Add Valleys mapgen.

1 files changed, 983 insertions, 0 deletions

diff --git a/src/mapgen_valleys.cpp b/src/mapgen_valleys.cpp
new file mode 100644
index 000000000..c14ceb51e
--- /dev/null
+++ b/src/mapgen_valleys.cpp
@@ -0,0 +1,983 @@
+/*
+Minetest Valleys C
+Copyright (C) 2010-2015 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2010-2015 paramat, Matt Gregory
+Copyright (C) 2016 Duane Robertson <duane@duanerobertson.com>
+
+Based on Valleys Mapgen by Gael de Sailly
+ (https://forum.minetest.net/viewtopic.php?f=9&t=11430)
+and mapgen_v7 by kwolekr and paramat.
+
+Licensing changed by permission of Gael de Sailly.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+
+#include "mapgen.h"
+#include "voxel.h"
+#include "noise.h"
+#include "mapblock.h"
+#include "mapnode.h"
+#include "map.h"
+#include "content_sao.h"
+#include "nodedef.h"
+#include "voxelalgorithms.h"
+#include "settings.h" // For g_settings
+#include "emerge.h"
+#include "dungeongen.h"
+#include "treegen.h"
+#include "mg_biome.h"
+#include "mg_ore.h"
+#include "mg_decoration.h"
+#include "mapgen_valleys.h"
+
+//#undef NDEBUG
+//#include "assert.h"
+
+//#include "util/timetaker.h"
+//#include "profiler.h"
+
+
+//static Profiler mapgen_prof;
+//Profiler *mapgen_profiler = &mapgen_prof;
+
+static FlagDesc flagdesc_mapgen_valleys[] = {
+	{"altitude_chill",  MG_VALLEYS_ALT_CHILL},
+	{"cliffs",          MG_VALLEYS_CLIFFS},
+	{"fast",            MG_VALLEYS_FAST},
+	{"humid_rivers",    MG_VALLEYS_HUMID_RIVERS},
+	{"rugged",          MG_VALLEYS_RUGGED},
+	{NULL,              0}
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+
+MapgenValleys::MapgenValleys(int mapgenid, MapgenParams *params, EmergeManager *emerge)
+	: Mapgen(mapgenid, params, emerge)
+{
+	this->m_emerge = emerge;
+	this->bmgr = emerge->biomemgr;
+
+	//// amount of elements to skip for the next index
+	//// for noise/height/biome maps (not vmanip)
+	this->ystride = csize.X;
+	this->zstride = csize.X * (csize.Y + 2);
+
+	this->biomemap  = new u8[csize.X * csize.Z];
+	this->heightmap = new s16[csize.X * csize.Z];
+	this->heatmap   = NULL;
+	this->humidmap  = NULL;
+
+	MapgenValleysParams *sp = (MapgenValleysParams *)params->sparams;
+	this->spflags = sp->spflags;
+
+	this->cliff_terrain      = (spflags & MG_VALLEYS_CLIFFS);
+	this->fast_terrain       = (spflags & MG_VALLEYS_FAST);
+	this->humid_rivers       = (spflags & MG_VALLEYS_HUMID_RIVERS);
+	this->rugged_terrain     = (spflags & MG_VALLEYS_RUGGED);
+	this->use_altitude_chill = (spflags & MG_VALLEYS_ALT_CHILL);
+
+	this->altitude_chill        = sp->altitude_chill;
+	this->cave_water_max_height = sp->cave_water_max_height;
+	this->humidity_adjust       = sp->humidity - 50.f;
+	this->humidity_break_point  = sp->humidity_break_point;
+	this->lava_max_height       = sp->lava_max_height;
+	this->river_depth           = sp->river_depth + 1.f;
+	this->river_size            = sp->river_size / 100.f;
+	this->temperature_adjust    = sp->temperature - 50.f;
+	this->water_features        = MYMAX(1, MYMIN(11, 11 - sp->water_features));
+
+	//// 2D Terrain noise
+	noise_cliffs             = new Noise(&sp->np_cliffs,             seed, csize.X, csize.Z);
+	noise_corr               = new Noise(&sp->np_corr,               seed, csize.X, csize.Z);
+	noise_filler_depth       = new Noise(&sp->np_filler_depth,       seed, csize.X, csize.Z);
+	noise_inter_valley_slope = new Noise(&sp->np_inter_valley_slope, seed, csize.X, csize.Z);
+	noise_rivers             = new Noise(&sp->np_rivers,             seed, csize.X, csize.Z);
+	noise_terrain_height     = new Noise(&sp->np_terrain_height,     seed, csize.X, csize.Z);
+	noise_valley_depth       = new Noise(&sp->np_valley_depth,       seed, csize.X, csize.Z);
+	noise_valley_profile     = new Noise(&sp->np_valley_profile,     seed, csize.X, csize.Z);
+
+	if (this->fast_terrain)
+		noise_inter_valley_fill = new Noise(&sp->np_inter_valley_fill, seed, csize.X, csize.Z);
+
+	//// 3D Terrain noise
+	noise_simple_caves_1 = new Noise(&sp->np_simple_caves_1, seed, csize.X, csize.Y + 2, csize.Z);
+	noise_simple_caves_2 = new Noise(&sp->np_simple_caves_2, seed, csize.X, csize.Y + 2, csize.Z);
+
+	if (!this->fast_terrain)
+		noise_inter_valley_fill = new Noise(&sp->np_inter_valley_fill, seed, csize.X, csize.Y + 2, csize.Z);
