code:
/*
Minetest
Copyright (C) 2010-2015 celeron55, Perttu Ahola <celeron55@gmail.com>
Copyright (C) 2013-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
Copyright (C) 2014-2017 paramat

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 "serverobject.h"
#include "content_sao.h"
#include "nodedef.h"
#include "voxelalgorithms.h"
//#include "profiler.h" // For TimeTaker
#include "settings.h" // For g_settings
#include "emerge.h"
#include "dungeongen.h"
#include "cavegen.h"
#include "treegen.h"
#include "mg_ore.h"
#include "mg_decoration.h"
#include "mapgen_v6.h"

FlagDesc flagdesc_mapgen_v6[] = {
	{"jungles",    MGV6_JUNGLES},
	{"biomeblend", MGV6_BIOMEBLEND},
	{"mudflow",    MGV6_MUDFLOW},
	{"snowbiomes", MGV6_SNOWBIOMES},
	{"flat",       MGV6_FLAT},
	{"trees",      MGV6_TREES},
	{NULL,         0}
};

/////////////////////////////////////////////////////////////////////////////

MapgenV6::MapgenV6(int mapgenid, MapgenV6Params *params, EmergeManager *emerge)
	: Mapgen(mapgenid, params, emerge)
{
	this->m_emerge = emerge;
	this->ystride = csize.X; //////fix this

	this->heightmap = new s16[csize.X * csize.Z];

	this->spflags     = params->spflags;
	this->freq_desert = params->freq_desert;
	this->freq_beach  = params->freq_beach;

	np_cave        = &params->np_cave;
	np_humidity    = &params->np_humidity;
	np_trees       = &params->np_trees;
	np_apple_trees = &params->np_apple_trees;

	//// Create noise objects
	noise_terrain_base   = new Noise(&params->np_terrain_base,   seed, csize.X, csize.Y);
	noise_terrain_higher = new Noise(&params->np_terrain_higher, seed, csize.X, csize.Y);
	noise_steepness      = new Noise(&params->np_steepness,      seed, csize.X, csize.Y);
	noise_height_select  = new Noise(&params->np_height_select,  seed, csize.X, csize.Y);
	noise_mud            = new Noise(&params->np_mud,            seed, csize.X, csize.Y);
	noise_beach          = new Noise(&params->np_beach,          seed, csize.X, csize.Y);
	noise_biome          = new Noise(&params->np_biome,          seed,
			csize.X + 2 * MAP_BLOCKSIZE, csize.Y + 2 * MAP_BLOCKSIZE);
	noise_humidity       = new Noise(&params->np_humidity,       seed,
			csize.X + 2 * MAP_BLOCKSIZE, csize.Y + 2 * MAP_BLOCKSIZE);

	//// Resolve nodes to be used
	INodeDefManager *ndef = emerge->ndef;

	c_stone           = ndef->getId("mapgen_stone");
	c_dirt            = ndef->getId("mapgen_dirt");
	c_dirt_with_grass = ndef->getId("mapgen_dirt_with_grass");
	c_sand            = ndef->getId("mapgen_sand");
	c_water_source    = ndef->getId("mapgen_water_source");
	c_lava_source     = ndef->getId("mapgen_lava_source");
	c_gravel          = ndef->getId("mapgen_gravel");
	c_desert_stone    = ndef->getId("mapgen_desert_stone");
	c_desert_sand     = ndef->getId("mapgen_desert_sand");
	c_dirt_with_snow  = ndef->getId("mapgen_dirt_with_snow");
	c_snow            = ndef->getId("mapgen_snow");
	c_snowblock       = ndef->getId("mapgen_snowblock");
	c_ice             = ndef->getId("mapgen_ice");

	if (c_gravel == CONTENT_IGNORE)
		c_gravel = c_stone;
	if (c_desert_stone == CONTENT_IGNORE)
		c_desert_stone = c_stone;
	if (c_desert_sand == CONTENT_IGNORE)
		c_desert_sand = c_sand;
	if (c_dirt_with_snow == CONTENT_IGNORE)
		c_dirt_with_snow = c_dirt_with_grass;
	if (c_snow == CONTENT_IGNORE)
		c_snow = CONTENT_AIR;
	if (c_snowblock == CONTENT_IGNORE)
		c_snowblock = c_dirt_with_grass;
	if (c_ice == CONTENT_IGNORE)
		c_ice = c_water_source;

	c_cobble             = ndef->getId("mapgen_cobble");
	c_mossycobble        = ndef->getId("mapgen_mossycobble");
	c_stair_cobble       = ndef->getId("mapgen_stair_cobble");
	c_stair_desert_stone = ndef->getId("mapgen_stair_desert_stone");

	if (c_mossycobble == CONTENT_IGNORE)
		c_mossycobble = c_cobble;
	if (c_stair_cobble == CONTENT_IGNORE)
		c_stair_cobble = c_cobble;
	if (c_stair_desert_stone == CONTENT_IGNORE)
		c_stair_desert_stone = c_desert_stone;
}

MapgenV6::~MapgenV6()
{
	delete noise_terrain_base;
	delete noise_terrain_higher;
	delete noise_steepness;
	delete noise_height_select;
	delete noise_mud;
	delete noise_beach;
	delete noise_biome;
	delete noise_humidity;

	delete[] heightmap;
}

MapgenV6Params::MapgenV6Params()
{
	spflags = MGV6_JUNGLES | MGV6_SNOWBIOMES | MGV6_TREES |
		MGV6_BIOMEBLEND | MGV6_MUDFLOW;

	freq_desert = 0.45;
	freq_beach  = 0.15;

	np_terrain_base   = NoiseParams(-4,   20.0, v3f(250.0, 250.0, 250.0), 82341,  5, 0.6,  2.0);
	np_terrain_higher = NoiseParams(20,   16.0, v3f(500.0, 500.0, 500.0), 85039,  5, 0.6,  2.0);
	np_steepness      = NoiseParams(0.85, 0.5,  v3f(125.0, 125.0, 125.0), -932,   5, 0.7,  2.0);
	np_height_select  = NoiseParams(0,    1.0,  v3f(250.0, 250.0, 250.0), 4213,   5, 0.69, 2.0);
	np_mud            = NoiseParams(4,    2.0,  v3f(200.0, 200.0, 200.0), 91013,  3, 0.55, 2.0);
	np_beach          = NoiseParams(0,    1.0,  v3f(250.0, 250.0, 250.0), 59420,  3, 0.50, 2.0);
	np_biome          = NoiseParams(0,    1.0,  v3f(500.0, 500.0, 500.0), 9130,   3, 0.50, 2.0);
	np_cave           = NoiseParams(6,    6.0,  v3f(250.0, 250.0, 250.0), 34329,  3, 0.50, 2.0);
	np_humidity       = NoiseParams(0.5,  0.5,  v3f(500.0, 500.0, 500.0), 72384,  3, 0.50, 2.0);
	np_trees          = NoiseParams(0,    1.0,  v3f(125.0, 125.0, 125.0), 2,      4, 0.66, 2.0);
	np_apple_trees    = NoiseParams(0,    1.0,  v3f(100.0, 100.0, 100.0), 342902, 3, 0.45, 2.0);
}

void MapgenV6Params::readParams(const Settings *settings)
{
	settings->getFlagStrNoEx("mgv6_spflags", spflags, flagdesc_mapgen_v6);
	settings->getFloatNoEx("mgv6_freq_desert", freq_desert);
	settings->getFloatNoEx("mgv6_freq_beach",  freq_beach);

	settings->getNoiseParams("mgv6_np_terrain_base",   np_terrain_base);
	settings->getNoiseParams("mgv6_np_terrain_higher", np_terrain_higher);
	settings->getNoiseParams("mgv6_np_steepness",      np_steepness);
	settings->getNoiseParams("mgv6_np_height_select",  np_height_select);
	settings->getNoiseParams("mgv6_np_mud",            np_mud);
	settings->getNoiseParams("mgv6_np_beach",          np_beach);
	settings->getNoiseParams("mgv6_np_biome",          np_biome);
	settings->getNoiseParams("mgv6_np_cave",           np_cave);
	settings->getNoiseParams("mgv6_np_humidity",       np_humidity);
	settings->getNoiseParams("mgv6_np_trees",          np_trees);
	settings->getNoiseParams("mgv6_np_apple_trees",    np_apple_trees);
}

void MapgenV6Params::writeParams(Settings *settings) const
{
	settings->setFlagStr("mgv6_spflags", spflags, flagdesc_mapgen_v6, U32_MAX);
	settings->setFloat("mgv6_freq_desert", freq_desert);
	settings->setFloat("mgv6_freq_beach",  freq_beach);

	settings->setNoiseParams("mgv6_np_terrain_base",   np_terrain_base);
	settings->setNoiseParams("mgv6_np_terrain_higher", np_terrain_higher);
	settings->setNoiseParams("mgv6_np_steepness",      np_steepness);
	settings->setNoiseParams("mgv6_np_height_select",  np_height_select);
	settings->setNoiseParams("mgv6_np_mud",            np_mud);
	settings->setNoiseParams("mgv6_np_beach",          np_beach);
	settings->setNoiseParams("mgv6_np_biome",          np_biome);
	settings->setNoiseParams("mgv6_np_cave",           np_cave);
	settings->setNoiseParams("mgv6_np_humidity",       np_humidity);
	settings->setNoiseParams("mgv6_np_trees",          np_trees);
	settings->setNoiseParams("mgv6_np_apple_trees",    np_apple_trees);
}

//////////////////////// Some helper functions for the map generator

// Returns Y one under area minimum if not found
s16 MapgenV6::find_stone_level(v2s16 p2d)
{
	v3s16 em = vm->m_area.getExtent();
	s16 y_nodes_max = vm->m_area.MaxEdge.Y;
	s16 y_nodes_min = vm->m_area.MinEdge.Y;
	u32 i = vm->m_area.index(p2d.X, y_nodes_max, p2d.Y);
	s16 y;

	for (y = y_nodes_max; y >= y_nodes_min; y--) {
		content_t c = vm->m_data[i].getContent();
		if (c != CONTENT_IGNORE && (c == c_stone || c == c_desert_stone))
			break;

		vm->m_area.add_y(em, i, -1);
	}
	return (y >= y_nodes_min) ? y : y_nodes_min - 1;
}

// Required by mapgen.h
bool MapgenV6::block_is_underground(u64 seed, v3s16 blockpos)
{
	/*s16 minimum_groundlevel = (s16)get_sector_minimum_ground_level(
			seed, v2s16(blockpos.X, blockpos.Z));*/
	// Nah, this is just a heuristic, just return something
	s16 minimum_groundlevel = water_level;

	if(blockpos.Y * MAP_BLOCKSIZE + MAP_BLOCKSIZE <= minimum_groundlevel)
		return true;
	else
		return false;
}

//////////////////////// Base terrain height functions

float MapgenV6::baseTerrainLevel(float terrain_base, float terrain_higher,
	float steepness, float height_select)
{
	float base   = 1 + terrain_base;
	float higher = 1 + terrain_higher;

	// Limit higher ground level to at least base
	if(higher < base)
		higher = base;

	// Steepness factor of cliffs
	float b = steepness;
	b = rangelim(b, 0.0, 1000.0);
	b = 5 * b * b * b * b * b * b * b;
	b = rangelim(b, 0.5, 1000.0);

