src/mapgen_v5.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_v5.h"
  41
  42
  43 FlagDesc flagdesc_mapgen_v5[] = {
  44         {NULL,         0}
  45 };
  46
  47
  48 MapgenV5::MapgenV5(int mapgenid, MapgenParams *params, EmergeManager *emerge)
  49         : Mapgen(mapgenid, params, emerge)
  50 {
  51         this->m_emerge = emerge;
  52         this->bmgr     = emerge->biomemgr;
  53
  54         // amount of elements to skip for the next index
  55         // for noise/height/biome maps (not vmanip)
  56         this->ystride = csize.X;
  57         // 1-down overgeneration
  58         this->zstride_1d = csize.X * (csize.Y + 1);
  59
  60         this->heightmap = new s16[csize.X * csize.Z];
  61
  62         MapgenV5Params *sp = (MapgenV5Params *)params->sparams;
  63
  64         this->spflags    = sp->spflags;
  65         this->cave_width = sp->cave_width;
  66
  67         // Terrain noise
  68         noise_filler_depth = new Noise(&sp->np_filler_depth, seed, csize.X, csize.Z);
  69         noise_factor       = new Noise(&sp->np_factor,       seed, csize.X, csize.Z);
  70         noise_height       = new Noise(&sp->np_height,       seed, csize.X, csize.Z);
  71
  72         // 3D terrain noise
  73         // 1-up 1-down overgeneration
  74         noise_ground = new Noise(&sp->np_ground, seed, csize.X, csize.Y + 2, csize.Z);
  75         // 1-down overgeneraion
  76         noise_cave1  = new Noise(&sp->np_cave1,  seed, csize.X, csize.Y + 1, csize.Z);
  77         noise_cave2  = new Noise(&sp->np_cave2,  seed, csize.X, csize.Y + 1, csize.Z);
  78
  79         //// Initialize biome generator
  80         biomegen = emerge->biomemgr->createBiomeGen(
  81                 BIOMEGEN_ORIGINAL, params->bparams, csize);
  82         biomemap = biomegen->biomemap;
  83
  84         //// Resolve nodes to be used
  85         c_stone                = ndef->getId("mapgen_stone");
  86         c_water_source         = ndef->getId("mapgen_water_source");
  87         c_lava_source          = ndef->getId("mapgen_lava_source");
  88         c_desert_stone         = ndef->getId("mapgen_desert_stone");
  89         c_ice                  = ndef->getId("mapgen_ice");
  90         c_sandstone            = ndef->getId("mapgen_sandstone");
  91
  92         c_cobble               = ndef->getId("mapgen_cobble");
  93         c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
  94         c_mossycobble          = ndef->getId("mapgen_mossycobble");
  95         c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
  96         c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
  97
  98         if (c_ice == CONTENT_IGNORE)
  99                 c_ice = CONTENT_AIR;
 100         if (c_mossycobble == CONTENT_IGNORE)
 101                 c_mossycobble = c_cobble;
 102         if (c_stair_cobble == CONTENT_IGNORE)
 103                 c_stair_cobble = c_cobble;
 104         if (c_sandstonebrick == CONTENT_IGNORE)
 105                 c_sandstonebrick = c_sandstone;
 106         if (c_stair_sandstonebrick == CONTENT_IGNORE)
 107                 c_stair_sandstonebrick = c_sandstone;
 108 }
 109
 110
 111 MapgenV5::~MapgenV5()
 112 {
 113         delete noise_filler_depth;
 114         delete noise_factor;
