Cavegen/Mgv5/Mgv7: Add optional giant caverns

Add to MapgenBasic for use by multiple mapgens.
Add to mgv5 and mgv7, enabled by default.

Similar to mgvalleys caverns but half the scale.
Parameters for upper y limit, distance caverns taper to full size, and
noise threshold (full cavern size).
As with mgvalleys caverns are generated first and classic caves are
disabled in any mapchunk containing a cavern, to avoid excessive
spreading volumes of liquids.
This also avoids floating blobs of liquid where a large classic cave
has overgenerated out into a neighbouring previously-generated mapchunk.

8 files changed, 250 insertions, 54 deletions

diff --git a/src/cavegen.cpp b/src/cavegen.cpp
index 1005640c1..6275c516e 100644
--- a/src/cavegen.cpp
+++ b/src/cavegen.cpp
@@ -151,6 +151,101 @@ void CavesNoiseIntersection::generateCaves(MMVManip *vm,
 
 
 ////
+//// CavernsNoise
+////
+
+CavernsNoise::CavernsNoise(
+	INodeDefManager *nodedef, v3s16 chunksize, NoiseParams *np_cavern,
+	s32 seed, float cavern_limit, float cavern_taper, float cavern_threshold)
+{
+	assert(nodedef);
+
+	m_ndef = nodedef;
+
+	m_csize = chunksize;
+	m_cavern_limit     = cavern_limit;
+	m_cavern_taper     = cavern_taper;
+	m_cavern_threshold = cavern_threshold;
+
+	m_ystride = m_csize.X;
+	m_zstride_1d = m_csize.X * (m_csize.Y + 1);
+
+	// Noise is created using 1-down overgeneration
+	// A Nx-by-1-by-Nz-sized plane is at the bottom of the desired for
+	// re-carving the solid overtop placed for blocking sunlight
+	noise_cavern = new Noise(np_cavern, seed, m_csize.X, m_csize.Y + 1, m_csize.Z);
+
+	c_water_source = m_ndef->getId("mapgen_water_source");
+	if (c_water_source == CONTENT_IGNORE)
+		c_water_source = CONTENT_AIR;
+
+	c_lava_source = m_ndef->getId("mapgen_lava_source");
+	if (c_lava_source == CONTENT_IGNORE)
+		c_lava_source = CONTENT_AIR;
+}
+
+
+CavernsNoise::~CavernsNoise()
+{
+	delete noise_cavern;
+}
+
+
+bool CavernsNoise::generateCaverns(MMVManip *vm, v3s16 nmin, v3s16 nmax)
+{
+	assert(vm);
+
+	// Calculate noise
+	noise_cavern->perlinMap3D(nmin.X, nmin.Y - 1, nmin.Z);
+
+	// Cache cavern_amp values
+	float cavern_amp[m_csize.Y + 1];
+	u8 cavern_amp_index = 0;  // Index zero at column top
+	for (s16 y = nmax.Y; y >= nmin.Y - 1; y--, cavern_amp_index++) {
+		cavern_amp[cavern_amp_index] =
+			MYMIN((m_cavern_limit - y) / (float)m_cavern_taper, 1.0f);
+	}
+
+	//// Place nodes
+	bool has_cavern = false;
+	v3s16 em = vm->m_area.getExtent();
+	u32 index2d = 0;
+
+	for (s16 z = nmin.Z; z <= nmax.Z; z++)
+	for (s16 x = nmin.X; x <= nmax.X; x++, index2d++) {
+		// Reset cave_amp index to column top
+		cavern_amp_index = 0;
+		// Initial voxelmanip index at column top
+		u32 vi = vm->m_area.index(x, nmax.Y, z);
+		// Initial 3D noise index at column top
+		u32 index3d = (z - nmin.Z) * m_zstride_1d + m_csize.Y * m_ystride +
+			(x - nmin.X);
+		// Don't excavate the overgenerated stone at node_max.Y + 1,
+		// this creates a 'roof' over the cavern, preventing light in
+		// caverns at mapchunk borders when generating mapchunks upwards.
+		// This 'roof' is excavated when the mapchunk above is generated.
+		for (s16 y = nmax.Y; y >= nmin.Y - 1; y--,
+				index3d -= m_ystride,
+				vm->m_area.add_y(em, vi, -1),
+				cavern_amp_index++) {
+			content_t c = vm->m_data[vi].getContent();
+			float nabs_cavern = fabs(noise_cavern->result[index3d]);
+			// Caverns generate first but still remove lava and water in case
+			// of overgenerated classic caves.
+			if (nabs_cavern * cavern_amp[cavern_amp_index] > m_cavern_threshold &&
+					(m_ndef->get(c).is_ground_content ||
+					c == c_lava_source || c == c_water_source)) {
+				vm->m_data[vi] = MapNode(CONTENT_AIR);
+				has_cavern = true;
+			}
+		}
+	}
+
+	return has_cavern;
+}
+
+
+////
 //// CavesRandomWalk
 ////
 