	// Values 1.5...100 give quite horrible looking slopes
	if (b > 1.5 && b < 100.0)
		b = (b < 10.0) ? 1.5 : 100.0;

	float a_off = -0.20; // Offset to more low
	float a = 0.5 + b * (a_off + height_select);
	a = rangelim(a, 0.0, 1.0); // Limit

	return base * (1.0 - a) + higher * a;
}

float MapgenV6::baseTerrainLevelFromNoise(v2s16 p)
{
	if (spflags & MGV6_FLAT)
		return water_level;

	float terrain_base   = NoisePerlin2D_PO(&noise_terrain_base->np,
							p.X, 0.5, p.Y, 0.5, seed);
	float terrain_higher = NoisePerlin2D_PO(&noise_terrain_higher->np,
							p.X, 0.5, p.Y, 0.5, seed);
	float steepness      = NoisePerlin2D_PO(&noise_steepness->np,
							p.X, 0.5, p.Y, 0.5, seed);
	float height_select  = NoisePerlin2D_PO(&noise_height_select->np,
							p.X, 0.5, p.Y, 0.5, seed);

	return baseTerrainLevel(terrain_base, terrain_higher,
							steepness, height_select);
}

float MapgenV6::baseTerrainLevelFromMap(v2s16 p)
{
	int index = (p.Y - node_min.Z) * ystride + (p.X - node_min.X);
	return baseTerrainLevelFromMap(index);
}

float MapgenV6::baseTerrainLevelFromMap(int index)
{
	if (spflags & MGV6_FLAT)
		return water_level;

	float terrain_base   = noise_terrain_base->result[index];
	float terrain_higher = noise_terrain_higher->result[index];
	float steepness      = noise_steepness->result[index];
	float height_select  = noise_height_select->result[index];

	return baseTerrainLevel(terrain_base, terrain_higher,
							steepness, height_select);
}

s16 MapgenV6::find_ground_level_from_noise(u64 seed, v2s16 p2d, s16 precision)
{
	return baseTerrainLevelFromNoise(p2d) + MGV6_AVERAGE_MUD_AMOUNT;
}

int MapgenV6::getGroundLevelAtPoint(v2s16 p)
{
	return baseTerrainLevelFromNoise(p) + MGV6_AVERAGE_MUD_AMOUNT;
}

int MapgenV6::getSpawnLevelAtPoint(v2s16 p)
{
	s16 level_at_point = baseTerrainLevelFromNoise(p) + MGV6_AVERAGE_MUD_AMOUNT;
	if (level_at_point <= water_level ||
			level_at_point > water_level + 16)
		return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
	else
		return level_at_point;
}

//////////////////////// Noise functions

float MapgenV6::getMudAmount(v2s16 p)
{
	int index = (p.Y - node_min.Z) * ystride + (p.X - node_min.X);
	return getMudAmount(index);
}

bool MapgenV6::getHaveBeach(v2s16 p)
{
	int index = (p.Y - node_min.Z) * ystride + (p.X - node_min.X);
	return getHaveBeach(index);
}

BiomeV6Type MapgenV6::getBiome(v2s16 p)
{
	int index = (p.Y - full_node_min.Z) * (ystride + 2 * MAP_BLOCKSIZE)
			+ (p.X - full_node_min.X);
	return getBiome(index, p);
}

float MapgenV6::getHumidity(v2s16 p)
{
	/*double noise = noise2d_perlin(
		0.5+(float)p.X/500, 0.5+(float)p.Y/500,
		seed+72384, 4, 0.66);
	noise = (noise + 1.0)/2.0;*/

	int index = (p.Y - full_node_min.Z) * (ystride + 2 * MAP_BLOCKSIZE)
			+ (p.X - full_node_min.X);
	float noise = noise_humidity->result[index];

	if (noise < 0.0)
		noise = 0.0;
	if (noise > 1.0)
		noise = 1.0;
	return noise;
}

float MapgenV6::getTreeAmount(v2s16 p)
{
	/*double noise = noise2d_perlin(
			0.5+(float)p.X/125, 0.5+(float)p.Y/125,
			seed+2, 4, 0.66);*/

	float noise = NoisePerlin2D(np_trees, p.X, p.Y, seed);
	float zeroval = -0.39;
	if (noise < zeroval)
		return 0;
	else
		return 0.04 * (noise - zeroval) / (1.0 - zeroval);
}

bool MapgenV6::getHaveAppleTree(v2s16 p)
{
	/*is_apple_tree = noise2d_perlin(
		0.5+(float)p.X/100, 0.5+(float)p.Z/100,
		data->seed+342902, 3, 0.45) > 0.2;*/

	float noise = NoisePerlin2D(np_apple_trees, p.X, p.Y, seed);

	return noise > 0.2;
}

float MapgenV6::getMudAmount(int index)
{
	if (spflags & MGV6_FLAT)
		return MGV6_AVERAGE_MUD_AMOUNT;

	/*return ((float)AVERAGE_MUD_AMOUNT + 2.0 * noise2d_perlin(
			0.5+(float)p.X/200, 0.5+(float)p.Y/200,
			seed+91013, 3, 0.55));*/

	return noise_mud->result[index];
}

bool MapgenV6::getHaveBeach(int index)
{
	// Determine whether to have sand here
	/*double sandnoise = noise2d_perlin(
			0.2+(float)p2d.X/250, 0.7+(float)p2d.Y/250,
			seed+59420, 3, 0.50);*/

	float sandnoise = noise_beach->result[index];
	return (sandnoise > freq_beach);
}

BiomeV6Type MapgenV6::getBiome(int index, v2s16 p)
{
	// Just do something very simple as for now
	/*double d = noise2d_perlin(
			0.6+(float)p2d.X/250, 0.2+(float)p2d.Y/250,
			seed+9130, 3, 0.50);*/

	float d = noise_biome->result[index];
	float h = noise_humidity->result[index];

	if (spflags & MGV6_SNOWBIOMES) {
		float blend = (spflags & MGV6_BIOMEBLEND) ? noise2d(p.X, p.Y, seed) / 40 : 0;

		if (d > MGV6_FREQ_HOT + blend) {
			if (h > MGV6_FREQ_JUNGLE + blend)
				return BT_JUNGLE;
			else
				return BT_DESERT;
		} else if (d < MGV6_FREQ_SNOW + blend) {
			if (h > MGV6_FREQ_TAIGA + blend)
				return BT_TAIGA;
			else
				return BT_TUNDRA;
		} else {
			return BT_NORMAL;
		}
	} else {
		if (d > freq_desert)
			return BT_DESERT;

		if ((spflags & MGV6_BIOMEBLEND) && (d > freq_desert - 0.10) &&
				((noise2d(p.X, p.Y, seed) + 1.0) > (freq_desert - d) * 20.0))
			return BT_DESERT;

		if ((spflags & MGV6_JUNGLES) && h > 0.75)
			return BT_JUNGLE;
		else
			return BT_NORMAL;
	}
}

u32 MapgenV6::get_blockseed(u64 seed, v3s16 p)
{
	s32 x = p.X, y = p.Y, z = p.Z;
	return (u32)(seed % 0x100000000ULL) + z * 38134234 + y * 42123 + x * 23;
}

//////////////////////// Map generator

void MapgenV6::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;

	// Hack: use minimum block coords for old code that assumes a single block
	v3s16 blockpos_min = data->blockpos_min;
	v3s16 blockpos_max = data->blockpos_max;

	// Area of central chunk
	node_min = blockpos_min * MAP_BLOCKSIZE;
	node_max = (blockpos_max + v3s16(1, 1, 1)) * MAP_BLOCKSIZE - v3s16(1, 1, 1);

	// Full allocated area
	full_node_min = (blockpos_min - 1) * MAP_BLOCKSIZE;
	full_node_max = (blockpos_max + 2) * MAP_BLOCKSIZE - v3s16(1, 1, 1);

	central_area_size = node_max - node_min + v3s16(1, 1, 1);
	assert(central_area_size.X == central_area_size.Z);

	int volume_blocks = (blockpos_max.X - blockpos_min.X + 1)
					  * (blockpos_max.Y - blockpos_min.Y + 1)
					  * (blockpos_max.Z - blockpos_max.Z + 1);

	volume_nodes = volume_blocks *
		MAP_BLOCKSIZE * MAP_BLOCKSIZE * MAP_BLOCKSIZE;

	// Create a block-specific seed
	blockseed = get_blockseed(data->seed, full_node_min);

	// Make some noise
	calculateNoise();

	// Maximum height of the stone surface and obstacles.
	// This is used to guide the cave generation
	s16 stone_surface_max_y;

	// Generate general ground level to full area
	stone_surface_max_y = generateGround();

	// Create initial heightmap to limit caves
	updateHeightmap(node_min, node_max);

	const s16 max_spread_amount = MAP_BLOCKSIZE;
	// Limit dirt flow area by 1 because mud is flown into neighbors.
	s16 mudflow_minpos = -max_spread_amount + 1;
	s16 mudflow_maxpos = central_area_size.X + max_spread_amount - 2;

	// Loop this part, it will make stuff look older and newer nicely
	const u32 age_loops = 2;
	for (u32 i_age = 0; i_age < age_loops; i_age++) { // Aging loop
		// Make caves (this code is relatively horrible)
		if (flags & MG_CAVES)
			generateCaves(stone_surface_max_y);

		// Add mud to the central chunk
		addMud();

		// Flow mud away from steep edges
		if (spflags & MGV6_MUDFLOW)
			flowMud(mudflow_minpos, mudflow_maxpos);

	}

	// Update heightmap after mudflow
	updateHeightmap(node_min, node_max);

	// Add dungeons
	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
		DungeonParams dp;

		dp.seed             = seed;
		dp.c_water          = c_water_source;
		dp.c_river_water    = c_water_source;

		dp.only_in_ground   = true;
		dp.corridor_len_min = 1;
		dp.corridor_len_max = 13;
		dp.rooms_min        = 2;
		dp.rooms_max        = 16;
		dp.y_min            = -MAX_MAP_GENERATION_LIMIT;
		dp.y_max            = MAX_MAP_GENERATION_LIMIT;

		dp.np_density
			= NoiseParams(0.9, 0.5, v3f(500.0, 500.0, 500.0), 0, 2, 0.8, 2.0);
		dp.np_alt_wall
			= NoiseParams(-0.4, 1.0, v3f(40.0, 40.0, 40.0), 32474, 6, 1.1, 2.0);

		if (getBiome(0, v2s16(node_min.X, node_min.Z)) == BT_DESERT) {
			dp.c_wall              = c_desert_stone;
			dp.c_alt_wall          = CONTENT_IGNORE;
			dp.c_stair             = c_stair_desert_stone;

			dp.diagonal_dirs       = true;
			dp.holesize            = v3s16(2, 3, 2);
			dp.room_size_min       = v3s16(6, 9, 6);
			dp.room_size_max       = v3s16(10, 11, 10);
			dp.room_size_large_min = v3s16(10, 13, 10);
			dp.room_size_large_max = v3s16(18, 21, 18);
			dp.notifytype          = GENNOTIFY_TEMPLE;
		} else {
			dp.c_wall              = c_cobble;
			dp.c_alt_wall          = c_mossycobble;
			dp.c_stair             = c_stair_cobble;

			dp.diagonal_dirs       = false;
			dp.holesize            = v3s16(1, 2, 1);
			dp.room_size_min       = v3s16(4, 4, 4);
			dp.room_size_max       = v3s16(8, 6, 8);
			dp.room_size_large_min = v3s16(8, 8, 8);
			dp.room_size_large_max = v3s16(16, 16, 16);
			dp.notifytype          = GENNOTIFY_DUNGEON;
		}

		DungeonGen dgen(ndef, &gennotify, &dp);
		dgen.generate(vm, blockseed, full_node_min, full_node_max);
	}

	// Add top and bottom side of water to transforming_liquid queue
	updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);

	// Add surface nodes
	growGrass();

	// Generate some trees, and add grass, if a jungle
	if (spflags & MGV6_TREES)
		placeTreesAndJungleGrass();

	// 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);

	// Calculate lighting
	if (flags & MG_LIGHT)
		calcLighting(node_min - v3s16(1, 1, 1) * MAP_BLOCKSIZE,
			node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE,
			full_node_min, full_node_max);

	this->generating = false;
}

void MapgenV6::calculateNoise()
{
	int x = node_min.X;
	int z = node_min.Z;
	int fx = full_node_min.X;
	int fz = full_node_min.Z;

	if (!(spflags & MGV6_FLAT)) {
		noise_terrain_base->perlinMap2D_PO(x, 0.5, z, 0.5);
		noise_terrain_higher->perlinMap2D_PO(x, 0.5, z, 0.5);
		noise_steepness->perlinMap2D_PO(x, 0.5, z, 0.5);
		noise_height_select->perlinMap2D_PO(x, 0.5, z, 0.5);
		noise_mud->perlinMap2D_PO(x, 0.5, z, 0.5);
	}

	noise_beach->perlinMap2D_PO(x, 0.2, z, 0.7);

	noise_biome->perlinMap2D_PO(fx, 0.6, fz, 0.2);
	noise_humidity->perlinMap2D_PO(fx, 0.0, fz, 0.0);
	// Humidity map does not need range limiting 0 to 1,
	// only humidity at point does
}

int MapgenV6::generateGround()
{
	//TimeTaker timer1("Generating ground level");
	MapNode n_air(CONTENT_AIR), n_water_source(c_water_source);
	MapNode n_stone(c_stone), n_desert_stone(c_desert_stone);
	MapNode n_ice(c_ice);
	int stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;

	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++) {
		// Surface height
		s16 surface_y = (s16)baseTerrainLevelFromMap(index);

		// Log it
		if (surface_y > stone_surface_max_y)
			stone_surface_max_y = surface_y;

		BiomeV6Type bt = getBiome(v2s16(x, z));

		// Fill ground with stone
		v3s16 em = vm->m_area.getExtent();
		u32 i = vm->m_area.index(x, node_min.Y, z);
		for (s16 y = node_min.Y; y <= node_max.Y; y++) {
			if (vm->m_data[i].getContent() == CONTENT_IGNORE) {
				if (y <= surface_y) {
					vm->m_data[i] = (y >= MGV6_DESERT_STONE_BASE
							&& bt == BT_DESERT) ?
						n_desert_stone : n_stone;
				} else if (y <= water_level) {
					vm->m_data[i] = (y >= MGV6_ICE_BASE
							&& bt == BT_TUNDRA) ?
						n_ice : n_water_source;
				} else {
					vm->m_data[i] = n_air;
				}
			}
			vm->m_area.add_y(em, i, 1);
		}
	}

	return stone_surface_max_y;
}

void MapgenV6::addMud()
{
	// 15ms @cs=8
	//TimeTaker timer1("add mud");
	MapNode n_dirt(c_dirt), n_gravel(c_gravel);
	MapNode n_sand(c_sand), n_desert_sand(c_desert_sand);
	MapNode addnode;

	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++) {
		// Randomize mud amount
		s16 mud_add_amount = getMudAmount(index) / 2.0 + 0.5;

		// Find ground level
		s16 surface_y = find_stone_level(v2s16(x, z)); /////////////////optimize this!

