Mapgen: Add flat mapgen in hidden form

build/android/jni/Android.mk

@@ -173,6 +173,7 @@ LOCAL_SRC_FILES :=                                \
 		jni/src/mapblock.cpp                      \
 		jni/src/mapblock_mesh.cpp                 \
 		jni/src/mapgen.cpp                        \
+		jni/src/mapgen_flat.cpp                   \
 		jni/src/mapgen_fractal.cpp                \
 		jni/src/mapgen_singlenode.cpp             \
 		jni/src/mapgen_v5.cpp                     \

builtin/settingtypes.txt

@@ -812,7 +812,7 @@ liquid_update (Liquid update tick) float 1.0
 
 #    Name of map generator to be used when creating a new world.
 #    Creating a world in the main menu will override this.
-mg_name (Mapgen name) enum v6 v5,v6,v7,fractal,singlenode
+mg_name (Mapgen name) enum v6 v5,v6,v7,flat,fractal,singlenode
 
 #    Water surface level of the world.
 water_level (Water level) int 1
@@ -928,6 +928,45 @@ mgv7_np_ridge (Mapgen v7 ridge noise parameters) noise_params 0, 1, (100, 100, 1
 mgv7_np_cave1 (Mapgen v7 cave1 noise parameters) noise_params 0, 12, (100, 100, 100), 52534, 4, 0.5, 2.0
 mgv7_np_cave2 (Mapgen v7 cave2 noise parameters) noise_params 0, 12, (100, 100, 100), 10325, 4, 0.5, 2.0
 
+[***Mapgen flat]
+
+#    Map generation attributes specific to Mapgen flat.
+#    Occasional lakes and hills added to the flat world.
+#    Flags that are not specified in the flag string are not modified from the default.
+#    Flags starting with "no" are used to explicitly disable them.
+mgflat_spflags (Mapgen flat flags) flags nolakes,nohills lakes,hills,nolakes,nohills
+
+#    Y of flat ground.
+mgflat_ground_level (Mapgen flat ground level) int 8
+
+#    Y of upper limit of large pseudorandom caves.
+mgflat_large_cave_depth (Mapgen flat large cave depth) int -33
+
+#    Terrain noise threshold for lakes.
+#    Controls proportion of world area covered by lakes.
+#    Adjust towards 0.0 for a larger proportion.
+mgflat_lake_threshold (Mapgen flat lake threshold) float -0.45
+
+#    Controls steepness/depth of lake depressions.
+mgflat_lake_steepness (Mapgen flat lake steepness) float 48.0
+
+#    Terrain noise threshold for hills.
+#    Controls proportion of world area covered by hills.
+#    Adjust towards 0.0 for a larger proportion.
+mgflat_hill_threshold (Mapgen flat hill threshold) float 0.45
+
+#    Controls steepness/height of hills.
+mgflat_hill_steepness (Mapgen flat hill steepness) float 64.0
+
+#    Determines terrain shape.
+#    The 3 numbers in brackets control the scale of the
+#    terrain, the 3 numbers should be identical.
+mgflat_np_terrain (Mapgen flat terrain noise parameters) noise_params 0, 1, (600, 600, 600), 7244, 5, 0.6, 2.0
+
+mgflat_np_filler_depth (Mapgen flat filler depth noise parameters) noise_params 0, 1.2, (150, 150, 150), 261, 3, 0.7, 2.0
+mgflat_np_cave1 (Mapgen flat cave1 noise parameters) noise_params 0, 12, (128, 128, 128), 52534, 4, 0.5, 2.0
+mgflat_np_cave2 (Mapgen flat cave2 noise parameters) noise_params 0, 12, (128, 128, 128), 10325, 4, 0.5, 2.0
+
 [***Mapgen fractal]
 
 #    Map generation attributes specific to Mapgen fractal.

minetest.conf.example

@@ -1000,7 +1000,7 @@
 
 #    Name of map generator to be used when creating a new world.
 #    Creating a world in the main menu will override this.
-#    type: enum values: v5, v6, v7, fractal, singlenode
+#    type: enum values: v5, v6, v7, flat, fractal, singlenode
 # mg_name = v6
 
 #    Water surface level of the world.
@@ -1179,6 +1179,58 @@
 #    type: noise_params
 # mgv7_np_cave2 = 0, 12, (100, 100, 100), 10325, 4, 0.5, 2.0
 
