src/mapgen_fractal.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2010-2013 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
   4 Additional development and fractal code by paramat
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU Lesser General Public License as published by
   8 the Free Software Foundation; either version 2.1 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU Lesser General Public License for more details.
  15
  16 You should have received a copy of the GNU Lesser General Public License along
  17 with this program; if not, write to the Free Software Foundation, Inc.,
  18 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21
  22 #include "mapgen.h"
  23 #include "voxel.h"
  24 #include "noise.h"
  25 #include "mapblock.h"
  26 #include "mapnode.h"
  27 #include "map.h"
  28 #include "content_sao.h"
  29 #include "nodedef.h"
  30 #include "voxelalgorithms.h"
  31 #include "settings.h" // For g_settings
  32 #include "emerge.h"
  33 #include "dungeongen.h"
  34 #include "cavegen.h"
  35 #include "treegen.h"
  36 #include "mg_biome.h"
  37 #include "mg_ore.h"
  38 #include "mg_decoration.h"
  39 #include "mapgen_fractal.h"
  40
  41
  42 FlagDesc flagdesc_mapgen_fractal[] = {
  43         {"julia", MGFRACTAL_JULIA},
  44         {NULL,    0}
  45 };
  46
  47 ///////////////////////////////////////////////////////////////////////////////////////
  48
  49
  50 MapgenFractal::MapgenFractal(int mapgenid, MapgenParams *params, EmergeManager *emerge)
  51         : Mapgen(mapgenid, params, emerge)
  52 {
  53         this->m_emerge = emerge;
  54         this->bmgr     = emerge->biomemgr;
  55
  56         //// amount of elements to skip for the next index
  57         //// for noise/height/biome maps (not vmanip)
  58         this->ystride = csize.X;
  59         this->zstride = csize.X * (csize.Y + 2);
  60
  61         this->biomemap        = new u8[csize.X * csize.Z];
  62         this->heightmap       = new s16[csize.X * csize.Z];
  63         this->heatmap         = NULL;
  64         this->humidmap        = NULL;
  65
  66         MapgenFractalParams *sp = (MapgenFractalParams *)params->sparams;
  67         this->spflags = sp->spflags;
  68         this->iterations = sp->iterations;
  69         this->scale_x = sp->scale_x;
  70         this->scale_y = sp->scale_y;
  71         this->scale_z = sp->scale_z;
  72         this->offset_x = sp->offset_x;
  73         this->offset_y = sp->offset_y;
  74         this->offset_z = sp->offset_z;
  75
  76         //// 3d terrain noise
  77         noise_cave1    = new Noise(&sp->np_cave1,    seed, csize.X, csize.Y + 2, csize.Z);
  78         noise_cave2    = new Noise(&sp->np_cave2,    seed, csize.X, csize.Y + 2, csize.Z);
  79
  80         //// Biome noise
  81         noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
  82         noise_humidity       = new Noise(&params->np_biome_humidity,       seed, csize.X, csize.Z);
  83         noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
  84         noise_humidity_blend = new Noise(&params->np_biome_humidity_blend, seed, csize.X, csize.Z);
  85
  86         //// Resolve nodes to be used
  87         INodeDefManager *ndef = emerge->ndef;
  88
  89         c_stone                = ndef->getId("mapgen_stone");
  90         c_water_source         = ndef->getId("mapgen_water_source");
  91         c_lava_source          = ndef->getId("mapgen_lava_source");
  92         c_desert_stone         = ndef->getId("mapgen_desert_stone");
  93         c_ice                  = ndef->getId("mapgen_ice");
  94         c_sandstone            = ndef->getId("mapgen_sandstone");
  95
  96         c_cobble               = ndef->getId("mapgen_cobble");
  97         c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
  98         c_mossycobble          = ndef->getId("mapgen_mossycobble");
  99         c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
 100         c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
 101
 102         if (c_ice == CONTENT_IGNORE)
 103                 c_ice = CONTENT_AIR;
 104         if (c_mossycobble == CONTENT_IGNORE)
 105                 c_mossycobble = c_cobble;