 115         delete noise_height;
 116         delete noise_cave1;
 117         delete noise_cave2;
 118         delete noise_ground;
 119
 120         delete biomegen;
 121
 122         delete[] heightmap;
 123 }
 124
 125
 126 MapgenV5Params::MapgenV5Params()
 127 {
 128         spflags    = 0;
 129         cave_width = 0.125;
 130
 131         np_filler_depth = NoiseParams(0, 1,  v3f(150, 150, 150), 261,    4, 0.7,  2.0);
 132         np_factor       = NoiseParams(0, 1,  v3f(250, 250, 250), 920381, 3, 0.45, 2.0);
 133         np_height       = NoiseParams(0, 10, v3f(250, 250, 250), 84174,  4, 0.5,  2.0);
 134         np_cave1        = NoiseParams(0, 12, v3f(50,  50,  50),  52534,  4, 0.5,  2.0);
 135         np_cave2        = NoiseParams(0, 12, v3f(50,  50,  50),  10325,  4, 0.5,  2.0);
 136         np_ground       = NoiseParams(0, 40, v3f(80,  80,  80),  983240, 4, 0.55, 2.0, NOISE_FLAG_EASED);
 137 }
 138
 139
 140 //#define CAVE_NOISE_SCALE 12.0
 141 //#define CAVE_NOISE_THRESHOLD (1.5/CAVE_NOISE_SCALE) = 0.125
 142
 143
 144 void MapgenV5Params::readParams(const Settings *settings)
 145 {
 146         settings->getFlagStrNoEx("mgv5_spflags",  spflags, flagdesc_mapgen_v5);
 147         settings->getFloatNoEx("mgv5_cave_width", cave_width);
 148
 149         settings->getNoiseParams("mgv5_np_filler_depth", np_filler_depth);
 150         settings->getNoiseParams("mgv5_np_factor",       np_factor);
 151         settings->getNoiseParams("mgv5_np_height",       np_height);
 152         settings->getNoiseParams("mgv5_np_cave1",        np_cave1);
 153         settings->getNoiseParams("mgv5_np_cave2",        np_cave2);
 154         settings->getNoiseParams("mgv5_np_ground",       np_ground);
 155 }
 156
 157
 158 void MapgenV5Params::writeParams(Settings *settings) const
 159 {
 160         settings->setFlagStr("mgv5_spflags",  spflags, flagdesc_mapgen_v5, U32_MAX);
 161         settings->setFloat("mgv5_cave_width", cave_width);
 162
 163         settings->setNoiseParams("mgv5_np_filler_depth", np_filler_depth);
 164         settings->setNoiseParams("mgv5_np_factor",       np_factor);
 165         settings->setNoiseParams("mgv5_np_height",       np_height);
 166         settings->setNoiseParams("mgv5_np_cave1",        np_cave1);
 167         settings->setNoiseParams("mgv5_np_cave2",        np_cave2);
 168         settings->setNoiseParams("mgv5_np_ground",       np_ground);
 169 }
 170
 171
 172 int MapgenV5::getSpawnLevelAtPoint(v2s16 p)
 173 {
 174         //TimeTaker t("getGroundLevelAtPoint", NULL, PRECISION_MICRO);
 175
 176         float f = 0.55 + NoisePerlin2D(&noise_factor->np, p.X, p.Y, seed);
 177         if (f < 0.01)
 178                 f = 0.01;
 179         else if (f >= 1.0)
 180                 f *= 1.6;
 181         float h = NoisePerlin2D(&noise_height->np, p.X, p.Y, seed);
 182
 183         for (s16 y = 128; y >= -128; y--) {
 184                 float n_ground = NoisePerlin3D(&noise_ground->np, p.X, y, p.Y, seed);
 185
 186                 if (n_ground * f > y - h) {  // If solid
 187                         // If either top 2 nodes of search are solid this is inside a
 188                         // mountain or floatland with possibly no space for the player to spawn.
