src/mapgen_flat.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 "profiler.h" // For TimeTaker
  32 #include "settings.h" // For g_settings
  33 #include "emerge.h"
  34 #include "dungeongen.h"
  35 #include "cavegen.h"
  36 #include "treegen.h"
  37 #include "mg_biome.h"
  38 #include "mg_ore.h"
  39 #include "mg_decoration.h"
  40 #include "mapgen_flat.h"
  41
  42
  43 FlagDesc flagdesc_mapgen_flat[] = {
  44         {"lakes", MGFLAT_LAKES},
  45         {"hills", MGFLAT_HILLS},
  46         {NULL,    0}
  47 };
  48
  49 ///////////////////////////////////////////////////////////////////////////////////////
  50
  51
  52 MapgenFlat::MapgenFlat(int mapgenid, MapgenParams *params, EmergeManager *emerge)
  53         : Mapgen(mapgenid, params, emerge)
  54 {
  55         this->m_emerge = emerge;
  56         this->bmgr     = emerge->biomemgr;
  57
  58         //// amount of elements to skip for the next index
  59         //// for noise/height/biome maps (not vmanip)
  60         this->ystride = csize.X;
  61         // 1-down overgeneration
  62         this->zstride_1d = csize.X * (csize.Y + 1);
  63
  64         this->biomemap        = new u8[csize.X * csize.Z];
  65         this->heightmap       = new s16[csize.X * csize.Z];
  66         this->heatmap         = NULL;
  67         this->humidmap        = NULL;
  68
  69         MapgenFlatParams *sp = (MapgenFlatParams *)params->sparams;
  70
  71         this->spflags          = sp->spflags;
  72         this->ground_level     = sp->ground_level;
  73         this->large_cave_depth = sp->large_cave_depth;
  74         this->cave_width       = sp->cave_width;
  75         this->lake_threshold   = sp->lake_threshold;
  76         this->lake_steepness   = sp->lake_steepness;
  77         this->hill_threshold   = sp->hill_threshold;
  78         this->hill_steepness   = sp->hill_steepness;
  79
  80         //// 2D noise
  81         noise_terrain      = new Noise(&sp->np_terrain,      seed, csize.X, csize.Z);
  82         noise_filler_depth = new Noise(&sp->np_filler_depth, seed, csize.X, csize.Z);
  83
  84         //// 3D noise
  85         // 1-down overgeneraion
  86         noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 1, csize.Z);
  87         noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 1, csize.Z);
  88
  89         //// Biome noise
  90         noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
  91         noise_humidity       = new Noise(&params->np_biome_humidity,       seed, csize.X, csize.Z);
  92         noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
  93         noise_humidity_blend = new Noise(&params->np_biome_humidity_blend, seed, csize.X, csize.Z);
  94
  95         //// Resolve nodes to be used
  96         INodeDefManager *ndef = emerge->ndef;
  97
  98         c_stone                = ndef->getId("mapgen_stone");
  99         c_water_source         = ndef->getId("mapgen_water_source");
 100         c_lava_source          = ndef->getId("mapgen_lava_source");
 101         c_desert_stone         = ndef->getId("mapgen_desert_stone");
 102         c_ice                  = ndef->getId("mapgen_ice");
 103         c_sandstone            = ndef->getId("mapgen_sandstone");
 104
 105         c_cobble               = ndef->getId("mapgen_cobble");
 106         c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
 107         c_mossycobble          = ndef->getId("mapgen_mossycobble");
 108         c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
 109         c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
 110
 111         if (c_ice == CONTENT_IGNORE)
 112                 c_ice = CONTENT_AIR;
 113         if (c_mossycobble == CONTENT_IGNORE)
 114                 c_mossycobble = c_cobble;
 115         if (c_stair_cobble == CONTENT_IGNORE)
 116                 c_stair_cobble = c_cobble;
 117         if (c_sandstonebrick == CONTENT_IGNORE)
 118                 c_sandstonebrick = c_sandstone;
 119         if (c_stair_sandstonebrick == CONTENT_IGNORE)
 120                 c_stair_sandstonebrick = c_sandstone;
 121 }
 122
 123
 124 MapgenFlat::~MapgenFlat()
 125 {
 126         delete noise_terrain;