+
+	//// Biome noise
+	noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
+	noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
+	noise_humidity_blend = new Noise(&params->np_biome_humidity_blend, seed, csize.X, csize.Z);
+	noise_humidity       = new Noise(&params->np_biome_humidity,       seed, csize.X, csize.Z);
+
+	//// Resolve nodes to be used
+	INodeDefManager *ndef = emerge->ndef;
+
+	c_cobble               = ndef->getId("mapgen_cobble");
+	c_desert_stone         = ndef->getId("mapgen_desert_stone");
+	c_dirt                 = ndef->getId("mapgen_dirt");
+	c_lava_source          = ndef->getId("mapgen_lava_source");
+	c_mossycobble          = ndef->getId("mapgen_mossycobble");
+	c_river_water_source   = ndef->getId("mapgen_river_water_source");
+	c_sand                 = ndef->getId("mapgen_sand");
+	c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
+	c_sandstone            = ndef->getId("mapgen_sandstone");
+	c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
+	c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
+	c_stone                = ndef->getId("mapgen_stone");
+	c_water_source         = ndef->getId("mapgen_water_source");
+
+	if (c_mossycobble == CONTENT_IGNORE)
+		c_mossycobble = c_cobble;
+	if (c_river_water_source == CONTENT_IGNORE)
+		c_river_water_source = c_water_source;
+	if (c_sand == CONTENT_IGNORE)
+		c_sand = c_stone;
+	if (c_sandstonebrick == CONTENT_IGNORE)
+		c_sandstonebrick = c_sandstone;
+	if (c_stair_cobble == CONTENT_IGNORE)
+		c_stair_cobble = c_cobble;
+	if (c_stair_sandstonebrick == CONTENT_IGNORE)
+		c_stair_sandstonebrick = c_sandstone;
+}
+
+
+MapgenValleys::~MapgenValleys()
+{
+	delete noise_cliffs;
+	delete noise_corr;
+	delete noise_filler_depth;
+	delete noise_heat;
+	delete noise_heat_blend;
+	delete noise_humidity;
+	delete noise_humidity_blend;
+	delete noise_inter_valley_fill;
+	delete noise_inter_valley_slope;
+	delete noise_rivers;
+	delete noise_simple_caves_1;
+	delete noise_simple_caves_2;
+	delete noise_terrain_height;
+	delete noise_valley_depth;
+	delete noise_valley_profile;
+
+	delete[] heightmap;
+	delete[] biomemap;
+}
+
+
+MapgenValleysParams::MapgenValleysParams()
+{
+	spflags = MG_VALLEYS_CLIFFS | MG_VALLEYS_RUGGED
+	         	| MG_VALLEYS_HUMID_RIVERS | MG_VALLEYS_ALT_CHILL;
+
+	altitude_chill         =  90; // The altitude at which temperature drops by 20C.
+	// Water in caves will never be higher than this.
+	cave_water_max_height  =  MAX_MAP_GENERATION_LIMIT;
+	humidity               =  50;
+	// the maximum humidity around rivers in otherwise dry areas
+	humidity_break_point   =  65;
+	lava_max_height        =  0;  // Lava will never be higher than this.
+	river_depth            =  4;  // How deep to carve river channels.
+	river_size             =  5;  // How wide to make rivers.
+	temperature            =  50;
+	water_features         =  3;  // How often water will occur in caves.
+
+	np_cliffs             = NoiseParams(0.f,   1.f,  v3f(750,  750,  750),  8445,  5, 1.f,  2.f);
+	np_corr               = NoiseParams(0.f,   1.f,  v3f(40,   40,   40),   -3536, 4, 1.f,  2.f);
+	np_filler_depth       = NoiseParams(0.f,   1.2f, v3f(256,  256,  256),  1605,  3, 0.5f, 2.f);
+	np_inter_valley_fill  = NoiseParams(0.f,   1.f,  v3f(256,  512,  256),  1993,  6, 0.8f, 2.f);
+	np_inter_valley_slope = NoiseParams(0.5f,  0.5f, v3f(128,  128,  128),  746,   1, 1.f,  2.f);
+	np_rivers             = NoiseParams(0.f,   1.f,  v3f(256,  256,  256),  -6050, 5, 0.6f, 2.f);
+	np_simple_caves_1     = NoiseParams(0.f,   1.f,  v3f(64,   64,   64),   -8402, 3, 0.5f, 2.f);
+	np_simple_caves_2     = NoiseParams(0.f,   1.f,  v3f(64,   64,   64),   3944,  3, 0.5f, 2.f);
+	np_terrain_height     = NoiseParams(-10.f, 50.f, v3f(1024, 1024, 1024), 5202,  6, 0.4f, 2.f);
+	np_valley_depth       = NoiseParams(5.f,   4.f,  v3f(512,  512,  512),  -1914, 1, 1.f,  2.f);
+	np_valley_profile     = NoiseParams(0.6f,  0.5f, v3f(512,  512,  512),  777,   1, 1.f,  2.f);
+	}
+
+
+void MapgenValleysParams::readParams(const Settings *settings)
+{
+	settings->getFlagStrNoEx("mg_valleys_spflags", spflags, flagdesc_mapgen_valleys);
+
+	settings->getU16NoEx("mg_valleys_altitude_chill",        altitude_chill);