 189                         if (y >= 127) {
 190                                 return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
 191                         } else {  // Ground below at least 2 nodes of empty space
 192                                 if (y <= water_level || y > water_level + 16)
 193                                         return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
 194                                 else
 195                                         return y;
 196                         }
 197                 }
 198         }
 199
 200         //printf("getGroundLevelAtPoint: %dus\n", t.stop());
 201         return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn position, no ground found
 202 }
 203
 204
 205 void MapgenV5::makeChunk(BlockMakeData *data)
 206 {
 207         // Pre-conditions
 208         assert(data->vmanip);
 209         assert(data->nodedef);
 210         assert(data->blockpos_requested.X >= data->blockpos_min.X &&
 211                 data->blockpos_requested.Y >= data->blockpos_min.Y &&
 212                 data->blockpos_requested.Z >= data->blockpos_min.Z);
 213         assert(data->blockpos_requested.X <= data->blockpos_max.X &&
 214                 data->blockpos_requested.Y <= data->blockpos_max.Y &&
 215                 data->blockpos_requested.Z <= data->blockpos_max.Z);
 216
 217         this->generating = true;
 218         this->vm   = data->vmanip;
 219         this->ndef = data->nodedef;
 220         //TimeTaker t("makeChunk");
 221
 222         v3s16 blockpos_min = data->blockpos_min;
 223         v3s16 blockpos_max = data->blockpos_max;
 224         node_min = blockpos_min * MAP_BLOCKSIZE;
 225         node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 226         full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
 227         full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
 228
 229         // Create a block-specific seed
 230         blockseed = getBlockSeed2(full_node_min, seed);
 231
 232         // Make some noise
 233         calculateNoise();
 234
 235         // Generate base terrain
 236         s16 stone_surface_max_y = generateBaseTerrain();
 237
 238         // Create heightmap
 239         updateHeightmap(node_min, node_max);
 240
 241         // Init biome generator, place biome-specific nodes, and build biomemap
 242         biomegen->calcBiomeNoise(node_min);
 243         biomegen->getBiomes(heightmap);
 244         MgStoneType stone_type = generateBiomes();
 245
 246         // Generate caves
 247         if ((flags & MG_CAVES) && (stone_surface_max_y >= node_min.Y))
 248                 generateCaves(stone_surface_max_y);
 249
 250         // Generate dungeons and desert temples
 251         if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 252                 DungeonParams dp;
 253
 254                 dp.np_rarity  = nparams_dungeon_rarity;
 255                 dp.np_density = nparams_dungeon_density;
 256                 dp.np_wetness = nparams_dungeon_wetness;
 257                 dp.c_water    = c_water_source;
 258                 if (stone_type == STONE) {
 259                         dp.c_cobble = c_cobble;
 260                         dp.c_moss   = c_mossycobble;
 261                         dp.c_stair  = c_stair_cobble;
 262
 263                         dp.diagonal_dirs = false;
 264                         dp.mossratio     = 3.0;
 265                         dp.holesize      = v3s16(1, 2, 1);
 266                         dp.roomsize      = v3s16(0, 0, 0);
 267                         dp.notifytype    = GENNOTIFY_DUNGEON;
 268                 } else if (stone_type == DESERT_STONE) {
 269                         dp.c_cobble = c_desert_stone;
 270                         dp.c_moss   = c_desert_stone;
 271                         dp.c_stair  = c_desert_stone;
 272
 273                         dp.diagonal_dirs = true;
 274                         dp.mossratio     = 0.0;
 275                         dp.holesize      = v3s16(2, 3, 2);
 276                         dp.roomsize      = v3s16(2, 5, 2);
 277                         dp.notifytype    = GENNOTIFY_TEMPLE;
 278                 } else if (stone_type == SANDSTONE) {
 279                         dp.c_cobble = c_sandstonebrick;
 280                         dp.c_moss   = c_sandstonebrick;
 281                         dp.c_stair  = c_sandstonebrick;
 282
 283                         dp.diagonal_dirs = false;
 284                         dp.mossratio     = 0.0;
 285                         dp.holesize      = v3s16(2, 2, 2);
 286                         dp.roomsize      = v3s16(2, 0, 2);
 287                         dp.notifytype    = GENNOTIFY_DUNGEON;
 288                 }
 289
 290                 DungeonGen dgen(this, &dp);
 291                 dgen.generate(blockseed, full_node_min, full_node_max);
 292         }