		// Handle area not found
		if (surface_y == vm->m_area.MinEdge.Y - 1)
			continue;

		BiomeV6Type bt = getBiome(v2s16(x, z));
		addnode = (bt == BT_DESERT) ? n_desert_sand : n_dirt;

		if (bt == BT_DESERT && surface_y + mud_add_amount <= water_level + 1) {
			addnode = n_sand;
		} else if (mud_add_amount <= 0) {
			mud_add_amount = 1 - mud_add_amount;
			addnode = n_gravel;
		} else if (bt != BT_DESERT && getHaveBeach(index) &&
				surface_y + mud_add_amount <= water_level + 2) {
			addnode = n_sand;
		}

		if ((bt == BT_DESERT || bt == BT_TUNDRA) && surface_y > 20)
			mud_add_amount = MYMAX(0, mud_add_amount - (surface_y - 20) / 5);

		/* If topmost node is grass, change it to mud.  It might be if it was
		// flown to there from a neighboring chunk and then converted.
		u32 i = vm->m_area.index(x, surface_y, z);
		if (vm->m_data[i].getContent() == c_dirt_with_grass)
			vm->m_data[i] = n_dirt;*/

		// Add mud on ground
		s16 mudcount = 0;
		v3s16 em = vm->m_area.getExtent();
		s16 y_start = surface_y + 1;
		u32 i = vm->m_area.index(x, y_start, z);
		for (s16 y = y_start; y <= node_max.Y; y++) {
			if (mudcount >= mud_add_amount)
				break;

			vm->m_data[i] = addnode;
			mudcount++;

			vm->m_area.add_y(em, i, 1);
		}
	}
}

void MapgenV6::flowMud(s16 &mudflow_minpos, s16 &mudflow_maxpos)
{
	// 340ms @cs=8
	//TimeTaker timer1("flow mud");

	// Iterate a few times
	for (s16 k = 0; k < 3; k++) {
		for (s16 z = mudflow_minpos; z <= mudflow_maxpos; z++)
		for (s16 x = mudflow_minpos; x <= mudflow_maxpos; x++) {
			// Invert coordinates every 2nd iteration
			if (k % 2 == 0) {
				x = mudflow_maxpos - (x - mudflow_minpos);
				z = mudflow_maxpos - (z - mudflow_minpos);
			}

			// Node position in 2d
			v2s16 p2d = v2s16(node_min.X, node_min.Z) + v2s16(x, z);

			v3s16 em = vm->m_area.getExtent();
			u32 i = vm->m_area.index(p2d.X, node_max.Y, p2d.Y);
			s16 y = node_max.Y;

			while (y >= node_min.Y) {

			for (;; y--) {
				MapNode *n = NULL;
				// Find mud
				for (; y >= node_min.Y; y--) {
					n = &vm->m_data[i];
					if (n->getContent() == c_dirt ||
							n->getContent() == c_dirt_with_grass ||
							n->getContent() == c_gravel)
						break;

					vm->m_area.add_y(em, i, -1);
				}

				// Stop if out of area
				//if(vmanip.m_area.contains(i) == false)
				if (y < node_min.Y)
					break;

				if (n->getContent() == c_dirt ||
						n->getContent() == c_dirt_with_grass) {
					// Make it exactly mud
					n->setContent(c_dirt);

					// Don't flow it if the stuff under it is not mud
					{
						u32 i2 = i;
						vm->m_area.add_y(em, i2, -1);
						// Cancel if out of area
						if (vm->m_area.contains(i2) == false)
							continue;
						MapNode *n2 = &vm->m_data[i2];
						if (n2->getContent() != c_dirt &&
								n2->getContent() != c_dirt_with_grass)
							continue;
					}
				}

				v3s16 dirs4[4] = {
					v3s16(0, 0, 1), // back
					v3s16(1, 0, 0), // right
					v3s16(0, 0, -1), // front
					v3s16(-1, 0, 0), // left
				};

				// Check that upper is walkable. Cancel
				// dropping if upper keeps it in place.
				u32 i3 = i;
				vm->m_area.add_y(em, i3, 1);
				MapNode *n3 = NULL;

				if (vm->m_area.contains(i3)) {
					n3 = &vm->m_data[i3];
					if (ndef->get(*n3).walkable)
						continue;
				}

				// Drop mud on side
				for (u32 di = 0; di < 4; di++) {
					v3s16 dirp = dirs4[di];
					u32 i2 = i;
					// Move to side
					vm->m_area.add_p(em, i2, dirp);
					// Fail if out of area
					if (vm->m_area.contains(i2) == false)
						continue;
					// Check that side is air
					MapNode *n2 = &vm->m_data[i2];
					if (ndef->get(*n2).walkable)
						continue;
					// Check that under side is air
					vm->m_area.add_y(em, i2, -1);
					if (vm->m_area.contains(i2) == false)
						continue;
					n2 = &vm->m_data[i2];
					if (ndef->get(*n2).walkable)
						continue;
					// Loop further down until not air
					bool dropped_to_unknown = false;
					do {
						vm->m_area.add_y(em, i2, -1);
						n2 = &vm->m_data[i2];
						// if out of known area
						if (vm->m_area.contains(i2) == false ||
								n2->getContent() == CONTENT_IGNORE) {
							dropped_to_unknown = true;
							break;
						}
					} while (ndef->get(*n2).walkable == false);
					// Loop one up so that we're in air
					vm->m_area.add_y(em, i2, 1);
					n2 = &vm->m_data[i2];

					bool old_is_water = (n->getContent() == c_water_source);
					// Move mud to new place
					if (!dropped_to_unknown) {
						*n2 = *n;
						// Set old place to be air (or water)
						if (old_is_water) {
							*n = MapNode(c_water_source);
						} else {
							*n = MapNode(CONTENT_AIR);
							// Upper (n3) is not walkable or is NULL. If it is
							// not NULL and not air and not water it is a
							// decoration that needs removing, to avoid
							// unsupported decorations.
							if (n3 && n3->getContent() != CONTENT_AIR &&
									n3->getContent() != c_water_source)
								*n3 = MapNode(CONTENT_AIR);
						}
					}

					// Done
					break;
				}
			}
			}
		}
	}
}

void MapgenV6::placeTreesAndJungleGrass()
{
	//TimeTaker t("placeTrees");
	if (node_max.Y < water_level)
		return;

	PseudoRandom grassrandom(blockseed + 53);
	content_t c_junglegrass = ndef->getId("mapgen_junglegrass");
	// if we don't have junglegrass, don't place cignore... that's bad
	if (c_junglegrass == CONTENT_IGNORE)
		c_junglegrass = CONTENT_AIR;
	MapNode n_junglegrass(c_junglegrass);
	v3s16 em = vm->m_area.getExtent();

	// Divide area into parts
	s16 div = 8;
	s16 sidelen = central_area_size.X / div;
	double area = sidelen * sidelen;

	// N.B.  We must add jungle grass first, since tree leaves will
	// obstruct the ground, giving us a false ground level
	for (s16 z0 = 0; z0 < div; z0++)
	for (s16 x0 = 0; x0 < div; x0++) {
		// Center position of part of division
		v2s16 p2d_center(
			node_min.X + sidelen / 2 + sidelen * x0,
			node_min.Z + sidelen / 2 + sidelen * z0
		);
		// Minimum edge of part of division
		v2s16 p2d_min(
			node_min.X + sidelen * x0,
			node_min.Z + sidelen * z0
		);
		// Maximum edge of part of division
		v2s16 p2d_max(
			node_min.X + sidelen + sidelen * x0 - 1,
			node_min.Z + sidelen + sidelen * z0 - 1
		);

		// Get biome at center position of part of division
		BiomeV6Type bt = getBiome(p2d_center);

		// Amount of trees
		u32 tree_count;
		if (bt == BT_JUNGLE || bt == BT_TAIGA || bt == BT_NORMAL) {
			tree_count = area * getTreeAmount(p2d_center);
			if (bt == BT_JUNGLE)
				tree_count *= 4;
		} else {
			tree_count = 0;
		}

		// Add jungle grass
		if (bt == BT_JUNGLE) {
			float humidity = getHumidity(p2d_center);
			u32 grass_count = 5 * humidity * tree_count;
			for (u32 i = 0; i < grass_count; i++) {
				s16 x = grassrandom.range(p2d_min.X, p2d_max.X);
				s16 z = grassrandom.range(p2d_min.Y, p2d_max.Y);
				int mapindex = central_area_size.X * (z - node_min.Z)
								+ (x - node_min.X);
				s16 y = heightmap[mapindex];
				if (y < water_level)
					continue;

				u32 vi = vm->m_area.index(x, y, z);
				// place on dirt_with_grass, since we know it is exposed to sunlight
				if (vm->m_data[vi].getContent() == c_dirt_with_grass) {
					vm->m_area.add_y(em, vi, 1);
					vm->m_data[vi] = n_junglegrass;
				}
			}
		}

		// Put trees in random places on part of division
		for (u32 i = 0; i < tree_count; i++) {
			s16 x = myrand_range(p2d_min.X, p2d_max.X);
			s16 z = myrand_range(p2d_min.Y, p2d_max.Y);
			int mapindex = central_area_size.X * (z - node_min.Z)
							+ (x - node_min.X);
			s16 y = heightmap[mapindex];
			// Don't make a tree under water level
			// Don't make a tree so high that it doesn't fit
			if (y < water_level || y > node_max.Y - 6)
				continue;

			v3s16 p(x, y, z);
			// Trees grow only on mud and grass and snowblock
			{
				u32 i = vm->m_area.index(p);
				content_t c = vm->m_data[i].getContent();
				if (c != c_dirt &&
						c != c_dirt_with_grass &&
						c != c_dirt_with_snow &&
						c != c_snowblock)
					continue;
			}
			p.Y++;