+#### Mapgen flat
+
+#    Map generation attributes specific to Mapgen flat.
+#    Occasional lakes and hills added to the flat world.
+#    Flags that are not specified in the flag string are not modified from the default.
+#    Flags starting with "no" are used to explicitly disable them.
+#    type: flags possible values: lakes, hills, nolakes, nohills
+# mgflat_spflags = nolakes,nohills
+
+#    Y of flat ground.
+#    type: int
+# mgflat_ground_level = 8
+
+#    Y of upper limit of large pseudorandom caves.
+#    type: int
+# mgflat_large_cave_depth = -33
+
+#    Terrain noise threshold for lakes.
+#    Controls proportion of world area covered by lakes.
+#    Adjust towards 0.0 for a larger proportion.
+#    type: float
+# mgflat_lake_threshold = -0.45
+
+#    Controls steepness/depth of lake depressions.
+#    type: float
+# mgflat_lake_steepness = 48.0
+
+#    Terrain noise threshold for hills.
+#    Controls proportion of world area covered by hills.
+#    Adjust towards 0.0 for a larger proportion.
+#    type: float
+# mgflat_hill_threshold = 0.45
+
+#    Controls steepness/height of hills.
+#    type: float
+# mgflat_hill_steepness = 64.0
+
+#    Determines terrain shape.
+#    The 3 numbers in brackets control the scale of the
+#    terrain, the 3 numbers should be identical.
+#    type: noise_params
+# mgflat_np_terrain = 0, 1, (600, 600, 600), 7244, 5, 0.6, 2.0
+
+#    type: noise_params
+# mgflat_np_filler_depth = 0, 1.2, (150, 150, 150), 261, 3, 0.7, 2.0
+
+#    type: noise_params
+# mgflat_np_cave1 = 0, 12, (128, 128, 128), 52534, 4, 0.5, 2.0
+
+#    type: noise_params
+# mgflat_np_cave2 = 0, 12, (128, 128, 128), 10325, 4, 0.5, 2.0
+
 #### Mapgen fractal
 
 #    Map generation attributes specific to Mapgen fractal.

src/CMakeLists.txt

@@ -367,6 +367,7 @@ set(common_SRCS
 	map.cpp
 	mapblock.cpp
 	mapgen.cpp
+	mapgen_flat.cpp
 	mapgen_fractal.cpp
 	mapgen_singlenode.cpp
 	mapgen_v5.cpp

src/emerge.cpp

@@ -34,6 +34,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "log.h"
 #include "map.h"
 #include "mapblock.h"
+#include "mapgen_flat.h"
 #include "mapgen_fractal.h"
 #include "mapgen_v5.h"
 #include "mapgen_v6.h"
@@ -105,6 +106,7 @@ MapgenDesc g_reg_mapgens[] = {
 	{"v5",         new MapgenFactoryV5,         true},
 	{"v6",         new MapgenFactoryV6,         true},
 	{"v7",         new MapgenFactoryV7,         true},
+	{"flat",       new MapgenFactoryFlat,       false},
 	{"fractal",    new MapgenFactoryFractal,    false},
 	{"singlenode", new MapgenFactorySinglenode, false},
 };

