On Sat, Jul 5, 2014 at 6:22 PM, Marek Olšák <mar...@gmail.com> wrote:
> There is this vague statement in the sample shading spec:
>
> When the sample shading fraction is 1.0, a separate set of colors and
> other associated data are evaluated for each sample, each set of values
> are evaluated at the sample location.
>
> I thought it was about interpolation, meaning that the fraction must
> 1.0 for the per-sample interpolation to be enabled, right?
I guess so. I'm pretty much just doing what the intel driver is
doing... see brw_wm.c.
/* Gets the minimum number of shader invocations per fragment.
* This function is useful to determine if we need to do per
* sample shading or per fragment shading.
*/
GLint
_mesa_get_min_invocations_per_fragment(struct gl_context *ctx,
const struct gl_fragment_program *prog,
bool ignore_sample_qualifier)
So I guess instead of > 1 this should be checking for ==
ctx->DrawBuffer->Visual.samples? (and > 1)
Although in that case, I _really_ don't get the point of having
non-1.0/0.0 fractions ever existing. Why would you want it to be
shaded for e.g. 4/8 samples if all the inputs are going to get
interpolated the same way?
-ilia
>
> Marek
>
>
> On Sat, Jul 5, 2014 at 6:07 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote:
>> This enables a gallium driver not to care about the semantics of
>> ARB_sample_shading vs ARB_gpu_shader5 sample attributes. When
>> ARB_sample_shading-style sample shading is enabled, all of the fp inputs
>> are marked for interpolation at the sample location.
>>
>> Signed-off-by: Ilia Mirkin <imir...@alum.mit.edu>
>> ---
>>
>> I _think_ I got this right... at least the tests still pass. But my
>> understanding of all the various update atoms, etc is really weak... please
>> read carefully :)
>>
>> Now that I understand all this interpolation stuff better, I see why it was
>> suggested I add proper per-sample interpolation first and the
>> ARB_sample_shading stuff second. Oh well...
>>
>> src/mesa/state_tracker/st_atom_shader.c | 6 +++++-
>> src/mesa/state_tracker/st_program.c | 3 +++
>> src/mesa/state_tracker/st_program.h | 3 +++
>> 3 files changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/mesa/state_tracker/st_atom_shader.c
>> b/src/mesa/state_tracker/st_atom_shader.c
>> index 67c6157..6515a98 100644
>> --- a/src/mesa/state_tracker/st_atom_shader.c
>> +++ b/src/mesa/state_tracker/st_atom_shader.c
>> @@ -89,6 +89,10 @@ update_fp( struct st_context *st )
>> key.clamp_color = st->clamp_frag_color_in_shader &&
>> st->ctx->Color._ClampFragmentColor;
>>
>> + /* Ignore sample qualifier while computing this flag. */
>> + key.persample_shading =
>> + _mesa_get_min_invocations_per_fragment(st->ctx, &stfp->Base, true) >
>> 1;
>> +
>> st->fp_variant = st_get_fp_variant(st, stfp, &key);
>>
>> st_reference_fragprog(st, &st->fp, stfp);
>> @@ -108,7 +112,7 @@ update_fp( struct st_context *st )
>> const struct st_tracked_state st_update_fp = {
>> "st_update_fp", /* name */
>> { /* dirty */
>> - _NEW_BUFFERS, /* mesa */
>> + _NEW_BUFFERS | _NEW_MULTISAMPLE, /* mesa */
>> ST_NEW_FRAGMENT_PROGRAM /* st */
>> },
>> update_fp /* update */
>> diff --git a/src/mesa/state_tracker/st_program.c
>> b/src/mesa/state_tracker/st_program.c
>> index b603759..9d7b7c4 100644
>> --- a/src/mesa/state_tracker/st_program.c
>> +++ b/src/mesa/state_tracker/st_program.c
>> @@ -548,6 +548,9 @@ st_translate_fragment_program(struct st_context *st,
>> else
>> interpLocation[slot] = TGSI_INTERPOLATE_LOC_CENTER;
>>
>> + if (key->persample_shading)
>> + interpLocation[slot] = TGSI_INTERPOLATE_LOC_SAMPLE;
>> +
>> switch (attr) {
>> case VARYING_SLOT_POS:
>> input_semantic_name[slot] = TGSI_SEMANTIC_POSITION;
>> diff --git a/src/mesa/state_tracker/st_program.h
>> b/src/mesa/state_tracker/st_program.h
>> index ce9174f..9a5b6a8 100644
>> --- a/src/mesa/state_tracker/st_program.h
>> +++ b/src/mesa/state_tracker/st_program.h
>> @@ -58,6 +58,9 @@ struct st_fp_variant_key
>>
>> /** for ARB_color_buffer_float */
>> GLuint clamp_color:1;
>> +
>> + /** for ARB_sample_shading */
>> + GLuint persample_shading:1;
>> };
>>
>>
>> --
>> 1.8.5.5
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