 106         if (c_stair_cobble == CONTENT_IGNORE)
 107                 c_stair_cobble = c_cobble;
 108         if (c_sandstonebrick == CONTENT_IGNORE)
 109                 c_sandstonebrick = c_sandstone;
 110         if (c_stair_sandstonebrick == CONTENT_IGNORE)
 111                 c_stair_sandstonebrick = c_sandstone;
 112 }
 113
 114
 115 MapgenFractal::~MapgenFractal()
 116 {
 117         delete noise_cave1;
 118         delete noise_cave2;
 119
 120         delete noise_heat;
 121         delete noise_humidity;
 122         delete noise_heat_blend;
 123         delete noise_humidity_blend;
 124
 125         delete[] heightmap;
 126         delete[] biomemap;
 127 }
 128
 129
 130 MapgenFractalParams::MapgenFractalParams()
 131 {
 132         spflags = 0;
 133
 134         iterations = 9;
 135         scale_x = 1024;
 136         scale_y = 256;
 137         scale_z = 1024;
 138         offset_x = -1.75;
 139         offset_y = 0;
 140         offset_z = 0;
 141         slice_w = 0.5;
 142         julia_x = 0.33;
 143         julia_y = 0.33;
 144         julia_z = 0.33;
 145         julia_w = 0.33;
 146
 147         np_cave1 = NoiseParams(0, 12, v3f(128, 128, 128), 52534, 4, 0.5, 2.0);
 148         np_cave2 = NoiseParams(0, 12, v3f(128, 128, 128), 10325, 4, 0.5, 2.0);
 149 }
 150
 151
 152 void MapgenFractalParams::readParams(const Settings *settings)
 153 {
 154         settings->getFlagStrNoEx("mgfractal_spflags", spflags, flagdesc_mapgen_fractal);
 155
 156         settings->getU16NoEx("mgfractal_iterations", iterations);
 157         settings->getFloatNoEx("mgfractal_scale_x", scale_x);
 158         settings->getFloatNoEx("mgfractal_scale_y", scale_y);
 159         settings->getFloatNoEx("mgfractal_scale_z", scale_z);
 160         settings->getFloatNoEx("mgfractal_offset_x", offset_x);
 161         settings->getFloatNoEx("mgfractal_offset_y", offset_y);
 162         settings->getFloatNoEx("mgfractal_offset_z", offset_z);
 163         settings->getFloatNoEx("mgfractal_slice_w", slice_w);
 164         settings->getFloatNoEx("mgfractal_julia_x", julia_x);
 165         settings->getFloatNoEx("mgfractal_julia_y", julia_y);
 166         settings->getFloatNoEx("mgfractal_julia_z", julia_z);
 167         settings->getFloatNoEx("mgfractal_julia_w", julia_w);
 168
 169         settings->getNoiseParams("mgfractal_np_cave1", np_cave1);
 170         settings->getNoiseParams("mgfractal_np_cave2", np_cave2);
 171 }
 172
 173
 174 void MapgenFractalParams::writeParams(Settings *settings) const
 175 {
 176         settings->setFlagStr("mgfractal_spflags", spflags, flagdesc_mapgen_fractal, U32_MAX);
 177
 178         settings->setU16("mgfractal_iterations", iterations);
 179         settings->setFloat("mgfractal_scale_x", scale_x);
 180         settings->setFloat("mgfractal_scale_y", scale_y);
 181         settings->setFloat("mgfractal_scale_z", scale_z);
 182         settings->setFloat("mgfractal_offset_x", offset_x);
 183         settings->setFloat("mgfractal_offset_y", offset_y);
 184         settings->setFloat("mgfractal_offset_z", offset_z);
 185         settings->setFloat("mgfractal_slice_w", slice_w);
 186         settings->setFloat("mgfractal_julia_x", julia_x);
 187         settings->setFloat("mgfractal_julia_y", julia_y);
 188         settings->setFloat("mgfractal_julia_z", julia_z);
 189         settings->setFloat("mgfractal_julia_w", julia_w);
 190
 191         settings->setNoiseParams("mgfractal_np_cave1", np_cave1);
 192         settings->setNoiseParams("mgfractal_np_cave2", np_cave2);
 193 }
 194
 195
 196 /////////////////////////////////////////////////////////////////
 197
 198
 199 int MapgenFractal::getGroundLevelAtPoint(v2s16 p)
 200 {
 201         s16 search_top = water_level + 128;
 202         s16 search_base = water_level;
 203         s16 level = -MAX_MAP_GENERATION_LIMIT;
 204         for (s16 y = search_top; y >= search_base; y--) {
 205                 if (getTerrainAtPoint(p.X, y, p.Y))
 206                         return y;
 207         }
 208
 209         return level;
 210 }
 211
 212
 213 void MapgenFractal::makeChunk(BlockMakeData *data)
 214 {
 215         // Pre-conditions
 216         assert(data->vmanip);