			// Make a tree
			if (bt == BT_JUNGLE) {
				treegen::make_jungletree(*vm, p, ndef, myrand());
			} else if (bt == BT_TAIGA) {
				treegen::make_pine_tree(*vm, p - v3s16(0, 1, 0), ndef, myrand());
			} else if (bt == BT_NORMAL) {
				bool is_apple_tree = (myrand_range(0, 3) == 0) &&
							getHaveAppleTree(v2s16(x, z));
				treegen::make_tree(*vm, p, is_apple_tree, ndef, myrand());
			}
		}
	}
	//printf("placeTreesAndJungleGrass: %dms\n", t.stop());
}

void MapgenV6::growGrass() // Add surface nodes
{
	MapNode n_dirt_with_grass(c_dirt_with_grass);
	MapNode n_dirt_with_snow(c_dirt_with_snow);
	MapNode n_snowblock(c_snowblock);
	MapNode n_snow(c_snow);
	v3s16 em = vm->m_area.getExtent();

	u32 index = 0;
	for (s16 z = full_node_min.Z; z <= full_node_max.Z; z++)
	for (s16 x = full_node_min.X; x <= full_node_max.X; x++, index++) {
		// Find the lowest surface to which enough light ends up to make
		// grass grow.  Basically just wait until not air and not leaves.
		s16 surface_y = 0;
		{
			u32 i = vm->m_area.index(x, node_max.Y, z);
			s16 y;
			// Go to ground level
			for (y = node_max.Y; y >= full_node_min.Y; y--) {
				MapNode &n = vm->m_data[i];
				if (ndef->get(n).param_type != CPT_LIGHT ||
						ndef->get(n).liquid_type != LIQUID_NONE ||
						n.getContent() == c_ice)
					break;
				vm->m_area.add_y(em, i, -1);
			}
			surface_y = (y >= full_node_min.Y) ? y : full_node_min.Y;
		}

		BiomeV6Type bt = getBiome(index, v2s16(x, z));
		u32 i = vm->m_area.index(x, surface_y, z);
		content_t c = vm->m_data[i].getContent();
		if (surface_y >= water_level - 20) {
			if (bt == BT_TAIGA && c == c_dirt) {
				vm->m_data[i] = n_snowblock;
				vm->m_area.add_y(em, i, -1);
				vm->m_data[i] = n_dirt_with_snow;
			} else if (bt == BT_TUNDRA) {
				if (c == c_dirt) {
					vm->m_data[i] = n_dirt_with_snow;
				} else if (c == c_stone && surface_y < node_max.Y) {
					vm->m_area.add_y(em, i, 1);
					vm->m_data[i] = n_snow;
				}
			} else if (c == c_dirt) {
				vm->m_data[i] = n_dirt_with_grass;
			}
		}
	}
}

void MapgenV6::generateCaves(int max_stone_y)
{
	float cave_amount = NoisePerlin2D(np_cave, node_min.X, node_min.Y, seed);
	int volume_nodes = (node_max.X - node_min.X + 1) *
					   (node_max.Y - node_min.Y + 1) * MAP_BLOCKSIZE;
	cave_amount = MYMAX(0.0, cave_amount);
	u32 caves_count = cave_amount * volume_nodes / 50000;
	u32 bruises_count = 1;
	PseudoRandom ps(blockseed + 21343);
	PseudoRandom ps2(blockseed + 1032);

	if (ps.range(1, 6) == 1)
		bruises_count = ps.range(0, ps.range(0, 2));

	if (getBiome(v2s16(node_min.X, node_min.Z)) == BT_DESERT) {
		caves_count   /= 3;
		bruises_count /= 3;
	}

	for (u32 i = 0; i < caves_count + bruises_count; i++) {
		CavesV6 cave(ndef, &gennotify, water_level, c_water_source, c_lava_source);

		bool large_cave = (i >= caves_count);
		cave.makeCave(vm, node_min, node_max, &ps, &ps2,
			large_cave, max_stone_y, heightmap);
	}
}


code:
/*
Minetest
Copyright (C) 2010-2015 celeron55, Perttu Ahola <celeron55@gmail.com>
Copyright (C) 2013-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
Copyright (C) 2014-2017 paramat

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.
*/

#ifndef MAPGENV6_HEADER
#define MAPGENV6_HEADER

#include "mapgen.h"
#include "noise.h"

#define MGV6_AVERAGE_MUD_AMOUNT 4
#define MGV6_DESERT_STONE_BASE -32
#define MGV6_ICE_BASE 0
#define MGV6_FREQ_HOT 0.4
#define MGV6_FREQ_SNOW -0.4
#define MGV6_FREQ_TAIGA 0.5
#define MGV6_FREQ_JUNGLE 0.5

//////////// Mapgen V6 flags
#define MGV6_JUNGLES    0x01
#define MGV6_BIOMEBLEND 0x02
#define MGV6_MUDFLOW    0x04
#define MGV6_SNOWBIOMES 0x08
#define MGV6_FLAT       0x10
#define MGV6_TREES      0x20

extern FlagDesc flagdesc_mapgen_v6[];

enum BiomeV6Type
{
	BT_NORMAL,
	BT_DESERT,
	BT_JUNGLE,
	BT_TUNDRA,
	BT_TAIGA,
};

struct MapgenV6Params : public MapgenParams {
	u32 spflags;
	float freq_desert;
	float freq_beach;
	NoiseParams np_terrain_base;
	NoiseParams np_terrain_higher;
	NoiseParams np_steepness;
	NoiseParams np_height_select;
	NoiseParams np_mud;
	NoiseParams np_beach;
	NoiseParams np_biome;
	NoiseParams np_cave;
	NoiseParams np_humidity;
	NoiseParams np_trees;
	NoiseParams np_apple_trees;

	MapgenV6Params();
	~MapgenV6Params() {}

	void readParams(const Settings *settings);
	void writeParams(Settings *settings) const;
};

class MapgenV6 : public Mapgen {
public:
	EmergeManager *m_emerge;

	int ystride;
	u32 spflags;

	v3s16 node_min;
	v3s16 node_max;
	v3s16 full_node_min;
	v3s16 full_node_max;
	v3s16 central_area_size;
	int volume_nodes;

	Noise *noise_terrain_base;
	Noise *noise_terrain_higher;
	Noise *noise_steepness;
	Noise *noise_height_select;
	Noise *noise_mud;
	Noise *noise_beach;
	Noise *noise_biome;
	Noise *noise_humidity;
	NoiseParams *np_cave;
	NoiseParams *np_humidity;
	NoiseParams *np_trees;
	NoiseParams *np_apple_trees;
	float freq_desert;
	float freq_beach;

	content_t c_stone;
	content_t c_dirt;
	content_t c_dirt_with_grass;
	content_t c_sand;
	content_t c_water_source;
	content_t c_lava_source;
	content_t c_gravel;
	content_t c_desert_stone;
	content_t c_desert_sand;
	content_t c_dirt_with_snow;
	content_t c_snow;
	content_t c_snowblock;
	content_t c_ice;

	content_t c_cobble;
	content_t c_mossycobble;
	content_t c_stair_cobble;
	content_t c_stair_desert_stone;

	MapgenV6(int mapgenid, MapgenV6Params *params, EmergeManager *emerge);
	~MapgenV6();

	virtual MapgenType getType() const { return MAPGEN_V6; }

	void makeChunk(BlockMakeData *data);
	int getGroundLevelAtPoint(v2s16 p);
	int getSpawnLevelAtPoint(v2s16 p);

	float baseTerrainLevel(float terrain_base, float terrain_higher,
		float steepness, float height_select);
	virtual float baseTerrainLevelFromNoise(v2s16 p);
	virtual float baseTerrainLevelFromMap(v2s16 p);
	virtual float baseTerrainLevelFromMap(int index);

	s16 find_stone_level(v2s16 p2d);
	bool block_is_underground(u64 seed, v3s16 blockpos);
	s16 find_ground_level_from_noise(u64 seed, v2s16 p2d, s16 precision);

	float getHumidity(v2s16 p);
	float getTreeAmount(v2s16 p);
	bool getHaveAppleTree(v2s16 p);
	float getMudAmount(v2s16 p);
	virtual float getMudAmount(int index);
	bool getHaveBeach(v2s16 p);
	bool getHaveBeach(int index);
	BiomeV6Type getBiome(v2s16 p);
	BiomeV6Type getBiome(int index, v2s16 p);

	u32 get_blockseed(u64 seed, v3s16 p);

	virtual void calculateNoise();
	int generateGround();
	void addMud();
	void flowMud(s16 &mudflow_minpos, s16 &mudflow_maxpos);
	void growGrass();
	void placeTreesAndJungleGrass();
	virtual void generateCaves(int max_stone_y);
};

#endif

repo_name: pgimeno/minetest

license: unknown


code:
/*
Minetest
Copyright (C) 2013-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
Copyright (C) 2014-2017 paramat

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 "profiler.h" // For TimeTaker
#include "settings.h" // For g_settings
#include "emerge.h"
#include "dungeongen.h"
#include "cavegen.h"
#include "mg_biome.h"
#include "mg_ore.h"
#include "mg_decoration.h"
#include "mapgen_v7.h"

FlagDesc flagdesc_mapgen_v7[] = {
	{"mountains",  MGV7_MOUNTAINS},
	{"ridges",     MGV7_RIDGES},
	{"floatlands", MGV7_FLOATLANDS},
	{"caverns",    MGV7_CAVERNS},
	{NULL,         0}
};

///////////////////////////////////////////////////////////////////////////////

MapgenV7::MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge)
	: MapgenBasic(mapgenid, params, emerge)
{
	this->spflags             = params->spflags;
	this->cave_width          = params->cave_width;
	this->float_mount_density = params->float_mount_density;
	this->floatland_level     = params->floatland_level;
	this->shadow_limit        = params->shadow_limit;
	this->cavern_limit        = params->cavern_limit;
	this->cavern_taper        = params->cavern_taper;
	this->cavern_threshold    = params->cavern_threshold;

	// This is to avoid a divide-by-zero.
	// Parameter will be saved to map_meta.txt in limited form.
	params->float_mount_height = MYMAX(params->float_mount_height, 1.0f);
	this->float_mount_height   = params->float_mount_height;

	// 2D noise
	noise_terrain_base    = new Noise(&params->np_terrain_base,    seed, csize.X, csize.Z);
	noise_terrain_alt     = new Noise(&params->np_terrain_alt,     seed, csize.X, csize.Z);
	noise_terrain_persist = new Noise(&params->np_terrain_persist, seed, csize.X, csize.Z);
	noise_height_select   = new Noise(&params->np_height_select,   seed, csize.X, csize.Z);
	noise_filler_depth    = new Noise(&params->np_filler_depth,    seed, csize.X, csize.Z);

	if (spflags & MGV7_MOUNTAINS)
		noise_mount_height = new Noise(&params->np_mount_height, seed, csize.X, csize.Z);

	if (spflags & MGV7_FLOATLANDS) {
		noise_floatland_base    = new Noise(&params->np_floatland_base,    seed, csize.X, csize.Z);
		noise_float_base_height = new Noise(&params->np_float_base_height, seed, csize.X, csize.Z);
	}

	if (spflags & MGV7_RIDGES) {
		noise_ridge_uwater = new Noise(&params->np_ridge_uwater, seed, csize.X, csize.Z);
	// 3D noise, 1-up 1-down overgeneration
		noise_ridge = new Noise(&params->np_ridge, seed, csize.X, csize.Y + 2, csize.Z);
	}
	// 3D noise, 1 up, 1 down overgeneration
	if ((spflags & MGV7_MOUNTAINS) || (spflags & MGV7_FLOATLANDS))
		noise_mountain = new Noise(&params->np_mountain, seed, csize.X, csize.Y + 2, csize.Z);
	// 3D noise, 1 down overgeneration
	MapgenBasic::np_cave1  = params->np_cave1;
	MapgenBasic::np_cave2  = params->np_cave2;
	MapgenBasic::np_cavern = params->np_cavern;
}

MapgenV7::~MapgenV7()
{
	delete noise_terrain_base;
	delete noise_terrain_alt;
	delete noise_terrain_persist;
	delete noise_height_select;
	delete noise_filler_depth;

	if (spflags & MGV7_MOUNTAINS)
		delete noise_mount_height;

	if (spflags & MGV7_FLOATLANDS) {
		delete noise_floatland_base;
		delete noise_float_base_height;
	}

	if (spflags & MGV7_RIDGES) {
		delete noise_ridge_uwater;
		delete noise_ridge;
	}

	if ((spflags & MGV7_MOUNTAINS) || (spflags & MGV7_FLOATLANDS))
		delete noise_mountain;
}

