utils/sofa-support.cpp

   1 /*
   2  * SOFA utility methods for inspecting SOFA file metrics and determining HRTF
   3  * utility compatible layouts.
   4  *
   5  * Copyright (C) 2018-2019  Christopher Fitzgerald
   6  * Copyright (C) 2019  Christopher Robinson
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  * Or visit:  http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
  23  */
  24
  25 #include "sofa-support.h"
  26
  27
  28 #include <algorithm>
  29 #include <array>
  30 #include <cmath>
  31 #include <cstdio>
  32 #include <utility>
  33 #include <vector>
  34
  35 #include "mysofa.h"
  36
  37
  38 namespace {
  39
  40 using uint = unsigned int;
  41 using double3 = std::array<double,3>;
  42
  43
  44 /* Produces a sorted array of unique elements from a particular axis of the
  45  * triplets array.  The filters are used to focus on particular coordinates
  46  * of other axes as necessary.  The epsilons are used to constrain the
  47  * equality of unique elements.
  48  */
  49 std::vector<double> GetUniquelySortedElems(const std::vector<double3> &aers, const uint axis,
  50     const std::array<const double*,3> &filters, const std::array<double,3> &epsilons)
  51 {
  52     std::vector<double> elems;
  53     for(const double3 &aer : aers)
  54     {
  55         const double elem{aer[axis]};
  56
  57         uint j;
  58         for(j = 0;j < 3;j++)
  59         {
  60             if(filters[j] && std::abs(aer[j] - *filters[j]) > epsilons[j])
  61                 break;
  62         }
  63         if(j < 3)
  64             continue;
  65
  66         auto iter = elems.begin();
  67         for(;iter != elems.end();++iter)
  68         {
  69             const double delta{elem - *iter};
  70             if(delta > epsilons[axis]) continue;
  71             if(delta >= -epsilons[axis]) break;
  72
  73             iter = elems.emplace(iter, elem);
  74             break;
  75         }
  76         if(iter == elems.end())
  77             elems.emplace_back(elem);
  78     }
  79     return elems;
  80 }
  81
  82 /* Given a list of azimuths, this will produce the smallest step size that can
  83  * uniformly cover the list. Ideally this will be over half, but in degenerate
  84  * cases this can fall to a minimum of 5 (the lower limit).
  85  */
  86 double GetUniformAzimStep(const double epsilon, const std::vector<double> &elems)
  87 {
  88     if(elems.size() < 5) return 0.0;
  89
  90     /* Get the maximum count possible, given the first two elements. It would
  91      * be impossible to have more than this since the first element must be
  92      * included.
  93      */
  94     uint count{static_cast<uint>(std::ceil(360.0 / (elems[1]-elems[0])))};
  95     count = std::min(count, 255u);
  96
  97     for(;count >= 5;--count)
  98     {
  99         /* Given the stepping value for this number of elements, check each
 100          * multiple to ensure there's a matching element.
 101          */
 102         const double step{360.0 / count};
 103         bool good{true};
 104         size_t idx{1u};
 105         for(uint mult{1u};mult < count && good;++mult)
 106         {
 107             const double target{step*mult + elems[0]};
 108             while(idx < elems.size() && target-elems[idx] > epsilon)
 109                 ++idx;
 110             good &= (idx < elems.size()) && !(std::abs(target-elems[idx++]) > epsilon);
 111         }
 112         if(good)
 113             return step;
 114     }
 115     return 0.0;
 116 }
 117
 118 /* Given a list of elevations, this will produce the smallest step size that
 119  * can uniformly cover the list. Ideally this will be over half, but in
 120  * degenerate cases this can fall to a minimum of 5 (the lower limit).
 121  */
 122 double GetUniformElevStep(const double epsilon, std::vector<double> &elems)
 123 {
 124     if(elems.size() < 5) return 0.0;
 125
 126     /* Reverse the elevations so it increments starting with -90 (flipped from
 127      * +90). This makes it easier to work out a proper stepping value.
 128      */
 129     std::reverse(elems.begin(), elems.end());
 130     for(auto &v : elems) v *= -1.0;
 131
 132     uint count{static_cast<uint>(std::ceil(180.0 / (elems[1]-elems[0])))};
 133     count = std::min(count, 255u);
 134
 135     double ret{0.0};
 136     for(;count >= 5;--count)
 137     {
 138         const double step{180.0 / count};
 139         bool good{true};
 140         size_t idx{1u};
 141         /* Elevations don't need to match all multiples if there's not enough
 142          * elements to check. Missing elevations can be synthesized.