 293
 294         // Generate the registered decorations
 295         if (flags & MG_DECORATIONS)
 296                 m_emerge->decomgr->placeAllDecos(this, blockseed, node_min, node_max);
 297
 298         // Generate the registered ores
 299         m_emerge->oremgr->placeAllOres(this, blockseed, node_min, node_max);
 300
 301         // Sprinkle some dust on top after everything else was generated
 302         dustTopNodes();
 303
 304         //printf("makeChunk: %dms\n", t.stop());
 305
 306         // Add top and bottom side of water to transforming_liquid queue
 307         updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
 308
 309         // Calculate lighting
 310         if (flags & MG_LIGHT) {
 311                 calcLighting(node_min - v3s16(0, 1, 0), node_max + v3s16(0, 1, 0),
 312                         full_node_min, full_node_max);
 313         }
 314
 315         this->generating = false;
 316 }
 317
 318
 319 void MapgenV5::calculateNoise()
 320 {
 321         //TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
 322         s16 x = node_min.X;
 323         s16 y = node_min.Y - 1;
 324         s16 z = node_min.Z;
 325
 326         noise_factor->perlinMap2D(x, z);
 327         noise_height->perlinMap2D(x, z);
 328         noise_ground->perlinMap3D(x, y, z);
 329
 330         // Cave noises are calculated in generateCaves()
 331         // only if solid terrain is present in mapchunk
 332
 333         noise_filler_depth->perlinMap2D(x, z);
 334
 335         //printf("calculateNoise: %dus\n", t.stop());
 336 }
 337
 338
 339 //bool is_cave(u32 index) {
 340 //      double d1 = contour(noise_cave1->result[index]);
 341 //      double d2 = contour(noise_cave2->result[index]);
 342 //      return d1*d2 > CAVE_NOISE_THRESHOLD;
 343 //}
 344
 345 //bool val_is_ground(v3s16 p, u32 index, u32 index2d) {
 346 //      double f = 0.55 + noise_factor->result[index2d];
 347 //      if(f < 0.01)
 348 //              f = 0.01;
 349 //      else if(f >= 1.0)
 350 //              f *= 1.6;
 351 //      double h = WATER_LEVEL + 10 * noise_height->result[index2d];
 352 //      return (noise_ground->result[index] * f > (double)p.Y - h);
 353 //}
 354
 355
 356 int MapgenV5::generateBaseTerrain()
 357 {
 358         u32 index = 0;
 359         u32 index2d = 0;
 360         int stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
 361
 362         for (s16 z=node_min.Z; z<=node_max.Z; z++) {
 363                 for (s16 y=node_min.Y - 1; y<=node_max.Y + 1; y++) {
 364                         u32 vi = vm->m_area.index(node_min.X, y, z);
 365                         for (s16 x=node_min.X; x<=node_max.X; x++, vi++, index++, index2d++) {
 366                                 if (vm->m_data[vi].getContent() != CONTENT_IGNORE)
 367                                         continue;
 368
 369                                 float f = 0.55 + noise_factor->result[index2d];
 370                                 if (f < 0.01)
 371                                         f = 0.01;
 372                                 else if (f >= 1.0)
 373                                         f *= 1.6;
 374                                 float h = noise_height->result[index2d];
 375
 376                                 if (noise_ground->result[index] * f < y - h) {
 377                                         if (y <= water_level)
 378                                                 vm->m_data[vi] = MapNode(c_water_source);
 379                                         else
 380                                                 vm->m_data[vi] = MapNode(CONTENT_AIR);
 381                                 } else {
 382                                         vm->m_data[vi] = MapNode(c_stone);
 383                                         if (y > stone_surface_max_y)
 384                                                 stone_surface_max_y = y;
 385                                 }
 386                         }
 387                         index2d -= ystride;
 388                 }
 389                 index2d += ystride;
 390         }
 391
 392         return stone_surface_max_y;
 393 }
 394
 395
 396 MgStoneType MapgenV5::generateBiomes()
 397 {
 398         v3s16 em = vm->m_area.getExtent();
 399         u32 index = 0;
 400         MgStoneType stone_type = STONE;
 401
 402         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 403         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 404                 Biome *biome = NULL;
 405                 u16 depth_top = 0;
 406                 u16 base_filler = 0;
 407                 u16 depth_water_top = 0;
 408                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 409
 410                 // Check node at base of mapchunk above, either a node of a previously
 411                 // generated mapchunk or if not, a node of overgenerated base terrain.