 217         assert(data->nodedef);
 218         assert(data->blockpos_requested.X >= data->blockpos_min.X &&
 219                 data->blockpos_requested.Y >= data->blockpos_min.Y &&
 220                 data->blockpos_requested.Z >= data->blockpos_min.Z);
 221         assert(data->blockpos_requested.X <= data->blockpos_max.X &&
 222                 data->blockpos_requested.Y <= data->blockpos_max.Y &&
 223                 data->blockpos_requested.Z <= data->blockpos_max.Z);
 224
 225         this->generating = true;
 226         this->vm   = data->vmanip;
 227         this->ndef = data->nodedef;
 228         //TimeTaker t("makeChunk");
 229
 230         v3s16 blockpos_min = data->blockpos_min;
 231         v3s16 blockpos_max = data->blockpos_max;
 232         node_min = blockpos_min * MAP_BLOCKSIZE;
 233         node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 234         full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
 235         full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 236
 237         blockseed = getBlockSeed2(full_node_min, seed);
 238
 239         // Make some noise
 240         calculateNoise();
 241
 242         // Generate base terrain, mountains, and ridges with initial heightmaps
 243         s16 stone_surface_max_y = generateTerrain();
 244
 245         // Create heightmap
 246         updateHeightmap(node_min, node_max);
 247
 248         // Create biomemap at heightmap surface
 249         bmgr->calcBiomes(csize.X, csize.Z, noise_heat->result,
 250                 noise_humidity->result, heightmap, biomemap);
 251
 252         // Actually place the biome-specific nodes
 253         MgStoneType stone_type = generateBiomes(noise_heat->result, noise_humidity->result);
 254
 255         if (flags & MG_CAVES)
 256                 generateCaves(stone_surface_max_y);
 257
 258         if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 259                 DungeonParams dp;
 260
 261                 dp.np_rarity  = nparams_dungeon_rarity;
 262                 dp.np_density = nparams_dungeon_density;
 263                 dp.np_wetness = nparams_dungeon_wetness;
 264                 dp.c_water    = c_water_source;
 265                 if (stone_type == STONE) {
 266                         dp.c_cobble = c_cobble;
 267                         dp.c_moss   = c_mossycobble;
 268                         dp.c_stair  = c_stair_cobble;
 269
 270                         dp.diagonal_dirs = false;
 271                         dp.mossratio     = 3.0;
 272                         dp.holesize      = v3s16(1, 2, 1);
 273                         dp.roomsize      = v3s16(0, 0, 0);
 274                         dp.notifytype    = GENNOTIFY_DUNGEON;
 275                 } else if (stone_type == DESERT_STONE) {
 276                         dp.c_cobble = c_desert_stone;
 277                         dp.c_moss   = c_desert_stone;
 278                         dp.c_stair  = c_desert_stone;
 279
 280                         dp.diagonal_dirs = true;
 281                         dp.mossratio     = 0.0;
 282                         dp.holesize      = v3s16(2, 3, 2);
 283                         dp.roomsize      = v3s16(2, 5, 2);
 284                         dp.notifytype    = GENNOTIFY_TEMPLE;
 285                 } else if (stone_type == SANDSTONE) {
 286                         dp.c_cobble = c_sandstonebrick;
 287                         dp.c_moss   = c_sandstonebrick;
 288                         dp.c_stair  = c_sandstonebrick;
 289
 290                         dp.diagonal_dirs = false;
 291                         dp.mossratio     = 0.0;
 292                         dp.holesize      = v3s16(2, 2, 2);
 293                         dp.roomsize      = v3s16(2, 0, 2);
 294                         dp.notifytype    = GENNOTIFY_DUNGEON;
 295                 }
 296
 297                 DungeonGen dgen(this, &dp);
 298                 dgen.generate(blockseed, full_node_min, full_node_max);
 299         }
 300
 301         // Generate the registered decorations
 302         m_emerge->decomgr->placeAllDecos(this, blockseed, node_min, node_max);
 303
 304         // Generate the registered ores
