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

[Ilia Mirkin]

OK, so from the _looks_ of it, vertex and fragment texture/sampler
bindings are totally separate. Based on what I'm seeing, there are 16
slots for fragment shaders, and 4 for vertex shaders.

On Mon, Feb 3, 2014 at 8:51 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> 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