src/mapgen_fractal.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2010-2015 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
   4 Copyright (C) 2010-2015 paramat, Matt Gregory
   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         //// 2D terrain noise
  77         noise_seabed = new Noise(&sp->np_seabed, seed, csize.X, csize.Z);
  78
  79         //// 3D terrain noise
  80         noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 2, csize.Z);
  81         noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 2, csize.Z);
  82
  83         //// Biome noise
  84         noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
  85         noise_humidity       = new Noise(&params->np_biome_humidity,       seed, csize.X, csize.Z);
  86         noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
  87         noise_humidity_blend = new Noise(&params->np_biome_humidity_blend, seed, csize.X, csize.Z);
  88
  89         //// Resolve nodes to be used
  90         INodeDefManager *ndef = emerge->ndef;
  91
  92         c_stone                = ndef->getId("mapgen_stone");
  93         c_water_source         = ndef->getId("mapgen_water_source");
  94         c_lava_source          = ndef->getId("mapgen_lava_source");
  95         c_desert_stone         = ndef->getId("mapgen_desert_stone");
  96         c_ice                  = ndef->getId("mapgen_ice");
  97         c_sandstone            = ndef->getId("mapgen_sandstone");
  98
  99         c_cobble               = ndef->getId("mapgen_cobble");
 100         c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
 101         c_mossycobble          = ndef->getId("mapgen_mossycobble");
 102         c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
 103         c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
 104
 105         if (c_ice == CONTENT_IGNORE)
 106                 c_ice = CONTENT_AIR;
 107         if (c_mossycobble == CONTENT_IGNORE)
 108                 c_mossycobble = c_cobble;
 109         if (c_stair_cobble == CONTENT_IGNORE)
 110                 c_stair_cobble = c_cobble;
 111         if (c_sandstonebrick == CONTENT_IGNORE)
 112                 c_sandstonebrick = c_sandstone;
 113         if (c_stair_sandstonebrick == CONTENT_IGNORE)
 114                 c_stair_sandstonebrick = c_sandstone;
 115 }
 116
 117
 118 MapgenFractal::~MapgenFractal()
 119 {
 120         delete noise_seabed;
 121
 122         delete noise_cave1;
 123         delete noise_cave2;
 124
 125         delete noise_heat;
 126         delete noise_humidity;
 127         delete noise_heat_blend;
 128         delete noise_humidity_blend;
 129
 130         delete[] heightmap;
 131         delete[] biomemap;
 132 }
 133
 134
 135 MapgenFractalParams::MapgenFractalParams()
 136 {
 137         spflags = 0;
 138
 139         iterations = 9;
 140         scale_x = 1024.0;
 141         scale_y = 256.0;
 142         scale_z = 1024.0;
 143         offset_x = -1.75;
 144         offset_y = 0.0;
 145         offset_z = 0.0;
 146         slice_w = 0.5;
 147         julia_x = 0.33;
 148         julia_y = 0.33;
 149         julia_z = 0.33;
 150         julia_w = 0.33;
 151
 152         np_seabed = NoiseParams(-14, 9,  v3f(600, 600, 600), 41900, 5, 0.6, 2.0);
 153         np_cave1  = NoiseParams(0,   12, v3f(128, 128, 128), 52534, 4, 0.5, 2.0);
 154         np_cave2  = NoiseParams(0,   12, v3f(128, 128, 128), 10325, 4, 0.5, 2.0);
 155 }
 156
 157
 158 void MapgenFractalParams::readParams(const Settings *settings)
 159 {
 160         settings->getFlagStrNoEx("mgfractal_spflags", spflags, flagdesc_mapgen_fractal);
 161
 162         settings->getU16NoEx("mgfractal_iterations", iterations);
 163         settings->getFloatNoEx("mgfractal_scale_x", scale_x);
 164         settings->getFloatNoEx("mgfractal_scale_y", scale_y);
 165         settings->getFloatNoEx("mgfractal_scale_z", scale_z);
 166         settings->getFloatNoEx("mgfractal_offset_x", offset_x);
 167         settings->getFloatNoEx("mgfractal_offset_y", offset_y);
 168         settings->getFloatNoEx("mgfractal_offset_z", offset_z);
 169         settings->getFloatNoEx("mgfractal_slice_w", slice_w);
 170         settings->getFloatNoEx("mgfractal_julia_x", julia_x);
 171         settings->getFloatNoEx("mgfractal_julia_y", julia_y);
 172         settings->getFloatNoEx("mgfractal_julia_z", julia_z);
 173         settings->getFloatNoEx("mgfractal_julia_w", julia_w);
 174
 175         settings->getNoiseParams("mgfractal_np_seabed", np_seabed);
 176         settings->getNoiseParams("mgfractal_np_cave1", np_cave1);
 177         settings->getNoiseParams("mgfractal_np_cave2", np_cave2);
 178 }
 179
 180
 181 void MapgenFractalParams::writeParams(Settings *settings) const
 182 {
 183         settings->setFlagStr("mgfractal_spflags", spflags, flagdesc_mapgen_fractal, U32_MAX);
 184