 305         m_emerge->oremgr->placeAllOres(this, blockseed, node_min, node_max);
 306
 307         // Sprinkle some dust on top after everything else was generated
 308         dustTopNodes();
 309
 310         //printf("makeChunk: %dms\n", t.stop());
 311
 312         updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
 313
 314         if (flags & MG_LIGHT)
 315                 calcLighting(node_min - v3s16(0, 1, 0), node_max + v3s16(0, 1, 0),
 316                         full_node_min, full_node_max);
 317
 318         //setLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
 319         //                      node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE, 0xFF);
 320
 321         this->generating = false;
 322 }
 323
 324
 325 void MapgenFractal::calculateNoise()
 326 {
 327         //TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
 328         int x = node_min.X;
 329         int y = node_min.Y - 1;
 330         int z = node_min.Z;
 331
 332         if (flags & MG_CAVES) {
 333                 noise_cave1->perlinMap3D(x, y, z);
 334                 noise_cave2->perlinMap3D(x, y, z);
 335         }
 336
 337         noise_heat->perlinMap2D(x, z);
 338         noise_humidity->perlinMap2D(x, z);
 339         noise_heat_blend->perlinMap2D(x, z);
 340         noise_humidity_blend->perlinMap2D(x, z);
 341
 342         for (s32 i = 0; i < csize.X * csize.Z; i++) {
 343                 noise_heat->result[i] += noise_heat_blend->result[i];
 344                 noise_humidity->result[i] += noise_humidity_blend->result[i];
 345         }
 346
 347         heatmap = noise_heat->result;
 348         humidmap = noise_humidity->result;
 349         //printf("calculateNoise: %dus\n", t.stop());
 350 }
 351
 352
 353 bool MapgenFractal::getTerrainAtPoint(s16 x, s16 y, s16 z)
 354 {
 355         float cx, cy, cz, cw, ox, oy, oz, ow;
 356
 357         if (spflags & MGFRACTAL_JULIA) {  // Julia set
 358                 cx = julia_x;
 359                 cy = julia_y;
 360                 cz = julia_z;
 361                 cw = julia_w;
 362                 ox = (float)x / scale_x + offset_x;
 363                 oy = (float)y / scale_y + offset_y;
 364                 oz = (float)z / scale_z + offset_z;
 365                 ow = slice_w;
 366         } else {  // Mandelbrot set
 367                 cx = (float)x / scale_x + offset_x;
 368                 cy = (float)y / scale_y + offset_y;
 369                 cz = (float)z / scale_z + offset_z;
 370                 cw = slice_w;
 371                 ox = 0.0;
 372                 oy = 0.0;
 373                 oz = 0.0;
 374                 ow = 0.0;
 375         }
 376
 377         for (u16 iter = 0; iter < iterations; iter++) {
 378                 // 4D "Roundy" Mandelbrot set
 379                 float nx = ox * ox - oy * oy - oz * oz - ow * ow + cx;
 380                 float ny = 2.0 * (ox * oy + oz * ow) + cy;
 381                 float nz = 2.0 * (ox * oz + oy * ow) + cz;
 382                 float nw = 2.0 * (ox * ow + oy * oz) + cw;
 383
 384                 if (nx * nx + ny * ny + nz * nz + nw * nw > 4.0) {
 385                         return false;
 386                 }
 387
 388                 ox = nx;
 389                 oy = ny;
 390                 oz = nz;
 391                 ow = nw;
 392         }
 393
 394         return true;
 395 }
 396
 397
 398 s16 MapgenFractal::generateTerrain()
 399 {
 400         MapNode n_air(CONTENT_AIR);
 401         MapNode n_stone(c_stone);
 402         MapNode n_water(c_water_source);
 403
 404         s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
 405
 406         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 407         for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 408                 u32 i = vm->m_area.index(node_min.X, y, z);
 409                 for (s16 x = node_min.X; x <= node_max.X; x++, i++) {
 410                         if (vm->m_data[i].getContent() == CONTENT_IGNORE) {
 411                                 if (getTerrainAtPoint(x, y, z)) {
 412                                         vm->m_data[i] = n_stone;
 413                                         if (y > stone_surface_max_y)
