2 * Copyright © 2017 Broadcom
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
27 * Implements GL alpha testing by comparing the output color's alpha to the
28 * alpha_ref intrinsic and emitting a discard based on it.
30 * The alpha_to_one value overrides the source alpha to 1.0 to implement
31 * GL_SAMPLE_ALPHA_TO_ONE, which applies before the alpha test (and would be
32 * rather silly to use with alpha test, but the spec permits).
36 #include "nir/nir_builder.h"
39 nir_lower_alpha_test(nir_shader
*shader
, enum compare_func func
,
42 assert(shader
->info
.stage
== MESA_SHADER_FRAGMENT
);
44 nir_foreach_function(function
, shader
) {
45 nir_function_impl
*impl
= function
->impl
;
47 nir_builder_init(&b
, impl
);
48 b
.cursor
= nir_before_cf_list(&impl
->body
);
50 nir_foreach_block(block
, impl
) {
51 nir_foreach_instr_safe(instr
, block
) {
52 if (instr
->type
== nir_instr_type_intrinsic
) {
53 nir_intrinsic_instr
*intr
= nir_instr_as_intrinsic(instr
);
55 nir_variable
*out
= NULL
;
57 switch (intr
->intrinsic
) {
58 case nir_intrinsic_store_deref
:
59 out
= nir_deref_instr_get_variable(nir_src_as_deref(intr
->src
[0]));
61 case nir_intrinsic_store_output
:
62 /* already had i/o lowered.. lookup the matching output var: */
63 nir_foreach_variable(var
, &shader
->outputs
) {
64 int drvloc
= var
->data
.driver_location
;
65 if (nir_intrinsic_base(intr
) == drvloc
) {
76 if (out
->data
.mode
!= nir_var_shader_out
)
79 if (out
->data
.location
!= FRAG_RESULT_COLOR
&&
80 out
->data
.location
!= FRAG_RESULT_DATA0
)
83 b
.cursor
= nir_before_instr(&intr
->instr
);
87 alpha
= nir_imm_float(&b
, 1.0);
88 } else if (intr
->intrinsic
== nir_intrinsic_store_deref
) {
89 alpha
= nir_channel(&b
, nir_ssa_for_src(&b
, intr
->src
[1], 4),
92 alpha
= nir_channel(&b
, nir_ssa_for_src(&b
, intr
->src
[0], 4),
96 nir_ssa_def
*condition
=
97 nir_compare_func(&b
, func
,
98 alpha
, nir_load_alpha_ref_float(&b
));
100 nir_intrinsic_instr
*discard
=
101 nir_intrinsic_instr_create(b
.shader
,
102 nir_intrinsic_discard_if
);
103 discard
->num_components
= 1;
104 discard
->src
[0] = nir_src_for_ssa(nir_inot(&b
, condition
));
105 nir_builder_instr_insert(&b
, &discard
->instr
);
106 shader
->info
.fs
.uses_discard
= true;
111 nir_metadata_preserve(impl
, nir_metadata_block_index
|
112 nir_metadata_dominance
);