 185         settings->setU16("mgfractal_iterations", iterations);
 186         settings->setFloat("mgfractal_scale_x", scale_x);
 187         settings->setFloat("mgfractal_scale_y", scale_y);
 188         settings->setFloat("mgfractal_scale_z", scale_z);
 189         settings->setFloat("mgfractal_offset_x", offset_x);
 190         settings->setFloat("mgfractal_offset_y", offset_y);
 191         settings->setFloat("mgfractal_offset_z", offset_z);
 192         settings->setFloat("mgfractal_slice_w", slice_w);
 193         settings->setFloat("mgfractal_julia_x", julia_x);
 194         settings->setFloat("mgfractal_julia_y", julia_y);
 195         settings->setFloat("mgfractal_julia_z", julia_z);
 196         settings->setFloat("mgfractal_julia_w", julia_w);
 197
 198         settings->setNoiseParams("mgfractal_np_seabed", np_seabed);
 199         settings->setNoiseParams("mgfractal_np_cave1", np_cave1);
 200         settings->setNoiseParams("mgfractal_np_cave2", np_cave2);
 201 }
 202
 203
 204 /////////////////////////////////////////////////////////////////
 205
 206
 207 int MapgenFractal::getGroundLevelAtPoint(v2s16 p)
 208 {
 209         s16 search_start = 128;
 210         s16 search_end = -128;
 211
 212         for (s16 y = search_start; y >= search_end; y--) {
 213                 if (getFractalAtPoint(p.X, y, p.Y))
 214                         return y;
 215         }
 216
 217         return -MAX_MAP_GENERATION_LIMIT;
 218 }
 219
 220
 221 void MapgenFractal::makeChunk(BlockMakeData *data)
 222 {
 223         // Pre-conditions
 224         assert(data->vmanip);
 225         assert(data->nodedef);
 226         assert(data->blockpos_requested.X >= data->blockpos_min.X &&
 227                 data->blockpos_requested.Y >= data->blockpos_min.Y &&
 228                 data->blockpos_requested.Z >= data->blockpos_min.Z);
 229         assert(data->blockpos_requested.X <= data->blockpos_max.X &&
 230                 data->blockpos_requested.Y <= data->blockpos_max.Y &&
 231                 data->blockpos_requested.Z <= data->blockpos_max.Z);
 232
 233         this->generating = true;
 234         this->vm   = data->vmanip;
 235         this->ndef = data->nodedef;
 236         //TimeTaker t("makeChunk");
 237
 238         v3s16 blockpos_min = data->blockpos_min;
 239         v3s16 blockpos_max = data->blockpos_max;
 240         node_min = blockpos_min * MAP_BLOCKSIZE;
 241         node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 242         full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
 243         full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 244
 245         blockseed = getBlockSeed2(full_node_min, seed);
 246
 247         // Make some noise
 248         calculateNoise();
 249
 250         // Generate base terrain, mountains, and ridges with initial heightmaps
 251         s16 stone_surface_max_y = generateTerrain();
 252
 253         // Create heightmap
 254         updateHeightmap(node_min, node_max);
 255
 256         // Create biomemap at heightmap surface
 257         bmgr->calcBiomes(csize.X, csize.Z, noise_heat->result,
 258                 noise_humidity->result, heightmap, biomemap);
 259
 260         // Actually place the biome-specific nodes
 261         MgStoneType stone_type = generateBiomes(noise_heat->result, noise_humidity->result);
 262
 263         if (flags & MG_CAVES)
 264                 generateCaves(stone_surface_max_y);
 265
 266         if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 267                 DungeonParams dp;
 268
 269                 dp.np_rarity  = nparams_dungeon_rarity;
 270                 dp.np_density = nparams_dungeon_density;
 271                 dp.np_wetness = nparams_dungeon_wetness;
 272                 dp.c_water    = c_water_source;
 273                 if (stone_type == STONE) {
 274                         dp.c_cobble = c_cobble;
 275                         dp.c_moss   = c_mossycobble;
 276                         dp.c_stair  = c_stair_cobble;
 277
 278                         dp.diagonal_dirs = false;
 279                         dp.mossratio     = 3.0;
 280                         dp.holesize      = v3s16(1, 2, 1);
 281                         dp.roomsize      = v3s16(0, 0, 0);
 282                         dp.notifytype    = GENNOTIFY_DUNGEON;
 283                 } else if (stone_type == DESERT_STONE) {
 284                         dp.c_cobble = c_desert_stone;
 285                         dp.c_moss   = c_desert_stone;
 286                         dp.c_stair  = c_desert_stone;
 287
 288                         dp.diagonal_dirs = true;
 289                         dp.mossratio     = 0.0;
 290                         dp.holesize      = v3s16(2, 3, 2);
 291                         dp.roomsize      = v3s16(2, 5, 2);
 292                         dp.notifytype    = GENNOTIFY_TEMPLE;