src/mapgen_flat.cpp

+/*
+Minetest
+Copyright (C) 2010-2015 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2010-2015 paramat, Matt Gregory
+
+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 "treegen.h"
+#include "mg_biome.h"
+#include "mg_ore.h"
+#include "mg_decoration.h"
+#include "mapgen_flat.h"
+
+
+FlagDesc flagdesc_mapgen_flat[] = {
+	{"lakes", MGFLAT_LAKES},
+	{"hills", MGFLAT_HILLS},
+	{NULL,    0}
+};
+
+///////////////////////////////////////////////////////////////////////////////////////
+
+
+MapgenFlat::MapgenFlat(int mapgenid, MapgenParams *params, EmergeManager *emerge)
+	: Mapgen(mapgenid, params, emerge)
+{
+	this->m_emerge = emerge;
+	this->bmgr     = emerge->biomemgr;
+
+	//// amount of elements to skip for the next index
+	//// for noise/height/biome maps (not vmanip)
+	this->ystride = csize.X;
+	this->zstride = csize.X * (csize.Y + 2);
+
+	this->biomemap        = new u8[csize.X * csize.Z];
+	this->heightmap       = new s16[csize.X * csize.Z];
+	this->heatmap         = NULL;
+	this->humidmap        = NULL;
+
+	MapgenFlatParams *sp = (MapgenFlatParams *)params->sparams;
+	this->spflags = sp->spflags;
+
+	this->ground_level = sp->ground_level;
+	this->large_cave_depth = sp->large_cave_depth;
+	this->lake_threshold = sp->lake_threshold;
+	this->lake_steepness = sp->lake_steepness;
+	this->hill_threshold = sp->hill_threshold;
+	this->hill_steepness = sp->hill_steepness;
+
+	//// 2D noise
+	noise_terrain      = new Noise(&sp->np_terrain,      seed, csize.X, csize.Z);
+	noise_filler_depth = new Noise(&sp->np_filler_depth, seed, csize.X, csize.Z);
+
+	//// 3D noise
+	noise_cave1 = new Noise(&sp->np_cave1, seed, csize.X, csize.Y + 2, csize.Z);
+	noise_cave2 = new Noise(&sp->np_cave2, seed, csize.X, csize.Y + 2, csize.Z);
+
+	//// Biome noise
+	noise_heat           = new Noise(&params->np_biome_heat,           seed, csize.X, csize.Z);
+	noise_humidity       = new Noise(&params->np_biome_humidity,       seed, csize.X, csize.Z);
+	noise_heat_blend     = new Noise(&params->np_biome_heat_blend,     seed, csize.X, csize.Z);
+	noise_humidity_blend = new Noise(&params->np_biome_humidity_blend, seed, csize.X, csize.Z);
+
+	//// Resolve nodes to be used
+	INodeDefManager *ndef = emerge->ndef;
+
+	c_stone                = ndef->getId("mapgen_stone");
+	c_water_source         = ndef->getId("mapgen_water_source");
+	c_lava_source          = ndef->getId("mapgen_lava_source");
+	c_desert_stone         = ndef->getId("mapgen_desert_stone");
+	c_ice                  = ndef->getId("mapgen_ice");
+	c_sandstone            = ndef->getId("mapgen_sandstone");
+
+	c_cobble               = ndef->getId("mapgen_cobble");
+	c_stair_cobble         = ndef->getId("mapgen_stair_cobble");
+	c_mossycobble          = ndef->getId("mapgen_mossycobble");
+	c_sandstonebrick       = ndef->getId("mapgen_sandstonebrick");
+	c_stair_sandstonebrick = ndef->getId("mapgen_stair_sandstonebrick");
+
+	if (c_ice == CONTENT_IGNORE)
+		c_ice = CONTENT_AIR;
+	if (c_mossycobble == CONTENT_IGNORE)
+		c_mossycobble = c_cobble;
+	if (c_stair_cobble == CONTENT_IGNORE)
+		c_stair_cobble = c_cobble;
+	if (c_sandstonebrick == CONTENT_IGNORE)
+		c_sandstonebrick = c_sandstone;
+	if (c_stair_sandstonebrick == CONTENT_IGNORE)
+		c_stair_sandstonebrick = c_sandstone;
+}
+
+
+MapgenFlat::~MapgenFlat()
+{
+	delete noise_terrain;
+	delete noise_filler_depth;
+	delete noise_cave1;
+	delete noise_cave2;
+
+	delete noise_heat;
+	delete noise_humidity;
+	delete noise_heat_blend;
+	delete noise_humidity_blend;
+
+	delete[] heightmap;
+	delete[] biomemap;
+}
+
+
+MapgenFlatParams::MapgenFlatParams()
+{
+	spflags = 0;
+
+	ground_level = 8;
+	large_cave_depth = -33;
+	lake_threshold = -0.45;
+	lake_steepness = 48.0;
+	hill_threshold = 0.45;
+	hill_steepness = 64.0;
+
+	np_terrain      = NoiseParams(0, 1,   v3f(600, 600, 600), 7244,  5, 0.6, 2.0);
+	np_filler_depth = NoiseParams(0, 1.2, v3f(150, 150, 150), 261,   3, 0.7, 2.0);
+	np_cave1        = NoiseParams(0, 12,  v3f(128, 128, 128), 52534, 4, 0.5, 2.0);
+	np_cave2        = NoiseParams(0, 12,  v3f(128, 128, 128), 10325, 4, 0.5, 2.0);