 414                                                 stone_surface_max_y = y;
 415                                 } else if (y <= water_level) {
 416                                         vm->m_data[i] = n_water;
 417                                 } else {
 418                                         vm->m_data[i] = n_air;
 419                                 }
 420                         }
 421                 }
 422         }
 423
 424         return stone_surface_max_y;
 425 }
 426
 427
 428 MgStoneType MapgenFractal::generateBiomes(float *heat_map, float *humidity_map)
 429 {
 430         v3s16 em = vm->m_area.getExtent();
 431         u32 index = 0;
 432         MgStoneType stone_type = STONE;
 433
 434         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 435         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 436                 Biome *biome = NULL;
 437                 u16 depth_top = 0;
 438                 u16 base_filler = 0;
 439                 u16 depth_water_top = 0;
 440                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 441
 442                 // Check node at base of mapchunk above, either a node of a previously
 443                 // generated mapchunk or if not, a node of overgenerated base terrain.
 444                 content_t c_above = vm->m_data[vi + em.X].getContent();
 445                 bool air_above = c_above == CONTENT_AIR;
 446                 bool water_above = c_above == c_water_source;
 447
 448                 // If there is air or water above enable top/filler placement, otherwise force
 449                 // nplaced to stone level by setting a number exceeding any possible filler depth.
 450                 u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
 451
 452
 453                 for (s16 y = node_max.Y; y >= node_min.Y; y--) {
 454                         content_t c = vm->m_data[vi].getContent();
 455
 456                         // Biome is recalculated each time an upper surface is detected while
 457                         // working down a column. The selected biome then remains in effect for
 458                         // all nodes below until the next surface and biome recalculation.
 459                         // Biome is recalculated:
 460                         // 1. At the surface of stone below air or water.
 461                         // 2. At the surface of water below air.
 462                         // 3. When stone or water is detected but biome has not yet been calculated.
 463                         if ((c == c_stone && (air_above || water_above || !biome)) ||
 464                                         (c == c_water_source && (air_above || !biome))) {
 465                                 biome = bmgr->getBiome(heat_map[index], humidity_map[index], y);
 466                                 depth_top = biome->depth_top;
 467                                 base_filler = depth_top + biome->depth_filler;
 468                                 depth_water_top = biome->depth_water_top;
 469
 470                                 // Detect stone type for dungeons during every biome calculation.
 471                                 // This is more efficient than detecting per-node and will not
 472                                 // miss any desert stone or sandstone biomes.
 473                                 if (biome->c_stone == c_desert_stone)
 474                                         stone_type = DESERT_STONE;
 475                                 else if (biome->c_stone == c_sandstone)
 476                                         stone_type = SANDSTONE;
 477                         }
 478
 479                         if (c == c_stone) {
 480                                 content_t c_below = vm->m_data[vi - em.X].getContent();
 481
 482                                 // If the node below isn't solid, make this node stone, so that
 483                                 // any top/filler nodes above are structurally supported.
 484                                 // This is done by aborting the cycle of top/filler placement
 485                                 // immediately by forcing nplaced to stone level.