 293                 } else if (stone_type == SANDSTONE) {
 294                         dp.c_cobble = c_sandstonebrick;
 295                         dp.c_moss   = c_sandstonebrick;
 296                         dp.c_stair  = c_sandstonebrick;
 297
 298                         dp.diagonal_dirs = false;
 299                         dp.mossratio     = 0.0;
 300                         dp.holesize      = v3s16(2, 2, 2);
 301                         dp.roomsize      = v3s16(2, 0, 2);
 302                         dp.notifytype    = GENNOTIFY_DUNGEON;
 303                 }
 304
 305                 DungeonGen dgen(this, &dp);
 306                 dgen.generate(blockseed, full_node_min, full_node_max);
 307         }
 308
 309         // Generate the registered decorations
 310         m_emerge->decomgr->placeAllDecos(this, blockseed, node_min, node_max);
 311
 312         // Generate the registered ores
 313         m_emerge->oremgr->placeAllOres(this, blockseed, node_min, node_max);
 314
 315         // Sprinkle some dust on top after everything else was generated
 316         dustTopNodes();
 317
 318         //printf("makeChunk: %dms\n", t.stop());
 319
 320         updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
 321
 322         if (flags & MG_LIGHT)
 323                 calcLighting(node_min - v3s16(0, 1, 0), node_max + v3s16(0, 1, 0),
 324                         full_node_min, full_node_max);
 325
 326         //setLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
 327         //                      node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE, 0xFF);
 328
 329         this->generating = false;
 330 }
 331
 332
 333 void MapgenFractal::calculateNoise()
 334 {
 335         //TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
 336         int x = node_min.X;
 337         int y = node_min.Y - 1;
 338         int z = node_min.Z;
 339
 340         noise_seabed->perlinMap2D(x, z);
 341
 342         if (flags & MG_CAVES) {
 343                 noise_cave1->perlinMap3D(x, y, z);
 344                 noise_cave2->perlinMap3D(x, y, z);
 345         }
 346
 347         noise_heat->perlinMap2D(x, z);
 348         noise_humidity->perlinMap2D(x, z);
 349         noise_heat_blend->perlinMap2D(x, z);
 350         noise_humidity_blend->perlinMap2D(x, z);
 351
 352         for (s32 i = 0; i < csize.X * csize.Z; i++) {
 353                 noise_heat->result[i] += noise_heat_blend->result[i];
 354                 noise_humidity->result[i] += noise_humidity_blend->result[i];
 355         }
 356
 357         heatmap = noise_heat->result;
 358         humidmap = noise_humidity->result;
 359         //printf("calculateNoise: %dus\n", t.stop());
 360 }
 361
 362
 363 bool MapgenFractal::getFractalAtPoint(s16 x, s16 y, s16 z)
 364 {
 365         float cx, cy, cz, cw, ox, oy, oz, ow;
 366
 367         if (spflags & MGFRACTAL_JULIA) {  // Julia set
 368                 cx = julia_x;
 369                 cy = julia_y;
 370                 cz = julia_z;
 371                 cw = julia_w;
 372                 ox = (float)x / scale_x + offset_x;
 373                 oy = (float)y / scale_y + offset_y;
 374                 oz = (float)z / scale_z + offset_z;
 375                 ow = slice_w;
 376         } else {  // Mandelbrot set
 377                 cx = (float)x / scale_x + offset_x;
 378                 cy = (float)y / scale_y + offset_y;
 379                 cz = (float)z / scale_z + offset_z;
 380                 cw = slice_w;
 381                 ox = 0.0f;
 382                 oy = 0.0f;
 383                 oz = 0.0f;
 384                 ow = 0.0f;
 385         }
 386
 387         for (u16 iter = 0; iter < iterations; iter++) {
 388                 // 4D "Roundy" Mandelbrot set
 389                 float nx = ox * ox - oy * oy - oz * oz - ow * ow + cx;
 390                 float ny = 2.0f * (ox * oy + oz * ow) + cy;
 391                 float nz = 2.0f * (ox * oz + oy * ow) + cz;
 392                 float nw = 2.0f * (ox * ow + oy * oz) + cw;
 393
 394                 if (nx * nx + ny * ny + nz * nz + nw * nw > 4.0f)
 395                         return false;
 396
 397                 ox = nx;
 398                 oy = ny;
 399                 oz = nz;
 400                 ow = nw;
 401         }
 402
 403         return true;
 404 }
 405
 406
 407 s16 MapgenFractal::generateTerrain()
 408 {
 409         MapNode n_air(CONTENT_AIR);
 410         MapNode n_stone(c_stone);
 411         MapNode n_water(c_water_source);
 412
 413         s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
 414         u32 index2d = 0;
 415
 416         for (s16 z = node_min.Z; z <= node_max.Z; z++) {
 417                 for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 418                         u32 vi = vm->m_area.index(node_min.X, y, z);
 419                         for (s16 x = node_min.X; x <= node_max.X; x++, vi++, index2d++) {
