src/tgp.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file tgp.cpp OTTD Perlin Noise Landscape Generator, aka TerraGenesis Perlin */
   9
  10 #include "stdafx.h"
  11 #include "clear_map.h"
  12 #include "void_map.h"
  13 #include "genworld.h"
  14 #include "core/random_func.hpp"
  15 #include "landscape_type.h"
  16
  17 #include "safeguards.h"
  18
  19 /*
  20  *
  21  * Quickie guide to Perlin Noise
  22  * Perlin noise is a predictable pseudo random number sequence. By generating
  23  * it in 2 dimensions, it becomes a useful random map that, for a given seed
  24  * and starting X & Y, is entirely predictable. On the face of it, that may not
  25  * be useful. However, it means that if you want to replay a map in a different
  26  * terrain, or just vary the sea level, you just re-run the generator with the
  27  * same seed. The seed is an int32_t, and is randomised on each run of New Game.
  28  * The Scenario Generator does not randomise the value, so that you can
  29  * experiment with one terrain until you are happy, or click "Random" for a new
  30  * random seed.
  31  *
  32  * Perlin Noise is a series of "octaves" of random noise added together. By
  33  * reducing the amplitude of the noise with each octave, the first octave of
  34  * noise defines the main terrain sweep, the next the ripples on that, and the
  35  * next the ripples on that. I use 6 octaves, with the amplitude controlled by
  36  * a power ratio, usually known as a persistence or p value. This I vary by the
  37  * smoothness selection, as can be seen in the table below. The closer to 1,
  38  * the more of that octave is added. Each octave is however raised to the power
  39  * of its position in the list, so the last entry in the "smooth" row, 0.35, is
  40  * raised to the power of 6, so can only add 0.001838...  of the amplitude to
  41  * the running total.
  42  *
  43  * In other words; the first p value sets the general shape of the terrain, the
  44  * second sets the major variations to that, ... until finally the smallest
  45  * bumps are added.
  46  *
  47  * Usefully, this routine is totally scalable; so when 32bpp comes along, the
  48  * terrain can be as bumpy as you like! It is also infinitely expandable; a
  49  * single random seed terrain continues in X & Y as far as you care to
  50  * calculate. In theory, we could use just one seed value, but randomly select
  51  * where in the Perlin XY space we use for the terrain. Personally I prefer
  52  * using a simple (0, 0) to (X, Y), with a varying seed.
  53  *
  54  *
  55  * Other things i have had to do: mountainous wasn't mountainous enough, and
  56  * since we only have 0..15 heights available, I add a second generated map
  57  * (with a modified seed), onto the original. This generally raises the
  58  * terrain, which then needs scaling back down. Overall effect is a general
  59  * uplift.
  60  *
  61  * However, the values on the top of mountains are then almost guaranteed to go
  62  * too high, so large flat plateaus appeared at height 15. To counter this, I
  63  * scale all heights above 12 to proportion up to 15. It still makes the
  64  * mountains have flattish tops, rather than craggy peaks, but at least they
  65  * aren't smooth as glass.
  66  *
  67  *
  68  * For a full discussion of Perlin Noise, please visit:
  69  * http://freespace.virgin.net/hugo.elias/models/m_perlin.htm
  70  *
  71  *
  72  * Evolution II
  73  *
  74  * The algorithm as described in the above link suggests to compute each tile height
  75  * as composition of several noise waves. Some of them are computed directly by
  76  * noise(x, y) function, some are calculated using linear approximation. Our
  77  * first implementation of perlin_noise_2D() used 4 noise(x, y) calls plus
  78  * 3 linear interpolations. It was called 6 times for each tile. This was a bit
  79  * CPU expensive.
  80  *
  81  * The following implementation uses optimized algorithm that should produce
  82  * the same quality result with much less computations, but more memory accesses.
  83  * The overall speedup should be 300% to 800% depending on CPU and memory speed.
  84  *
  85  * I will try to explain it on the example below:
  86  *
  87  * Have a map of 4 x 4 tiles, our simplified noise generator produces only two
  88  * values -1 and +1, use 3 octaves with wave length 1, 2 and 4, with amplitudes
  89  * 3, 2, 1. Original algorithm produces:
  90  *
  91  * h00 = lerp(lerp(-3, 3, 0/4), lerp(3, -3, 0/4), 0/4) + lerp(lerp(-2,  2, 0/2), lerp( 2, -2, 0/2), 0/2) + -1 = lerp(-3.0,  3.0, 0/4) + lerp(-2,  2, 0/2) + -1 = -3.0  + -2 + -1 = -6.0
  92  * h01 = lerp(lerp(-3, 3, 1/4), lerp(3, -3, 1/4), 0/4) + lerp(lerp(-2,  2, 1/2), lerp( 2, -2, 1/2), 0/2) +  1 = lerp(-1.5,  1.5, 0/4) + lerp( 0,  0, 0/2) +  1 = -1.5  +  0 +  1 = -0.5
  93  * h02 = lerp(lerp(-3, 3, 2/4), lerp(3, -3, 2/4), 0/4) + lerp(lerp( 2, -2, 0/2), lerp(-2,  2, 0/2), 0/2) + -1 = lerp(   0,    0, 0/4) + lerp( 2, -2, 0/2) + -1 =    0  +  2 + -1 =  1.0
  94  * h03 = lerp(lerp(-3, 3, 3/4), lerp(3, -3, 3/4), 0/4) + lerp(lerp( 2, -2, 1/2), lerp(-2,  2, 1/2), 0/2) +  1 = lerp( 1.5, -1.5, 0/4) + lerp( 0,  0, 0/2) +  1 =  1.5  +  0 +  1 =  2.5
  95  *