+	settings->getS16NoEx("mg_valleys_cave_water_max_height", cave_water_max_height);
+	settings->getS16NoEx("mg_valleys_humidity",              humidity);
+	settings->getS16NoEx("mg_valleys_humidity_break_point",  humidity_break_point);
+	settings->getS16NoEx("mg_valleys_lava_max_height",       lava_max_height);
+	settings->getU16NoEx("mg_valleys_river_depth",           river_depth);
+	settings->getU16NoEx("mg_valleys_river_size",            river_size);
+	settings->getS16NoEx("mg_valleys_temperature",           temperature);
+	settings->getU16NoEx("mg_valleys_water_features",        water_features);
+
+	settings->getNoiseParams("mg_valleys_np_cliffs",             np_cliffs);
+	settings->getNoiseParams("mg_valleys_np_corr",               np_corr);
+	settings->getNoiseParams("mg_valleys_np_filler_depth",       np_filler_depth);
+	settings->getNoiseParams("mg_valleys_np_inter_valley_fill",  np_inter_valley_fill);
+	settings->getNoiseParams("mg_valleys_np_inter_valley_slope", np_inter_valley_slope);
+	settings->getNoiseParams("mg_valleys_np_rivers",             np_rivers);
+	settings->getNoiseParams("mg_valleys_np_simple_caves_1",     np_simple_caves_1);
+	settings->getNoiseParams("mg_valleys_np_simple_caves_2",     np_simple_caves_2);
+	settings->getNoiseParams("mg_valleys_np_terrain_height",     np_terrain_height);
+	settings->getNoiseParams("mg_valleys_np_valley_depth",       np_valley_depth);
+	settings->getNoiseParams("mg_valleys_np_valley_profile",     np_valley_profile);
+}
+
+
+void MapgenValleysParams::writeParams(Settings *settings) const
+{
+	settings->setFlagStr("mg_valleys_spflags", spflags, flagdesc_mapgen_valleys, U32_MAX);
+
+	settings->setU16("mg_valleys_altitude_chill",        altitude_chill);
+	settings->setS16("mg_valleys_cave_water_max_height", cave_water_max_height);
+	settings->setS16("mg_valleys_humidity",              humidity);
+	settings->setS16("mg_valleys_humidity_break_point",  humidity_break_point);
+	settings->setS16("mg_valleys_lava_max_height",       lava_max_height);
+	settings->setU16("mg_valleys_river_depth",           river_depth);
+	settings->setU16("mg_valleys_river_size",            river_size);
+	settings->setS16("mg_valleys_temperature",           temperature);
+	settings->setU16("mg_valleys_water_features",        water_features);
+
+	settings->setNoiseParams("mg_valleys_np_cliffs",             np_cliffs);
+	settings->setNoiseParams("mg_valleys_np_corr",               np_corr);
+	settings->setNoiseParams("mg_valleys_np_filler_depth",       np_filler_depth);
+	settings->setNoiseParams("mg_valleys_np_inter_valley_fill",  np_inter_valley_fill);
+	settings->setNoiseParams("mg_valleys_np_inter_valley_slope", np_inter_valley_slope);
+	settings->setNoiseParams("mg_valleys_np_rivers",             np_rivers);
+	settings->setNoiseParams("mg_valleys_np_simple_caves_1",     np_simple_caves_1);
+	settings->setNoiseParams("mg_valleys_np_simple_caves_2",     np_simple_caves_2);
+	settings->setNoiseParams("mg_valleys_np_terrain_height",     np_terrain_height);
+	settings->setNoiseParams("mg_valleys_np_valley_depth",       np_valley_depth);
+	settings->setNoiseParams("mg_valleys_np_valley_profile",     np_valley_profile);
+}
+
+
+///////////////////////////////////////
+
+
+void MapgenValleys::makeChunk(BlockMakeData *data)
+{
+	// Pre-conditions
+	assert(data->vmanip);
+	assert(data->nodedef);
+	assert(data->blockpos_requested.X >= data->blockpos_min.X &&
+		data->blockpos_requested.Y >= data->blockpos_min.Y &&
+		data->blockpos_requested.Z >= data->blockpos_min.Z);
+	assert(data->blockpos_requested.X <= data->blockpos_max.X &&
+		data->blockpos_requested.Y <= data->blockpos_max.Y &&
+		data->blockpos_requested.Z <= data->blockpos_max.Z);
+
+	this->generating = true;
+	this->vm   = data->vmanip;
+	this->ndef = data->nodedef;
+
+	//TimeTaker t("makeChunk");
+
+	v3s16 blockpos_min = data->blockpos_min;
+	v3s16 blockpos_max = data->blockpos_max;
+	node_min = blockpos_min * MAP_BLOCKSIZE;
+	node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
+	full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
+	full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);
+
+	blockseed = getBlockSeed2(full_node_min, seed);
+
+	// Generate noise maps and base terrain height.