 420                                 if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
 421                                         s16 seabed_height = noise_seabed->result[index2d];
 422
 423                                         if (y <= seabed_height || getFractalAtPoint(x, y, z)) {
 424                                                 vm->m_data[vi] = n_stone;
 425                                                 if (y > stone_surface_max_y)
 426                                                         stone_surface_max_y = y;
 427                                         } else if (y <= water_level) {
 428                                                 vm->m_data[vi] = n_water;
 429                                         } else {
 430                                                 vm->m_data[vi] = n_air;
 431                                         }
 432                                 }
 433                         }
 434                         index2d -= ystride;
 435                 }
 436                 index2d += ystride;
 437         }
 438
 439         return stone_surface_max_y;
 440 }
 441
 442
 443 MgStoneType MapgenFractal::generateBiomes(float *heat_map, float *humidity_map)
 444 {
 445         v3s16 em = vm->m_area.getExtent();
 446         u32 index = 0;
 447         MgStoneType stone_type = STONE;
 448
 449         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 450         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 451                 Biome *biome = NULL;
 452                 u16 depth_top = 0;
 453                 u16 base_filler = 0;
 454                 u16 depth_water_top = 0;
 455                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 456
 457                 // Check node at base of mapchunk above, either a node of a previously
 458                 // generated mapchunk or if not, a node of overgenerated base terrain.
 459                 content_t c_above = vm->m_data[vi + em.X].getContent();
 460                 bool air_above = c_above == CONTENT_AIR;
 461                 bool water_above = c_above == c_water_source;
 462
 463                 // If there is air or water above enable top/filler placement, otherwise force
 464                 // nplaced to stone level by setting a number exceeding any possible filler depth.
 465                 u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
 466
 467
 468                 for (s16 y = node_max.Y; y >= node_min.Y; y--) {
 469                         content_t c = vm->m_data[vi].getContent();
 470
 471                         // Biome is recalculated each time an upper surface is detected while
 472                         // working down a column. The selected biome then remains in effect for
 473                         // all nodes below until the next surface and biome recalculation.
 474                         // Biome is recalculated:
 475                         // 1. At the surface of stone below air or water.
 476                         // 2. At the surface of water below air.
 477                         // 3. When stone or water is detected but biome has not yet been calculated.
 478                         if ((c == c_stone && (air_above || water_above || !biome)) ||
 479                                         (c == c_water_source && (air_above || !biome))) {
 480                                 biome = bmgr->getBiome(heat_map[index], humidity_map[index], y);
 481                                 depth_top = biome->depth_top;
 482                                 base_filler = depth_top + biome->depth_filler;
 483                                 depth_water_top = biome->depth_water_top;
 484
 485                                 // Detect stone type for dungeons during every biome calculation.
 486                                 // This is more efficient than detecting per-node and will not
 487                                 // miss any desert stone or sandstone biomes.
 488                                 if (biome->c_stone == c_desert_stone)
 489                                         stone_type = DESERT_STONE;
 490                                 else if (biome->c_stone == c_sandstone)
 491                                         stone_type = SANDSTONE;
 492                         }
 493
 494                         if (c == c_stone) {
 495                                 content_t c_below = vm->m_data[vi - em.X].getContent();
 496
 497                                 // If the node below isn't solid, make this node stone, so that
 498                                 // any top/filler nodes above are structurally supported.
 499                                 // This is done by aborting the cycle of top/filler placement
 500                                 // immediately by forcing nplaced to stone level.