  96  * h10 = lerp(lerp(-3, 3, 0/4), lerp(3, -3, 0/4), 1/4) + lerp(lerp(-2,  2, 0/2), lerp( 2, -2, 0/2), 1/2) +  1 = lerp(-3.0,  3.0, 1/4) + lerp(-2,  2, 1/2) +  1 = -1.5  +  0 +  1 = -0.5
  97  * h11 = lerp(lerp(-3, 3, 1/4), lerp(3, -3, 1/4), 1/4) + lerp(lerp(-2,  2, 1/2), lerp( 2, -2, 1/2), 1/2) + -1 = lerp(-1.5,  1.5, 1/4) + lerp( 0,  0, 1/2) + -1 = -0.75 +  0 + -1 = -1.75
  98  * h12 = lerp(lerp(-3, 3, 2/4), lerp(3, -3, 2/4), 1/4) + lerp(lerp( 2, -2, 0/2), lerp(-2,  2, 0/2), 1/2) +  1 = lerp(   0,    0, 1/4) + lerp( 2, -2, 1/2) +  1 =    0  +  0 +  1 =  1.0
  99  * h13 = lerp(lerp(-3, 3, 3/4), lerp(3, -3, 3/4), 1/4) + lerp(lerp( 2, -2, 1/2), lerp(-2,  2, 1/2), 1/2) + -1 = lerp( 1.5, -1.5, 1/4) + lerp( 0,  0, 1/2) + -1 =  0.75 +  0 + -1 = -0.25
 100  *
 101  *
 102  * Optimization 1:
 103  *
 104  * 1) we need to allocate a bit more tiles: (size_x + 1) * (size_y + 1) = (5 * 5):
 105  *
 106  * 2) setup corner values using amplitude 3
 107  * {    -3.0        X          X          X          3.0   }
 108  * {     X          X          X          X          X     }
 109  * {     X          X          X          X          X     }
 110  * {     X          X          X          X          X     }
 111  * {     3.0        X          X          X         -3.0   }
 112  *
 113  * 3a) interpolate values in the middle
 114  * {    -3.0        X          0.0        X          3.0   }
 115  * {     X          X          X          X          X     }
 116  * {     0.0        X          0.0        X          0.0   }
 117  * {     X          X          X          X          X     }
 118  * {     3.0        X          0.0        X         -3.0   }
 119  *
 120  * 3b) add patches with amplitude 2 to them
 121  * {    -5.0        X          2.0        X          1.0   }
 122  * {     X          X          X          X          X     }
 123  * {     2.0        X         -2.0        X          2.0   }
 124  * {     X          X          X          X          X     }
 125  * {     1.0        X          2.0        X         -5.0   }
 126  *
 127  * 4a) interpolate values in the middle
 128  * {    -5.0       -1.5        2.0        1.5        1.0   }
 129  * {    -1.5       -0.75       0.0        0.75       1.5   }
 130  * {     2.0        0.0       -2.0        0.0        2.0   }
 131  * {     1.5        0.75       0.0       -0.75      -1.5   }
 132  * {     1.0        1.5        2.0       -1.5       -5.0   }
 133  *
 134  * 4b) add patches with amplitude 1 to them
 135  * {    -6.0       -0.5        1.0        2.5        0.0   }
 136  * {    -0.5       -1.75       1.0       -0.25       2.5   }
 137  * {     1.0        1.0       -3.0        1.0        1.0   }
 138  * {     2.5       -0.25       1.0       -1.75      -0.5   }
 139  * {     0.0        2.5        1.0       -0.5       -6.0   }
 140  *
 141  *
 142  *
 143  * Optimization 2:
 144  *
 145  * As you can see above, each noise function was called just once. Therefore
 146  * we don't need to use noise function that calculates the noise from x, y and
 147  * some prime. The same quality result we can obtain using standard Random()
 148  * function instead.
 149  *
 150  */
 151
 152 /** Fixed point type for heights */
 153 using Height = int16_t;
 154 static const int height_decimal_bits = 4;
 155
 156 /** Fixed point array for amplitudes (and percent values) */
 157 using Amplitude = int;
 158 static const int amplitude_decimal_bits = 10;
 159
 160 /** Height map - allocated array of heights (MapSizeX() + 1) x (MapSizeY() + 1) */
 161 struct HeightMap
 162 {
 163         std::vector<Height> h; //< array of heights
 164         /* Even though the sizes are always positive, there are many cases where
 165          * X and Y need to be signed integers due to subtractions. */
 166         int      dim_x;      //< height map size_x Map::SizeX() + 1
 167         int      size_x;     //< Map::SizeX()
 168         int      size_y;     //< Map::SizeY()
 169
 170         /**
 171          * Height map accessor
 172          * @param x X position
 173          * @param y Y position
 174          * @return height as fixed point number
 175          */
 176         inline Height &height(uint x, uint y)
 177         {
 178                 return h[x + y * dim_x];
 179         }
 180 };
 181
 182 /** Global height map instance */
 183 static HeightMap _height_map = { {}, 0, 0, 0 };
 184
 185 /** Conversion: int to Height */
 186 #define I2H(i) ((i) << height_decimal_bits)
 187 /** Conversion: Height to int */
 188 #define H2I(i) ((i) >> height_decimal_bits)
 189
 190 /** Conversion: Amplitude to int */
 191 #define A2I(i) ((i) >> amplitude_decimal_bits)
 192
 193 /** Conversion: Amplitude to Height */
 194 #define A2H(a) ((a) >> (amplitude_decimal_bits - height_decimal_bits))
 195
 196 /** Maximum number of TGP noise frequencies. */
 197 static const int MAX_TGP_FREQUENCIES = 10;
 198
 199 /** Desired water percentage (100% == 1024) - indexed by _settings_game.difficulty.quantity_sea_lakes */
 200 static const Amplitude _water_percent[4] = {70, 170, 270, 420};
 201
 202 /**
 203  * Gets the maximum allowed height while generating a map based on
 204  * mapsize, terraintype, and the maximum height level.
 205  * @return The maximum height for the map generation.
 206  * @note Values should never be lower than 3 since the minimum snowline height is 2.
