[Mesa-dev] [PATCH 3/4] st/mesa: ignore primitive restart if FixedIndex is enabled in DrawArraysIndirect

[Marek Olšák]

Radeon hardware doesn't support primitive restart for DrawArrays either.

Marek

On Mon, Jan 5, 2015 at 5:48 PM, Roland Scheidegger <sroland at vmware.com> wrote:
> I'm wondering how this is supposed to work with draw (and draw_info in
> general). Looks like draw will not do prim restart for non-indexed calls
> - d3d10 apparently works like the FIXED_INDEX case of gl (so, arrays
> won't trigger restarts). I wasn't even aware that GL triggers restarts
> for DrawArray calls, seems kind of weird to match the restart value to
> some internally made up index value but OTOH seems quite logical given
> how GL specifies "transfer of elements".
> So I guess it's not too surprising it doesn't work with
> softpipe/llvmpipe, I wonder though if it's even worth fixing is there
> some real use case for this?
>
> Roland
>
>
> Am 04.01.2015 um 22:54 schrieb Ilia Mirkin:
>> FWIW the piglit you posted recently
>> (arb_draw_indirect-draw-arrays-prim-restart) works with nvc0 with
>> upstream mesa as-is. (But fails on llvmpipe/softpipe.)
>>
>> On Sun, Jan 4, 2015 at 4:44 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>> From: Marek Olšák <marek.olsak at amd.com>
>>>
>>> From GL 4.4 Core profile:
>>>
>>>   If both PRIMITIVE_RESTART and PRIMITIVE_RESTART_FIXED_INDEX are
>>>   enabled, the index value determined by PRIMITIVE_RESTART_FIXED_INDEX is
>>>   used. If PRIMITIVE_RESTART_FIXED_INDEX is enabled, primitive restart is not
>>>   performed for array elements transferred by any drawing command not taking a
>>>   type parameter, including all of the *Draw* commands other than *DrawEle-
>>>   ments*.
>>>
>>> If only I had a driver where primitive restart works with DrawArraysIndirect.
>>> I can't test this, sorry.
>>> ---
>>>  src/mesa/state_tracker/st_draw.c | 12 +++++++++---
>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
>>> index b6ccdd7..9e5a5a9 100644
>>> --- a/src/mesa/state_tracker/st_draw.c
>>> +++ b/src/mesa/state_tracker/st_draw.c
>>> @@ -248,9 +248,15 @@ st_draw_vbo(struct gl_context *ctx,
>>>     if (indirect) {
>>>        info.indirect = st_buffer_object(indirect)->buffer;
>>>
>>> -      /* Primitive restart is not handled by the VBO module in this case. */
>>> -      info.primitive_restart = ctx->Array._PrimitiveRestart;
>>> -      info.restart_index = ctx->Array.RestartIndex;
>>> +      /* Primitive restart for DrawArrays is not handled by the VBO module
>>> +       * in this case.
>>> +       *
>>> +       * If PrimitiveRestartFixedIndex is enabled, primitive_restart must
>>> +       * be disabled for DrawArrays. DrawElements is handled above. */
>>> +      if (!ib && !ctx->Array.PrimitiveRestartFixedIndex) {
>>> +         info.primitive_restart = ctx->Array.PrimitiveRestart;
>>> +         info.restart_index = ctx->Array.RestartIndex;
>>> +      }
>>>     }
>>>
>>>     /* do actual drawing */
>>> --
>>> 2.1.0
>>>
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>