+	calculateNoise();
+
+	// Generate base terrain with initial heightmaps
+	s16 stone_surface_max_y = generateTerrain();
+
+	// Create biomemap at heightmap surface
+	bmgr->calcBiomes(csize.X, csize.Z, heatmap, humidmap, heightmap, biomemap);
+
+	// Actually place the biome-specific nodes
+	MgStoneType stone_type = generateBiomes(heatmap, humidmap);
+
+	// Cave creation.
+	if (flags & MG_CAVES)
+		generateSimpleCaves(stone_surface_max_y);
+
+	// Dungeon creation
+	if ((flags & MG_DUNGEONS) && node_max.Y < 50 && (stone_surface_max_y >= node_min.Y)) {
+		DungeonParams dp;
+
+		dp.np_rarity  = nparams_dungeon_rarity;
+		dp.np_density = nparams_dungeon_density;
+		dp.np_wetness = nparams_dungeon_wetness;
+		dp.c_water    = c_water_source;
+		if (stone_type == STONE) {
+			dp.c_cobble = c_cobble;
+			dp.c_moss   = c_mossycobble;
+			dp.c_stair  = c_stair_cobble;
+
+			dp.diagonal_dirs = false;
+			dp.mossratio     = 3.f;
+			dp.holesize      = v3s16(1, 2, 1);
+			dp.roomsize      = v3s16(0, 0, 0);
+			dp.notifytype    = GENNOTIFY_DUNGEON;
+		} else if (stone_type == DESERT_STONE) {
+			dp.c_cobble = c_desert_stone;
+			dp.c_moss   = c_desert_stone;
+			dp.c_stair  = c_desert_stone;
+
+			dp.diagonal_dirs = true;
+			dp.mossratio     = 0.f;
+			dp.holesize      = v3s16(2, 3, 2);
+			dp.roomsize      = v3s16(2, 5, 2);
+			dp.notifytype    = GENNOTIFY_TEMPLE;
+		} else if (stone_type == SANDSTONE) {
+			dp.c_cobble = c_sandstonebrick;
+			dp.c_moss   = c_sandstonebrick;
+			dp.c_stair  = c_sandstonebrick;
+
+			dp.diagonal_dirs = false;
+			dp.mossratio     = 0.f;
+			dp.holesize      = v3s16(2, 2, 2);
+			dp.roomsize      = v3s16(2, 0, 2);
+			dp.notifytype    = GENNOTIFY_DUNGEON;
+		}
+
+		DungeonGen dgen(this, &dp);
+		dgen.generate(blockseed, full_node_min, full_node_max);
+	}
+
+	// Generate the registered decorations
+	if (flags & MG_DECORATIONS)
+		m_emerge->decomgr->placeAllDecos(this, blockseed, node_min, node_max);
+
+	// Generate the registered ores
+	m_emerge->oremgr->placeAllOres(this, blockseed, node_min, node_max);
+
+	// Sprinkle some dust on top after everything else was generated
+	dustTopNodes();
+
+	//TimeTaker tll("liquid_lighting");
+
+	updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);
+
+	if (flags & MG_LIGHT)
+		calcLighting(
+				node_min - v3s16(0, 1, 0), 
+				node_max + v3s16(0, 1, 0), 
+				full_node_min, 
+				full_node_max);
+
+	//mapgen_profiler->avg("liquid_lighting", tll.stop() / 1000.f);
+	//mapgen_profiler->avg("makeChunk", t.stop() / 1000.f);
+
+	this->generating = false;
+}
+
+
+// Populate the noise tables and do most of the
+// calculation necessary to determine terrain height.
+void MapgenValleys::calculateNoise()
+{
+	//TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
+
+	int x = node_min.X;
+	int y = node_min.Y - 1;
+	int z = node_min.Z;
+
+	//TimeTaker tcn("actualNoise");
+
+	noise_filler_depth->perlinMap2D(x, z);
+	noise_heat_blend->perlinMap2D(x, z);
+	noise_heat->perlinMap2D(x, z);
+	noise_humidity_blend->perlinMap2D(x, z);
+	noise_humidity->perlinMap2D(x, z);
+	noise_inter_valley_slope->perlinMap2D(x, z);
+	noise_rivers->perlinMap2D(x, z);
+	noise_terrain_height->perlinMap2D(x, z);
+	noise_valley_depth->perlinMap2D(x, z);
+	noise_valley_profile->perlinMap2D(x, z);
+
+	if (fast_terrain) {
+		// Make this 2D for speed, if requested.
+		noise_inter_valley_fill->perlinMap2D(x, z);
+
+		if (cliff_terrain)
+			noise_cliffs->perlinMap2D(x, z);
+		if (rugged_terrain)
+			noise_corr->perlinMap2D(x, z);
+	} else {
+		noise_inter_valley_fill->perlinMap3D(x, y, z);
+	}
+
+	if (flags & MG_CAVES) {
+		noise_simple_caves_1->perlinMap3D(x, y, z);
+		noise_simple_caves_2->perlinMap3D(x, y, z);
+	}
+
+	//mapgen_profiler->avg("noisemaps", tcn.stop() / 1000.f);
+
+	for (s32 index = 0; index < csize.X * csize.Z; index++) {
+		noise_heat->result[index] += noise_heat_blend->result[index];
+		noise_heat->result[index] += temperature_adjust;
+		noise_humidity->result[index] += noise_humidity_blend->result[index];
+	}
+
+	TerrainNoise tn;
+
+	u32 index = 0;
+	for (tn.z = node_min.Z; tn.z <= node_max.Z; tn.z++)
+	for (tn.x = node_min.X; tn.x <= node_max.X; tn.x++, index++) {
+		// The parameters that we actually need to generate terrain
+		//  are passed by address (and the return value).