 207  */
 208 static Height TGPGetMaxHeight()
 209 {
 210         if (_settings_game.difficulty.terrain_type == CUSTOM_TERRAIN_TYPE_NUMBER_DIFFICULTY) {
 211                 /* TGP never reaches this height; this means that if a user inputs "2",
 212                  * it would create a flat map without the "+ 1". But that would
 213                  * overflow on "255". So we reduce it by 1 to get back in range. */
 214                 return I2H(_settings_game.game_creation.custom_terrain_type + 1) - 1;
 215         }
 216
 217         /**
 218          * Desired maximum height - indexed by:
 219          *  - _settings_game.difficulty.terrain_type
 220          *  - min(Map::LogX(), Map::LogY()) - MIN_MAP_SIZE_BITS
 221          *
 222          * It is indexed by map size as well as terrain type since the map size limits the height of
 223          * a usable mountain. For example, on a 64x64 map a 24 high single peak mountain (as if you
 224          * raised land 24 times in the center of the map) will leave only a ring of about 10 tiles
 225          * around the mountain to build on. On a 4096x4096 map, it won't cover any major part of the map.
 226          */
 227         static const int max_height[5][MAX_MAP_SIZE_BITS - MIN_MAP_SIZE_BITS + 1] = {
 228                 /* 64  128  256  512 1024 2048 4096 */
 229                 {   3,   3,   3,   3,   4,   5,   7 }, ///< Very flat
 230                 {   5,   7,   8,   9,  14,  19,  31 }, ///< Flat
 231                 {   8,   9,  10,  15,  23,  37,  61 }, ///< Hilly
 232                 {  10,  11,  17,  19,  49,  63,  73 }, ///< Mountainous
 233                 {  12,  19,  25,  31,  67,  75,  87 }, ///< Alpinist
 234         };
 235
 236         int map_size_bucket = std::min(Map::LogX(), Map::LogY()) - MIN_MAP_SIZE_BITS;
 237         int max_height_from_table = max_height[_settings_game.difficulty.terrain_type][map_size_bucket];
 238
 239         /* If there is a manual map height limit, clamp to it. */
 240         if (_settings_game.construction.map_height_limit != 0) {
 241                 max_height_from_table = std::min<uint>(max_height_from_table, _settings_game.construction.map_height_limit);
 242         }
 243
 244         return I2H(max_height_from_table);
 245 }
 246
 247 /**
 248  * Get an overestimation of the highest peak TGP wants to generate.
 249  */
 250 uint GetEstimationTGPMapHeight()
 251 {
 252         return H2I(TGPGetMaxHeight());
 253 }
 254
 255 /**
 256  * Get the amplitude associated with the currently selected
 257  * smoothness and maximum height level.
 258  * @param frequency The frequency to get the amplitudes for
 259  * @return The amplitudes to apply to the map.
 260  */
 261 static Amplitude GetAmplitude(int frequency)
 262 {
 263         /* Base noise amplitudes (multiplied by 1024) and indexed by "smoothness setting" and log2(frequency). */
 264         static const Amplitude amplitudes[][7] = {
 265                 /* lowest frequency ...... highest (every corner) */
 266                 {16000,  5600,  1968,   688,   240,    16,    16}, ///< Very smooth
 267                 {24000, 12800,  6400,  2700,  1024,   128,    16}, ///< Smooth
 268                 {32000, 19200, 12800,  8000,  3200,   256,    64}, ///< Rough
 269                 {48000, 24000, 19200, 16000,  8000,   512,   320}, ///< Very rough
 270         };
 271         /*
 272          * Extrapolation factors for ranges before the table.
 273          * The extrapolation is needed to account for the higher map heights. They need larger
 274          * areas with a particular gradient so that we are able to create maps without too
 275          * many steep slopes up to the wanted height level. It's definitely not perfect since
 276          * it will bring larger rectangles with similar slopes which makes the rectangular
 277          * behaviour of TGP more noticeable. However, these height differentiations cannot
 278          * happen over much smaller areas; we basically double the "range" to give a similar
 279          * slope for every doubling of map height.
 280          */
 281         static const double extrapolation_factors[] = { 3.3, 2.8, 2.3, 1.8 };
 282
 283         int smoothness = _settings_game.game_creation.tgen_smoothness;
 284
 285         /* Get the table index, and return that value if possible. */
 286         int index = frequency - MAX_TGP_FREQUENCIES + static_cast<int>(std::size(amplitudes[smoothness]));
 287         Amplitude amplitude = amplitudes[smoothness][std::max(0, index)];
 288         if (index >= 0) return amplitude;
 289
 290         /* We need to extrapolate the amplitude. */
 291         double extrapolation_factor = extrapolation_factors[smoothness];
 292         int height_range = I2H(16);
 293         do {
 294                 amplitude = (Amplitude)(extrapolation_factor * (double)amplitude);
 295                 height_range <<= 1;
 296                 index++;
 297         } while (index < 0);
 298
 299         return Clamp((TGPGetMaxHeight() - height_range) / height_range, 0, 1) * amplitude;
 300 }
 301
 302 /**
 303  * Check if a X/Y set are within the map.
 304  * @param x coordinate x
 305  * @param y coordinate y
 306  * @return true if within the map
 307  */
 308 static inline bool IsValidXY(int x, int y)
 309 {
 310         return x >= 0 && x < _height_map.size_x && y >= 0 && y < _height_map.size_y;
 311 }
 312
 313
 314 /**
 315  * Allocate array of (MapSizeX()+1)*(MapSizeY()+1) heights and init the _height_map structure members
 316  * @return true on success
 317  */
 318 static inline bool AllocHeightMap()
 319 {
 320         assert(_height_map.h.empty());
 321
 322         _height_map.size_x = Map::SizeX();
 323         _height_map.size_y = Map::SizeY();
 324
 325         /* Allocate memory block for height map row pointers */
 326         size_t total_size = static_cast<size_t>(_height_map.size_x + 1) * (_height_map.size_y + 1);
 327         _height_map.dim_x = _height_map.size_x + 1;
 328         _height_map.h.resize(total_size);
 329
 330         return true;
 331 }
 332
 333 /** Free height map */
 334 static inline void FreeHeightMap()
 335 {
 336         _height_map.h.clear();
 337 }
 338
 339 /**
 340  * Generates new random height in given amplitude (generated numbers will range from - amplitude to + amplitude)
 341  * @param rMax Limit of result
 342  * @return generated height
 343  */
 344 static inline Height RandomHeight(Amplitude rMax)
 345 {
 346         /* Spread height into range -rMax..+rMax */
 347         return A2H(RandomRange(2 * rMax + 1) - rMax);
 348 }
 349
 350 /**
 351  * Base Perlin noise generator - fills height map with raw Perlin noise.