 143          */
 144         for(uint mult{1u};mult <= count && idx < elems.size() && good;++mult)
 145         {
 146             const double target{step*mult + elems[0]};
 147             while(idx < elems.size() && target-elems[idx] > epsilon)
 148                 ++idx;
 149             good &= !(idx < elems.size()) || !(std::abs(target-elems[idx++]) > epsilon);
 150         }
 151         if(good)
 152         {
 153             ret = step;
 154             break;
 155         }
 156     }
 157     /* Re-reverse the elevations to restore the correct order. */
 158     for(auto &v : elems) v *= -1.0;
 159     std::reverse(elems.begin(), elems.end());
 160
 161     return ret;
 162 }
 163
 164 } // namespace
 165
 166
 167 const char *SofaErrorStr(int err)
 168 {
 169     switch(err)
 170     {
 171     case MYSOFA_OK: return "OK";
 172     case MYSOFA_INVALID_FORMAT: return "Invalid format";
 173     case MYSOFA_UNSUPPORTED_FORMAT: return "Unsupported format";
 174     case MYSOFA_INTERNAL_ERROR: return "Internal error";
 175     case MYSOFA_NO_MEMORY: return "Out of memory";
 176     case MYSOFA_READ_ERROR: return "Read error";
 177     }
 178     return "Unknown";
 179 }
 180
 181 auto GetCompatibleLayout(const al::span<const float> xyzs) -> std::vector<SofaField>
 182 {
 183     auto aers = std::vector<double3>(xyzs.size()/3, double3{});
 184     for(size_t i{0u};i < aers.size();++i)
 185     {
 186         std::array vals{xyzs[i*3], xyzs[i*3 + 1], xyzs[i*3 + 2]};
 187         mysofa_c2s(vals.data());
 188         aers[i] = {vals[0], vals[1], vals[2]};
 189     }
 190
 191     auto radii = GetUniquelySortedElems(aers, 2, {}, {0.1, 0.1, 0.001});
 192     std::vector<SofaField> fds;
 193     fds.reserve(radii.size());
 194
 195     for(const double dist : radii)
 196     {
 197         auto elevs = GetUniquelySortedElems(aers, 1, {nullptr, nullptr, &dist}, {0.1, 0.1, 0.001});
 198
 199         /* Remove elevations that don't have a valid set of azimuths. */
 200         auto invalid_elev = [&dist,&aers](const double ev) -> bool
 201         {
 202             auto azims = GetUniquelySortedElems(aers, 0, {nullptr, &ev, &dist}, {0.1, 0.1, 0.001});
 203
 204             if(std::abs(ev) > 89.999)
 205                 return azims.size() != 1;
 206             if(azims.empty() || !(std::abs(azims[0]) < 0.1))
 207                 return true;
 208             return GetUniformAzimStep(0.1, azims) <= 0.0;
 209         };
 210         elevs.erase(std::remove_if(elevs.begin(), elevs.end(), invalid_elev), elevs.end());
 211
 212         double step{GetUniformElevStep(0.1, elevs)};
 213         if(step <= 0.0)
 214         {
 215             if(elevs.empty())
 216                 printf("No usable elevations on field distance %f.\n", dist);
 217             else
 218             {
 219                 printf("Non-uniform elevations on field distance %.3f.\nGot: %+.2f", dist,
 220                     elevs[0]);
 221                 for(size_t ei{1u};ei < elevs.size();++ei)
 222                     printf(", %+.2f", elevs[ei]);
 223                 fputc('\n', stdout);
 224             }
 225             continue;
 226         }
 227
 228         uint evStart{0u};
 229         for(uint ei{0u};ei < elevs.size();ei++)
 230         {
 231             if(!(elevs[ei] < 0.0))
 232             {
 233                 printf("Too many missing elevations on field distance %f.\n", dist);
 234                 return fds;
 235             }
 236
 237             double eif{(90.0+elevs[ei]) / step};
 238             const double ev_start{std::round(eif)};
 239
 240             if(std::abs(eif - ev_start) < (0.1/step))
 241             {
 242                 evStart = static_cast<uint>(ev_start);
 243                 break;
 244             }
 245         }
 246
 247         const auto evCount = static_cast<uint>(std::round(180.0 / step)) + 1;
 248         if(evCount < 5)
 249         {
 250             printf("Too few uniform elevations on field distance %f.\n", dist);
 251             continue;
 252         }
 253
 254         SofaField field{};
 255         field.mDistance = dist;
 256         field.mEvCount = evCount;
 257         field.mEvStart = evStart;
 258         field.mAzCounts.resize(evCount, 0u);
 259         auto &azCounts = field.mAzCounts;
 260
 261         for(uint ei{evStart};ei < evCount;ei++)
 262         {
 263             double ev{-90.0 + ei*180.0/(evCount - 1)};
 264             auto azims = GetUniquelySortedElems(aers, 0, {nullptr, &ev, &dist}, {0.1, 0.1, 0.001});
 265
 266             if(ei == 0 || ei == (evCount-1))
 267             {
 268                 if(azims.size() != 1)
 269                 {
 270                     printf("Non-singular poles on field distance %f.\n", dist);
 271                     return fds;
 272                 }
 273                 azCounts[ei] = 1;
 274             }
 275             else
 276             {
 277                 step = GetUniformAzimStep(0.1, azims);
 278                 if(step <= 0.0)
 279                 {
 280                     printf("Non-uniform azimuths on elevation %f, field distance %f.\n", ev, dist);
 281                     return fds;
 282                 }
 283                 azCounts[ei] = static_cast<uint>(std::round(360.0f / step));
 284             }
 285         }
 286
 287         fds.emplace_back(std::move(field));
 288     }
 289
 290     return fds;
 291 }