+		tn.terrain_height = noise_terrain_height->result[index];
+		// River noise is replaced with base terrain, which
+		// is basically the height of the water table.
+		tn.rivers = &noise_rivers->result[index];
+		// Valley depth noise is replaced with the valley
+		// number that represents the height of terrain
+		// over rivers and is used to determine about
+		// how close a river is for humidity calculation.
+		tn.valley = &noise_valley_depth->result[index];
+		tn.valley_profile = noise_valley_profile->result[index];
+		// Slope noise is replaced by the calculated slope
+		// which is used to get terrain height in the slow
+		// method, to create sharper mountains.
+		tn.slope = &noise_inter_valley_slope->result[index];
+		tn.inter_valley_fill = noise_inter_valley_fill->result[index];
+		tn.cliffs = noise_cliffs->result[index];
+		tn.corr = noise_corr->result[index];
+
+		// This is the actual terrain height.
+		float mount = terrainLevelFromNoise(&tn);
+		noise_terrain_height->result[index] = mount;
+
+		if (fast_terrain) {
+			// Assign humidity adjusted by water proximity.
+			// I can't think of a reason why a mod would expect base humidity
+			//  from noise or at any altitude other than ground level.
+			noise_humidity->result[index] = humidityByTerrain(
+					noise_humidity->result[index],
+					mount,
+					noise_rivers->result[index],
+					noise_valley_depth->result[index]);
+
+			// Assign heat adjusted by altitude. See humidity, above.
+			if (use_altitude_chill && mount > 0.f)
+				noise_heat->result[index] *= pow(0.5f, (mount - altitude_chill / 3.f) / altitude_chill);
+		}
+	}
+
+	heatmap = noise_heat->result;
+	humidmap = noise_humidity->result;
+}
+
+
+// This keeps us from having to maintain two similar sets of
+//  complicated code to determine ground level.
+float MapgenValleys::terrainLevelFromNoise(TerrainNoise *tn)
+{
+	float inter_valley_slope = *tn->slope;
+
+	// The square function changes the behaviour of this noise:
+	//  very often small, and sometimes very high.
+	float valley_d = pow(*tn->valley, 2);
+
+	// valley_d is here because terrain is generally higher where valleys
+	//  are deep (mountains). base represents the height of the
+	//  rivers, most of the surface is above.
+	float base = tn->terrain_height + valley_d;
+
+	// "river" represents the distance from the river, in arbitrary units.
+	float river = fabs(*tn->rivers) - river_size;
+
+	// Use the curve of the function 1−exp(−(x/a)²) to model valleys.
+	//  Making "a" vary (0 < a ≤ 1) changes the shape of the valleys.
+	//  Try it with a geometry software !
+	//   (here x = "river" and a = valley_profile).
+	//  "valley" represents the height of the terrain, from the rivers.
+	*tn->valley = valley_d * (1.f - exp(- pow(river / tn->valley_profile, 2)));
+
+	// approximate height of the terrain at this point
+	float mount = base + *tn->valley;
+
+	*tn->slope *= *tn->valley;
+
+	// Rivers are placed where "river" is negative, so where the original
+	//  noise value is close to zero.
+	// Base ground is returned as rivers since it's basically the water table.
+	*tn->rivers = base;
+	if (river < 0.f) {
+		// Use the the function −sqrt(1−x²) which models a circle.
+		float depth = (river_depth * sqrt(1.f - pow((river / river_size + 1), 2)));
+
+		// base - depth : height of the bottom of the river
+		// water_level - 2 : don't make rivers below 2 nodes under the surface
+		u16 min_bottom = 2;
+		if (!fast_terrain)
+			min_bottom = 6;
+		mount = fmin(fmax(base - depth, (float) (water_level - min_bottom)), mount);
+
+		// Slope has no influence on rivers.
+		*tn->slope = 0.f;
+	}
+
+	if (fast_terrain) {
+		// The penultimate step builds up the heights, but we reduce it 
+		//  occasionally to create cliffs.
+		float delta = sin(tn->inter_valley_fill) * *tn->slope;
+		if (cliff_terrain && tn->cliffs >= 0.2f)
+			mount += delta * 0.66f;
+		else
+			mount += delta;
+
+		// Use yet another noise to make the heights look more rugged.
+		if (rugged_terrain 
+				&& mount > water_level 
+				&& fabs(inter_valley_slope * tn->inter_valley_fill) < 0.3f)
+			mount += ((delta < 0.f) ? -1.f : 1.f) * pow(fabs(delta), 0.5f) * fabs(sin(tn->corr));
+	}
+
+	return mount;
+}
+
+
+// This avoids duplicating the code in terrainLevelFromNoise, adding
+// only the final step of terrain generation without a noise map.