MapgenV7Params::MapgenV7Params()
{
	spflags             = MGV7_MOUNTAINS | MGV7_RIDGES | MGV7_CAVERNS;
	cave_width          = 0.09;
	float_mount_density = 0.6;
	float_mount_height  = 128.0;
	floatland_level     = 1280;
	shadow_limit        = 1024;
	cavern_limit        = -256;
	cavern_taper        = 256;
	cavern_threshold    = 0.7;

	np_terrain_base      = NoiseParams(4,    70,   v3f(600,  600,  600),  82341, 5, 0.6,  2.0);
	np_terrain_alt       = NoiseParams(4,    25,   v3f(600,  600,  600),  5934,  5, 0.6,  2.0);
	np_terrain_persist   = NoiseParams(0.6,  0.1,  v3f(2000, 2000, 2000), 539,   3, 0.6,  2.0);
	np_height_select     = NoiseParams(-8,   16,   v3f(500,  500,  500),  4213,  6, 0.7,  2.0);
	np_filler_depth      = NoiseParams(0,    1.2,  v3f(150,  150,  150),  261,   3, 0.7,  2.0);
	np_mount_height      = NoiseParams(256,  112,  v3f(1000, 1000, 1000), 72449, 3, 0.6,  2.0);
	np_ridge_uwater      = NoiseParams(0,    1,    v3f(1000, 1000, 1000), 85039, 5, 0.6,  2.0);
	np_floatland_base    = NoiseParams(-0.6, 1.5,  v3f(600,  600,  600),  114,   5, 0.6,  2.0);
	np_float_base_height = NoiseParams(48,   24,   v3f(300,  300,  300),  907,   4, 0.7,  2.0);
	np_mountain          = NoiseParams(-0.6, 1,    v3f(250,  350,  250),  5333,  5, 0.63, 2.0);
	np_ridge             = NoiseParams(0,    1,    v3f(100,  100,  100),  6467,  4, 0.75, 2.0);
	np_cavern            = NoiseParams(0,    1,    v3f(384,  128,  384),  723,   5, 0.63, 2.0);
	np_cave1             = NoiseParams(0,    12,   v3f(61,   61,   61),   52534, 3, 0.5,  2.0);
	np_cave2             = NoiseParams(0,    12,   v3f(67,   67,   67),   10325, 3, 0.5,  2.0);
}

void MapgenV7Params::readParams(const Settings *settings)
{
	settings->getFlagStrNoEx("mgv7_spflags",           spflags, flagdesc_mapgen_v7);
	settings->getFloatNoEx("mgv7_cave_width",          cave_width);
	settings->getFloatNoEx("mgv7_float_mount_density", float_mount_density);
	settings->getFloatNoEx("mgv7_float_mount_height",  float_mount_height);
	settings->getS16NoEx("mgv7_floatland_level",       floatland_level);
	settings->getS16NoEx("mgv7_shadow_limit",          shadow_limit);
	settings->getS16NoEx("mgv7_cavern_limit",          cavern_limit);
	settings->getS16NoEx("mgv7_cavern_taper",          cavern_taper);
	settings->getFloatNoEx("mgv7_cavern_threshold",    cavern_threshold);

	settings->getNoiseParams("mgv7_np_terrain_base",      np_terrain_base);
	settings->getNoiseParams("mgv7_np_terrain_alt",       np_terrain_alt);
	settings->getNoiseParams("mgv7_np_terrain_persist",   np_terrain_persist);
	settings->getNoiseParams("mgv7_np_height_select",     np_height_select);
	settings->getNoiseParams("mgv7_np_filler_depth",      np_filler_depth);
	settings->getNoiseParams("mgv7_np_mount_height",      np_mount_height);
	settings->getNoiseParams("mgv7_np_ridge_uwater",      np_ridge_uwater);
	settings->getNoiseParams("mgv7_np_floatland_base",    np_floatland_base);
	settings->getNoiseParams("mgv7_np_float_base_height", np_float_base_height);
	settings->getNoiseParams("mgv7_np_mountain",          np_mountain);
	settings->getNoiseParams("mgv7_np_ridge",             np_ridge);
	settings->getNoiseParams("mgv7_np_cavern",            np_cavern);
	settings->getNoiseParams("mgv7_np_cave1",             np_cave1);
	settings->getNoiseParams("mgv7_np_cave2",             np_cave2);
}

void MapgenV7Params::writeParams(Settings *settings) const
{
	settings->setFlagStr("mgv7_spflags",           spflags, flagdesc_mapgen_v7, U32_MAX);
	settings->setFloat("mgv7_cave_width",          cave_width);
	settings->setFloat("mgv7_float_mount_density", float_mount_density);
	settings->setFloat("mgv7_float_mount_height",  float_mount_height);
	settings->setS16("mgv7_floatland_level",       floatland_level);
	settings->setS16("mgv7_shadow_limit",          shadow_limit);
	settings->setS16("mgv7_cavern_limit",          cavern_limit);
	settings->setS16("mgv7_cavern_taper",          cavern_taper);
	settings->setFloat("mgv7_cavern_threshold",    cavern_threshold);

	settings->setNoiseParams("mgv7_np_terrain_base",      np_terrain_base);
	settings->setNoiseParams("mgv7_np_terrain_alt",       np_terrain_alt);
	settings->setNoiseParams("mgv7_np_terrain_persist",   np_terrain_persist);
	settings->setNoiseParams("mgv7_np_height_select",     np_height_select);
	settings->setNoiseParams("mgv7_np_filler_depth",      np_filler_depth);
	settings->setNoiseParams("mgv7_np_mount_height",      np_mount_height);
	settings->setNoiseParams("mgv7_np_ridge_uwater",      np_ridge_uwater);
	settings->setNoiseParams("mgv7_np_floatland_base",    np_floatland_base);
	settings->setNoiseParams("mgv7_np_float_base_height", np_float_base_height);
	settings->setNoiseParams("mgv7_np_mountain",          np_mountain);
	settings->setNoiseParams("mgv7_np_ridge",             np_ridge);
	settings->setNoiseParams("mgv7_np_cavern",            np_cavern);
	settings->setNoiseParams("mgv7_np_cave1",             np_cave1);
	settings->setNoiseParams("mgv7_np_cave2",             np_cave2);
}

///////////////////////////////////////////////////////////////////////////////

int MapgenV7::getSpawnLevelAtPoint(v2s16 p)
{
	// Base terrain calculation
	s16 y = baseTerrainLevelAtPoint(p.X, p.Y);

	// If enabled, check if inside a river
	if (spflags & MGV7_RIDGES) {
		float width = 0.2;
		float uwatern = NoisePerlin2D(&noise_ridge_uwater->np, p.X, p.Y, seed) * 2;
		if (fabs(uwatern) <= width)
			return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
	}

	// If mountains are disabled, terrain level is base terrain level
	// Avoids spawn on non-existant mountain terrain
	if (!(spflags & MGV7_MOUNTAINS)) {
		if (y <= water_level || y > water_level + 16)
			return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
		else
			return y;
	}

	// Mountain terrain calculation
	int iters = 128;
	while (iters--) {
		if (!getMountainTerrainAtPoint(p.X, y + 1, p.Y)) {  // If air above
			if (y <= water_level || y > water_level + 16)
				return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
			else
				return y;
		}
		y++;
	}

	// Unsuitable spawn point, no mountain surface found
	return MAX_MAP_GENERATION_LIMIT;
}

void MapgenV7::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 base and mountain terrain
	// An initial heightmap is no longer created here for use in generateRidgeTerrain()
	s16 stone_surface_max_y = generateTerrain();

	// Generate rivers
	if (spflags & MGV7_RIDGES)
		generateRidgeTerrain();

	// Create heightmap
	updateHeightmap(node_min, node_max);

	// Init biome generator, place biome-specific nodes, and build biomemap
	biomegen->calcBiomeNoise(node_min);
	MgStoneType stone_type = generateBiomes();

	// Generate caverns, tunnels and classic caves
	if (flags & MG_CAVES) {
		bool near_cavern = false;
		// Generate caverns
		if (spflags & MGV7_CAVERNS)
			near_cavern = generateCaverns(stone_surface_max_y);
		// Generate tunnels and classic caves
		if (near_cavern)
			// Disable classic caves in this mapchunk by setting
			// 'large cave depth' to world base. Avoids excessive liquid in
			// large caverns and floating blobs of overgenerated liquid.
			generateCaves(stone_surface_max_y, -MAX_MAP_GENERATION_LIMIT);
		else
			generateCaves(stone_surface_max_y, water_level);
	}

	// Generate dungeons
	if (flags & MG_DUNGEONS)
		generateDungeons(stone_surface_max_y, stone_type);

	// 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();

	//printf("makeChunk: %dms\n", t.stop());

	// Update liquids
	updateLiquid(&data->transforming_liquid, full_node_min, full_node_max);

	// Calculate lighting
	// Limit floatland shadow
	bool propagate_shadow = !((spflags & MGV7_FLOATLANDS) &&
		node_min.Y <= shadow_limit && node_max.Y >= shadow_limit);

	if (flags & MG_LIGHT)
		calcLighting(node_min - v3s16(0, 1, 0), node_max + v3s16(0, 1, 0),
			full_node_min, full_node_max, propagate_shadow);

	//setLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
	//			node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE, 0xFF);

	this->generating = false;
}

float MapgenV7::baseTerrainLevelAtPoint(s16 x, s16 z)
{
	float hselect = NoisePerlin2D(&noise_height_select->np, x, z, seed);
	hselect = rangelim(hselect, 0.0, 1.0);

	float persist = NoisePerlin2D(&noise_terrain_persist->np, x, z, seed);

	noise_terrain_base->np.persist = persist;
	float height_base = NoisePerlin2D(&noise_terrain_base->np, x, z, seed);

	noise_terrain_alt->np.persist = persist;
	float height_alt = NoisePerlin2D(&noise_terrain_alt->np, x, z, seed);

	if (height_alt > height_base)
		return height_alt;

	return (height_base * hselect) + (height_alt * (1.0 - hselect));
}

float MapgenV7::baseTerrainLevelFromMap(int index)
{
	float hselect     = rangelim(noise_height_select->result[index], 0.0, 1.0);
	float height_base = noise_terrain_base->result[index];
	float height_alt  = noise_terrain_alt->result[index];

	if (height_alt > height_base)
		return height_alt;

	return (height_base * hselect) + (height_alt * (1.0 - hselect));
}

bool MapgenV7::getMountainTerrainAtPoint(s16 x, s16 y, s16 z)
{
	float mnt_h_n =
			MYMAX(NoisePerlin2D(&noise_mount_height->np, x, z, seed), 1.0f);
	float density_gradient = -((float)y / mnt_h_n);
	float mnt_n = NoisePerlin3D(&noise_mountain->np, x, y, z, seed);

	return mnt_n + density_gradient >= 0.0;
}

bool MapgenV7::getMountainTerrainFromMap(int idx_xyz, int idx_xz, s16 y)
{
	float mounthn = MYMAX(noise_mount_height->result[idx_xz], 1.0f);
	float density_gradient = -((float)y / mounthn);
	float mountn = noise_mountain->result[idx_xyz];

	return mountn + density_gradient >= 0.0;
}

bool MapgenV7::getFloatlandMountainFromMap(int idx_xyz, int idx_xz, s16 y)
{
	// Make rim 2 nodes thick to match floatland base terrain
	float density_gradient = (y >= floatland_level) ?
		-pow((float)(y - floatland_level) / float_mount_height, 0.75f) :
		-pow((float)(floatland_level - 1 - y) / float_mount_height, 0.75f);

	float floatn = noise_mountain->result[idx_xyz] + float_mount_density;

	return floatn + density_gradient >= 0.0f;
}

void MapgenV7::floatBaseExtentFromMap(s16 *float_base_min, s16 *float_base_max, int idx_xz)
{
	// '+1' to avoid a layer of stone at y = MAX_MAP_GENERATION_LIMIT
	s16 base_min = MAX_MAP_GENERATION_LIMIT + 1;
	s16 base_max = MAX_MAP_GENERATION_LIMIT;

	float n_base = noise_floatland_base->result[idx_xz];
	if (n_base > 0.0f) {
		float n_base_height =
				MYMAX(noise_float_base_height->result[idx_xz], 1.0f);
		float amp = n_base * n_base_height;
		float ridge = n_base_height / 3.0f;
		base_min = floatland_level - amp / 1.5f;

		if (amp > ridge * 2.0f) {
			// Lake bed
			base_max = floatland_level - (amp - ridge * 2.0f) / 2.0f;
		} else {
			// Hills and ridges
			float diff = fabs(amp - ridge) / ridge;
			// Smooth ridges using the 'smoothstep function'
			float smooth_diff = diff * diff * (3.0f - 2.0f * diff);
			base_max = floatland_level + ridge - smooth_diff * ridge;
		}
	}

	*float_base_min = base_min;
	*float_base_max = base_max;
}

int MapgenV7::generateTerrain()
{
	MapNode n_air(CONTENT_AIR);
	MapNode n_stone(c_stone);
	MapNode n_water(c_water_source);

