2 * Copyright © 2015 Red Hat
3 * Copyright © 2016 Intel Corporation
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
26 #include "nir_builder.h"
27 #include "program/prog_instruction.h"
30 * This pass adds <0.5, 0.5> to all uses of gl_FragCoord.
32 * Run before nir_lower_io().
34 * For a more full featured pass, consider using nir_lower_wpos_ytransform(),
35 * which can handle pixel center integer / half integer, and origin lower
36 * left / upper left transformations.
38 * This simple pass is primarily intended for use by Vulkan drivers on
39 * hardware which provides an integer pixel center. Vulkan mandates that
40 * the pixel center must be half-integer, and also that the coordinate
41 * system's origin must be upper left. This means that there's no need
42 * for a uniform - we can always just add a constant.
46 add_half_to_fragcoord(nir_builder
*b
, nir_intrinsic_instr
*intr
)
48 nir_ssa_def
*wpos
= &intr
->dest
.ssa
;
50 assert(intr
->dest
.is_ssa
);
52 b
->cursor
= nir_after_instr(&intr
->instr
);
54 wpos
= nir_fadd(b
, wpos
, nir_imm_vec4(b
, 0.5f
, 0.5f
, 0.0f
, 0.0f
));
56 nir_ssa_def_rewrite_uses_after(&intr
->dest
.ssa
, nir_src_for_ssa(wpos
),
61 lower_wpos_center_block(nir_builder
*b
, nir_block
*block
)
63 bool progress
= false;
65 nir_foreach_instr(instr
, block
) {
66 if (instr
->type
== nir_instr_type_intrinsic
) {
67 nir_intrinsic_instr
*intr
= nir_instr_as_intrinsic(instr
);
68 if (intr
->intrinsic
== nir_intrinsic_load_var
) {
69 nir_deref_var
*dvar
= intr
->variables
[0];
70 nir_variable
*var
= dvar
->var
;
72 if (var
->data
.mode
== nir_var_shader_in
&&
73 var
->data
.location
== VARYING_SLOT_POS
) {
74 /* gl_FragCoord should not have array/struct deref's: */
75 assert(dvar
->deref
.child
== NULL
);
76 add_half_to_fragcoord(b
, intr
);
87 nir_lower_wpos_center(nir_shader
*shader
)
89 bool progress
= false;
92 assert(shader
->stage
== MESA_SHADER_FRAGMENT
);
94 nir_foreach_function(function
, shader
) {
96 nir_builder_init(&b
, function
->impl
);
98 nir_foreach_block(block
, function
->impl
) {
99 progress
= lower_wpos_center_block(&b
, block
) || progress
;
101 nir_metadata_preserve(function
->impl
, nir_metadata_block_index
|
102 nir_metadata_dominance
);