 127         delete noise_filler_depth;
 128         delete noise_cave1;
 129         delete noise_cave2;
 130
 131         delete noise_heat;
 132         delete noise_humidity;
 133         delete noise_heat_blend;
 134         delete noise_humidity_blend;
 135
 136         delete[] heightmap;
 137         delete[] biomemap;
 138 }
 139
 140
 141 MapgenFlatParams::MapgenFlatParams()
 142 {
 143         spflags          = 0;
 144         ground_level     = 8;
 145         large_cave_depth = -33;
 146         cave_width       = 0.3;
 147         lake_threshold   = -0.45;
 148         lake_steepness   = 48.0;
 149         hill_threshold   = 0.45;
 150         hill_steepness   = 64.0;
 151
 152         np_terrain      = NoiseParams(0, 1,   v3f(600, 600, 600), 7244,  5, 0.6, 2.0);
 153         np_filler_depth = NoiseParams(0, 1.2, v3f(150, 150, 150), 261,   3, 0.7, 2.0);
 154         np_cave1        = NoiseParams(0, 12,  v3f(96,  96,  96),  52534, 4, 0.5, 2.0);
 155         np_cave2        = NoiseParams(0, 12,  v3f(96,  96,  96),  10325, 4, 0.5, 2.0);
 156 }
 157
 158
 159 void MapgenFlatParams::readParams(const Settings *settings)
 160 {
 161         settings->getFlagStrNoEx("mgflat_spflags",      spflags, flagdesc_mapgen_flat);
 162         settings->getS16NoEx("mgflat_ground_level",     ground_level);
 163         settings->getS16NoEx("mgflat_large_cave_depth", large_cave_depth);
 164         settings->getFloatNoEx("mgflat_cave_width",     cave_width);
 165         settings->getFloatNoEx("mgflat_lake_threshold", lake_threshold);
 166         settings->getFloatNoEx("mgflat_lake_steepness", lake_steepness);
 167         settings->getFloatNoEx("mgflat_hill_threshold", hill_threshold);
 168         settings->getFloatNoEx("mgflat_hill_steepness", hill_steepness);
 169
 170         settings->getNoiseParams("mgflat_np_terrain",      np_terrain);
 171         settings->getNoiseParams("mgflat_np_filler_depth", np_filler_depth);
 172         settings->getNoiseParams("mgflat_np_cave1",        np_cave1);
 173         settings->getNoiseParams("mgflat_np_cave2",        np_cave2);
 174 }
 175
 176
 177 void MapgenFlatParams::writeParams(Settings *settings) const
 178 {
 179         settings->setFlagStr("mgflat_spflags",      spflags, flagdesc_mapgen_flat, U32_MAX);
 180         settings->setS16("mgflat_ground_level",     ground_level);
 181         settings->setS16("mgflat_large_cave_depth", large_cave_depth);
 182         settings->setFloat("mgflat_cave_width",     cave_width);
 183         settings->setFloat("mgflat_lake_threshold", lake_threshold);
 184         settings->setFloat("mgflat_lake_steepness", lake_steepness);
 185         settings->setFloat("mgflat_hill_threshold", hill_threshold);
 186         settings->setFloat("mgflat_hill_steepness", hill_steepness);
 187
 188         settings->setNoiseParams("mgflat_np_terrain",      np_terrain);
 189         settings->setNoiseParams("mgflat_np_filler_depth", np_filler_depth);
 190         settings->setNoiseParams("mgflat_np_cave1",        np_cave1);
 191         settings->setNoiseParams("mgflat_np_cave2",        np_cave2);
 192 }
 193
 194
 195 /////////////////////////////////////////////////////////////////
 196
 197
 198 int MapgenFlat::getSpawnLevelAtPoint(v2s16 p)
 199 {
 200         s16 level_at_point = ground_level;
 201         float n_terrain = NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed);
 202
 203         if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
 204                 level_at_point = ground_level -
 205                         (lake_threshold - n_terrain) * lake_steepness;
 206         } else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
 207                 level_at_point = ground_level +
 208                         (n_terrain - hill_threshold) * hill_steepness;
 209         }
 210
 211         if (ground_level < water_level)  // Ocean world, allow spawn in water
 212                 return MYMAX(level_at_point, water_level);
 213         else if (level_at_point > water_level)
 214                 return level_at_point;  // Spawn on land
 215         else
 216                 return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