+}
+
+
+void MapgenFlatParams::readParams(const Settings *settings)
+{
+	settings->getFlagStrNoEx("mgflat_spflags", spflags, flagdesc_mapgen_flat);
+
+	settings->getS16NoEx("mgflat_ground_level",     ground_level);
+	settings->getS16NoEx("mgflat_large_cave_depth", large_cave_depth);
+	settings->getFloatNoEx("mgflat_lake_threshold", lake_threshold);
+	settings->getFloatNoEx("mgflat_lake_steepness", lake_steepness);
+	settings->getFloatNoEx("mgflat_hill_threshold", hill_threshold);
+	settings->getFloatNoEx("mgflat_hill_steepness", hill_steepness);
+
+	settings->getNoiseParams("mgflat_np_terrain",      np_terrain);
+	settings->getNoiseParams("mgflat_np_filler_depth", np_filler_depth);
+	settings->getNoiseParams("mgflat_np_cave1",        np_cave1);
+	settings->getNoiseParams("mgflat_np_cave2",        np_cave2);
+}
+
+
+void MapgenFlatParams::writeParams(Settings *settings) const
+{
+	settings->setFlagStr("mgflat_spflags", spflags, flagdesc_mapgen_flat, U32_MAX);
+
+	settings->setS16("mgflat_ground_level",     ground_level);
+	settings->setS16("mgflat_large_cave_depth", large_cave_depth);
+	settings->setFloat("mgflat_lake_threshold", lake_threshold);
+	settings->setFloat("mgflat_lake_steepness", lake_steepness);
+	settings->setFloat("mgflat_hill_threshold", hill_threshold);
+	settings->setFloat("mgflat_hill_steepness", hill_steepness);
+
+	settings->setNoiseParams("mgflat_np_terrain",      np_terrain);
+	settings->setNoiseParams("mgflat_np_filler_depth", np_filler_depth);
+	settings->setNoiseParams("mgflat_np_cave1",        np_cave1);
+	settings->setNoiseParams("mgflat_np_cave2",        np_cave2);
+}
+
+
+/////////////////////////////////////////////////////////////////
+
+
+int MapgenFlat::getGroundLevelAtPoint(v2s16 p)
+{
+	float n_terrain = NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed);
+	if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
+		s16 depress = (lake_threshold - n_terrain) * lake_steepness;
+		return ground_level - depress;
+	} else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
+		s16 rise = (n_terrain - hill_threshold) * hill_steepness;
+		return ground_level + rise;
+	} else {
+		return ground_level;
+	}
+}
+
+
+void MapgenFlat::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);
+
+	// Make some noise
+	calculateNoise();
+
+	// Generate base terrain, mountains, and ridges with initial heightmaps
+	s16 stone_surface_max_y = generateTerrain();
+
+	// Create heightmap
+	updateHeightmap(node_min, node_max);
+
+	// Create biomemap at heightmap surface
+	bmgr->calcBiomes(csize.X, csize.Z, noise_heat->result,
+		noise_humidity->result, heightmap, biomemap);
+
+	// Actually place the biome-specific nodes
+	MgStoneType stone_type = generateBiomes(noise_heat->result, noise_humidity->result);
+
+	if (flags & MG_CAVES)
+		generateCaves(stone_surface_max_y);
+
+	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
+		DungeonParams dp;
+
+		dp.np_rarity  = nparams_dungeon_rarity;
+		dp.np_density = nparams_dungeon_density;
+		dp.np_wetness = nparams_dungeon_wetness;
+		dp.c_water    = c_water_source;
+		if (stone_type == STONE) {
+			dp.c_cobble = c_cobble;
+			dp.c_moss   = c_mossycobble;
+			dp.c_stair  = c_stair_cobble;
+
+			dp.diagonal_dirs = false;
+			dp.mossratio     = 3.0;
+			dp.holesize      = v3s16(1, 2, 1);
+			dp.roomsize      = v3s16(0, 0, 0);
+			dp.notifytype    = GENNOTIFY_DUNGEON;
+		} else if (stone_type == DESERT_STONE) {
+			dp.c_cobble = c_desert_stone;
+			dp.c_moss   = c_desert_stone;
+			dp.c_stair  = c_desert_stone;
+
+			dp.diagonal_dirs = true;
+			dp.mossratio     = 0.0;
+			dp.holesize      = v3s16(2, 3, 2);
+			dp.roomsize      = v3s16(2, 5, 2);
+			dp.notifytype    = GENNOTIFY_TEMPLE;
+		} else if (stone_type == SANDSTONE) {
+			dp.c_cobble = c_sandstonebrick;
+			dp.c_moss   = c_sandstonebrick;
+			dp.c_stair  = c_sandstonebrick;
+
+			dp.diagonal_dirs = false;
+			dp.mossratio     = 0.0;
+			dp.holesize      = v3s16(2, 2, 2);
+			dp.roomsize      = v3s16(2, 0, 2);
+			dp.notifytype    = GENNOTIFY_DUNGEON;
+		}
+
