diff options
Diffstat (limited to 'src/broadcom/compiler/v3d_nir_lower_line_smooth.c')
| -rw-r--r-- | src/broadcom/compiler/v3d_nir_lower_line_smooth.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/src/broadcom/compiler/v3d_nir_lower_line_smooth.c b/src/broadcom/compiler/v3d_nir_lower_line_smooth.c new file mode 100644 index 00000000000..ace7d5cb5ca --- /dev/null +++ b/src/broadcom/compiler/v3d_nir_lower_line_smooth.c @@ -0,0 +1,163 @@ +/* + * Copyright © 2020 Raspberry Pi + * + * 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 "compiler/v3d_compiler.h" +#include "compiler/nir/nir_builder.h" +#include <math.h> + +/** + * Lowers line smoothing by modifying the alpha component of fragment outputs + * using the distance from the center of the line. + */ + +struct lower_line_smooth_state { + nir_shader *shader; + nir_variable *coverage; +}; + +static void +lower_line_smooth_intrinsic(struct lower_line_smooth_state *state, + nir_builder *b, + nir_intrinsic_instr *intr) +{ + b->cursor = nir_before_instr(&intr->instr); + + nir_ssa_def *one = nir_imm_float(b, 1.0f); + + nir_ssa_def *coverage = nir_load_var(b, state->coverage); + + nir_ssa_def *new_val = nir_fmul(b, nir_vec4(b, one, one, one, coverage), + intr->src[0].ssa); + + nir_instr_rewrite_src(&intr->instr, + &intr->src[0], + nir_src_for_ssa(new_val)); +} + +static void +lower_line_smooth_func(struct lower_line_smooth_state *state, + nir_function_impl *impl) +{ + nir_builder b; + + nir_builder_init(&b, impl); + + nir_foreach_block(block, impl) { + nir_foreach_instr_safe(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *intr = + nir_instr_as_intrinsic(instr); + + if (intr->intrinsic != nir_intrinsic_store_output || + nir_intrinsic_base(intr) != 0 || + intr->num_components != 4 || + !intr->src[0].is_ssa) + continue; + + lower_line_smooth_intrinsic(state, &b, intr); + } + } +} + +static void +initialise_coverage_var(struct lower_line_smooth_state *state, + nir_function_impl *impl) +{ + nir_builder b; + + nir_builder_init(&b, impl); + + b.cursor = nir_before_block(nir_start_block(impl)); + + nir_ssa_def *line_width = nir_load_line_width(&b); + + nir_ssa_def *real_line_width = nir_load_aa_line_width(&b); + + /* The line coord varies from 0.0 to 1.0 across the width of the line */ + nir_ssa_def *line_coord = nir_load_line_coord(&b); + + /* fabs(line_coord - 0.5) * real_line_width */ + nir_ssa_def *pixels_from_center = + nir_fmul(&b, real_line_width, + nir_fabs(&b, nir_fsub(&b, line_coord, + nir_imm_float(&b, 0.5f)))); + + /* 0.5 - 1/√2 * (pixels_from_center - line_width * 0.5) */ + nir_ssa_def *coverage = + nir_fsub(&b, + nir_imm_float(&b, 0.5f), + nir_fmul(&b, + nir_imm_float(&b, 1.0f / M_SQRT2), + nir_fsub(&b, pixels_from_center, + nir_fmul(&b, + line_width, + nir_imm_float(&b, 0.5f))))); + + /* Discard fragments that aren’t covered at all by the line */ + nir_ssa_def *outside = nir_fge(&b, nir_imm_float(&b, 0.0f), coverage); + + nir_intrinsic_instr *discard = + nir_intrinsic_instr_create(state->shader, + nir_intrinsic_discard_if); + discard->src[0] = nir_src_for_ssa(outside); + nir_builder_instr_insert(&b, &discard->instr); + + /* Clamp to at most 1.0. If it was less than 0.0 then the fragment will + * be discarded so we don’t need to handle that. + */ + nir_ssa_def *clamped = nir_fmin(&b, coverage, nir_imm_float(&b, 1.0f)); + + nir_store_var(&b, state->coverage, clamped, 0x1 /* writemask */); +} + +static nir_variable * +make_coverage_var(nir_shader *s) +{ + nir_variable *var = nir_variable_create(s, + nir_var_shader_temp, + glsl_float_type(), + "line_coverage"); + var->data.how_declared = nir_var_hidden; + + return var; +} + +void +v3d_nir_lower_line_smooth(nir_shader *s) +{ + assert(s->info.stage == MESA_SHADER_FRAGMENT); + + struct lower_line_smooth_state state = { + .shader = s, + .coverage = make_coverage_var(s), + }; + + nir_foreach_function(function, s) { + if (function->is_entrypoint) + initialise_coverage_var(&state, function->impl); + + lower_line_smooth_func(&state, function->impl); + } +} |