 217 }
 218
 219
 220 void MapgenFlat::makeChunk(BlockMakeData *data)
 221 {
 222         // Pre-conditions
 223         assert(data->vmanip);
 224         assert(data->nodedef);
 225         assert(data->blockpos_requested.X >= data->blockpos_min.X &&
 226                 data->blockpos_requested.Y >= data->blockpos_min.Y &&
 227                 data->blockpos_requested.Z >= data->blockpos_min.Z);
 228         assert(data->blockpos_requested.X <= data->blockpos_max.X &&
 229                 data->blockpos_requested.Y <= data->blockpos_max.Y &&
 230                 data->blockpos_requested.Z <= data->blockpos_max.Z);
 231
 232         this->generating = true;
 233         this->vm   = data->vmanip;
 234         this->ndef = data->nodedef;
 235         //TimeTaker t("makeChunk");
 236
 237         v3s16 blockpos_min = data->blockpos_min;
 238         v3s16 blockpos_max = data->blockpos_max;
 239         node_min = blockpos_min * MAP_BLOCKSIZE;
 240         node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 241         full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
 242         full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 243
 244         blockseed = getBlockSeed2(full_node_min, seed);
 245
 246         // Make some noise
 247         calculateNoise();
 248
 249         // Generate base terrain, mountains, and ridges with initial heightmaps
 250         s16 stone_surface_max_y = generateTerrain();
 251
 252         // Create heightmap
 253         updateHeightmap(node_min, node_max);
 254
 255         // Create biomemap at heightmap surface
 256         bmgr->calcBiomes(csize.X, csize.Z, noise_heat->result,
 257                 noise_humidity->result, heightmap, biomemap);
 258
 259         // Actually place the biome-specific nodes
 260         MgStoneType stone_type = generateBiomes(noise_heat->result, noise_humidity->result);
 261
 262         if (flags & MG_CAVES)
 263                 generateCaves(stone_surface_max_y);
 264
 265         if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 266                 DungeonParams dp;
 267
 268                 dp.np_rarity  = nparams_dungeon_rarity;
 269                 dp.np_density = nparams_dungeon_density;
 270                 dp.np_wetness = nparams_dungeon_wetness;
 271                 dp.c_water    = c_water_source;
 272                 if (stone_type == STONE) {
 273                         dp.c_cobble = c_cobble;
 274                         dp.c_moss   = c_mossycobble;
 275                         dp.c_stair  = c_stair_cobble;
 276
 277                         dp.diagonal_dirs = false;
 278                         dp.mossratio     = 3.0;
 279                         dp.holesize      = v3s16(1, 2, 1);
 280                         dp.roomsize      = v3s16(0, 0, 0);
 281                         dp.notifytype    = GENNOTIFY_DUNGEON;
 282                 } else if (stone_type == DESERT_STONE) {
 283                         dp.c_cobble = c_desert_stone;
 284                         dp.c_moss   = c_desert_stone;
 285                         dp.c_stair  = c_desert_stone;
 286
 287                         dp.diagonal_dirs = true;
 288                         dp.mossratio     = 0.0;
 289                         dp.holesize      = v3s16(2, 3, 2);
 290                         dp.roomsize      = v3s16(2, 5, 2);
 291                         dp.notifytype    = GENNOTIFY_TEMPLE;
 292                 } else if (stone_type == SANDSTONE) {
 293                         dp.c_cobble = c_sandstonebrick;
 294                         dp.c_moss   = c_sandstonebrick;
 295                         dp.c_stair  = c_sandstonebrick;
 296
 297                         dp.diagonal_dirs = false;
 298                         dp.mossratio     = 0.0;
 299                         dp.holesize      = v3s16(2, 2, 2);
 300                         dp.roomsize      = v3s16(2, 0, 2);
 301                         dp.notifytype    = GENNOTIFY_DUNGEON;
 302                 }
 303
 304                 DungeonGen dgen(this, &dp);
 305                 dgen.generate(blockseed, full_node_min, full_node_max);
 306         }
 307
 308         // Generate the registered decorations
