I could enable interpolation of gl_FragCoord at the sample instead of
centroid and do:
gl_SamplePos = fract(gl_FragCoord.xy);
gl_FragCoord.xy = floor(gl_FragCoord.xy) + vec2(0.5); // center
However, I wouldn't be able to get gl_FragCoord at the centroid.
I'm also not sure how gl_FragCoord should be interpolated if sample
shading is enabled.
Marek
On Wed, May 7, 2014 at 5:00 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote:
> On Wed, May 7, 2014 at 10:00 AM, Marek Olšák <mar...@gmail.com> wrote:
>> From: Marek Olšák <marek.ol...@amd.com>
>>
>> The sample positions are read from a constant buffer.
>
> FWIW I had to do the same thing in both nv50 and nvc0. I had proposed
> that this should actually be done directly by the state tracker, but I
> think claims were made to the effect that there might be hw which can
> look up the positions directly. I figured radeon was such hw, but I
> guess not.
>
> Anyways, seems like a nice refactor would be to have mesa/st (or
> mesa/main) supply the constbufs and rip out the extra logic from
> nv50/nvc0/radeonsi. [Certainly don't have to do it now, esp now that
> you've done it this way.] The sample count is already handled this way
> by mesa core.
>
> -ilia
>
>> ---
>> src/gallium/drivers/radeon/cayman_msaa.c | 17 +++++++++++++++++
>> src/gallium/drivers/radeon/r600_pipe_common.c | 1 +
>> src/gallium/drivers/radeon/r600_pipe_common.h | 10 ++++++++++
>> src/gallium/drivers/radeonsi/si_shader.c | 23 +++++++++++++++++++++++
>> src/gallium/drivers/radeonsi/si_state.c | 25 +++++++++++++++++++++++++
>> 5 files changed, 76 insertions(+)
>>
>> diff --git a/src/gallium/drivers/radeon/cayman_msaa.c
>> b/src/gallium/drivers/radeon/cayman_msaa.c
>> index 8727f3e..47fc5c4 100644
>> --- a/src/gallium/drivers/radeon/cayman_msaa.c
>> +++ b/src/gallium/drivers/radeon/cayman_msaa.c
>> @@ -123,6 +123,23 @@ void cayman_get_sample_position(struct pipe_context
>> *ctx, unsigned sample_count,
>> }
>> }
>>
>> +void cayman_init_msaa(struct pipe_context *ctx)
>> +{
>> + struct r600_common_context *rctx = (struct r600_common_context*)ctx;
>> + int i;
>> +
>> + cayman_get_sample_position(ctx, 1, 0, rctx->sample_locations_1x[0]);
>> +
>> + for (i = 0; i < 2; i++)
>> + cayman_get_sample_position(ctx, 2, i,
>> rctx->sample_locations_2x[i]);
>> + for (i = 0; i < 4; i++)
>> + cayman_get_sample_position(ctx, 4, i,
>> rctx->sample_locations_4x[i]);
>> + for (i = 0; i < 8; i++)
>> + cayman_get_sample_position(ctx, 8, i,
>> rctx->sample_locations_8x[i]);
>> + for (i = 0; i < 16; i++)
>> + cayman_get_sample_position(ctx, 16, i,
>> rctx->sample_locations_16x[i]);
>> +}
>> +
>> void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int
>> nr_samples)
>> {
>> switch (nr_samples) {
>> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.c
>> b/src/gallium/drivers/radeon/r600_pipe_common.c
>> index 70c4d1a..4c6cf0e 100644
>> --- a/src/gallium/drivers/radeon/r600_pipe_common.c
>> +++ b/src/gallium/drivers/radeon/r600_pipe_common.c
>> @@ -154,6 +154,7 @@ bool r600_common_context_init(struct r600_common_context
>> *rctx,
>> r600_init_context_texture_functions(rctx);
>> r600_streamout_init(rctx);
>> r600_query_init(rctx);
>> + cayman_init_msaa(&rctx->b);
>>
>> rctx->allocator_so_filled_size = u_suballocator_create(&rctx->b,
>> 4096, 4,
>> 0,
>> PIPE_USAGE_DEFAULT, TRUE);
>> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h
>> b/src/gallium/drivers/radeon/r600_pipe_common.h
>> index 4c3e9ce..8862d31 100644
>> --- a/src/gallium/drivers/radeon/r600_pipe_common.h
>> +++ b/src/gallium/drivers/radeon/r600_pipe_common.h
>> @@ -357,6 +357,15 @@ struct r600_common_context {
>> boolean saved_render_cond_cond;
>> unsigned saved_render_cond_mode;
>>
>> + /* MSAA sample locations.
>> + * The first index is the sample index.