	//// Calculate noise for terrain generation
	noise_terrain_persist->perlinMap2D(node_min.X, node_min.Z);
	float *persistmap = noise_terrain_persist->result;

	noise_terrain_base->perlinMap2D(node_min.X, node_min.Z, persistmap);
	noise_terrain_alt->perlinMap2D(node_min.X, node_min.Z, persistmap);
	noise_height_select->perlinMap2D(node_min.X, node_min.Z);

	if ((spflags & MGV7_MOUNTAINS) || (spflags & MGV7_FLOATLANDS)) {
		noise_mountain->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
	}

	if (spflags & MGV7_MOUNTAINS) {
		noise_mount_height->perlinMap2D(node_min.X, node_min.Z);
	}

	if (spflags & MGV7_FLOATLANDS) {
		noise_floatland_base->perlinMap2D(node_min.X, node_min.Z);
		noise_float_base_height->perlinMap2D(node_min.X, node_min.Z);
	}

	//// Place nodes
	v3s16 em = vm->m_area.getExtent();
	s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
	u32 index2d = 0;

	for (s16 z = node_min.Z; z <= node_max.Z; z++)
	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
		s16 surface_y = baseTerrainLevelFromMap(index2d);
		if (surface_y > stone_surface_max_y)
			stone_surface_max_y = surface_y;

		// Get extent of floatland base terrain
		// '+1' to avoid a layer of stone at y = MAX_MAP_GENERATION_LIMIT
		s16 float_base_min = MAX_MAP_GENERATION_LIMIT + 1;
		s16 float_base_max = MAX_MAP_GENERATION_LIMIT;
		if (spflags & MGV7_FLOATLANDS)
			floatBaseExtentFromMap(&float_base_min, &float_base_max, index2d);

		u32 vi = vm->m_area.index(x, node_min.Y - 1, z);
		u32 index3d = (z - node_min.Z) * zstride_1u1d + (x - node_min.X);

		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
			if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
				if (y <= surface_y) {
					vm->m_data[vi] = n_stone;  // Base terrain
				} else if ((spflags & MGV7_MOUNTAINS) &&
						getMountainTerrainFromMap(index3d, index2d, y)) {
					vm->m_data[vi] = n_stone;  // Mountain terrain
					if (y > stone_surface_max_y)
						stone_surface_max_y = y;
				} else if ((spflags & MGV7_FLOATLANDS) &&
						((y >= float_base_min && y <= float_base_max) ||
						getFloatlandMountainFromMap(index3d, index2d, y))) {
					vm->m_data[vi] = n_stone;  // Floatland terrain
					stone_surface_max_y = node_max.Y;
				} else if (y <= water_level) {
					vm->m_data[vi] = n_water;  // Ground level water
				} else if ((spflags & MGV7_FLOATLANDS) &&
						(y >= float_base_max && y <= floatland_level)) {
					vm->m_data[vi] = n_water;  // Floatland water
				} else {
					vm->m_data[vi] = n_air;
				}
			}
			vm->m_area.add_y(em, vi, 1);
			index3d += ystride;
		}
	}

	return stone_surface_max_y;
}

void MapgenV7::generateRidgeTerrain()
{
	if ((node_max.Y < water_level - 16) || (node_max.Y > shadow_limit))
		return;

	noise_ridge->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
	noise_ridge_uwater->perlinMap2D(node_min.X, node_min.Z);

	MapNode n_water(c_water_source);
	MapNode n_air(CONTENT_AIR);
	u32 index = 0;
	float width = 0.2;

	for (s16 z = node_min.Z; z <= node_max.Z; z++)
	for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
		u32 vi = vm->m_area.index(node_min.X, y, z);
		for (s16 x = node_min.X; x <= node_max.X; x++, index++, vi++) {
			int j = (z - node_min.Z) * csize.X + (x - node_min.X);

			float uwatern = noise_ridge_uwater->result[j] * 2;
			if (fabs(uwatern) > width)
				continue;

			float altitude = y - water_level;
			float height_mod = (altitude + 17) / 2.5;
			float width_mod  = width - fabs(uwatern);
			float nridge = noise_ridge->result[index] * MYMAX(altitude, 0) / 7.0;

			if (nridge + width_mod * height_mod < 0.6)
				continue;

			vm->m_data[vi] = (y > water_level) ? n_air : n_water;
		}
	}
}

////////////////////////////////////////////////////////////////////////////////
//// Code Boneyard
////
//// Much of the stuff here has potential to become useful again at some point
//// in the future, but we don't want it to get lost or forgotten in version
//// control.
////

#if 0
int MapgenV7::generateMountainTerrain(s16 ymax)
{
	MapNode n_stone(c_stone);
	u32 j = 0;

	for (s16 z = node_min.Z; z <= node_max.Z; z++)
	for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
		u32 vi = vm->m_area.index(node_min.X, y, z);
		for (s16 x = node_min.X; x <= node_max.X; x++) {
			int index = (z - node_min.Z) * csize.X + (x - node_min.X);
			content_t c = vm->m_data[vi].getContent();

			if (getMountainTerrainFromMap(j, index, y)
					&& (c == CONTENT_AIR || c == c_water_source)) {
				vm->m_data[vi] = n_stone;
				if (y > ymax)
					ymax = y;
			}

			vi++;
			j++;
		}
	}

	return ymax;
}
#endif

#if 0
void MapgenV7::carveRivers() {
	MapNode n_air(CONTENT_AIR), n_water_source(c_water_source);
	MapNode n_stone(c_stone);
	u32 index = 0;

	int river_depth = 4;

	for (s16 z = node_min.Z; z <= node_max.Z; z++)
	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
		float terrain_mod  = noise_terrain_mod->result[index];
		NoiseParams *np = noise_terrain_river->np;
		np.persist = noise_terrain_persist->result[index];
		float terrain_river = NoisePerlin2DNoTxfm(np, x, z, seed);
		float height = terrain_river * (1 - abs(terrain_mod)) *
						noise_terrain_river->np.scale;
		height = log(height * height); //log(h^3) is pretty interesting for terrain

		s16 y = heightmap[index];
		if (height < 1.0 && y > river_depth &&
			y - river_depth >= node_min.Y && y <= node_max.Y) {

			for (s16 ry = y; ry != y - river_depth; ry--) {
				u32 vi = vm->m_area.index(x, ry, z);
				vm->m_data[vi] = n_air;
			}

			u32 vi = vm->m_area.index(x, y - river_depth, z);
			vm->m_data[vi] = n_water_source;
		}
	}
}
#endif

#if 0
void MapgenV7::addTopNodes()
{
	v3s16 em = vm->m_area.getExtent();
	s16 ntopnodes;
	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 = bmgr->biomes[biomemap[index]];

		//////////////////// First, add top nodes below the ridge
		s16 y = ridge_heightmap[index];

		// This cutoff is good enough, but not perfect.
		// It will cut off potentially placed top nodes at chunk boundaries
		if (y < node_min.Y)
			continue;
		if (y > node_max.Y) {
			y = node_max.Y; // Let's see if we can still go downward anyway
			u32 vi = vm->m_area.index(x, y, z);
			content_t c = vm->m_data[vi].getContent();
			if (ndef->get(c).walkable)
				continue;
		}

		// N.B.  It is necessary to search downward since ridge_heightmap[i]
		// might not be the actual height, just the lowest part in the chunk
		// where a ridge had been carved
		u32 i = vm->m_area.index(x, y, z);
		for (; y >= node_min.Y; y--) {
			content_t c = vm->m_data[i].getContent();
			if (ndef->get(c).walkable)
				break;
			vm->m_area.add_y(em, i, -1);
		}

		if (y != node_min.Y - 1 && y >= water_level) {
			ridge_heightmap[index] = y; //update ridgeheight
			ntopnodes = biome->top_depth;
			for (; y <= node_max.Y && ntopnodes; y++) {
				ntopnodes--;
				vm->m_data[i] = MapNode(biome->c_top);
				vm->m_area.add_y(em, i, 1);
			}
			// If dirt, grow grass on it.
			if (y > water_level - 10 &&
				vm->m_data[i].getContent() == CONTENT_AIR) {
				vm->m_area.add_y(em, i, -1);
				if (vm->m_data[i].getContent() == c_dirt)
					vm->m_data[i] = MapNode(c_dirt_with_grass);
			}
		}

		//////////////////// Now, add top nodes on top of the ridge
		y = heightmap[index];
		if (y > node_max.Y) {
			y = node_max.Y; // Let's see if we can still go downward anyway
			u32 vi = vm->m_area.index(x, y, z);
			content_t c = vm->m_data[vi].getContent();
			if (ndef->get(c).walkable)
				continue;
		}

		i = vm->m_area.index(x, y, z);
		for (; y >= node_min.Y; y--) {
			content_t c = vm->m_data[i].getContent();
			if (ndef->get(c).walkable)
				break;
			vm->m_area.add_y(em, i, -1);
		}

		if (y != node_min.Y - 1) {
			ntopnodes = biome->top_depth;
			// Let's see if we've already added it...
			if (y == ridge_heightmap[index] + ntopnodes - 1)
				continue;

			for (; y <= node_max.Y && ntopnodes; y++) {
				ntopnodes--;
				vm->m_data[i] = MapNode(biome->c_top);
				vm->m_area.add_y(em, i, 1);
			}
			// If dirt, grow grass on it.
			if (y > water_level - 10 &&
				vm->m_data[i].getContent() == CONTENT_AIR) {
				vm->m_area.add_y(em, i, -1);
				if (vm->m_data[i].getContent() == c_dirt)
					vm->m_data[i] = MapNode(c_dirt_with_grass);
			}
		}
	}
}
#endif


code:
/*
Minetest
Copyright (C) 2013-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
Copyright (C) 2014-2017 paramat

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.
*/

#ifndef MAPGEN_V7_HEADER
#define MAPGEN_V7_HEADER

#include "mapgen.h"

//////////// Mapgen V7 flags
#define MGV7_MOUNTAINS  0x01
#define MGV7_RIDGES     0x02
#define MGV7_FLOATLANDS 0x04
#define MGV7_CAVERNS    0x08

class BiomeManager;

extern FlagDesc flagdesc_mapgen_v7[];

struct MapgenV7Params : public MapgenParams {
	u32 spflags;
	float cave_width;
	float float_mount_density;
	float float_mount_height;
	s16 floatland_level;
	s16 shadow_limit;
	s16 cavern_limit;
	s16 cavern_taper;
	float cavern_threshold;

	NoiseParams np_terrain_base;
	NoiseParams np_terrain_alt;
	NoiseParams np_terrain_persist;
	NoiseParams np_height_select;
	NoiseParams np_filler_depth;
	NoiseParams np_mount_height;
	NoiseParams np_ridge_uwater;
	NoiseParams np_floatland_base;
	NoiseParams np_float_base_height;
	NoiseParams np_mountain;
	NoiseParams np_ridge;
	NoiseParams np_cavern;
	NoiseParams np_cave1;
	NoiseParams np_cave2;

	MapgenV7Params();
	~MapgenV7Params() {}

	void readParams(const Settings *settings);
	void writeParams(Settings *settings) const;
};

class MapgenV7 : public MapgenBasic {
public:
	MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge);
	~MapgenV7();

	virtual MapgenType getType() const { return MAPGEN_V7; }

	virtual void makeChunk(BlockMakeData *data);
	int getSpawnLevelAtPoint(v2s16 p);

	float baseTerrainLevelAtPoint(s16 x, s16 z);
	float baseTerrainLevelFromMap(int index);
	bool getMountainTerrainAtPoint(s16 x, s16 y, s16 z);
	bool getMountainTerrainFromMap(int idx_xyz, int idx_xz, s16 y);
	bool getFloatlandMountainFromMap(int idx_xyz, int idx_xz, s16 y);
	void floatBaseExtentFromMap(s16 *float_base_min, s16 *float_base_max, int idx_xz);

	int generateTerrain();
	void generateRidgeTerrain();

private:
	float float_mount_density;
	float float_mount_height;
	s16 floatland_level;
	s16 shadow_limit;

	Noise *noise_terrain_base;
	Noise *noise_terrain_alt;
	Noise *noise_terrain_persist;
	Noise *noise_height_select;
	Noise *noise_mount_height;
	Noise *noise_ridge_uwater;
	Noise *noise_floatland_base;
	Noise *noise_float_base_height;
	Noise *noise_mountain;
	Noise *noise_ridge;
};