 412                 content_t c_above = vm->m_data[vi + em.X].getContent();
 413                 bool air_above = c_above == CONTENT_AIR;
 414                 bool water_above = c_above == c_water_source;
 415
 416                 // If there is air or water above enable top/filler placement, otherwise force
 417                 // nplaced to stone level by setting a number exceeding any possible filler depth.
 418                 u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
 419
 420                 for (s16 y = node_max.Y; y >= node_min.Y; y--) {
 421                         content_t c = vm->m_data[vi].getContent();
 422
 423                         // Biome is recalculated each time an upper surface is detected while
 424                         // working down a column. The selected biome then remains in effect for
 425                         // all nodes below until the next surface and biome recalculation.
 426                         // Biome is recalculated:
 427                         // 1. At the surface of stone below air or water.
 428                         // 2. At the surface of water below air.
 429                         // 3. When stone or water is detected but biome has not yet been calculated.
 430                         if ((c == c_stone && (air_above || water_above || !biome)) ||
 431                                         (c == c_water_source && (air_above || !biome))) {
 432                                 biome = biomegen->getBiomeAtIndex(index, y);
 433
 434                                 depth_top = biome->depth_top;
 435                                 base_filler = MYMAX(depth_top + biome->depth_filler
 436                                                 + noise_filler_depth->result[index], 0);
 437                                 depth_water_top = biome->depth_water_top;
 438
 439                                 // Detect stone type for dungeons during every biome calculation.
 440                                 // This is more efficient than detecting per-node and will not
 441                                 // miss any desert stone or sandstone biomes.
 442                                 if (biome->c_stone == c_desert_stone)
 443                                         stone_type = DESERT_STONE;
 444                                 else if (biome->c_stone == c_sandstone)
 445                                         stone_type = SANDSTONE;
 446                         }
 447
 448                         if (c == c_stone) {
 449                                 content_t c_below = vm->m_data[vi - em.X].getContent();
 450
 451                                 // If the node below isn't solid, make this node stone, so that
 452                                 // any top/filler nodes above are structurally supported.
 453                                 // This is done by aborting the cycle of top/filler placement
 454                                 // immediately by forcing nplaced to stone level.
 455                                 if (c_below == CONTENT_AIR || c_below == c_water_source)
 456                                         nplaced = U16_MAX;
 457
 458                                 if (nplaced < depth_top) {
 459                                         vm->m_data[vi] = MapNode(biome->c_top);
 460                                         nplaced++;
 461                                 } else if (nplaced < base_filler) {
 462                                         vm->m_data[vi] = MapNode(biome->c_filler);
 463                                         nplaced++;
 464                                 } else {
 465                                         vm->m_data[vi] = MapNode(biome->c_stone);
 466                                 }
 467
 468                                 air_above = false;
 469                                 water_above = false;
 470                         } else if (c == c_water_source) {
 471                                 vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) ?
