src/compiler/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 bool
  37 normalize_cubemap_coords_block(nir_block *block, nir_builder *b)
  38 {
  39    bool progress = false;
  40
  41    nir_foreach_instr(instr, block) {
  42       if (instr->type != nir_instr_type_tex)
  43          continue;
  44
  45       nir_tex_instr *tex = nir_instr_as_tex(instr);
  46       if (tex->sampler_dim != GLSL_SAMPLER_DIM_CUBE)
  47          continue;
  48
  49       b->cursor = nir_before_instr(&tex->instr);
  50
  51       for (unsigned i = 0; i < tex->num_srcs; i++) {
  52          if (tex->src[i].src_type != nir_tex_src_coord)
  53             continue;
  54
  55          nir_ssa_def *orig_coord =
  56             nir_ssa_for_src(b, tex->src[i].src, nir_tex_instr_src_size(tex, i));
  57          assert(orig_coord->num_components >= 3);
  58
  59          nir_ssa_def *abs = nir_fabs(b, orig_coord);
  60          nir_ssa_def *norm = nir_fmax(b, nir_channel(b, abs, 0),
  61                                          nir_fmax(b, nir_channel(b, abs, 1),
  62                                                      nir_channel(b, abs, 2)));
  63
  64          nir_ssa_def *normalized = nir_fmul(b, orig_coord, nir_frcp(b, norm));
  65
  66          /* Array indices don't have to be normalized, so make a new vector
  67           * with the coordinate's array index untouched.
  68           */
  69          if (tex->coord_components == 4) {
  70             normalized = nir_vec4(b,
  71                                   nir_channel(b, normalized, 0),
  72                                   nir_channel(b, normalized, 1),
  73                                   nir_channel(b, normalized, 2),
  74                                   nir_channel(b, orig_coord, 3));
  75          }
  76
  77          nir_instr_rewrite_src(&tex->instr,
  78                                &tex->src[i].src,
  79                                nir_src_for_ssa(normalized));
  80
  81          progress = true;
  82       }
  83    }
  84
  85    return progress;
  86 }
  87
  88 static bool
  89 normalize_cubemap_coords_impl(nir_function_impl *impl)
  90 {
  91    nir_builder b;
  92    nir_builder_init(&b, impl);
  93    bool progress = false;
  94
  95    nir_foreach_block(block, impl) {
  96       progress |= normalize_cubemap_coords_block(block, &b);
  97    }
  98
  99    nir_metadata_preserve(impl, nir_metadata_block_index |
 100                                nir_metadata_dominance);
 101
 102    return progress;
 103 }
 104
 105 bool
 106 nir_normalize_cubemap_coords(nir_shader *shader)
 107 {
 108    bool progress = false;
 109
 110    nir_foreach_function(function, shader) {
 111       if (function->impl)
 112          progress = normalize_cubemap_coords_impl(function->impl) || progress;
 113    }
 114
 115    return progress;
 116 }