#endif


code:
/*
Minetest Valleys C
Copyright (C) 2016-2017 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2017 paramat

Based on Valleys Mapgen by Gael de Sailly
 (https://forum.minetest.net/viewtopic.php?f=9&t=11430)
and mapgen_v7, mapgen_flat 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 "mg_biome.h"
#include "mg_ore.h"
#include "mg_decoration.h"
#include "mapgen_valleys.h"
#include "cavegen.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", MGVALLEYS_ALT_CHILL},
	{"humid_rivers",   MGVALLEYS_HUMID_RIVERS},
	{NULL,             0}
};

///////////////////////////////////////////////////////////////////////////////

MapgenValleys::MapgenValleys(int mapgenid, MapgenValleysParams *params, EmergeManager *emerge)
	: MapgenBasic(mapgenid, params, emerge)
{
	// NOTE: MapgenValleys has a hard dependency on BiomeGenOriginal
	this->m_bgen = (BiomeGenOriginal *)biomegen;

	BiomeParamsOriginal *bp = (BiomeParamsOriginal *)params->bparams;

	this->spflags            = params->spflags;
	this->altitude_chill     = params->altitude_chill;
	this->large_cave_depth   = params->large_cave_depth;
	this->lava_features_lim  = rangelim(params->lava_features, 0, 10);
	this->massive_cave_depth = params->massive_cave_depth;
	this->river_depth_bed    = params->river_depth + 1.f;
	this->river_size_factor  = params->river_size / 100.f;
	this->water_features_lim = rangelim(params->water_features, 0, 10);
	this->cave_width         = params->cave_width;

	//// 2D Terrain noise
	noise_filler_depth       = new Noise(&params->np_filler_depth,       seed, csize.X, csize.Z);
	noise_inter_valley_slope = new Noise(&params->np_inter_valley_slope, seed, csize.X, csize.Z);
	noise_rivers             = new Noise(&params->np_rivers,             seed, csize.X, csize.Z);
	noise_terrain_height     = new Noise(&params->np_terrain_height,     seed, csize.X, csize.Z);
	noise_valley_depth       = new Noise(&params->np_valley_depth,       seed, csize.X, csize.Z);
	noise_valley_profile     = new Noise(&params->np_valley_profile,     seed, csize.X, csize.Z);

	//// 3D Terrain noise
	// 1-up 1-down overgeneration
	noise_inter_valley_fill = new Noise(&params->np_inter_valley_fill, seed, csize.X, csize.Y + 2, csize.Z);
	// 1-down overgeneraion
	noise_cave1             = new Noise(&params->np_cave1,             seed, csize.X, csize.Y + 1, csize.Z);
	noise_cave2             = new Noise(&params->np_cave2,             seed, csize.X, csize.Y + 1, csize.Z);
	noise_massive_caves     = new Noise(&params->np_massive_caves,     seed, csize.X, csize.Y + 1, csize.Z);

	this->humid_rivers       = (spflags & MGVALLEYS_HUMID_RIVERS);
	this->use_altitude_chill = (spflags & MGVALLEYS_ALT_CHILL);
	this->humidity_adjust    = bp->np_humidity.offset - 50.f;

	// a small chance of overflows if the settings are very high
	this->cave_water_max_height = water_level + MYMAX(0, water_features_lim - 4) * 50;
	this->lava_max_height       = water_level + MYMAX(0, lava_features_lim - 4) * 50;

	tcave_cache = new float[csize.Y + 2];
}

MapgenValleys::~MapgenValleys()
{
	delete noise_cave1;
	delete noise_cave2;
	delete noise_filler_depth;
	delete noise_inter_valley_fill;
	delete noise_inter_valley_slope;
	delete noise_rivers;
	delete noise_massive_caves;
	delete noise_terrain_height;
	delete noise_valley_depth;
	delete noise_valley_profile;

	delete[] tcave_cache;
}

MapgenValleysParams::MapgenValleysParams()
{
	spflags            = MGVALLEYS_HUMID_RIVERS | MGVALLEYS_ALT_CHILL;
	altitude_chill     = 90; // The altitude at which temperature drops by 20C.
	large_cave_depth   = -33;
	lava_features      = 0;  // How often water will occur in caves.
	massive_cave_depth = -256;  // highest altitude of massive caves
	river_depth        = 4;  // How deep to carve river channels.
	river_size         = 5;  // How wide to make rivers.
	water_features     = 0;  // How often water will occur in caves.
	cave_width         = 0.09;

	np_cave1              = NoiseParams(0,     12,   v3f(61,   61,   61),   52534, 3, 0.5,   2.0);
	np_cave2              = NoiseParams(0,     12,   v3f(67,   67,   67),   10325, 3, 0.5,   2.0);
	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_massive_caves      = NoiseParams(0.f,   1.f,  v3f(768,  256,  768),  59033, 6, 0.63f, 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("mgvalleys_spflags",        spflags, flagdesc_mapgen_valleys);
	settings->getU16NoEx("mgvalleys_altitude_chill",     altitude_chill);
	settings->getS16NoEx("mgvalleys_large_cave_depth",   large_cave_depth);
	settings->getU16NoEx("mgvalleys_lava_features",      lava_features);
	settings->getS16NoEx("mgvalleys_massive_cave_depth", massive_cave_depth);
	settings->getU16NoEx("mgvalleys_river_depth",        river_depth);
	settings->getU16NoEx("mgvalleys_river_size",         river_size);
	settings->getU16NoEx("mgvalleys_water_features",     water_features);
	settings->getFloatNoEx("mgvalleys_cave_width",       cave_width);

	settings->getNoiseParams("mgvalleys_np_cave1",              np_cave1);
	settings->getNoiseParams("mgvalleys_np_cave2",              np_cave2);
	settings->getNoiseParams("mgvalleys_np_filler_depth",       np_filler_depth);
	settings->getNoiseParams("mgvalleys_np_inter_valley_fill",  np_inter_valley_fill);
	settings->getNoiseParams("mgvalleys_np_inter_valley_slope", np_inter_valley_slope);
	settings->getNoiseParams("mgvalleys_np_rivers",             np_rivers);
	settings->getNoiseParams("mgvalleys_np_massive_caves",      np_massive_caves);
	settings->getNoiseParams("mgvalleys_np_terrain_height",     np_terrain_height);
	settings->getNoiseParams("mgvalleys_np_valley_depth",       np_valley_depth);
	settings->getNoiseParams("mgvalleys_np_valley_profile",     np_valley_profile);
}

void MapgenValleysParams::writeParams(Settings *settings) const
{
	settings->setFlagStr("mgvalleys_spflags",        spflags, flagdesc_mapgen_valleys, U32_MAX);
	settings->setU16("mgvalleys_altitude_chill",     altitude_chill);
	settings->setS16("mgvalleys_large_cave_depth",   large_cave_depth);
	settings->setU16("mgvalleys_lava_features",      lava_features);
	settings->setS16("mgvalleys_massive_cave_depth", massive_cave_depth);
	settings->setU16("mgvalleys_river_depth",        river_depth);
	settings->setU16("mgvalleys_river_size",         river_size);
	settings->setU16("mgvalleys_water_features",     water_features);
	settings->setFloat("mgvalleys_cave_width",       cave_width);

	settings->setNoiseParams("mgvalleys_np_cave1",              np_cave1);
	settings->setNoiseParams("mgvalleys_np_cave2",              np_cave2);
	settings->setNoiseParams("mgvalleys_np_filler_depth",       np_filler_depth);
	settings->setNoiseParams("mgvalleys_np_inter_valley_fill",  np_inter_valley_fill);
	settings->setNoiseParams("mgvalleys_np_inter_valley_slope", np_inter_valley_slope);
	settings->setNoiseParams("mgvalleys_np_rivers",             np_rivers);
	settings->setNoiseParams("mgvalleys_np_massive_caves",      np_massive_caves);
	settings->setNoiseParams("mgvalleys_np_terrain_height",     np_terrain_height);
	settings->setNoiseParams("mgvalleys_np_valley_depth",       np_valley_depth);
	settings->setNoiseParams("mgvalleys_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 biome noises.  Note this must be executed strictly before
	// generateTerrain, because generateTerrain depends on intermediate
	// biome-related noises.
	m_bgen->calcBiomeNoise(node_min);

	// Generate noise maps and base terrain height.
	// Modify heat and humidity maps.
	calculateNoise();

	// Generate base terrain with initial heightmaps
	s16 stone_surface_max_y = generateTerrain();

	// Recalculate heightmap
	updateHeightmap(node_min, node_max);

	// Place biome-specific nodes and build biomemap
	MgStoneType stone_type = generateBiomes();

	// Cave creation.
	if (flags & MG_CAVES)
		generateCaves(stone_surface_max_y, large_cave_depth);

	// Dungeon creation
	if ((flags & MG_DUNGEONS) && node_max.Y < 50)
		generateDungeons(stone_surface_max_y, stone_type);

	// 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_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);

	noise_inter_valley_fill->perlinMap3D(x, y, z);

	//mapgen_profiler->avg("noisemaps", tcn.stop() / 1000.f);

	float heat_offset = 0.f;
	float humidity_scale = 1.f;

	// Altitude chill tends to reduce the average heat.
	if (use_altitude_chill)
		heat_offset = 5.f;

	// River humidity tends to increase the humidity range.
	if (humid_rivers) {
		humidity_scale = 0.8f;
	}

	for (s32 index = 0; index < csize.X * csize.Z; index++) {
		m_bgen->heatmap[index] += heat_offset;
		m_bgen->humidmap[index] *= humidity_scale;
	}

	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];

		// This is the actual terrain height.
		float mount = terrainLevelFromNoise(&tn);
		noise_terrain_height->result[index] = mount;
	}
}

// This keeps us from having to maintain two similar sets of
//  complicated code to determine ground level.
float MapgenValleys::terrainLevelFromNoise(TerrainNoise *tn)
{
	// The square function changes the behaviour of this noise:
	//  very often small, and sometimes very high.
	float valley_d = MYSQUARE(*tn->valley);

	// 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_factor;

	// 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.
	{
		float t = river / tn->valley_profile;
		*tn->valley = valley_d * (1.f - exp(- MYSQUARE(t)));
	}

	// 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-x^2) which models a circle.
		float depth;
		{
			float t = river / river_size_factor + 1;
			depth = (river_depth_bed * sqrt(MYMAX(0, 1.f - MYSQUARE(t))));
		}

		// base - depth : height of the bottom of the river
		// water_level - 3 : don't make rivers below 3 nodes under the surface
		// We use three because that's as low as the swamp biomes go.
		// There is no logical equivalent to this using rangelim.
		mount = MYMIN(MYMAX(base - depth, (float)(water_level - 3)), mount);

		// Slope has no influence on rivers.
		*tn->slope = 0.f;
	}

	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);
	s16 y_start = myround(mount);

	for (s16 y = y_start; y <= y_start + 1000; y++) {
		float fill = NoisePerlin3D(&noise_inter_valley_fill->np, tn->x, y, tn->z, seed);

		if (fill * *tn->slope < y - mount) {
			mount = MYMAX(y - 1, mount);
			break;
		}
	}

	return mount;
}

int MapgenValleys::getSpawnLevelAtPoint(v2s16 p)
{
	// Check to make sure this isn't a request for a location in a river.
	float rivers = NoisePerlin2D(&noise_rivers->np, p.X, p.Y, seed);
	if (fabs(rivers) < river_size_factor)
		return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point

	s16 level_at_point = terrainLevelAtPoint(p.X, p.Y);
	if (level_at_point <= water_level ||
			level_at_point > water_level + 32)
		return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
	else
		return level_at_point;
}

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;

	return adjustedTerrainLevelFromNoise(&tn);
}

int MapgenValleys::generateTerrain()
{
	// Raising this reduces the rate of evaporation.
	static const float evaporation = 300.f;
	// from the lua
	static const float humidity_dropoff = 4.f;
	// constant to convert altitude chill (compatible with lua) to heat
	static const float alt_to_heat = 20.f;
	// humidity reduction by altitude
	static const float alt_to_humid = 10.f;

