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bdd85c8393
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33146>
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/*
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* Copyright © 2017 Broadcom
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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/**
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* @file
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*
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* Implements GL alpha testing by comparing the output color's alpha to the
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* alpha_ref intrinsic and emitting a discard based on it.
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*
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* The alpha_to_one value overrides the source alpha to 1.0 to implement
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* GL_SAMPLE_ALPHA_TO_ONE, which applies before the alpha test (and would be
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* rather silly to use with alpha test, but the spec permits).
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*/
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#include "nir/nir.h"
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#include "nir/nir_builder.h"
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struct alpha_test_state {
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bool alpha_to_one;
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enum compare_func func;
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const gl_state_index16 *alpha_ref_state_tokens;
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};
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static bool
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is_color_output(int location)
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{
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return location == FRAG_RESULT_COLOR || location == FRAG_RESULT_DATA0;
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}
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static bool
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lower(nir_builder *b, nir_intrinsic_instr *intr, void *data)
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{
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struct alpha_test_state *state = data;
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switch (intr->intrinsic) {
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case nir_intrinsic_store_output:
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if (!is_color_output(nir_intrinsic_io_semantics(intr).location))
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return false;
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break;
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default:
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return false;
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}
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b->cursor = nir_before_instr(&intr->instr);
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nir_def *alpha;
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if (state->alpha_to_one)
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alpha = nir_imm_float(b, 1.0);
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else
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alpha = nir_channel(b, intr->src[0].ssa, 3);
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nir_variable *var = nir_state_variable_create(b->shader, glsl_float_type(),
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"gl_AlphaRefMESA",
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state->alpha_ref_state_tokens);
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nir_def *alpha_ref = nir_load_var(b, var);
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nir_def *condition = nir_compare_func(b, state->func, alpha, alpha_ref);
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nir_discard_if(b, nir_inot(b, condition));
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b->shader->info.fs.uses_discard = true;
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return true;
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}
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bool
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nir_lower_alpha_test(nir_shader *shader, enum compare_func func,
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bool alpha_to_one,
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const gl_state_index16 *alpha_ref_state_tokens)
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{
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assert(shader->info.io_lowered);
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struct alpha_test_state state = {
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.alpha_ref_state_tokens = alpha_ref_state_tokens,
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.alpha_to_one = alpha_to_one,
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.func = func,
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};
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return nir_shader_intrinsics_pass(shader, lower,
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nir_metadata_control_flow,
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&state);
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}
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