 501                                 if (c_below == CONTENT_AIR || c_below == c_water_source)
 502                                         nplaced = U16_MAX;
 503
 504                                 if (nplaced < depth_top) {
 505                                         vm->m_data[vi] = MapNode(biome->c_top);
 506                                         nplaced++;
 507                                 } else if (nplaced < base_filler) {
 508                                         vm->m_data[vi] = MapNode(biome->c_filler);
 509                                         nplaced++;
 510                                 } else {
 511                                         vm->m_data[vi] = MapNode(biome->c_stone);
 512                                 }
 513
 514                                 air_above = false;
 515                                 water_above = false;
 516                         } else if (c == c_water_source) {
 517                                 vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) ?
 518                                                 biome->c_water_top : biome->c_water);
 519                                 nplaced = 0;  // Enable top/filler placement for next surface
 520                                 air_above = false;
 521                                 water_above = true;
 522                         } else if (c == CONTENT_AIR) {
 523                                 nplaced = 0;  // Enable top/filler placement for next surface
 524                                 air_above = true;
 525                                 water_above = false;
 526                         } else {  // Possible various nodes overgenerated from neighbouring mapchunks
 527                                 nplaced = U16_MAX;  // Disable top/filler placement
 528                                 air_above = false;
 529                                 water_above = false;
 530                         }
 531
 532                         vm->m_area.add_y(em, vi, -1);
 533                 }
 534         }
 535
 536         return stone_type;
 537 }
 538
 539
 540 void MapgenFractal::dustTopNodes()
 541 {
 542         if (node_max.Y < water_level)
 543                 return;
 544
 545         v3s16 em = vm->m_area.getExtent();
 546         u32 index = 0;
 547
 548         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 549         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 550                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
 551
 552                 if (biome->c_dust == CONTENT_IGNORE)
 553                         continue;
 554
 555                 u32 vi = vm->m_area.index(x, full_node_max.Y, z);
 556                 content_t c_full_max = vm->m_data[vi].getContent();
 557                 s16 y_start;
 558
 559                 if (c_full_max == CONTENT_AIR) {
 560                         y_start = full_node_max.Y - 1;
 561                 } else if (c_full_max == CONTENT_IGNORE) {
 562                         vi = vm->m_area.index(x, node_max.Y + 1, z);
 563                         content_t c_max = vm->m_data[vi].getContent();
 564
 565                         if (c_max == CONTENT_AIR)
 566                                 y_start = node_max.Y;
 567                         else
 568                                 continue;
 569                 } else {
 570                         continue;
 571                 }
 572
 573                 vi = vm->m_area.index(x, y_start, z);
 574                 for (s16 y = y_start; y >= node_min.Y - 1; y--) {
 575                         if (vm->m_data[vi].getContent() != CONTENT_AIR)
 576                                 break;
 577
 578                         vm->m_area.add_y(em, vi, -1);
 579                 }
 580
 581                 content_t c = vm->m_data[vi].getContent();
 582                 if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
 583                         vm->m_area.add_y(em, vi, 1);
 584                         vm->m_data[vi] = MapNode(biome->c_dust);
 585                 }
 586         }
 587 }
 588
 589
 590 void MapgenFractal::generateCaves(s16 max_stone_y)
 591 {
 592         if (max_stone_y >= node_min.Y) {
 593                 u32 index = 0;
 594
 595                 for (s16 z = node_min.Z; z <= node_max.Z; z++)
 596                 for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 597                         u32 vi = vm->m_area.index(node_min.X, y, z);
 598                         for (s16 x = node_min.X; x <= node_max.X; x++, vi++, index++) {
 599                                 float d1 = contour(noise_cave1->result[index]);
 600                                 float d2 = contour(noise_cave2->result[index]);
 601                                 if (d1 * d2 > 0.3) {
 602                                         content_t c = vm->m_data[vi].getContent();
 603                                         if (!ndef->get(c).is_ground_content || c == CONTENT_AIR)
 604                                                 continue;
 605
 606                                         vm->m_data[vi] = MapNode(CONTENT_AIR);
 607                                 }
 608                         }
 609                 }
 610         }
 611
 612         if (node_max.Y > MGFRACTAL_LARGE_CAVE_DEPTH)
 613                 return;
 614
 615         PseudoRandom ps(blockseed + 21343);
 616         u32 bruises_count = (ps.range(1, 4) == 1) ? ps.range(1, 2) : 0;
 617         for (u32 i = 0; i < bruises_count; i++) {
 618                 CaveFractal cave(this, &ps);
 619                 cave.makeCave(node_min, node_max, max_stone_y);
 620         }
 621 }