 309         if (flags & MG_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 MapgenFlat::calculateNoise()
 334 {
 335         //TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
 336         s16 x = node_min.X;
 337         s16 z = node_min.Z;
 338
 339         if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
 340                 noise_terrain->perlinMap2D(x, z);
 341
 342         // Cave noises are calculated in generateCaves()
 343         // only if solid terrain is present in mapchunk
 344
 345         noise_filler_depth->perlinMap2D(x, z);
 346         noise_heat->perlinMap2D(x, z);
 347         noise_humidity->perlinMap2D(x, z);
 348         noise_heat_blend->perlinMap2D(x, z);
 349         noise_humidity_blend->perlinMap2D(x, z);
 350
 351         for (s32 i = 0; i < csize.X * csize.Z; i++) {
 352                 noise_heat->result[i] += noise_heat_blend->result[i];
 353                 noise_humidity->result[i] += noise_humidity_blend->result[i];
 354         }
 355
 356         heatmap = noise_heat->result;
 357         humidmap = noise_humidity->result;
 358         //printf("calculateNoise: %dus\n", t.stop());
 359 }
 360
 361
 362 s16 MapgenFlat::generateTerrain()
 363 {
 364         MapNode n_air(CONTENT_AIR);
 365         MapNode n_stone(c_stone);
 366         MapNode n_water(c_water_source);
 367
 368         v3s16 em = vm->m_area.getExtent();
 369         s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
 370         u32 ni2d = 0;
 371
 372         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 373         for (s16 x = node_min.X; x <= node_max.X; x++, ni2d++) {
 374                 s16 stone_level = ground_level;
 375                 float n_terrain = 0.0f;
 376
 377                 if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
 378                         n_terrain = noise_terrain->result[ni2d];
 379
 380                 if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
 381                         s16 depress = (lake_threshold - n_terrain) * lake_steepness;
 382                         stone_level = ground_level - depress;
 383                 } else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
 384                         s16 rise = (n_terrain - hill_threshold) * hill_steepness;
 385                         stone_level = ground_level + rise;
 386                 }
 387
 388                 u32 vi = vm->m_area.index(x, node_min.Y - 1, z);
 389                 for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 390                         if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
 391                                 if (y <= stone_level) {
 392                                         vm->m_data[vi] = n_stone;
 393                                         if (y > stone_surface_max_y)
 394                                                 stone_surface_max_y = y;
 395                                 } else if (y <= water_level) {
 396                                         vm->m_data[vi] = n_water;
 397                                 } else {
 398                                         vm->m_data[vi] = n_air;
 399                                 }
 400                         }
 401                         vm->m_area.add_y(em, vi, 1);
 402                 }
 403         }
 404
 405         return stone_surface_max_y;
 406 }
 407
 408
 409 MgStoneType MapgenFlat::generateBiomes(float *heat_map, float *humidity_map)
 410 {
 411         v3s16 em = vm->m_area.getExtent();
 412         u32 index = 0;
 413         MgStoneType stone_type = STONE;
 414
 415         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 416         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 417                 Biome *biome = NULL;
 418                 u16 depth_top = 0;
 419                 u16 base_filler = 0;
 420                 u16 depth_water_top = 0;
 421                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 422
 423                 // Check node at base of mapchunk above, either a node of a previously
 424                 // generated mapchunk or if not, a node of overgenerated base terrain.