	MapNode n_air(CONTENT_AIR);
	MapNode n_river_water(c_river_water_source);
	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++) {
		float river_y = noise_rivers->result[index_2d];
		float surface_y = noise_terrain_height->result[index_2d];
		float slope = noise_inter_valley_slope->result[index_2d];
		float t_heat = m_bgen->heatmap[index_2d];

		heightmap[index_2d] = -MAX_MAP_GENERATION_LIMIT;

		if (surface_y > surface_max_y)
			surface_max_y = ceil(surface_y);

		if (humid_rivers) {
			// Derive heat from (base) altitude. This will be most correct
			// at rivers, since other surface heights may vary below.
			if (use_altitude_chill && (surface_y > 0.f || river_y > 0.f))
				t_heat -= alt_to_heat * MYMAX(surface_y, river_y) / altitude_chill;

			// If humidity is low or heat is high, lower the water table.
			float delta = m_bgen->humidmap[index_2d] - 50.f;
			if (delta < 0.f) {
				float t_evap = (t_heat - 32.f) / evaporation;
				river_y += delta * MYMAX(t_evap, 0.08f);
			}
		}

		u32 index_3d = (z - node_min.Z) * zstride_1u1d + (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++) {
			if (vm->m_data[index_data].getContent() == CONTENT_IGNORE) {
				float fill = noise_inter_valley_fill->result[index_3d];
				float surface_delta = (float)y - surface_y;
				bool river = y + 1 < river_y;

				if (slope * fill > surface_delta) {
					// ground
					vm->m_data[index_data] = n_stone;
					if (y > heightmap[index_2d])
						heightmap[index_2d] = y;
					if (y > surface_max_y)
						surface_max_y = y;
				} else if (y <= water_level) {
					// sea
					vm->m_data[index_data] = n_water;
				} else if (river) {
					// river
					vm->m_data[index_data] = n_river_water;
				} else {  // air
					vm->m_data[index_data] = n_air;
				}
			}

			vm->m_area.add_y(em, index_data, 1);
			index_3d += ystride;
		}

		if (heightmap[index_2d] == -MAX_MAP_GENERATION_LIMIT) {
			s16 surface_y_int = myround(surface_y);
			if (surface_y_int > node_max.Y + 1 || surface_y_int < node_min.Y - 1) {
				// If surface_y is outside the chunk, it's good enough.
				heightmap[index_2d] = surface_y_int;
			} else {
				// If the ground is outside of this chunk, but surface_y
				// is within the chunk, give a value outside.
				heightmap[index_2d] = node_min.Y - 2;
			}
		}

		if (humid_rivers) {
			// Use base ground (water table) in a riverbed, to
			// avoid an unnatural rise in humidity.
			float t_alt = MYMAX(noise_rivers->result[index_2d], (float)heightmap[index_2d]);
			float humid = m_bgen->humidmap[index_2d];
			float water_depth = (t_alt - river_y) / humidity_dropoff;
			humid *= 1.f + pow(0.5f, MYMAX(water_depth, 1.f));

			// Reduce humidity with altitude (ignoring riverbeds).
			// This is similar to the lua version's seawater adjustment,
			// but doesn't increase the base humidity, which causes
			// problems with the default biomes.
			if (t_alt > 0.f)
				humid -= alt_to_humid * t_alt / altitude_chill;

			m_bgen->humidmap[index_2d] = humid;
		}

		// Assign the heat adjusted by any changed altitudes.
		// The altitude will change about half the time.
		if (use_altitude_chill) {
			// ground height ignoring riverbeds
			float t_alt = MYMAX(noise_rivers->result[index_2d], (float)heightmap[index_2d]);
			if (humid_rivers && heightmap[index_2d] == (s16)myround(surface_y))
				// The altitude hasn't changed. Use the first result.
				m_bgen->heatmap[index_2d] = t_heat;
			else if (t_alt > 0.f)
				m_bgen->heatmap[index_2d] -= alt_to_heat * t_alt / altitude_chill;
		}
	}

	return surface_max_y;
}

void MapgenValleys::generateCaves(s16 max_stone_y, s16 large_cave_depth)
{
	if (max_stone_y < node_min.Y)
		return;

	noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
	noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);

	PseudoRandom ps(blockseed + 72202);

	MapNode n_air(CONTENT_AIR);
	MapNode n_lava(c_lava_source);
	MapNode n_water(c_river_water_source);

	v3s16 em = vm->m_area.getExtent();

	// Cave blend distance near YMIN, YMAX
	const float massive_cave_blend = 128.f;
	// noise threshold for massive caves
	const float massive_cave_threshold = 0.6f;
	// mct: 1 = small rare caves, 0.5 1/3rd ground volume, 0 = 1/2 ground volume.

	float yblmin = -mapgen_limit + massive_cave_blend * 1.5f;
	float yblmax = massive_cave_depth - massive_cave_blend * 1.5f;
	bool made_a_big_one = false;

	// Cache the tcave values as they only vary by altitude.
	if (node_max.Y <= massive_cave_depth) {
		noise_massive_caves->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);

		for (s16 y = node_min.Y - 1; y <= node_max.Y; y++) {
			float tcave = massive_cave_threshold;

			if (y < yblmin) {
				float t = (yblmin - y) / massive_cave_blend;
				tcave += MYSQUARE(t);
			} else if (y > yblmax) {
				float t = (y - yblmax) / massive_cave_blend;
				tcave += MYSQUARE(t);
			}

			tcave_cache[y - node_min.Y + 1] = tcave;
		}
	}

	// lava_depth varies between one and ten as you approach
	//  the bottom of the world.
	s16 lava_depth = ceil((lava_max_height - node_min.Y + 1) * 10.f / mapgen_limit);
	// This allows random lava spawns to be less common at the surface.
	s16 lava_chance = MYCUBE(lava_features_lim) * lava_depth;
	// water_depth varies between ten and one on the way down.
	s16 water_depth = ceil((mapgen_limit - abs(node_min.Y) + 1) * 10.f / mapgen_limit);
	// This allows random water spawns to be more common at the surface.
	s16 water_chance = MYCUBE(water_features_lim) * water_depth;

	// Reduce the odds of overflows even further.
	if (node_max.Y > water_level) {
		lava_chance /= 3;
		water_chance /= 3;
	}

	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++) {
		Biome *biome = (Biome *)m_bmgr->getRaw(biomemap[index_2d]);
		bool tunnel_air_above = false;
		bool is_under_river = false;
		bool underground = false;
		u32 index_data = vm->m_area.index(x, node_max.Y, z);
		u32 index_3d = (z - node_min.Z) * zstride_1d + csize.Y * ystride + (x - node_min.X);

		// Dig caves on down loop to check for air above.
		// Don't excavate the overgenerated stone at node_max.Y + 1,
		// this creates a 'roof' over the tunnel, preventing light in
		// tunnels at mapchunk borders when generating mapchunks upwards.
		// This 'roof' is removed when the mapchunk above is generated.
		for (s16 y = node_max.Y; 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.
			if (y > terrain + 10)
				continue;
			else if (y < terrain - 40)
				underground = true;

			// Dig massive caves.
			if (node_max.Y <= massive_cave_depth
					&& noise_massive_caves->result[index_3d]
					> tcave_cache[y - node_min.Y + 1]) {
				vm->m_data[index_data] = n_air;
				made_a_big_one = true;
				continue;
			}

			content_t c = vm->m_data[index_data].getContent();
			// Detect river water to place riverbed nodes in tunnels
			if (c == biome->c_river_water)
				is_under_river = true;

			float d1 = contour(noise_cave1->result[index_3d]);
			float d2 = contour(noise_cave2->result[index_3d]);

			if (d1 * d2 > cave_width && ndef->get(c).is_ground_content) {
				// in a tunnel
				vm->m_data[index_data] = n_air;
				tunnel_air_above = true;
			} else if (c == biome->c_filler || c == biome->c_stone) {
				if (tunnel_air_above) {
					// at the tunnel floor
					s16 sr = ps.range(0, 39);
					u32 j = index_data;
					vm->m_area.add_y(em, j, 1);

					if (sr > terrain - y) {
						// Put biome nodes in tunnels near the surface
						if (is_under_river)
							vm->m_data[index_data] = MapNode(biome->c_riverbed);
						else if (underground)
							vm->m_data[index_data] = MapNode(biome->c_filler);
						else
							vm->m_data[index_data] = MapNode(biome->c_top);
					} else if (sr < 3 && underground) {
						sr = abs(ps.next());
						if (lava_features_lim > 0 && y <= lava_max_height
								&& c == biome->c_stone && sr < lava_chance)
							vm->m_data[j] = n_lava;

						sr -= lava_chance;

						// If sr < 0 then we should have already placed lava --
						// don't immediately dump water on it.
						if (water_features_lim > 0 && y <= cave_water_max_height
								&& sr >= 0 && sr < water_chance)
							vm->m_data[j] = n_water;
					}
				}

				tunnel_air_above = false;
				underground = true;
			} else {
				tunnel_air_above = false;
			}
		}
	}

	if (node_max.Y <= large_cave_depth && !made_a_big_one) {
		u32 bruises_count = ps.range(0, 2);
		for (u32 i = 0; i < bruises_count; i++) {
			CavesRandomWalk cave(ndef, &gennotify, seed, water_level,
				c_water_source, c_lava_source);

			cave.makeCave(vm, node_min, node_max, &ps, true, max_stone_y, heightmap);
		}
	}
}


code:
/*
Minetest Valleys C
Copyright (C) 2016-2017 Duane Robertson <duane@duanerobertson.com>
Copyright (C) 2016-2017 paramat

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.
*/

#ifndef MAPGEN_VALLEYS_HEADER
#define MAPGEN_VALLEYS_HEADER

#include "mapgen.h"

////////////// Mapgen Valleys flags
#define MGVALLEYS_ALT_CHILL    0x01
#define MGVALLEYS_HUMID_RIVERS 0x02

// Feed only one variable into these.
#define MYSQUARE(x) (x) * (x)
#define MYCUBE(x) (x) * (x) * (x)

class BiomeManager;
class BiomeGenOriginal;

// Global profiler
//class Profiler;
//extern Profiler *mapgen_profiler;

struct MapgenValleysParams : public MapgenParams {
	u32 spflags;
	s16 large_cave_depth;
	s16 massive_cave_depth;
	u16 altitude_chill;
	u16 lava_features;
	u16 river_depth;
	u16 river_size;
	u16 water_features;
	float cave_width;
	NoiseParams np_cave1;
	NoiseParams np_cave2;
	NoiseParams np_filler_depth;
	NoiseParams np_inter_valley_fill;
	NoiseParams np_inter_valley_slope;
	NoiseParams np_rivers;
	NoiseParams np_massive_caves;
	NoiseParams np_terrain_height;
	NoiseParams np_valley_depth;
	NoiseParams np_valley_profile;

	MapgenValleysParams();
	~MapgenValleysParams() {}

	void readParams(const Settings *settings);
	void writeParams(Settings *settings) const;
};

struct TerrainNoise {
	s16 x;
	s16 z;
	float terrain_height;
	float *rivers;
	float *valley;
	float valley_profile;
	float *slope;
	float inter_valley_fill;
};

class MapgenValleys : public MapgenBasic {
public:

	MapgenValleys(int mapgenid, MapgenValleysParams *params, EmergeManager *emerge);
	~MapgenValleys();

	virtual MapgenType getType() const { return MAPGEN_VALLEYS; }

	virtual void makeChunk(BlockMakeData *data);
	int getSpawnLevelAtPoint(v2s16 p);

	s16 large_cave_depth;

private:
	BiomeGenOriginal *m_bgen;

	bool humid_rivers;
	bool use_altitude_chill;
	float humidity_adjust;
	s16 cave_water_max_height;
	s16 lava_max_height;

	float altitude_chill;
	s16 lava_features_lim;
	s16 massive_cave_depth;
	float river_depth_bed;
	float river_size_factor;
	float *tcave_cache;
	s16 water_features_lim;
	Noise *noise_inter_valley_fill;
	Noise *noise_inter_valley_slope;
	Noise *noise_rivers;
	Noise *noise_cave1;
	Noise *noise_cave2;
	Noise *noise_massive_caves;
	Noise *noise_terrain_height;
	Noise *noise_valley_depth;
	Noise *noise_valley_profile;

	float terrainLevelAtPoint(s16 x, s16 z);

	void calculateNoise();

	virtual int generateTerrain();
	float terrainLevelFromNoise(TerrainNoise *tn);
	float adjustedTerrainLevelFromNoise(TerrainNoise *tn);

	virtual void generateCaves(s16 max_stone_y, s16 large_cave_depth);
};

#endif