+float MapgenValleys::adjustedTerrainLevelFromNoise(TerrainNoise *tn)
+{
+	float mount = terrainLevelFromNoise(tn);
+
+	if (!fast_terrain) {
+		for (s16 y = round(mount); y <= round(mount) + 1000; y++) {
+			float fill = NoisePerlin3D(&noise_inter_valley_fill->np, tn->x, y, tn->z, seed);
+
+			if (fill * *tn->slope <= y - mount) {
+				mount = fmax(y - 1, mount);
+				break;
+			}
+		}
+	}
+
+	return mount;
+}
+
+
+float MapgenValleys::humidityByTerrain(
+		float humidity_base, 
+		float mount, 
+		float rivers, 
+		float valley)
+{
+	// Although the original valleys adjusts humidity by distance
+	// from seawater, this causes problems with the default biomes.
+	// Adjust only by freshwater proximity.
+	float humidity = humidity_base + humidity_adjust;
+
+	if (humid_rivers && mount > water_level) {
+		// Offset to make everything average the same.
+		humidity -= (humidity_break_point - humidity_adjust) / 3.f;
+
+		// This method is from the original lua.
+		float water_table = pow(0.5f, fmax(rivers / 3.f, 0.f));
+		// This adds humidity next to rivers and lakes.
+		float river_water = pow(0.5f, fmax(valley / 12.f, 0.f));
+		// Combine the two.
+		float water = water_table + (1.f - water_table) * river_water;
+		humidity = fmax(humidity, (humidity_break_point * water));
+	}
+
+	return humidity;
+}
+
+
+inline int MapgenValleys::getGroundLevelAtPoint(v2s16 p)
+{
+	// Base terrain calculation
+	return terrainLevelAtPoint(p.X, p.Y);
+}
+
+
+float MapgenValleys::terrainLevelAtPoint(s16 x, s16 z)
+{
+	TerrainNoise tn;
+
+	float rivers = NoisePerlin2D(&noise_rivers->np, x, z, seed);
+	float valley = NoisePerlin2D(&noise_valley_depth->np, x, z, seed);
+	float inter_valley_slope = NoisePerlin2D(&noise_inter_valley_slope->np, x, z, seed);
+
+	tn.x = x;
+	tn.z = z;
+	tn.terrain_height = NoisePerlin2D(&noise_terrain_height->np, x, z, seed);
+	tn.rivers = &rivers;
+	tn.valley = &valley;
+	tn.valley_profile = NoisePerlin2D(&noise_valley_profile->np, x, z, seed);
+	tn.slope = &inter_valley_slope;
+	tn.inter_valley_fill = 0.f;
+	tn.cliffs = 0.f;
+	tn.corr = 0.f;
+
+	if (fast_terrain) {
+		tn.inter_valley_fill = NoisePerlin2D(&noise_inter_valley_fill->np, x, z, seed);
+
+		if (cliff_terrain)
+			tn.cliffs = NoisePerlin2D(&noise_cliffs->np, x, z, seed);
+		if (rugged_terrain)
+			tn.corr = NoisePerlin2D(&noise_corr->np, x, z, seed);
+	}
+
+	return adjustedTerrainLevelFromNoise(&tn);
+}
+
+
+int MapgenValleys::generateTerrain()
+{
+	MapNode n_air(CONTENT_AIR);
+	MapNode n_river_water(c_river_water_source);
+	MapNode n_sand(c_sand);
+	MapNode n_stone(c_stone);
+	MapNode n_water(c_water_source);
+
+	v3s16 em = vm->m_area.getExtent();
+	s16 surface_max_y = -MAX_MAP_GENERATION_LIMIT;
+	u32 index_2d = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index_2d++) {
+		s16 river_y = round(noise_rivers->result[index_2d]);
+		s16 surface_y = round(noise_terrain_height->result[index_2d]);
+		float slope = noise_inter_valley_slope->result[index_2d];
+
+		heightmap[index_2d] = surface_y;
+
+		if (surface_y > surface_max_y)
+			surface_max_y = surface_y;
+
+		u32 index_3d = 0;
+		if (!fast_terrain)
+			index_3d = (z - node_min.Z) * zstride + (x - node_min.X);
+
+		u32 index_data = vm->m_area.index(x, node_min.Y - 1, z);
+
+		// Mapgens concern themselves with stone and water.
+		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
+			float fill = 0.f;
+			if (!fast_terrain)
+				fill = noise_inter_valley_fill->result[index_3d];
+
+			if (vm->m_data[index_data].getContent() == CONTENT_IGNORE) {
+				bool river = (river_y > surface_y);
+
+				if (river && y == surface_y) {
+					// river bottom
+					vm->m_data[index_data] = n_sand;
+				} else if ((fast_terrain || river) && y <= surface_y) {
+					// ground
+					vm->m_data[index_data] = n_stone;
+				} else if (river && y < river_y) {
+					// river
+					vm->m_data[index_data] = n_river_water;
+				} else if ((!fast_terrain) && (!river) && fill * slope > y - surface_y) {
+					// ground (slow method)
+					vm->m_data[index_data] = n_stone;
+					heightmap[index_2d] = surface_max_y = y;
+				} else if (y <= water_level) {
+					// sea
+					vm->m_data[index_data] = n_water;
+				} else {
+					vm->m_data[index_data] = n_air;
+				}
+			}
+
+			vm->m_area.add_y(em, index_data, 1);
+			if (!fast_terrain)
+				index_3d += ystride;
+		}
+
+		if (!fast_terrain) {
+			// Assign the humidity adjusted by water proximity.
