1 /*
2 * Copyright © 2015 Red Hat
3 *
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:
10 *
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
13 * Software.
14 *
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 FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 */
23
24 #include "nir.h"
25 #include "nir_builder.h"
26
27 /* Lower glBitmap().
28 *
29 * This is based on the logic in st_get_bitmap_shader() in TGSI compiler.
30 * From st_cb_bitmap.c:
31 *
32 * glBitmaps are drawn as textured quads. The user's bitmap pattern
33 * is stored in a texture image. An alpha8 texture format is used.
34 * The fragment shader samples a bit (texel) from the texture, then
35 * discards the fragment if the bit is off.
36 *
37 * Note that we actually store the inverse image of the bitmap to
38 * simplify the fragment program. An "on" bit gets stored as texel=0x0
39 * and an "off" bit is stored as texel=0xff. Then we kill the
40 * fragment if the negated texel value is less than zero.
41 *
42 * Note that the texture format will be, according to what driver supports,
43 * in order of preference (with swizzle):
44 *
45 * I8_UNORM - .xxxx
46 * A8_UNORM - .000x
47 * L8_UNORM - .xxx1
48 *
49 * If L8_UNORM, options->swizzle_xxxx is true. Otherwise we can just use
50 * the .w comp.
51 *
52 * Run before nir_lower_io.
53 */
54
55 static nir_variable *
get_texcoord(nir_shader * shader)56 get_texcoord(nir_shader *shader)
57 {
58 nir_variable *texcoord =
59 nir_find_variable_with_location(shader, nir_var_shader_in,
60 VARYING_SLOT_TEX0);
61 /* otherwise create it: */
62 if (texcoord == NULL) {
63 texcoord = nir_variable_create(shader,
64 nir_var_shader_in,
65 glsl_vec4_type(),
66 "gl_TexCoord");
67 texcoord->data.location = VARYING_SLOT_TEX0;
68 }
69
70 return texcoord;
71 }
72
73 static void
lower_bitmap(nir_shader * shader,nir_builder * b,const nir_lower_bitmap_options * options)74 lower_bitmap(nir_shader *shader, nir_builder *b,
75 const nir_lower_bitmap_options *options)
76 {
77 nir_ssa_def *texcoord;
78 nir_tex_instr *tex;
79 nir_ssa_def *cond;
80
81 texcoord = nir_load_var(b, get_texcoord(shader));
82
83 const struct glsl_type *sampler2D =
84 glsl_sampler_type(GLSL_SAMPLER_DIM_2D, false, false, GLSL_TYPE_FLOAT);
85
86 nir_variable *tex_var =
87 nir_variable_create(shader, nir_var_uniform, sampler2D, "bitmap_tex");
88 tex_var->data.binding = options->sampler;
89 tex_var->data.explicit_binding = true;
90 tex_var->data.how_declared = nir_var_hidden;
91
92 nir_deref_instr *tex_deref = nir_build_deref_var(b, tex_var);
93
94 tex = nir_tex_instr_create(shader, 3);
95 tex->op = nir_texop_tex;
96 tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
97 tex->coord_components = 2;
98 tex->dest_type = nir_type_float32;
99 tex->src[0].src_type = nir_tex_src_texture_deref;
100 tex->src[0].src = nir_src_for_ssa(&tex_deref->dest.ssa);
101 tex->src[1].src_type = nir_tex_src_sampler_deref;
102 tex->src[1].src = nir_src_for_ssa(&tex_deref->dest.ssa);
103 tex->src[2].src_type = nir_tex_src_coord;
104 tex->src[2].src =
105 nir_src_for_ssa(nir_channels(b, texcoord,
106 (1 << tex->coord_components) - 1));
107
108 nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
109 nir_builder_instr_insert(b, &tex->instr);
110
111 /* kill if tex != 0.0.. take .x or .w channel according to format: */
112 cond = nir_f2b(b, nir_channel(b, &tex->dest.ssa,
113 options->swizzle_xxxx ? 0 : 3));
114
115 nir_discard_if(b, cond);
116
117 shader->info.fs.uses_discard = true;
118 }
119
120 static void
lower_bitmap_impl(nir_function_impl * impl,const nir_lower_bitmap_options * options)121 lower_bitmap_impl(nir_function_impl *impl,
122 const nir_lower_bitmap_options *options)
123 {
124 nir_builder b;
125
126 nir_builder_init(&b, impl);
127 b.cursor = nir_before_cf_list(&impl->body);
128
129 lower_bitmap(impl->function->shader, &b, options);
130
131 nir_metadata_preserve(impl, nir_metadata_block_index |
132 nir_metadata_dominance);
133 }
134
135 void
nir_lower_bitmap(nir_shader * shader,const nir_lower_bitmap_options * options)136 nir_lower_bitmap(nir_shader *shader,
137 const nir_lower_bitmap_options *options)
138 {
139 assert(shader->info.stage == MESA_SHADER_FRAGMENT);
140
141 lower_bitmap_impl(nir_shader_get_entrypoint(shader), options);
142 }
143