 472                                                 biome->c_water_top : biome->c_water);
 473                                 nplaced = 0;  // Enable top/filler placement for next surface
 474                                 air_above = false;
 475                                 water_above = true;
 476                         } else if (c == CONTENT_AIR) {
 477                                 nplaced = 0;  // Enable top/filler placement for next surface
 478                                 air_above = true;
 479                                 water_above = false;
 480                         } else {  // Possible various nodes overgenerated from neighbouring mapchunks
 481                                 nplaced = U16_MAX;  // Disable top/filler placement
 482                                 air_above = false;
 483                                 water_above = false;
 484                         }
 485
 486                         vm->m_area.add_y(em, vi, -1);
 487                 }
 488         }
 489
 490         return stone_type;
 491 }
 492
 493
 494 void MapgenV5::dustTopNodes()
 495 {
 496         if (node_max.Y < water_level)
 497                 return;
 498
 499         v3s16 em = vm->m_area.getExtent();
 500         u32 index = 0;
 501
 502         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 503         for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
 504                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
 505
 506                 if (biome->c_dust == CONTENT_IGNORE)
 507                         continue;
 508
 509                 u32 vi = vm->m_area.index(x, full_node_max.Y, z);
 510                 content_t c_full_max = vm->m_data[vi].getContent();
 511                 s16 y_start;
 512
 513                 if (c_full_max == CONTENT_AIR) {
 514                         y_start = full_node_max.Y - 1;
 515                 } else if (c_full_max == CONTENT_IGNORE) {
 516                         vi = vm->m_area.index(x, node_max.Y + 1, z);
 517                         content_t c_max = vm->m_data[vi].getContent();
 518
 519                         if (c_max == CONTENT_AIR)
 520                                 y_start = node_max.Y;
 521                         else
 522                                 continue;
 523                 } else {
 524                         continue;
 525                 }
 526
 527                 vi = vm->m_area.index(x, y_start, z);
 528                 for (s16 y = y_start; y >= node_min.Y - 1; y--) {
 529                         if (vm->m_data[vi].getContent() != CONTENT_AIR)
 530                                 break;
 531
 532                         vm->m_area.add_y(em, vi, -1);
 533                 }
 534
 535                 content_t c = vm->m_data[vi].getContent();
 536                 if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
 537                         vm->m_area.add_y(em, vi, 1);
 538                         vm->m_data[vi] = MapNode(biome->c_dust);
 539                 }
 540         }
 541 }
 542
 543
 544 void MapgenV5::generateCaves(int max_stone_y)
 545 {
 546         if (max_stone_y < node_min.Y)
 547                 return;
 548
 549         noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
 550         noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
 551
 552         v3s16 em = vm->m_area.getExtent();
 553         u32 index2d = 0;
 554
 555         for (s16 z = node_min.Z; z <= node_max.Z; z++)
 556         for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
 557                 bool column_is_open = false;  // Is column open to overground
 558                 bool is_tunnel = false;  // Is tunnel or tunnel floor
 559                 // Indexes at column top (node_max.Y)
 560                 u32 vi = vm->m_area.index(x, node_max.Y, z);
 561                 u32 index3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride +
 562                         (x - node_min.X);
 563                 // Biome of column
 564                 Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
 565
 566                 // Don't excavate the overgenerated stone at node_max.Y + 1,
 567                 // this creates a 'roof' over the tunnel, preventing light in
 568                 // tunnels at mapchunk borders when generating mapchunks upwards.
 569                 // This 'roof' is removed when the mapchunk above is generated.
 570                 for (s16 y = node_max.Y; y >= node_min.Y - 1; y--,
 571                                 index3d -= ystride,
 572                                 vm->m_area.add_y(em, vi, -1)) {
 573
 574                         content_t c = vm->m_data[vi].getContent();
 575                         if (c == CONTENT_AIR || c == biome->c_water_top ||
 576                                         c == biome->c_water) {
 577                                 column_is_open = true;
 578                                 continue;
 579                         }
 580                         // Ground
 581                         float d1 = contour(noise_cave1->result[index3d]);
 582                         float d2 = contour(noise_cave2->result[index3d]);
 583
 584                         if (d1 * d2 > cave_width && ndef->get(c).is_ground_content) {
 585                                 // In tunnel and ground content, excavate
 586                                 vm->m_data[vi] = MapNode(CONTENT_AIR);
 587                                 is_tunnel = true;
 588                         } else {
 589                                 // Not in tunnel or not ground content
 590                                 if (is_tunnel && column_is_open &&
 591                                                 (c == biome->c_filler || c == biome->c_stone))
 592                                         // Tunnel entrance floor
 593                                         vm->m_data[vi] = MapNode(biome->c_top);
 594
 595                                 column_is_open = false;
 596                                 is_tunnel = false;
 597                         }
 598                 }
 599         }
 600
 601         if (node_max.Y > MGV5_LARGE_CAVE_DEPTH)
 602                 return;
 603
 604         PseudoRandom ps(blockseed + 21343);
 605         u32 bruises_count = ps.range(0, 2);
 606         for (u32 i = 0; i < bruises_count; i++) {
 607                 CaveV5 cave(this, &ps);
 608                 cave.makeCave(node_min, node_max, max_stone_y);
 609         }
 610 }