[Mesa-dev] [PATCH 1/2] st/mesa: fix samplerCubeShadow with bias

[Ilia Mirkin]

On Fri, Jul 4, 2014 at 3:30 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Fri, Jul 4, 2014 at 2:49 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Fri, Jul 4, 2014 at 8:10 AM, Marek Olšák <maraeo at gmail.com> wrote:
>>> From: Marek Olšák <marek.olsak at amd.com>
>>>
>>> It has 5 coordinates: (x,y,z,depth,lodbias)
>>>
>>> Cc: mesa-stable at lists.freedesktop.org
>>
>> Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>
>>
>> Although I still haven't worked out what else is wrong with nouveau...
>> nv50 hits an assert, while nvc0 just generates wrong code. But it does
>> look like your patch is correct.
>
> Actually this makes the TXL2 instruction pretty confusing =/
>
> Right now it's always just used for cube arrays, so the shadow/lod are
> in a fixed position (first and second components of second arg). I
> think that behaviour should be maintained -- for example, TXB
> (http://gallium.readthedocs.org/en/latest/tgsi.html#opcode-TXB) always
> has the bias in the 'w' component [ugh, should fix the docs on that,
> it says 'z']. Same with TXL.

Err, sorry, I got confused between TXL and TXB. But my point still stands.

Unless we're doing something horribly wrong in nouveau, it appears
that for cube arrays, the lod is in src1.x and shadow is in src1.y,
while for the samplerCubeShadow case, lod is in src1.x while shadow is
in src0.w. Once I adjusted that, the texture(bias) CubeShadow case
started passing.

In any case, it'd be great of TEX2/TXB2/TXL2 could be documented in
the TGSI docs...

  -ilia

>
>   -ilia
>
>>
>>> ---
>>>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 8 +++++++-
>>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>> index 9e19431..65ef89c 100644
>>> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
>>> @@ -2820,7 +2820,13 @@ glsl_to_tgsi_visitor::visit(ir_texture *ir)
>>>        }
>>>        break;
>>>     case ir_txb:
>>> -      opcode = is_cube_array ? TGSI_OPCODE_TXB2 : TGSI_OPCODE_TXB;
>>> +      if (is_cube_array ||
>>> +          sampler_type == glsl_type::samplerCubeShadow_type) {
>>> +         opcode = TGSI_OPCODE_TXB2;
>>> +      }
>>> +      else {
>>> +         opcode = TGSI_OPCODE_TXB;
>>> +      }
>>>        ir->lod_info.bias->accept(this);
>>>        lod_info = this->result;
>>>        if (ir->offset) {
>>> --
>>> 1.9.1
>>>
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