 425                 content_t c_above = vm->m_data[vi + em.X].getContent();
 426                 bool air_above = c_above == CONTENT_AIR;
 427                 bool water_above = c_above == c_water_source;
 428
 429                 // If there is air or water above enable top/filler placement, otherwise force
 430                 // nplaced to stone level by setting a number exceeding any possible filler depth.
 431                 u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
 432
 433
 434                 for (s16 y = node_max.Y; y >= node_min.Y; y--) {
 435                         content_t c = vm->m_data[vi].getContent();
 436
 437                         // Biome is recalculated each time an upper surface is detected while
 438                         // working down a column. The selected biome then remains in effect for
 439                         // all nodes below until the next surface and biome recalculation.
 440                         // Biome is recalculated:
 441                         // 1. At the surface of stone below air or water.
 442                         // 2. At the surface of water below air.
 443                         // 3. When stone or water is detected but biome has not yet been calculated.
 444                         if ((c == c_stone && (air_above || water_above || !biome)) ||
 445                                         (c == c_water_source && (air_above || !biome))) {
 446                                 biome = bmgr->getBiome(heat_map[index], humidity_map[index], y);
 447                                 depth_top = biome->depth_top;
 448                                 base_filler = MYMAX(depth_top + biome->depth_filler
 449                                         + noise_filler_depth->result[index], 0);
 450                                 depth_water_top = biome->depth_water_top;
 451
 452                                 // Detect stone type for dungeons during every biome calculation.
 453                                 // This is more efficient than detecting per-node and will not
 454                                 // miss any desert stone or sandstone biomes.
 455                                 if (biome->c_stone == c_desert_stone)
 456                                         stone_type = DESERT_STONE;
 457                                 else if (biome->c_stone == c_sandstone)
 458                                         stone_type = SANDSTONE;
 459                         }
 460
 461                         if (c == c_stone) {
 462                                 content_t c_below = vm->m_data[vi - em.X].getContent();
 463
 464                                 // If the node below isn't solid, make this node stone, so that
 465                                 // any top/filler nodes above are structurally supported.
 466                                 // This is done by aborting the cycle of top/filler placement
 467                                 // immediately by forcing nplaced to stone level.
 468                                 if (c_below == CONTENT_AIR || c_below == c_water_source)
 469                                         nplaced = U16_MAX;
 470
 471                                 if (nplaced < depth_top) {
 472                                         vm->m_data[vi] = MapNode(biome->c_top);
 473                                         nplaced++;
 474                                 } else if (nplaced < base_filler) {
 475                                         vm->m_data[vi] = MapNode(biome->c_filler);
 476                                         nplaced++;
 477                                 } else {
 478                                         vm->m_data[vi] = MapNode(biome->c_stone);
 479                                 }
 480
 481                                 air_above = false;
 482                                 water_above = false;
 483                         } else if (c == c_water_source) {
 484                                 vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) ?