>> + * The second index is the coordinate: X, Y. */
>> + float sample_locations_1x[1][2];
>> + float sample_locations_2x[2][2];
>> + float sample_locations_4x[4][2];
>> + float sample_locations_8x[8][2];
>> + float sample_locations_16x[16][2];
>> +
>> /* Copy one resource to another using async DMA. */
>> void (*dma_copy)(struct pipe_context *ctx,
>> struct pipe_resource *dst,
>> @@ -472,6 +481,7 @@ extern const uint32_t eg_sample_locs_4x[4];
>> extern const unsigned eg_max_dist_4x;
>> void cayman_get_sample_position(struct pipe_context *ctx, unsigned
>> sample_count,
>> unsigned sample_index, float *out_value);
>> +void cayman_init_msaa(struct pipe_context *ctx);
>> void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int
>> nr_samples);
>> void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
>> int ps_iter_samples);
>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c
>> b/src/gallium/drivers/radeonsi/si_shader.c
>> index 0195e54..d8b7b9c 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>> @@ -559,6 +559,8 @@ static void declare_system_value(
>> {
>> struct si_shader_context *si_shader_ctx =
>> si_shader_context(&radeon_bld->soa.bld_base);
>> + struct lp_build_context *uint_bld =
>> &radeon_bld->soa.bld_base.uint_bld;
>> + struct gallivm_state *gallivm = &radeon_bld->gallivm;
>> LLVMValueRef value = 0;
>>
>> switch (decl->Semantic.Name) {
>> @@ -576,6 +578,27 @@ static void declare_system_value(
>> value = get_sample_id(radeon_bld);
>> break;
>>
>> + case TGSI_SEMANTIC_SAMPLEPOS:
>> + {
>> + LLVMBuilderRef builder = gallivm->builder;
>> + LLVMValueRef desc =
>> LLVMGetParam(si_shader_ctx->radeon_bld.main_fn, SI_PARAM_CONST);
>> + LLVMValueRef buf_index = lp_build_const_int32(gallivm,
>> NUM_PIPE_CONST_BUFFERS);
>> + LLVMValueRef resource = build_indexed_load(si_shader_ctx,
>> desc, buf_index);
>> +
>> + /* offset = sample_id * 8 (8 = 2 floats containing
>> samplepos.xy) */
>> + LLVMValueRef offset0 = lp_build_mul_imm(uint_bld,
>> get_sample_id(radeon_bld), 8);
>> + LLVMValueRef offset1 = LLVMBuildAdd(builder, offset0,
>> lp_build_const_int32(gallivm, 4), "");
>> +
>> + LLVMValueRef pos[4] = {
>> + load_const(builder, resource, offset0,
>> radeon_bld->soa.bld_base.base.elem_type),
>> + load_const(builder, resource, offset1,
>> radeon_bld->soa.bld_base.base.elem_type),
>> + lp_build_const_float(gallivm, 0),
>> + lp_build_const_float(gallivm, 0)
>> + };
>> + value = lp_build_gather_values(gallivm, pos, 4);
>> + break;
>> + }
>> +
>> default:
>> assert(!"unknown system value");
>> return;
>> diff --git a/src/gallium/drivers/radeonsi/si_state.c
>> b/src/gallium/drivers/radeonsi/si_state.c
>> index fd9de05..3c1af06 100644
>> --- a/src/gallium/drivers/radeonsi/si_state.c
>> +++ b/src/gallium/drivers/radeonsi/si_state.c
>> @@ -1859,6 +1859,7 @@ static void si_set_framebuffer_state(struct
>> pipe_context *ctx,
>> const struct pipe_framebuffer_state
>> *state)
>> {
>> struct si_context *sctx = (struct si_context *)ctx;
>> + struct pipe_constant_buffer constbuf = {0};
>> struct r600_surface *surf = NULL;
>> struct r600_texture *rtex;
>> int i;
>> @@ -1924,6 +1925,30 @@ static void si_set_framebuffer_state(struct
>> pipe_context *ctx,
>> sctx->framebuffer.atom.num_dw += 18; /* MSAA sample locations */
>> sctx->framebuffer.atom.dirty = true;
>> sctx->msaa_config.dirty = true;
>> +
>> + /* Set sample locations as fragment shader constants. */
>> + switch (sctx->framebuffer.nr_samples) {
>> + case 1:
>> + constbuf.user_buffer = sctx->b.sample_locations_1x;
>> + break;
>> + case 2:
>> + constbuf.user_buffer = sctx->b.sample_locations_2x;
>> + break;
>> + case 4:
>> + constbuf.user_buffer = sctx->b.sample_locations_4x;
>> + break;
>> + case 8:
>> + constbuf.user_buffer = sctx->b.sample_locations_8x;
>> + break;
>> + case 16:
>> + constbuf.user_buffer = sctx->b.sample_locations_16x;
>> + break;
>> + default:
>> + assert(0);
>> + }
>> + constbuf.buffer_size = sctx->framebuffer.nr_samples * 2 * 4;
>> + ctx->set_constant_buffer(ctx, PIPE_SHADER_FRAGMENT,
>> + NUM_PIPE_CONST_BUFFERS, &constbuf);
>> }
>>
>> static void si_emit_framebuffer_state(struct si_context *sctx, struct
>> r600_atom *atom)
>> --
>> 1.9.1
>>
>> _______________________________________________
>> 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