+			noise_humidity->result[index_2d] = humidityByTerrain(
+					noise_humidity->result[index_2d], 
+					surface_max_y, 
+					noise_rivers->result[index_2d], 
+					noise_valley_depth->result[index_2d]);
+
+			// Assign the heat adjusted by altitude. See humidity, above.
+			if (use_altitude_chill && surface_max_y > 0)
+				noise_heat->result[index_2d] 
+					*= pow(0.5f, (surface_max_y - altitude_chill / 3.f) / altitude_chill);
+		}
+	}
+
+	return surface_max_y;
+}
+
+
+MgStoneType MapgenValleys::generateBiomes(float *heat_map, float *humidity_map)
+{
+	v3s16 em = vm->m_area.getExtent();
+	u32 index = 0;
+	MgStoneType stone_type = STONE;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
+		Biome *biome = NULL;
+		u16 depth_top = 0;
+		u16 base_filler = 0;
+		u16 depth_water_top = 0;
+		u32 vi = vm->m_area.index(x, node_max.Y, z);
+
+		// Check node at base of mapchunk above, either a node of a previously
+		// generated mapchunk or if not, a node of overgenerated base terrain.
+		content_t c_above = vm->m_data[vi + em.X].getContent();
+		bool air_above = c_above == CONTENT_AIR;
+		bool water_above = (c_above == c_water_source);
+
+		// If there is air or water above enable top/filler placement, otherwise force
+		// nplaced to stone level by setting a number exceeding any possible filler depth.
+		u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
+
+		for (s16 y = node_max.Y; y >= node_min.Y; y--) {
+			content_t c = vm->m_data[vi].getContent();
+
+			// Biome is recalculated each time an upper surface is detected while
+			// working down a column. The selected biome then remains in effect for
+			// all nodes below until the next surface and biome recalculation.
+			// Biome is recalculated:
+			// 1. At the surface of stone below air or water.
+			// 2. At the surface of water below air.
+			// 3. When stone or water is detected but biome has not yet been calculated.
+			if ((c == c_stone && (air_above || water_above || !biome)) 
+					|| ((c == c_water_source || c == c_river_water_source) 
+							&& (air_above || !biome))) {
+				// Both heat and humidity have already been adjusted for altitude.
+				biome = bmgr->getBiome(heat_map[index], humidity_map[index], y);
+
+				depth_top = biome->depth_top;
+				base_filler = MYMAX(depth_top 
+						+ biome->depth_filler 
+						+ noise_filler_depth->result[index], 0.f);
+				depth_water_top = biome->depth_water_top;
+
+				// Detect stone type for dungeons during every biome calculation.
+				// This is more efficient than detecting per-node and will not
+				// miss any desert stone or sandstone biomes.
+				if (biome->c_stone == c_desert_stone)
+					stone_type = DESERT_STONE;
+				else if (biome->c_stone == c_sandstone)
+					stone_type = SANDSTONE;
+			}
+
+			if (c == c_stone) {
+				content_t c_below = vm->m_data[vi - em.X].getContent();
+
+				// If the node below isn't solid, make this node stone, so that
+				// any top/filler nodes above are structurally supported.
+				// This is done by aborting the cycle of top/filler placement
+				// immediately by forcing nplaced to stone level.
+				if (c_below == CONTENT_AIR 
+						|| c_below == c_water_source 
+						|| c_below == c_river_water_source)
+					nplaced = U16_MAX;
+
+				if (nplaced < depth_top) {
+					vm->m_data[vi] = MapNode(biome->c_top);
+					nplaced++;
+				} else if (nplaced < base_filler) {
+					vm->m_data[vi] = MapNode(biome->c_filler);
+					nplaced++;
+				} else {
+					vm->m_data[vi] = MapNode(biome->c_stone);
+				}
+
+				air_above = false;
+				water_above = false;
+			} else if (c == c_water_source) {
+				vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) 
+						? biome->c_water_top : biome->c_water);
+				nplaced = 0;  // Enable top/filler placement for next surface
+				air_above = false;
+				water_above = true;
+			} else if (c == c_river_water_source) {
+				vm->m_data[vi] = MapNode(biome->c_river_water);
+				nplaced = U16_MAX;  // Sand was already placed under rivers.