diff --git a/src/cavegen.h b/src/cavegen.h
index 2bf503d47..e322c181c 100644
--- a/src/cavegen.h
+++ b/src/cavegen.h
@@ -63,6 +63,36 @@ private:
 };
 
 /*
+	CavernsNoise is a cave digging algorithm
+*/
+class CavernsNoise {
+public:
+	CavernsNoise(INodeDefManager *nodedef, v3s16 chunksize, NoiseParams *np_cavern,
+	s32 seed, float cavern_limit, float cavern_taper, float cavern_threshold);
+	~CavernsNoise();
+
+	bool generateCaverns(MMVManip *vm, v3s16 nmin, v3s16 nmax);
+
+private:
+	INodeDefManager *m_ndef;
+
+	// configurable parameters
+	v3s16 m_csize;
+	float m_cavern_limit;
+	float m_cavern_taper;
+	float m_cavern_threshold;
+
+	// intermediate state variables
+	u16 m_ystride;
+	u16 m_zstride_1d;
+
+	Noise *noise_cavern;
+
+	content_t c_water_source;
+	content_t c_lava_source;
+};
+
+/*
 	CavesRandomWalk is an implementation of a cave-digging algorithm that
 	operates on the principle of a "random walk" to approximate the stochiastic
 	activity of cavern development.
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index b6e8c0fd1..c63c426fa 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -840,6 +840,18 @@ void MapgenBasic::generateCaves(s16 max_stone_y, s16 large_cave_depth)
 }
 
 
+bool MapgenBasic::generateCaverns(s16 max_stone_y)
+{
+	if (node_min.Y > max_stone_y || node_min.Y > cavern_limit)
+		return false;
+
+	CavernsNoise caverns_noise(ndef, csize, &np_cavern,
+		seed, cavern_limit, cavern_taper, cavern_threshold);
+
+	return caverns_noise.generateCaverns(vm, node_min, node_max);
+}
+
+
 void MapgenBasic::generateDungeons(s16 max_stone_y, MgStoneType stone_type)
 {
 	if (max_stone_y < node_min.Y)
diff --git a/src/mapgen.h b/src/mapgen.h
index c4e1652e8..f738b1bce 100644
--- a/src/mapgen.h
+++ b/src/mapgen.h
@@ -243,6 +243,7 @@ public:
 	virtual ~MapgenBasic();
 
 	virtual void generateCaves(s16 max_stone_y, s16 large_cave_depth);
+	virtual bool generateCaverns(s16 max_stone_y);
 	virtual void generateDungeons(s16 max_stone_y, MgStoneType stone_type);
 	virtual MgStoneType generateBiomes();
 	virtual void dustTopNodes();
@@ -282,7 +283,11 @@ protected:
 
 	NoiseParams np_cave1;
 	NoiseParams np_cave2;
+	NoiseParams np_cavern;
 	float cave_width;
+	float cavern_limit;
+	float cavern_taper;
+	float cavern_threshold;
 };
 
 #endif
diff --git a/src/mapgen_v5.cpp b/src/mapgen_v5.cpp
index 9f189e253..b983026e6 100644
--- a/src/mapgen_v5.cpp
+++ b/src/mapgen_v5.cpp
@@ -41,15 +41,19 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 FlagDesc flagdesc_mapgen_v5[] = {
-	{NULL,         0}
+	{"caverns", MGV5_CAVERNS},
+	{NULL,      0}
 };
 