+		DungeonGen dgen(this, &dp);
+		dgen.generate(blockseed, full_node_min, full_node_max);
+	}
+
+	// Generate the registered decorations
+	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());
+
+	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);
+
+	//setLighting(node_min - v3s16(1, 0, 1) * MAP_BLOCKSIZE,
+	//			node_max + v3s16(1, 0, 1) * MAP_BLOCKSIZE, 0xFF);
+
+	this->generating = false;
+}
+
+
+void MapgenFlat::calculateNoise()
+{
+	//TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
+	int x = node_min.X;
+	int y = node_min.Y - 1;
+	int z = node_min.Z;
+
+	if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
+		noise_terrain->perlinMap2D(x, z);
+
+	noise_filler_depth->perlinMap2D(x, z);
+
+	if (flags & MG_CAVES) {
+		noise_cave1->perlinMap3D(x, y, z);
+		noise_cave2->perlinMap3D(x, y, z);
+	}
+
+	noise_heat->perlinMap2D(x, z);
+	noise_humidity->perlinMap2D(x, z);
+	noise_heat_blend->perlinMap2D(x, z);
+	noise_humidity_blend->perlinMap2D(x, z);
+
+	for (s32 i = 0; i < csize.X * csize.Z; i++) {
+		noise_heat->result[i] += noise_heat_blend->result[i];
+		noise_humidity->result[i] += noise_humidity_blend->result[i];
+	}
+
+	heatmap = noise_heat->result;
+	humidmap = noise_humidity->result;
+	//printf("calculateNoise: %dus\n", t.stop());
+}
+
+
+s16 MapgenFlat::generateTerrain()
+{
+	MapNode n_air(CONTENT_AIR);
+	MapNode n_stone(c_stone);
+	MapNode n_water(c_water_source);
+
+	v3s16 em = vm->m_area.getExtent();
+	s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
+	u32 ni2d = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, ni2d++) {
+		s16 stone_level = ground_level;
+		float n_terrain = 0.0f;
+
+		if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
+			n_terrain = noise_terrain->result[ni2d];
+
+		if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
+			s16 depress = (lake_threshold - n_terrain) * lake_steepness;
+			stone_level = ground_level - depress;
+		} else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
+			s16 rise = (n_terrain - hill_threshold) * hill_steepness;
+		 	stone_level = ground_level + rise;
+		}
+
+		u32 vi = vm->m_area.index(x, node_min.Y - 1, z);
+		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
+			if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
+				if (y <= stone_level) {
+					vm->m_data[vi] = n_stone;
+					if (y > stone_surface_max_y)
+						stone_surface_max_y = y;
+				} else if (y <= water_level) {
+					vm->m_data[vi] = n_water;
+				} else {
+					vm->m_data[vi] = n_air;
+				}
+			}
+			vm->m_area.add_y(em, vi, 1);
+		}
+	}
+
+	return stone_surface_max_y;
+}
+
+
+MgStoneType MapgenFlat::generateBiomes(float *heat_map, float *humidity_map)
+{
+	v3s16 em = vm->m_area.getExtent();
+	u32 index = 0;
+	MgStoneType stone_type = STONE;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
+		Biome *biome = NULL;
+		u16 depth_top = 0;
+		u16 base_filler = 0;
+		u16 depth_water_top = 0;
+		u32 vi = vm->m_area.index(x, node_max.Y, z);
+
+		// Check node at base of mapchunk above, either a node of a previously
+		// generated mapchunk or if not, a node of overgenerated base terrain.
+		content_t c_above = vm->m_data[vi + em.X].getContent();
+		bool air_above = c_above == CONTENT_AIR;
+		bool water_above = c_above == c_water_source;
+
+		// If there is air or water above enable top/filler placement, otherwise force
+		// nplaced to stone level by setting a number exceeding any possible filler depth.
+		u16 nplaced = (air_above || water_above) ? 0 : U16_MAX;
+
+
+		for (s16 y = node_max.Y; y >= node_min.Y; y--) {
+			content_t c = vm->m_data[vi].getContent();
+
+			// Biome is recalculated each time an upper surface is detected while
+			// working down a column. The selected biome then remains in effect for
+			// all nodes below until the next surface and biome recalculation.
+			// Biome is recalculated:
+			// 1. At the surface of stone below air or water.
+			// 2. At the surface of water below air.
+			// 3. When stone or water is detected but biome has not yet been calculated.
+			if ((c == c_stone && (air_above || water_above || !biome)) ||