 352  *
 353  * This runs several iterations with increasing precision; the last iteration looks at areas
 354  * of 1 by 1 tiles, the second to last at 2 by 2 tiles and the initial 2**MAX_TGP_FREQUENCIES
 355  * by 2**MAX_TGP_FREQUENCIES tiles.
 356  */
 357 static void HeightMapGenerate()
 358 {
 359         /* Trying to apply noise to uninitialized height map */
 360         assert(!_height_map.h.empty());
 361
 362         int start = std::max(MAX_TGP_FREQUENCIES - (int)std::min(Map::LogX(), Map::LogY()), 0);
 363         bool first = true;
 364
 365         for (int frequency = start; frequency < MAX_TGP_FREQUENCIES; frequency++) {
 366                 const Amplitude amplitude = GetAmplitude(frequency);
 367
 368                 /* Ignore zero amplitudes; it means our map isn't height enough for this
 369                  * amplitude, so ignore it and continue with the next set of amplitude. */
 370                 if (amplitude == 0) continue;
 371
 372                 const int step = 1 << (MAX_TGP_FREQUENCIES - frequency - 1);
 373
 374                 if (first) {
 375                         /* This is first round, we need to establish base heights with step = size_min */
 376                         for (int y = 0; y <= _height_map.size_y; y += step) {
 377                                 for (int x = 0; x <= _height_map.size_x; x += step) {
 378                                         Height height = (amplitude > 0) ? RandomHeight(amplitude) : 0;
 379                                         _height_map.height(x, y) = height;
 380                                 }
 381                         }
 382                         first = false;
 383                         continue;
 384                 }
 385
 386                 /* It is regular iteration round.
 387                  * Interpolate height values at odd x, even y tiles */
 388                 for (int y = 0; y <= _height_map.size_y; y += 2 * step) {
 389                         for (int x = 0; x <= _height_map.size_x - 2 * step; x += 2 * step) {
 390                                 Height h00 = _height_map.height(x + 0 * step, y);
 391                                 Height h02 = _height_map.height(x + 2 * step, y);
 392                                 Height h01 = (h00 + h02) / 2;
 393                                 _height_map.height(x + 1 * step, y) = h01;
 394                         }
 395                 }
 396
 397                 /* Interpolate height values at odd y tiles */
 398                 for (int y = 0; y <= _height_map.size_y - 2 * step; y += 2 * step) {
 399                         for (int x = 0; x <= _height_map.size_x; x += step) {
 400                                 Height h00 = _height_map.height(x, y + 0 * step);
 401                                 Height h20 = _height_map.height(x, y + 2 * step);
 402                                 Height h10 = (h00 + h20) / 2;
 403                                 _height_map.height(x, y + 1 * step) = h10;
 404                         }
 405                 }
 406
 407                 /* Add noise for next higher frequency (smaller steps) */
 408                 for (int y = 0; y <= _height_map.size_y; y += step) {
 409                         for (int x = 0; x <= _height_map.size_x; x += step) {
 410                                 _height_map.height(x, y) += RandomHeight(amplitude);
 411                         }
 412                 }
 413         }
 414 }
 415
 416 /** Returns min, max and average height from height map */
 417 static void HeightMapGetMinMaxAvg(Height *min_ptr, Height *max_ptr, Height *avg_ptr)
 418 {
 419         Height h_min, h_max, h_avg;
 420         int64_t h_accu = 0;
 421         h_min = h_max = _height_map.height(0, 0);
 422
 423         /* Get h_min, h_max and accumulate heights into h_accu */
 424         for (const Height &h : _height_map.h) {
 425                 if (h < h_min) h_min = h;
 426                 if (h > h_max) h_max = h;
 427                 h_accu += h;
 428         }
 429
 430         /* Get average height */
 431         h_avg = (Height)(h_accu / (_height_map.size_x * _height_map.size_y));
 432
 433         /* Return required results */
 434         if (min_ptr != nullptr) *min_ptr = h_min;
 435         if (max_ptr != nullptr) *max_ptr = h_max;
 436         if (avg_ptr != nullptr) *avg_ptr = h_avg;
 437 }
 438
 439 /** Dill histogram and return pointer to its base point - to the count of zero heights */
 440 static int *HeightMapMakeHistogram(Height h_min, [[maybe_unused]] Height h_max, int *hist_buf)
 441 {
 442         int *hist = hist_buf - h_min;
 443
 444         /* Count the heights and fill the histogram */
 445         for (const Height &h : _height_map.h) {
 446                 assert(h >= h_min);
 447                 assert(h <= h_max);
 448                 hist[h]++;
 449         }
 450         return hist;
 451 }
 452
 453 /** Applies sine wave redistribution onto height map */
 454 static void HeightMapSineTransform(Height h_min, Height h_max)
 455 {
 456         for (Height &h : _height_map.h) {
 457                 double fheight;
 458
 459                 if (h < h_min) continue;
 460
 461                 /* Transform height into 0..1 space */
 462                 fheight = (double)(h - h_min) / (double)(h_max - h_min);
 463                 /* Apply sine transform depending on landscape type */
 464                 switch (_settings_game.game_creation.landscape) {
 465                         case LT_TOYLAND:
 466                         case LT_TEMPERATE:
 467                                 /* Move and scale 0..1 into -1..+1 */
 468                                 fheight = 2 * fheight - 1;
 469                                 /* Sine transform */
 470                                 fheight = sin(fheight * M_PI_2);
 471                                 /* Transform it back from -1..1 into 0..1 space */
 472                                 fheight = 0.5 * (fheight + 1);
 473                                 break;
 474
 475                         case LT_ARCTIC:
 476                                 {
 477                                         /* Arctic terrain needs special height distribution.