 485                                                 biome->c_water_top : biome->c_water);
 486                                 nplaced = 0;  // Enable top/filler placement for next surface
 487                                 air_above = false;
 488                                 water_above = true;
 489                         } else if (c == CONTENT_AIR) {
 490                                 nplaced = 0;  // Enable top/filler placement for next surface
 491                                 air_above = true;
 492                                 water_above = false;
 493                         } else {  // Possible various nodes overgenerated from neighbouring mapchunks
 494                                 nplaced = U16_MAX;  // Disable top/filler placement
 495                                 air_above = false;
 496                                 water_above = false;
 497                         }
 498
 499                         vm->m_area.add_y(em, vi, -1);
 500                 }
 501         }
 502
 503         return stone_type;
 504 }
 505
 506
 507 void MapgenFlat::dustTopNodes()
 508 {
 509         if (node_max.Y < water_level)
 510                 return;
 511
 512         v3s16 em = vm->m_area.getExtent();
 513         u32 index = 0;
 514
 515         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 516         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 517                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
 518
 519                 if (biome->c_dust == CONTENT_IGNORE)
 520                         continue;
 521
 522                 u32 vi = vm->m_area.index(x, full_node_max.Y, z);
 523                 content_t c_full_max = vm->m_data[vi].getContent();
 524                 s16 y_start;
 525
 526                 if (c_full_max == CONTENT_AIR) {
 527                         y_start = full_node_max.Y - 1;
 528                 } else if (c_full_max == CONTENT_IGNORE) {
 529                         vi = vm->m_area.index(x, node_max.Y + 1, z);
 530                         content_t c_max = vm->m_data[vi].getContent();
 531
 532                         if (c_max == CONTENT_AIR)
 533                                 y_start = node_max.Y;
 534                         else
 535                                 continue;
 536                 } else {
 537                         continue;
 538                 }
 539
 540                 vi = vm->m_area.index(x, y_start, z);
 541                 for (s16 y = y_start; y >= node_min.Y - 1; y--) {
 542                         if (vm->m_data[vi].getContent() != CONTENT_AIR)
 543                                 break;
 544
 545                         vm->m_area.add_y(em, vi, -1);
 546                 }
 547
 548                 content_t c = vm->m_data[vi].getContent();
 549                 if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
 550                         vm->m_area.add_y(em, vi, 1);
 551                         vm->m_data[vi] = MapNode(biome->c_dust);
 552                 }
 553         }
 554 }
 555
 556
 557 void MapgenFlat::generateCaves(s16 max_stone_y)
 558 {
 559         if (max_stone_y < node_min.Y)
 560                 return;
 561
 562         noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
 563         noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
 564
 565         v3s16 em = vm->m_area.getExtent();
 566         u32 index2d = 0;
 567
 568         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 569         for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
 570                 bool column_is_open = false;  // Is column open to overground
 571                 bool is_tunnel = false;  // Is tunnel or tunnel floor
 572                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 573                 u32 index3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride +
 574                         (x - node_min.X);
 575                 // Biome of column
 576                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
 577
 578                 // Don't excavate the overgenerated stone at node_max.Y + 1,
 579                 // this creates a 'roof' over the tunnel, preventing light in
 580                 // tunnels at mapchunk borders when generating mapchunks upwards.
 581                 // This 'roof' is removed when the mapchunk above is generated.
 582                 for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
 583                                 index3d -= ystride,
 584                                 vm->m_area.add_y(em, vi, -1)) {
 585
 586                         content_t c = vm->m_data[vi].getContent();
 587                         if (c == CONTENT_AIR || c == biome->c_water_top ||
 588                                         c == biome->c_water) {
 589                                 column_is_open = true;
 590                                 continue;
 591                         }
 592                         // Ground
 593                         float d1 = contour(noise_cave1->result[index3d]);
 594                         float d2 = contour(noise_cave2->result[index3d]);
 595
 596                         if (d1 * d2 > cave_width && ndef->get(c).is_ground_content) {
 597                                 // In tunnel and ground content, excavate
 598                                 vm->m_data[vi] = MapNode(CONTENT_AIR);
 599                                 is_tunnel = true;
 600                         } else {
 601                                 // Not in tunnel or not ground content
 602                                 if (is_tunnel && column_is_open &&
 603                                                 (c == biome->c_filler || c == biome->c_stone))
 604                                         // Tunnel entrance floor
 605                                         vm->m_data[vi] = MapNode(biome->c_top);
 606
 607                                 column_is_open = false;
 608                                 is_tunnel = false;
 609                         }
 610                 }
 611         }
 612
 613         if (node_max.Y > large_cave_depth)
 614                 return;
 615
 616         PseudoRandom ps(blockseed + 21343);
 617         u32 bruises_count = ps.range(0, 2);
 618         for (u32 i = 0; i < bruises_count; i++) {
 619                 CaveV5 cave(this, &ps);
 620                 cave.makeCave(node_min, node_max, max_stone_y);
 621         }
 622 }