textures for nv40?
>>
>> Unfortunately my knowledge of these things is... limited. I haven't
>> really touched the nv30 shader stuff much, esp not relating to
>> textures. Ben, do you know what Marek is talking about? If not, I'll
>> try to investigate.
>>
>> Marek -- perhaps you can give me an example of what you mean? Are you
>> talking about, e.g. texture(sampler2D, ...), and whether one can do
>> that from within the vertex shader and whether one can attach those
>> samplers/textures to vs/fs independently or not? (Sorry, my knowledge
>> of opengl and 3d hardware and esp terminology is still very poor. But
>> I'm learning...)
>>
>>>
>>> Marek
>>>
>>> On Wed, Jan 22, 2014 at 9:36 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>> On Mon, Jan 20, 2014 at 3:35 PM, Brian Paul <brianp at vmware.com> wrote:
>>>>> I'm not sure about this.  The concept of MAX_COMBINED_TEXTURE_IMAGE_UNITS
>>>>> goes back to the first shader hardware where texture image units might be
>>>>> shared between the VS and FS.
>>>>>
>>>>> The question is whether any of the hardware we care about has that
>>>>> restriction.
>>>>
>>>> I'm not aware of any hardware which has the restriction. I think
>>>> the reason MAX_COMBINED_TEXTURE_IMAGE_UNITS exists is that the OpenGL
>>>> texture units are shared by all shader stages.
>>>>
>>>> Marek