 478                                          * Redistribute heights to have more tiles at highest (75%..100%) range */
 479                                         double sine_upper_limit = 0.75;
 480                                         double linear_compression = 2;
 481                                         if (fheight >= sine_upper_limit) {
 482                                                 /* Over the limit we do linear compression up */
 483                                                 fheight = 1.0 - (1.0 - fheight) / linear_compression;
 484                                         } else {
 485                                                 double m = 1.0 - (1.0 - sine_upper_limit) / linear_compression;
 486                                                 /* Get 0..sine_upper_limit into -1..1 */
 487                                                 fheight = 2.0 * fheight / sine_upper_limit - 1.0;
 488                                                 /* Sine wave transform */
 489                                                 fheight = sin(fheight * M_PI_2);
 490                                                 /* Get -1..1 back to 0..(1 - (1 - sine_upper_limit) / linear_compression) == 0.0..m */
 491                                                 fheight = 0.5 * (fheight + 1.0) * m;
 492                                         }
 493                                 }
 494                                 break;
 495
 496                         case LT_TROPIC:
 497                                 {
 498                                         /* Desert terrain needs special height distribution.
 499                                          * Half of tiles should be at lowest (0..25%) heights */
 500                                         double sine_lower_limit = 0.5;
 501                                         double linear_compression = 2;
 502                                         if (fheight <= sine_lower_limit) {
 503                                                 /* Under the limit we do linear compression down */
 504                                                 fheight = fheight / linear_compression;
 505                                         } else {
 506                                                 double m = sine_lower_limit / linear_compression;
 507                                                 /* Get sine_lower_limit..1 into -1..1 */
 508                                                 fheight = 2.0 * ((fheight - sine_lower_limit) / (1.0 - sine_lower_limit)) - 1.0;
 509                                                 /* Sine wave transform */
 510                                                 fheight = sin(fheight * M_PI_2);
 511                                                 /* Get -1..1 back to (sine_lower_limit / linear_compression)..1.0 */
 512                                                 fheight = 0.5 * ((1.0 - m) * fheight + (1.0 + m));
 513                                         }
 514                                 }
 515                                 break;
 516
 517                         default:
 518                                 NOT_REACHED();
 519                                 break;
 520                 }
 521                 /* Transform it back into h_min..h_max space */
 522                 h = (Height)(fheight * (h_max - h_min) + h_min);
 523                 if (h < 0) h = I2H(0);
 524                 if (h >= h_max) h = h_max - 1;
 525         }
 526 }
 527
 528 /**
 529  * Additional map variety is provided by applying different curve maps
 530  * to different parts of the map. A randomized low resolution grid contains
 531  * which curve map to use on each part of the make. This filtered non-linearly
 532  * to smooth out transitions between curves, so each tile could have between
 533  * 100% of one map applied or 25% of four maps.
 534  *
 535  * The curve maps define different land styles, i.e. lakes, low-lands, hills
 536  * and mountain ranges, although these are dependent on the landscape style
 537  * chosen as well.
 538  *
 539  * The level parameter dictates the resolution of the grid. A low resolution
 540  * grid will result in larger continuous areas of a land style, a higher
 541  * resolution grid splits the style into smaller areas.
 542  * @param level Rough indication of the size of the grid sections to style. Small level means large grid sections.
 543  */
 544 static void HeightMapCurves(uint level)
 545 {
 546         Height mh = TGPGetMaxHeight() - I2H(1); // height levels above sea level only
 547
 548         /** Basically scale height X to height Y. Everything in between is interpolated. */
 549         struct ControlPoint {
 550                 Height x; ///< The height to scale from.
 551                 Height y; ///< The height to scale to.
 552         };
 553         /* Scaled curve maps; value is in height_ts. */
 554 #define F(fraction) ((Height)(fraction * mh))
 555         const ControlPoint curve_map_1[] = { { F(0.0), F(0.0) },                       { F(0.8), F(0.13) },                       { F(1.0), F(0.4)  } };
 556         const ControlPoint curve_map_2[] = { { F(0.0), F(0.0) }, { F(0.53), F(0.13) }, { F(0.8), F(0.27) },                       { F(1.0), F(0.6)  } };
 557         const ControlPoint curve_map_3[] = { { F(0.0), F(0.0) }, { F(0.53), F(0.27) }, { F(0.8), F(0.57) },                       { F(1.0), F(0.8)  } };
 558         const ControlPoint curve_map_4[] = { { F(0.0), F(0.0) }, { F(0.4),  F(0.3)  }, { F(0.7), F(0.8)  }, { F(0.92), F(0.99) }, { F(1.0), F(0.99) } };
 559 #undef F
 560
 561         const std::span<const ControlPoint> curve_maps[] = { curve_map_1, curve_map_2, curve_map_3, curve_map_4 };
 562
 563         std::array<Height, std::size(curve_maps)> ht{};
 564
 565         /* Set up a grid to choose curve maps based on location; attempt to get a somewhat square grid */
 566         float factor = sqrt((float)_height_map.size_x / (float)_height_map.size_y);
 567         uint sx = Clamp((int)(((1 << level) * factor) + 0.5), 1, 128);
 568         uint sy = Clamp((int)(((1 << level) / factor) + 0.5), 1, 128);
 569         std::vector<uint8_t> c(static_cast<size_t>(sx) * sy);
 570
 571         for (uint i = 0; i < sx * sy; i++) {
 572                 c[i] = RandomRange(static_cast<uint32_t>(std::size(curve_maps)));
 573         }
 574
 575         /* Apply curves */
 576         for (int x = 0; x < _height_map.size_x; x++) {
 577
 578                 /* Get our X grid positions and bi-linear ratio */
 579                 float fx = (float)(sx * x) / _height_map.size_x + 1.0f;
 580                 uint x1 = (uint)fx;
 581                 uint x2 = x1;
 582                 float xr = 2.0f * (fx - x1) - 1.0f;
 583                 xr = sin(xr * M_PI_2);