 
 MapgenV5::MapgenV5(int mapgenid, MapgenV5Params *params, EmergeManager *emerge)
 	: MapgenBasic(mapgenid, params, emerge)
 {
-	this->spflags    = params->spflags;
-	this->cave_width = params->cave_width;
+	this->spflags          = params->spflags;
+	this->cave_width       = params->cave_width;
+	this->cavern_limit     = params->cavern_limit;
+	this->cavern_taper     = params->cavern_taper;
+	this->cavern_threshold = params->cavern_threshold;
 
 	// Terrain noise
 	noise_filler_depth = new Noise(&params->np_filler_depth, seed, csize.X, csize.Z);
@@ -59,9 +63,10 @@ MapgenV5::MapgenV5(int mapgenid, MapgenV5Params *params, EmergeManager *emerge)
 	// 3D terrain noise
 	// 1-up 1-down overgeneration
 	noise_ground = new Noise(&params->np_ground, seed, csize.X, csize.Y + 2, csize.Z);
-
-	MapgenBasic::np_cave1 = params->np_cave1;
-	MapgenBasic::np_cave2 = params->np_cave2;
+	// 1 down overgeneration
+	MapgenBasic::np_cave1  = params->np_cave1;
+	MapgenBasic::np_cave2  = params->np_cave2;
+	MapgenBasic::np_cavern = params->np_cavern;
 }
 
 
@@ -76,47 +81,55 @@ MapgenV5::~MapgenV5()
 
 MapgenV5Params::MapgenV5Params()
 {
-	spflags    = 0;
-	cave_width = 0.125;
+	spflags          = MGV5_CAVERNS;
+	cave_width       = 0.125;
+	cavern_limit     = -256;
+	cavern_taper     = 256;
+	cavern_threshold = 0.7;
 
 	np_filler_depth = NoiseParams(0, 1,  v3f(150, 150, 150), 261,    4, 0.7,  2.0);
 	np_factor       = NoiseParams(0, 1,  v3f(250, 250, 250), 920381, 3, 0.45, 2.0);
 	np_height       = NoiseParams(0, 10, v3f(250, 250, 250), 84174,  4, 0.5,  2.0);
+	np_ground       = NoiseParams(0, 40, v3f(80,  80,  80),  983240, 4, 0.55, 2.0, NOISE_FLAG_EASED);
 	np_cave1        = NoiseParams(0, 12, v3f(50,  50,  50),  52534,  4, 0.5,  2.0);
 	np_cave2        = NoiseParams(0, 12, v3f(50,  50,  50),  10325,  4, 0.5,  2.0);
-	np_ground       = NoiseParams(0, 40, v3f(80,  80,  80),  983240, 4, 0.55, 2.0, NOISE_FLAG_EASED);
+	np_cavern       = NoiseParams(0, 1,  v3f(384, 128, 384), 723,    5, 0.63, 2.0);
 }
 
 
-//#define CAVE_NOISE_SCALE 12.0
-//#define CAVE_NOISE_THRESHOLD (1.5/CAVE_NOISE_SCALE) = 0.125
-
-
 void MapgenV5Params::readParams(const Settings *settings)
 {
-	settings->getFlagStrNoEx("mgv5_spflags",  spflags, flagdesc_mapgen_v5);
-	settings->getFloatNoEx("mgv5_cave_width", cave_width);
+	settings->getFlagStrNoEx("mgv5_spflags",        spflags, flagdesc_mapgen_v5);
+	settings->getFloatNoEx("mgv5_cave_width",       cave_width);
+	settings->getS16NoEx("mgv5_cavern_limit",       cavern_limit);
+	settings->getS16NoEx("mgv5_cavern_taper",       cavern_taper);
+	settings->getFloatNoEx("mgv5_cavern_threshold", cavern_threshold);
 
 	settings->getNoiseParams("mgv5_np_filler_depth", np_filler_depth);
 	settings->getNoiseParams("mgv5_np_factor",       np_factor);
 	settings->getNoiseParams("mgv5_np_height",       np_height);
+	settings->getNoiseParams("mgv5_np_ground",       np_ground);
 	settings->getNoiseParams("mgv5_np_cave1",        np_cave1);
 	settings->getNoiseParams("mgv5_np_cave2",        np_cave2);
-	settings->getNoiseParams("mgv5_np_ground",       np_ground);
+	settings->getNoiseParams("mgv5_np_cavern",       np_cavern);
 }
 