 486                                 if (c_below == CONTENT_AIR || c_below == c_water_source)
 487                                         nplaced = U16_MAX;
 488
 489                                 if (nplaced < depth_top) {
 490                                         vm->m_data[vi] = MapNode(biome->c_top);
 491                                         nplaced++;
 492                                 } else if (nplaced < base_filler) {
 493                                         vm->m_data[vi] = MapNode(biome->c_filler);
 494                                         nplaced++;
 495                                 } else {
 496                                         vm->m_data[vi] = MapNode(biome->c_stone);
 497                                 }
 498
 499                                 air_above = false;
 500                                 water_above = false;
 501                         } else if (c == c_water_source) {
 502                                 vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) ?
 503                                                 biome->c_water_top : biome->c_water);
 504                                 nplaced = 0;  // Enable top/filler placement for next surface
 505                                 air_above = false;
 506                                 water_above = true;
 507                         } else if (c == CONTENT_AIR) {
 508                                 nplaced = 0;  // Enable top/filler placement for next surface
 509                                 air_above = true;
 510                                 water_above = false;
 511                         } else {  // Possible various nodes overgenerated from neighbouring mapchunks
 512                                 nplaced = U16_MAX;  // Disable top/filler placement
 513                                 air_above = false;
 514                                 water_above = false;
 515                         }
 516
 517                         vm->m_area.add_y(em, vi, -1);
 518                 }
 519         }
 520
 521         return stone_type;
 522 }
 523
 524
 525 void MapgenFractal::dustTopNodes()
 526 {
 527         if (node_max.Y < water_level)
 528                 return;
 529
 530         v3s16 em = vm->m_area.getExtent();
 531         u32 index = 0;
 532
 533         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 534         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 535                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
 536
 537                 if (biome->c_dust == CONTENT_IGNORE)
 538                         continue;
 539
 540                 u32 vi = vm->m_area.index(x, full_node_max.Y, z);
 541                 content_t c_full_max = vm->m_data[vi].getContent();
 542                 s16 y_start;
 543
 544                 if (c_full_max == CONTENT_AIR) {
 545                         y_start = full_node_max.Y - 1;
 546                 } else if (c_full_max == CONTENT_IGNORE) {
 547                         vi = vm->m_area.index(x, node_max.Y + 1, z);
 548                         content_t c_max = vm->m_data[vi].getContent();
 549
 550                         if (c_max == CONTENT_AIR)
 551                                 y_start = node_max.Y;
 552                         else
 553                                 continue;
 554                 } else {
 555                         continue;
 556                 }
 557
 558                 vi = vm->m_area.index(x, y_start, z);
 559                 for (s16 y = y_start; y >= node_min.Y - 1; y--) {
 560                         if (vm->m_data[vi].getContent() != CONTENT_AIR)
 561                                 break;
 562
 563                         vm->m_area.add_y(em, vi, -1);
 564                 }
 565
 566                 content_t c = vm->m_data[vi].getContent();
 567                 if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
 568                         vm->m_area.add_y(em, vi, 1);
 569                         vm->m_data[vi] = MapNode(biome->c_dust);
 570                 }
 571         }
 572 }
 573
 574
 575 void MapgenFractal::generateCaves(s16 max_stone_y)
 576 {
 577         if (max_stone_y >= node_min.Y) {
 578                 u32 index   = 0;
 579
 580                 for (s16 z = node_min.Z; z <= node_max.Z; z++)
 581                 for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 582                         u32 i = vm->m_area.index(node_min.X, y, z);
 583                         for (s16 x = node_min.X; x <= node_max.X; x++, i++, index++) {
 584                                 float d1 = contour(noise_cave1->result[index]);
 585                                 float d2 = contour(noise_cave2->result[index]);
 586                                 if (d1 * d2 > 0.3) {
 587                                         content_t c = vm->m_data[i].getContent();
 588                                         if (!ndef->get(c).is_ground_content || c == CONTENT_AIR)
 589                                                 continue;
 590
 591                                         vm->m_data[i] = MapNode(CONTENT_AIR);
 592                                 }
 593                         }
 594                 }
 595         }
 596 }
 597