 584                 xr = sin(xr * M_PI_2);
 585                 xr = 0.5f * (xr + 1.0f);
 586                 float xri = 1.0f - xr;
 587
 588                 if (x1 > 0) {
 589                         x1--;
 590                         if (x2 >= sx) x2--;
 591                 }
 592
 593                 for (int y = 0; y < _height_map.size_y; y++) {
 594
 595                         /* Get our Y grid position and bi-linear ratio */
 596                         float fy = (float)(sy * y) / _height_map.size_y + 1.0f;
 597                         uint y1 = (uint)fy;
 598                         uint y2 = y1;
 599                         float yr = 2.0f * (fy - y1) - 1.0f;
 600                         yr = sin(yr * M_PI_2);
 601                         yr = sin(yr * M_PI_2);
 602                         yr = 0.5f * (yr + 1.0f);
 603                         float yri = 1.0f - yr;
 604
 605                         if (y1 > 0) {
 606                                 y1--;
 607                                 if (y2 >= sy) y2--;
 608                         }
 609
 610                         uint corner_a = c[x1 + sx * y1];
 611                         uint corner_b = c[x1 + sx * y2];
 612                         uint corner_c = c[x2 + sx * y1];
 613                         uint corner_d = c[x2 + sx * y2];
 614
 615                         /* Bitmask of which curve maps are chosen, so that we do not bother
 616                          * calculating a curve which won't be used. */
 617                         uint corner_bits = 0;
 618                         corner_bits |= 1 << corner_a;
 619                         corner_bits |= 1 << corner_b;
 620                         corner_bits |= 1 << corner_c;
 621                         corner_bits |= 1 << corner_d;
 622
 623                         Height *h = &_height_map.height(x, y);
 624
 625                         /* Do not touch sea level */
 626                         if (*h < I2H(1)) continue;
 627
 628                         /* Only scale above sea level */
 629                         *h -= I2H(1);
 630
 631                         /* Apply all curve maps that are used on this tile. */
 632                         for (size_t t = 0; t < std::size(curve_maps); t++) {
 633                                 if (!HasBit(corner_bits, static_cast<uint8_t>(t))) continue;
 634
 635                                 [[maybe_unused]] bool found = false;
 636                                 auto &cm = curve_maps[t];
 637                                 for (size_t i = 0; i < cm.size() - 1; i++) {
 638                                         const ControlPoint &p1 = cm[i];
 639                                         const ControlPoint &p2 = cm[i + 1];
 640
 641                                         if (*h >= p1.x && *h < p2.x) {
 642                                                 ht[t] = p1.y + (*h - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
 643 #ifdef WITH_ASSERT
 644                                                 found = true;
 645 #endif
 646                                                 break;
 647                                         }
 648                                 }
 649                                 assert(found);
 650                         }
 651
 652                         /* Apply interpolation of curve map results. */
 653                         *h = (Height)((ht[corner_a] * yri + ht[corner_b] * yr) * xri + (ht[corner_c] * yri + ht[corner_d] * yr) * xr);
 654
 655                         /* Readd sea level */
 656                         *h += I2H(1);
 657                 }
 658         }
 659 }
 660
 661 /** Adjusts heights in height map to contain required amount of water tiles */
 662 static void HeightMapAdjustWaterLevel(Amplitude water_percent, Height h_max_new)
 663 {
 664         Height h_min, h_max, h_avg, h_water_level;
 665         int64_t water_tiles, desired_water_tiles;
 666         int *hist;
 667
 668         HeightMapGetMinMaxAvg(&h_min, &h_max, &h_avg);
 669
 670         /* Allocate histogram buffer and clear its cells */
 671         std::vector<int> hist_buf(h_max - h_min + 1);
 672         /* Fill histogram */
 673         hist = HeightMapMakeHistogram(h_min, h_max, hist_buf.data());
 674
 675         /* How many water tiles do we want? */
 676         desired_water_tiles = A2I(((int64_t)water_percent) * (int64_t)(_height_map.size_x * _height_map.size_y));
 677
 678         /* Raise water_level and accumulate values from histogram until we reach required number of water tiles */
 679         for (h_water_level = h_min, water_tiles = 0; h_water_level < h_max; h_water_level++) {
 680                 water_tiles += hist[h_water_level];
 681                 if (water_tiles >= desired_water_tiles) break;
 682         }
 683
 684         /* We now have the proper water level value.
 685          * Transform the height map into new (normalized) height map:
 686          *   values from range: h_min..h_water_level will become negative so it will be clamped to 0
 687          *   values from range: h_water_level..h_max are transformed into 0..h_max_new
 688          *   where h_max_new is depending on terrain type and map size.
 689          */
 690         for (Height &h : _height_map.h) {
 691                 /* Transform height from range h_water_level..h_max into 0..h_max_new range */
 692                 h = (Height)(((int)h_max_new) * (h - h_water_level) / (h_max - h_water_level)) + I2H(1);
 693                 /* Make sure all values are in the proper range (0..h_max_new) */
 694                 if (h < 0) h = I2H(0);
 695                 if (h >= h_max_new) h = h_max_new - 1;
 696         }
 697 }
 698
 699 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime);
 700
 701 /**
 702  * This routine sculpts in from the edge a random amount, again a Perlin
 703  * sequence, to avoid the rigid flat-edge slopes that were present before. The
 704  * Perlin noise map doesn't know where we are going to slice across, and so we
 705  * often cut straight through high terrain. The smoothing routine makes it
 706  * legal, gradually increasing up from the edge to the original terrain height.
 707  * By cutting parts of this away, it gives a far more irregular edge to the
 708  * map-edge. Sometimes it works beautifully with the existing sea & lakes, and
 709  * creates a very realistic coastline. Other times the variation is less, and
 710  * the map-edge shows its cliff-like roots.
 711  *
 712  * This routine may be extended to randomly sculpt the height of the terrain
 713  * near the edge. This will have the coast edge at low level (1-3), rising in
 714  * smoothed steps inland to about 15 tiles in. This should make it look as
 715  * though the map has been built for the map size, rather than a slice through
 716  * a larger map.
