| /* |
| * Copyright © 2022 Advanced Micro Devices, Inc. |
| * |
| * 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. |
| */ |
| |
| #include "nir.h" |
| #include "nir_builder.h" |
| #include "nir_builtin_builder.h" |
| |
| /** |
| * This NIR lowers pass for point smoothing by modifying the alpha value of |
| * fragment outputs using the distance from the center of the point. |
| * Anti-aliased points get rounded with respect to their radius. |
| */ |
| |
| static bool |
| lower_point_smooth(nir_builder *b, nir_instr *instr, UNUSED void *_state) |
| { |
| if (instr->type != nir_instr_type_intrinsic) |
| return false; |
| |
| nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr); |
| |
| if (intr->intrinsic != nir_intrinsic_store_output) |
| return false; |
| |
| int location = nir_intrinsic_io_semantics(intr).location; |
| if ((location != FRAG_RESULT_COLOR && location < FRAG_RESULT_DATA0) || |
| nir_intrinsic_src_type(intr) != nir_type_float32) |
| return false; |
| |
| assert(intr->src[0].is_ssa); |
| assert(intr->num_components == 4); |
| |
| b->cursor = nir_before_instr(&intr->instr); |
| |
| nir_ssa_def *coord = nir_build_load_point_coord_maybe_flipped(b); |
| |
| /* point_size = 1.0 / dFdx(gl_PointCoord.x); */ |
| nir_ssa_def *point_size = nir_frcp(b, nir_fddx(b, nir_channel(b, coord, 0))); |
| |
| /* radius = point_size * 0.5 */ |
| nir_ssa_def *radius = nir_fmul_imm(b, point_size, 0.5);; |
| |
| /** |
| * Compute the distance of point from centre |
| * distance = √ (x - 0.5)^2 + (y - 0.5)^2 |
| */ |
| nir_ssa_def *distance = nir_fast_distance(b, coord, |
| nir_imm_vec2(b, 0.5, 0.5)); |
| distance = nir_fmul(b, distance, point_size); |
| |
| /* alpha = min(max(radius - distance, 0.0), 1.0) */ |
| nir_ssa_def *coverage = nir_fsat(b, nir_fsub(b, radius, distance)); |
| |
| /* Discard fragments that are not covered by the point */ |
| nir_discard_if(b, nir_feq(b, nir_imm_float(b, 0.0f), coverage)); |
| |
| /* Write out the fragment color*vec4(1, 1, 1, coverage)*/ |
| nir_ssa_def *one = nir_imm_float(b, 1.0f); |
| nir_ssa_def *new_val = nir_fmul(b, nir_vec4(b, one, one, one, coverage), |
| intr->src[0].ssa); |
| nir_instr_rewrite_src(instr, &intr->src[0], nir_src_for_ssa(new_val)); |
| |
| return true; |
| } |
| |
| bool |
| nir_lower_point_smooth(nir_shader *shader) |
| { |
| assert(shader->info.stage == MESA_SHADER_FRAGMENT); |
| return nir_shader_instructions_pass(shader, lower_point_smooth, |
| nir_metadata_loop_analysis | |
| nir_metadata_block_index | |
| nir_metadata_dominance, NULL); |
| } |