src/glsl/nir/nir_normalize_cubemap_coords.c

   1 /*
   2  * Copyright © 2015 Intel Corporation
   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
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Jason Ekstrand <jason@jlekstrand.net>
  25  */
  26
  27 #include "nir.h"
  28 #include "nir_builder.h"
  29
  30 /**
  31  * This file implements a NIR lowering pass to perform the normalization of
  32  * the cubemap coordinates to have the largest magnitude component be -1.0
  33  * or 1.0.  This is based on the old GLSL IR based pass by Eric.
  34  */
  35
  36 static nir_ssa_def *
  37 channel(nir_builder *b, nir_ssa_def *def, int c)
  38 {
  39    return nir_swizzle(b, def, (unsigned[4]){c, c, c, c}, 1, false);
  40 }
  41
  42 static bool
  43 normalize_cubemap_coords_block(nir_block *block, void *void_state)
  44 {
  45    nir_builder *b = void_state;
  46
  47    nir_foreach_instr(block, instr) {
  48       if (instr->type != nir_instr_type_tex)
  49          continue;
  50
  51       nir_tex_instr *tex = nir_instr_as_tex(instr);
  52       if (tex->sampler_dim != GLSL_SAMPLER_DIM_CUBE)
  53          continue;
  54
  55       b->cursor = nir_before_instr(&tex->instr);
  56
  57       for (unsigned i = 0; i < tex->num_srcs; i++) {
  58          if (tex->src[i].src_type != nir_tex_src_coord)
  59             continue;
  60
  61          nir_ssa_def *orig_coord =
  62             nir_ssa_for_src(b, tex->src[i].src, nir_tex_instr_src_size(tex, i));
  63          assert(orig_coord->num_components >= 3);
  64
  65          nir_ssa_def *abs = nir_fabs(b, orig_coord);
  66          nir_ssa_def *norm = nir_fmax(b, channel(b, abs, 0),
  67                                          nir_fmax(b, channel(b, abs, 1),
  68                                                      channel(b, abs, 2)));
  69
  70          nir_ssa_def *normalized = nir_fmul(b, orig_coord, nir_frcp(b, norm));
  71
  72          /* Array indices don't have to be normalized, so make a new vector
  73           * with the coordinate's array index untouched.
  74           */
  75          if (tex->coord_components == 4) {
  76             normalized = nir_vec4(b,
  77                                   channel(b, normalized, 0),
  78                                   channel(b, normalized, 1),
  79                                   channel(b, normalized, 2),
  80                                   channel(b, orig_coord, 3));
  81          }
  82
  83          nir_instr_rewrite_src(&tex->instr,
  84                                &tex->src[i].src,
  85                                nir_src_for_ssa(normalized));
  86       }
  87    }
  88
  89    return true;
  90 }
  91
  92 static void
  93 normalize_cubemap_coords_impl(nir_function_impl *impl)
  94 {
  95    nir_builder b;
  96    nir_builder_init(&b, impl);
  97
  98    nir_foreach_block(impl, normalize_cubemap_coords_block, &b);
  99
 100    nir_metadata_preserve(impl, nir_metadata_block_index |
 101                                nir_metadata_dominance);
 102 }
 103
 104 void
 105 nir_normalize_cubemap_coords(nir_shader *shader)
 106 {
 107    nir_foreach_overload(shader, overload)
 108       if (overload->impl)
 109          normalize_cubemap_coords_impl(overload->impl);
 110 }