 717  *
 718  * Please note that all the small numbers; 53, 101, 167, etc. are small primes
 719  * to help give the perlin noise a bit more of a random feel.
 720  */
 721 static void HeightMapCoastLines(uint8_t water_borders)
 722 {
 723         int smallest_size = std::min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
 724         const int margin = 4;
 725         int y, x;
 726         double max_x;
 727         double max_y;
 728
 729         /* Lower to sea level */
 730         for (y = 0; y <= _height_map.size_y; y++) {
 731                 if (HasBit(water_borders, BORDER_NE)) {
 732                         /* Top right */
 733                         max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.9, 53) + 0.25) * 5 + (perlin_coast_noise_2D(y, y, 0.35, 179) + 1) * 12);
 734                         max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
 735                         if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
 736                         for (x = 0; x < max_x; x++) {
 737                                 _height_map.height(x, y) = 0;
 738                         }
 739                 }
 740
 741                 if (HasBit(water_borders, BORDER_SW)) {
 742                         /* Bottom left */
 743                         max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.85, 101) + 0.3) * 6 + (perlin_coast_noise_2D(y, y, 0.45,  67) + 0.75) * 8);
 744                         max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
 745                         if (smallest_size < 8 && max_x > 5) max_x /= 1.5;
 746                         for (x = _height_map.size_x; x > (_height_map.size_x - 1 - max_x); x--) {
 747                                 _height_map.height(x, y) = 0;
 748                         }
 749                 }
 750         }
 751
 752         /* Lower to sea level */
 753         for (x = 0; x <= _height_map.size_x; x++) {
 754                 if (HasBit(water_borders, BORDER_NW)) {
 755                         /* Top left */
 756                         max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 2, 0.9, 167) + 0.4) * 5 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.4, 211) + 0.7) * 9);
 757                         max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
 758                         if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
 759                         for (y = 0; y < max_y; y++) {
 760                                 _height_map.height(x, y) = 0;
 761                         }
 762                 }
 763
 764                 if (HasBit(water_borders, BORDER_SE)) {
 765                         /* Bottom right */
 766                         max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.85, 71) + 0.25) * 6 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.35, 193) + 0.75) * 12);
 767                         max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
 768                         if (smallest_size < 8 && max_y > 5) max_y /= 1.5;
 769                         for (y = _height_map.size_y; y > (_height_map.size_y - 1 - max_y); y--) {
 770                                 _height_map.height(x, y) = 0;
 771                         }
 772                 }
 773         }
 774 }
 775
 776 /** Start at given point, move in given direction, find and Smooth coast in that direction */
 777 static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int dir_y)
 778 {
 779         const int max_coast_dist_from_edge = 35;
 780         const int max_coast_Smooth_depth = 35;
 781
 782         int x, y;
 783         int ed; // coast distance from edge
 784         int depth;
 785
 786         Height h_prev = I2H(1);
 787         Height h;
 788
 789         assert(IsValidXY(org_x, org_y));
 790
 791         /* Search for the coast (first non-water tile) */
 792         for (x = org_x, y = org_y, ed = 0; IsValidXY(x, y) && ed < max_coast_dist_from_edge; x += dir_x, y += dir_y, ed++) {
 793                 /* Coast found? */
 794                 if (_height_map.height(x, y) >= I2H(1)) break;
 795
 796                 /* Coast found in the neighborhood? */
 797                 if (IsValidXY(x + dir_y, y + dir_x) && _height_map.height(x + dir_y, y + dir_x) > 0) break;
 798
 799                 /* Coast found in the neighborhood on the other side */
 800                 if (IsValidXY(x - dir_y, y - dir_x) && _height_map.height(x - dir_y, y - dir_x) > 0) break;
 801         }
 802
 803         /* Coast found or max_coast_dist_from_edge has been reached.
 804          * Soften the coast slope */
 805         for (depth = 0; IsValidXY(x, y) && depth <= max_coast_Smooth_depth; depth++, x += dir_x, y += dir_y) {
 806                 h = _height_map.height(x, y);
 807                 h = static_cast<Height>(std::min<uint>(h, h_prev + (4 + depth))); // coast softening formula
 808                 _height_map.height(x, y) = h;
 809                 h_prev = h;
 810         }
 811 }
 812
 813 /** Smooth coasts by modulating height of tiles close to map edges with cosine of distance from edge */
 814 static void HeightMapSmoothCoasts(uint8_t water_borders)
 815 {
 816         int x, y;
 817         /* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
 818         for (x = 0; x < _height_map.size_x; x++) {
 819                 if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
 820                 if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
 821         }
 822         /* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
 823         for (y = 0; y < _height_map.size_y; y++) {
 824                 if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
 825                 if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
 826         }
 827 }
 828
 829 /**
 830  * This routine provides the essential cleanup necessary before OTTD can
 831  * display the terrain. When generated, the terrain heights can jump more than
 832  * one level between tiles. This routine smooths out those differences so that
 833  * the most it can change is one level. When OTTD can support cliffs, this
 834  * routine may not be necessary.