+					(c == c_water_source && (air_above || !biome))) {
+				biome = bmgr->getBiome(heat_map[index], humidity_map[index], y);
+				depth_top = biome->depth_top;
+				base_filler = MYMAX(depth_top + biome->depth_filler
+					+ noise_filler_depth->result[index], 0);
+				depth_water_top = biome->depth_water_top;
+
+				// Detect stone type for dungeons during every biome calculation.
+				// This is more efficient than detecting per-node and will not
+				// miss any desert stone or sandstone biomes.
+				if (biome->c_stone == c_desert_stone)
+					stone_type = DESERT_STONE;
+				else if (biome->c_stone == c_sandstone)
+					stone_type = SANDSTONE;
+			}
+
+			if (c == c_stone) {
+				content_t c_below = vm->m_data[vi - em.X].getContent();
+
+				// If the node below isn't solid, make this node stone, so that
+				// any top/filler nodes above are structurally supported.
+				// This is done by aborting the cycle of top/filler placement
+				// immediately by forcing nplaced to stone level.
+				if (c_below == CONTENT_AIR || c_below == c_water_source)
+					nplaced = U16_MAX;
+
+				if (nplaced < depth_top) {
+					vm->m_data[vi] = MapNode(biome->c_top);
+					nplaced++;
+				} else if (nplaced < base_filler) {
+					vm->m_data[vi] = MapNode(biome->c_filler);
+					nplaced++;
+				} else {
+					vm->m_data[vi] = MapNode(biome->c_stone);
+				}
+
+				air_above = false;
+				water_above = false;
+			} else if (c == c_water_source) {
+				vm->m_data[vi] = MapNode((y > (s32)(water_level - depth_water_top)) ?
+						biome->c_water_top : biome->c_water);
+				nplaced = 0;  // Enable top/filler placement for next surface
+				air_above = false;
+				water_above = true;
+			} else if (c == CONTENT_AIR) {
+				nplaced = 0;  // Enable top/filler placement for next surface
+				air_above = true;
+				water_above = false;
+			} else {  // Possible various nodes overgenerated from neighbouring mapchunks
+				nplaced = U16_MAX;  // Disable top/filler placement
+				air_above = false;
+				water_above = false;
+			}
+
+			vm->m_area.add_y(em, vi, -1);
+		}
+	}
+
+	return stone_type;
+}
+
+
+void MapgenFlat::dustTopNodes()
+{
+	if (node_max.Y < water_level)
+		return;
+
+	v3s16 em = vm->m_area.getExtent();
+	u32 index = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
+		Biome *biome = (Biome *)bmgr->getRaw(biomemap[index]);
+
+		if (biome->c_dust == CONTENT_IGNORE)
+			continue;
+
+		u32 vi = vm->m_area.index(x, full_node_max.Y, z);
+		content_t c_full_max = vm->m_data[vi].getContent();
+		s16 y_start;
+
+		if (c_full_max == CONTENT_AIR) {
+			y_start = full_node_max.Y - 1;
+		} else if (c_full_max == CONTENT_IGNORE) {
+			vi = vm->m_area.index(x, node_max.Y + 1, z);
+			content_t c_max = vm->m_data[vi].getContent();
+
+			if (c_max == CONTENT_AIR)
+				y_start = node_max.Y;
+			else
+				continue;
+		} else {
+			continue;
+		}
+
+		vi = vm->m_area.index(x, y_start, z);
+		for (s16 y = y_start; y >= node_min.Y - 1; y--) {
+			if (vm->m_data[vi].getContent() != CONTENT_AIR)
+				break;
+
+			vm->m_area.add_y(em, vi, -1);
+		}
+
+		content_t c = vm->m_data[vi].getContent();
+		if (!ndef->get(c).buildable_to && c != CONTENT_IGNORE && c != biome->c_dust) {
+			vm->m_area.add_y(em, vi, 1);
+			vm->m_data[vi] = MapNode(biome->c_dust);
+		}
+	}
+}
+
+
+void MapgenFlat::generateCaves(s16 max_stone_y)
+{
+	if (max_stone_y >= node_min.Y) {
+		u32 index = 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++, vi++, index++) {
+				float d1 = contour(noise_cave1->result[index]);
+				float d2 = contour(noise_cave2->result[index]);
+				if (d1 * d2 > 0.4f) {
+					content_t c = vm->m_data[vi].getContent();
+					if (!ndef->get(c).is_ground_content || c == CONTENT_AIR)
+						continue;
+
+					vm->m_data[vi] = MapNode(CONTENT_AIR);
+				}
+			}
+		}
+	}
+
+	if (node_max.Y > large_cave_depth)
+		return;
+
+	PseudoRandom ps(blockseed + 21343);
+	u32 bruises_count = (ps.range(1, 4) == 1) ? ps.range(1, 2) : 0;
+	for (u32 i = 0; i < bruises_count; i++) {
+		CaveV5 cave(this, &ps);
+		cave.makeCave(node_min, node_max, max_stone_y);
+	}
+}