 
 void MapgenV5Params::writeParams(Settings *settings) const
 {
-	settings->setFlagStr("mgv5_spflags",  spflags, flagdesc_mapgen_v5, U32_MAX);
-	settings->setFloat("mgv5_cave_width", cave_width);
+	settings->setFlagStr("mgv5_spflags",        spflags, flagdesc_mapgen_v5, U32_MAX);
+	settings->setFloat("mgv5_cave_width",       cave_width);
+	settings->setS16("mgv5_cavern_limit",       cavern_limit);
+	settings->setS16("mgv5_cavern_taper",       cavern_taper);
+	settings->setFloat("mgv5_cavern_threshold", cavern_threshold);
 
 	settings->setNoiseParams("mgv5_np_filler_depth", np_filler_depth);
 	settings->setNoiseParams("mgv5_np_factor",       np_factor);
 	settings->setNoiseParams("mgv5_np_height",       np_height);
+	settings->setNoiseParams("mgv5_np_ground",       np_ground);
 	settings->setNoiseParams("mgv5_np_cave1",        np_cave1);
 	settings->setNoiseParams("mgv5_np_cave2",        np_cave2);
-	settings->setNoiseParams("mgv5_np_ground",       np_ground);
+	settings->setNoiseParams("mgv5_np_cavern",       np_cavern);
 }
 
 
@@ -190,9 +203,21 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 	biomegen->calcBiomeNoise(node_min);
 	MgStoneType stone_type = generateBiomes();
 
-	// Generate caves
-	if ((flags & MG_CAVES) && (stone_surface_max_y >= node_min.Y))
-		generateCaves(stone_surface_max_y, MGV5_LARGE_CAVE_DEPTH);
+	// Generate caverns, tunnels and classic caves
+	if (flags & MG_CAVES) {
+		bool has_cavern = false;
+		// Generate caverns
+		if (spflags & MGV5_CAVERNS)
+			has_cavern = generateCaverns(stone_surface_max_y);
+		// Generate tunnels and classic caves
+		if (has_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, MGV5_LARGE_CAVE_DEPTH);
+	}
 
 	// Generate dungeons and desert temples
 	if (flags & MG_DUNGEONS)
@@ -223,23 +248,6 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 }
 
 
-//bool is_cave(u32 index) {
-//	double d1 = contour(noise_cave1->result[index]);
-//	double d2 = contour(noise_cave2->result[index]);
-//	return d1*d2 > CAVE_NOISE_THRESHOLD;
-//}
-
-//bool val_is_ground(v3s16 p, u32 index, u32 index2d) {
-//	double f = 0.55 + noise_factor->result[index2d];
-//	if(f < 0.01)
-//		f = 0.01;
-//	else if(f >= 1.0)
-//		f *= 1.6;
-//	double h = WATER_LEVEL + 10 * noise_height->result[index2d];
-//	return (noise_ground->result[index] * f > (double)p.Y - h);
-//}
-
-
 int MapgenV5::generateBaseTerrain()
 {
 	u32 index = 0;
diff --git a/src/mapgen_v5.h b/src/mapgen_v5.h
index ddb090a9c..034d53560 100644
--- a/src/mapgen_v5.h
+++ b/src/mapgen_v5.h
@@ -25,6 +25,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #define MGV5_LARGE_CAVE_DEPTH -256
 
+///////// Mapgen V5 flags
+#define MGV5_CAVERNS 0x01
+
 class BiomeManager;
 
 extern FlagDesc flagdesc_mapgen_v5[];
@@ -33,12 +36,17 @@ extern FlagDesc flagdesc_mapgen_v5[];
 struct MapgenV5Params : public MapgenParams {
 	u32 spflags;
 	float cave_width;
+	s16 cavern_limit;
+	s16 cavern_taper;
+	float cavern_threshold;
+
 	NoiseParams np_filler_depth;
 	NoiseParams np_factor;
 	NoiseParams np_height;
+	NoiseParams np_ground;
 	NoiseParams np_cave1;
 	NoiseParams np_cave2;
-	NoiseParams np_ground;
+	NoiseParams np_cavern;
 
