| /* |
| * Copyright © 2017 Broadcom |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
| * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice (including the next |
| * paragraph) shall be included in all copies or substantial portions of the |
| * Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| * IN THE SOFTWARE. |
| */ |
| |
| /** |
| * @file |
| * |
| * Implements GL alpha testing by comparing the output color's alpha to the |
| * alpha_ref intrinsic and emitting a discard based on it. |
| * |
| * The alpha_to_one value overrides the source alpha to 1.0 to implement |
| * GL_SAMPLE_ALPHA_TO_ONE, which applies before the alpha test (and would be |
| * rather silly to use with alpha test, but the spec permits). |
| */ |
| |
| #include "nir/nir.h" |
| #include "nir/nir_builder.h" |
| |
| void |
| nir_lower_alpha_test(nir_shader *shader, enum compare_func func, |
| bool alpha_to_one) |
| { |
| assert(shader->info.stage == MESA_SHADER_FRAGMENT); |
| |
| nir_foreach_function(function, shader) { |
| nir_function_impl *impl = function->impl; |
| nir_builder b; |
| nir_builder_init(&b, impl); |
| b.cursor = nir_before_cf_list(&impl->body); |
| |
| nir_foreach_block(block, impl) { |
| nir_foreach_instr_safe(instr, block) { |
| if (instr->type == nir_instr_type_intrinsic) { |
| nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr); |
| |
| nir_variable *out = NULL; |
| |
| switch (intr->intrinsic) { |
| case nir_intrinsic_store_deref: |
| out = nir_deref_instr_get_variable(nir_src_as_deref(intr->src[0])); |
| break; |
| case nir_intrinsic_store_output: |
| /* already had i/o lowered.. lookup the matching output var: */ |
| nir_foreach_variable(var, &shader->outputs) { |
| int drvloc = var->data.driver_location; |
| if (nir_intrinsic_base(intr) == drvloc) { |
| out = var; |
| break; |
| } |
| } |
| assume(out); |
| break; |
| default: |
| continue; |
| } |
| |
| if (out->data.mode != nir_var_shader_out) |
| continue; |
| |
| if (out->data.location != FRAG_RESULT_COLOR && |
| out->data.location != FRAG_RESULT_DATA0) |
| continue; |
| |
| b.cursor = nir_before_instr(&intr->instr); |
| |
| nir_ssa_def *alpha; |
| if (alpha_to_one) { |
| alpha = nir_imm_float(&b, 1.0); |
| } else if (intr->intrinsic == nir_intrinsic_store_deref) { |
| alpha = nir_channel(&b, nir_ssa_for_src(&b, intr->src[1], 4), |
| 3); |
| } else { |
| alpha = nir_channel(&b, nir_ssa_for_src(&b, intr->src[0], 4), |
| 3); |
| } |
| |
| nir_ssa_def *condition = |
| nir_compare_func(&b, func, |
| alpha, nir_load_alpha_ref_float(&b)); |
| |
| nir_intrinsic_instr *discard = |
| nir_intrinsic_instr_create(b.shader, |
| nir_intrinsic_discard_if); |
| discard->num_components = 1; |
| discard->src[0] = nir_src_for_ssa(nir_inot(&b, condition)); |
| nir_builder_instr_insert(&b, &discard->instr); |
| shader->info.fs.uses_discard = true; |
| } |
| } |
| } |
| |
| nir_metadata_preserve(impl, nir_metadata_block_index | |
| nir_metadata_dominance); |
| } |
| } |