 835  */
 836 static void HeightMapSmoothSlopes(Height dh_max)
 837 {
 838         for (int y = 0; y <= (int)_height_map.size_y; y++) {
 839                 for (int x = 0; x <= (int)_height_map.size_x; x++) {
 840                         Height h_max = std::min(_height_map.height(x > 0 ? x - 1 : x, y), _height_map.height(x, y > 0 ? y - 1 : y)) + dh_max;
 841                         if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
 842                 }
 843         }
 844         for (int y = _height_map.size_y; y >= 0; y--) {
 845                 for (int x = _height_map.size_x; x >= 0; x--) {
 846                         Height h_max = std::min(_height_map.height(x < _height_map.size_x ? x + 1 : x, y), _height_map.height(x, y < _height_map.size_y ? y + 1 : y)) + dh_max;
 847                         if (_height_map.height(x, y) > h_max) _height_map.height(x, y) = h_max;
 848                 }
 849         }
 850 }
 851
 852 /**
 853  * Height map terraform post processing:
 854  *  - water level adjusting
 855  *  - coast Smoothing
 856  *  - slope Smoothing
 857  *  - height histogram redistribution by sine wave transform
 858  */
 859 static void HeightMapNormalize()
 860 {
 861         int sea_level_setting = _settings_game.difficulty.quantity_sea_lakes;
 862         const Amplitude water_percent = sea_level_setting != (int)CUSTOM_SEA_LEVEL_NUMBER_DIFFICULTY ? _water_percent[sea_level_setting] : _settings_game.game_creation.custom_sea_level * 1024 / 100;
 863         const Height h_max_new = TGPGetMaxHeight();
 864         const Height roughness = 7 + 3 * _settings_game.game_creation.tgen_smoothness;
 865
 866         HeightMapAdjustWaterLevel(water_percent, h_max_new);
 867
 868         uint8_t water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
 869         if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
 870
 871         HeightMapCoastLines(water_borders);
 872         HeightMapSmoothSlopes(roughness);
 873
 874         HeightMapSmoothCoasts(water_borders);
 875         HeightMapSmoothSlopes(roughness);
 876
 877         HeightMapSineTransform(I2H(1), h_max_new);
 878
 879         if (_settings_game.game_creation.variety > 0) {
 880                 HeightMapCurves(_settings_game.game_creation.variety);
 881         }
 882
 883         HeightMapSmoothSlopes(I2H(1));
 884 }
 885
 886 /**
 887  * The Perlin Noise calculation using large primes
 888  * The initial number is adjusted by two values; the generation_seed, and the
 889  * passed parameter; prime.
 890  * prime is used to allow the perlin noise generator to create useful random
 891  * numbers from slightly different series.
 892  */
 893 static double int_noise(const long x, const long y, const int prime)
 894 {
 895         long n = x + y * prime + _settings_game.game_creation.generation_seed;
 896
 897         n = (n << 13) ^ n;
 898
 899         /* Pseudo-random number generator, using several large primes */
 900         return 1.0 - (double)((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0;
 901 }
 902
 903
 904 /**
 905  * This routine determines the interpolated value between a and b
 906  */
 907 static inline double linear_interpolate(const double a, const double b, const double x)
 908 {
 909         return a + x * (b - a);
 910 }
 911
 912
 913 /**
 914  * This routine returns the smoothed interpolated noise for an x and y, using
 915  * the values from the surrounding positions.
 916  */
 917 static double interpolated_noise(const double x, const double y, const int prime)
 918 {
 919         const int integer_X = (int)x;
 920         const int integer_Y = (int)y;
 921
 922         const double fractional_X = x - (double)integer_X;
 923         const double fractional_Y = y - (double)integer_Y;
 924
 925         const double v1 = int_noise(integer_X,     integer_Y,     prime);
 926         const double v2 = int_noise(integer_X + 1, integer_Y,     prime);
 927         const double v3 = int_noise(integer_X,     integer_Y + 1, prime);
 928         const double v4 = int_noise(integer_X + 1, integer_Y + 1, prime);
 929
 930         const double i1 = linear_interpolate(v1, v2, fractional_X);
 931         const double i2 = linear_interpolate(v3, v4, fractional_X);
 932
 933         return linear_interpolate(i1, i2, fractional_Y);
 934 }
 935
 936
 937 /**
 938  * This is a similar function to the main perlin noise calculation, but uses
 939  * the value p passed as a parameter rather than selected from the predefined
 940  * sequences. as you can guess by its title, i use this to create the indented
 941  * coastline, which is just another perlin sequence.
 942  */
 943 static double perlin_coast_noise_2D(const double x, const double y, const double p, const int prime)
 944 {
 945         double total = 0.0;
 946
 947         for (int i = 0; i < 6; i++) {
 948                 const double frequency = (double)(1 << i);
 949                 const double amplitude = pow(p, (double)i);
 950
 951                 total += interpolated_noise((x * frequency) / 64.0, (y * frequency) / 64.0, prime) * amplitude;
 952         }
 953
 954         return total;
 955 }
 956
 957
 958 /** A small helper function to initialize the terrain */
 959 static void TgenSetTileHeight(TileIndex tile, int height)
 960 {
 961         SetTileHeight(tile, height);
 962
 963         /* Only clear the tiles within the map area. */
 964         if (IsInnerTile(tile)) {
 965                 MakeClear(tile, CLEAR_GRASS, 3);
 966         }
 967 }
 968
 969 /**
 970  * The main new land generator using Perlin noise. Desert landscape is handled
 971  * different to all others to give a desert valley between two high mountains.
 972  * Clearly if a low height terrain (flat/very flat) is chosen, then the tropic
 973  * areas won't be high enough, and there will be very little tropic on the map.
 974  * Thus Tropic works best on Hilly or Mountainous.
 975  */
 976 void GenerateTerrainPerlin()
 977 {
 978         if (!AllocHeightMap()) return;
 979         GenerateWorldSetAbortCallback(FreeHeightMap);
 980
 981         HeightMapGenerate();
 982
 983         IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
 984
 985         HeightMapNormalize();
 986
 987         IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
 988
 989         /* First make sure the tiles at the north border are void tiles if needed. */
 990         if (_settings_game.construction.freeform_edges) {
 991                 for (uint x = 0; x < Map::SizeX(); x++) MakeVoid(TileXY(x, 0));
 992                 for (uint y = 0; y < Map::SizeY(); y++) MakeVoid(TileXY(0, y));
 993         }
 994
 995         int max_height = H2I(TGPGetMaxHeight());
 996
 997         /* Transfer height map into OTTD map */
 998         for (int y = 0; y < _height_map.size_y; y++) {
 999                 for (int x = 0; x < _height_map.size_x; x++) {
1000                         TgenSetTileHeight(TileXY(x, y), Clamp(H2I(_height_map.height(x, y)), 0, max_height));
1001                 }
1002         }
1003
1004         IncreaseGeneratingWorldProgress(GWP_LANDSCAPE);
1005
1006         FreeHeightMap();
1007         GenerateWorldSetAbortCallback(nullptr);
1008 }