src/mapgen_flat.h

+/*
+Minetest
+Copyright (C) 2010-2015 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2010-2015 paramat, Matt Gregory
+
+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_FLAT_HEADER
+#define MAPGEN_FLAT_HEADER
+
+#include "mapgen.h"
+
+/////// Mapgen Flat flags
+#define MGFLAT_LAKES 0x01
+#define MGFLAT_HILLS 0x02
+
+class BiomeManager;
+
+extern FlagDesc flagdesc_mapgen_flat[];
+
+
+struct MapgenFlatParams : public MapgenSpecificParams {
+	u32 spflags;
+
+	s16 ground_level;
+	s16 large_cave_depth;
+	float lake_threshold;
+	float lake_steepness;
+	float hill_threshold;
+	float hill_steepness;
+
+	NoiseParams np_terrain;
+	NoiseParams np_filler_depth;
+	NoiseParams np_cave1;
+	NoiseParams np_cave2;
+
+	MapgenFlatParams();
+	~MapgenFlatParams() {}
+
+	void readParams(const Settings *settings);
+	void writeParams(Settings *settings) const;
+};
+
+class MapgenFlat : public Mapgen {
+public:
+	EmergeManager *m_emerge;
+	BiomeManager *bmgr;
+
+	int ystride;
+	int zstride;
+	u32 spflags;
+
+	v3s16 node_min;
+	v3s16 node_max;
+	v3s16 full_node_min;
+	v3s16 full_node_max;
+
+	s16 ground_level;
+	s16 large_cave_depth;
+	float lake_threshold;
+	float lake_steepness;
+	float hill_threshold;
+	float hill_steepness;
+
+	Noise *noise_terrain;
+	Noise *noise_filler_depth;
+	Noise *noise_cave1;
+	Noise *noise_cave2;
+
+	Noise *noise_heat;
+	Noise *noise_humidity;
+	Noise *noise_heat_blend;
+	Noise *noise_humidity_blend;
+
+	content_t c_stone;
+	content_t c_water_source;
+	content_t c_lava_source;
+	content_t c_desert_stone;
+	content_t c_ice;
+	content_t c_sandstone;
+
+	content_t c_cobble;
+	content_t c_stair_cobble;
+	content_t c_mossycobble;
+	content_t c_sandstonebrick;
+	content_t c_stair_sandstonebrick;
+
+	MapgenFlat(int mapgenid, MapgenParams *params, EmergeManager *emerge);
+	~MapgenFlat();
+
+	virtual void makeChunk(BlockMakeData *data);
+	int getGroundLevelAtPoint(v2s16 p);
+	void calculateNoise();
+	s16 generateTerrain();
+	MgStoneType generateBiomes(float *heat_map, float *humidity_map);
+	void dustTopNodes();
+	void generateCaves(s16 max_stone_y);
+};
+
+struct MapgenFactoryFlat : public MapgenFactory {
+	Mapgen *createMapgen(int mgid, MapgenParams *params, EmergeManager *emerge)
+	{
+		return new MapgenFlat(mgid, params, emerge);
+	};
+
+	MapgenSpecificParams *createMapgenParams()
+	{
+		return new MapgenFlatParams();
+	};
+};
+
+#endif