+				air_above = false;
+				water_above = true;
+			} else if (c == CONTENT_AIR) {
+				nplaced = 0;  // Enable top/filler placement for next surface
+				air_above = true;
+				water_above = false;
+			} else {  // Possible various nodes overgenerated from neighbouring mapchunks
+				nplaced = U16_MAX;  // Disable top/filler placement
+				air_above = false;
+				water_above = false;
+			}
+
+			vm->m_area.add_y(em, vi, -1);
+		}
+	}
+
+	return stone_type;
+}
+
+
+void MapgenValleys::dustTopNodes()
+{
+	if (node_max.Y < water_level)
+		return;
+
+	v3s16 em = vm->m_area.getExtent();
+	u32 index = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
+		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
+
+		if (biome->c_dust == CONTENT_IGNORE)
+			continue;
+
+		u32 vi = vm->m_area.index(x, full_node_max.Y, z);
+		content_t c_full_max = vm->m_data[vi].getContent();
+		s16 y_start;
+
+		if (c_full_max == CONTENT_AIR) {
+			y_start = full_node_max.Y - 1;
+		} else if (c_full_max == CONTENT_IGNORE) {
+			vi = vm->m_area.index(x, node_max.Y + 1, z);
+			content_t c_max = vm->m_data[vi].getContent();
+
+			if (c_max == CONTENT_AIR)
+				y_start = node_max.Y;
+			else
+				continue;
+		} else {
+			continue;
+		}
+
+		vi = vm->m_area.index(x, y_start, z);
+		for (s16 y = y_start; y >= node_min.Y - 1; y--) {
+			if (vm->m_data[vi].getContent() != CONTENT_AIR)
+				break;
+
+			vm->m_area.add_y(em, vi, -1);
+		}
+
+		content_t c = vm->m_data[vi].getContent();
+		if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
+			vm->m_area.add_y(em, vi, 1);
+			vm->m_data[vi] = MapNode(biome->c_dust);
+		}
+	}
+}
+
+
+void MapgenValleys::generateSimpleCaves(s16 max_stone_y)
+{
+	PseudoRandom ps(blockseed + 72202);
+
+	MapNode n_air(CONTENT_AIR);
+	MapNode n_dirt(c_dirt);
+	MapNode n_lava(c_lava_source);
+	MapNode n_water(c_river_water_source);
+
+	v3s16 em = vm->m_area.getExtent();
+
+	s16 base_water_chance = 0;
+	if (water_features < 11)
+		base_water_chance = ceil(MAX_MAP_GENERATION_LIMIT / (water_features * 1000));
+
+	if (max_stone_y >= node_min.Y) {
+		u32 index_2d = 0;
+		u32 index_3d = 0;
+		for (s16 z = node_min.Z; z <= node_max.Z; z++)
+		for (s16 x = node_min.X; x <= node_max.X; x++, index_2d++) {
+			bool air_above = false;
+			//bool underground = false;
+			u32 index_data = vm->m_area.index(x, node_max.Y + 1, z);
+
+			index_3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride + (x - node_min.X);
+
+			// Dig caves on down loop to check for air above.
+			for (s16 y = node_max.Y + 1; 
+					y >= node_min.Y - 1; 
+					y--, index_3d -= ystride, vm->m_area.add_y(em, index_data, -1)) {
+				float terrain = noise_terrain_height->result[index_2d];
+
+				// Saves some time and prevents removing above ground nodes.
+				if (y > terrain + 1) {
+					air_above = true;
+					continue;
+				}
+
+				content_t c = vm->m_data[index_data].getContent();
+				bool n1 = (fabs(noise_simple_caves_1->result[index_3d]) < 0.07f);
+				bool n2 = (fabs(noise_simple_caves_2->result[index_3d]) < 0.07f);
+
+				// River water is (foolishly) not set as ground content
+				// in the default game. This can produce strange results
+				// when a cave undercuts a river. However, that's not for
+				// the mapgen to correct. Fix it in lua.
+
+				if (c == CONTENT_AIR) {
+					air_above = true;
+				} else if (n1 && n2 && ndef->get(c).is_ground_content) {
+					// When both n's are true, we're in a cave.
+					vm->m_data[index_data] = n_air;
+					air_above = true;
+				} else if (air_above 
+						&& (c == c_stone || c == c_sandstone || c == c_desert_stone)) {
+					// At the cave floor
+					s16 sr = ps.next() & 1023;
+					u32 j = index_data;
+					vm->m_area.add_y(em, j, 1);
+
+					if (sr > (terrain - y) * 25) {
+						// Put dirt in caves near the surface.
+						Biome *biome = (Biome *)bmgr->getRaw(biomemap[index_2d]);
+						vm->m_data[index_data] = MapNode(biome->c_filler);
+					} else {
+						s16 lava_chance = 0;
+
+						if (y <= lava_max_height && c == c_stone) {
+							// Lava spawns increase with depth.
+							lava_chance = ceil((lava_max_height - y + 1) / 10000);
+
+							if (sr < lava_chance)
+								vm->m_data[j] = n_lava;
+						}
+
+						if (base_water_chance > 0 && y <= cave_water_max_height) {
+							s16 water_chance = base_water_chance 
+								- (abs(y - water_level) / (water_features * 1000));
+
+							// Waterfalls may get out of control above ground.
+							sr -= lava_chance;
+							// If sr < 0 then we should have already placed lava --
+							// don't immediately dump water on it.
+							if (sr >= 0 && sr < water_chance)
+								vm->m_data[j] = n_water;
+						}
+					}
+
+					air_above = false;
+				}
+
+				// If we're not in a cave, there's no open space.
+				if (!(n1 && n2))
+					air_above = false;
+			}
+		}
+	}
+}