 	MapgenV5Params();
 	~MapgenV5Params() {}
diff --git a/src/mapgen_v7.cpp b/src/mapgen_v7.cpp
index 04a9e3c16..760299fd6 100644
--- a/src/mapgen_v7.cpp
+++ b/src/mapgen_v7.cpp
@@ -41,10 +41,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 FlagDesc flagdesc_mapgen_v7[] = {
-	{"mountains",    MGV7_MOUNTAINS},
-	{"ridges",       MGV7_RIDGES},
-	{"floatlands",   MGV7_FLOATLANDS},
-	{NULL,           0}
+	{"mountains",  MGV7_MOUNTAINS},
+	{"ridges",     MGV7_RIDGES},
+	{"floatlands", MGV7_FLOATLANDS},
+	{"caverns",    MGV7_CAVERNS},
+	{NULL,         0}
 };
 
 
@@ -60,6 +61,9 @@ MapgenV7::MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge)
 	this->float_mount_height  = params->float_mount_height;
 	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;
 
 	//// Terrain noise
 	noise_terrain_base      = new Noise(&params->np_terrain_base,      seed, csize.X, csize.Z);
@@ -76,9 +80,10 @@ MapgenV7::MapgenV7(int mapgenid, MapgenV7Params *params, EmergeManager *emerge)
 	// 1-up 1-down overgeneration
 	noise_mountain = new Noise(&params->np_mountain, seed, csize.X, csize.Y + 2, csize.Z);
 	noise_ridge    = new Noise(&params->np_ridge,    seed, csize.X, csize.Y + 2, csize.Z);
-
-	MapgenBasic::np_cave1 = params->np_cave1;
-	MapgenBasic::np_cave2 = params->np_cave2;
+	// 1 down overgeneration
+	MapgenBasic::np_cave1  = params->np_cave1;
+	MapgenBasic::np_cave2  = params->np_cave2;
+	MapgenBasic::np_cavern = params->np_cavern;
 }
 
 
@@ -100,12 +105,15 @@ MapgenV7::~MapgenV7()
 
 MapgenV7Params::MapgenV7Params()
 {
-	spflags             = MGV7_MOUNTAINS | MGV7_RIDGES;
+	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);
@@ -118,6 +126,7 @@ MapgenV7Params::MapgenV7Params()
 	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);
 }
@@ -131,6 +140,9 @@ void MapgenV7Params::readParams(const Settings *settings)
 	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);
@@ -143,6 +155,7 @@ void MapgenV7Params::readParams(const Settings *settings)
 	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);
 }
@@ -156,6 +169,9 @@ void MapgenV7Params::writeParams(Settings *settings) const
 	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);
@@ -168,6 +184,7 @@ void MapgenV7Params::writeParams(Settings *settings) const
 	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);
 }
@@ -256,9 +273,23 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 	biomegen->calcBiomeNoise(node_min);
 	MgStoneType stone_type = generateBiomes();
 
-	if (flags & MG_CAVES)
-		generateCaves(stone_surface_max_y, water_level);
+	// Generate caverns, tunnels and classic caves
+	if (flags & MG_CAVES) {
+		bool has_cavern = false;
+		// Generate caverns
+		if (spflags & MGV7_CAVERNS)
+			has_cavern = generateCaverns(stone_surface_max_y);
+		// Generate tunnels and classic caves
+		if (has_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);
 
@@ -274,8 +305,10 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 
 	//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);
diff --git a/src/mapgen_v7.h b/src/mapgen_v7.h
index 3972387a7..71a341afe 100644
--- a/src/mapgen_v7.h
+++ b/src/mapgen_v7.h
@@ -23,10 +23,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "mapgen.h"
 
-////////////// Mapgen V7 flags
-#define MGV7_MOUNTAINS    0x01
-#define MGV7_RIDGES       0x02
-#define MGV7_FLOATLANDS   0x04
+//////////// Mapgen V7 flags
+#define MGV7_MOUNTAINS  0x01
+#define MGV7_RIDGES     0x02
+#define MGV7_FLOATLANDS 0x04
+#define MGV7_CAVERNS    0x08
 
 class BiomeManager;
 
@@ -40,6 +41,9 @@ struct MapgenV7Params : public MapgenParams {
 	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;
@@ -52,6 +56,7 @@ struct MapgenV7Params : public MapgenParams {
 	NoiseParams np_float_base_height;
 	NoiseParams np_mountain;
 	NoiseParams np_ridge;
+	NoiseParams np_cavern;
 	NoiseParams np_cave1;
 	NoiseParams np_cave2;