Mapgen Flat: Add caverns, disabled by default (#9913)

Add the caverns used in V5, V7, Valleys, Carpathian.
Disabled by default to not be force-enabled in existing worlds.

builtin/mainmenu/dlg_create_world.lua

@@ -61,6 +61,7 @@ local flag_checkboxes = {
 		fgettext("Low humidity and high heat causes shallow or dry rivers") },
 	},
 	flat = {
+		cb_caverns,
 		{ "hills", fgettext("Hills"), "hills" },
 		{ "lakes", fgettext("Lakes"), "lakes" },
 	},

builtin/settingtypes.txt

@@ -1860,7 +1860,7 @@ mgcarpathian_np_dungeons (Dungeon noise) noise_params_3d 0.9, 0.5, (500, 500, 50
 
 #    Map generation attributes specific to Mapgen Flat.
 #    Occasional lakes and hills can be added to the flat world.
-mgflat_spflags (Mapgen Flat specific flags) flags nolakes,nohills lakes,hills,nolakes,nohills
+mgflat_spflags (Mapgen Flat specific flags) flags nolakes,nohills,nocaverns lakes,hills,caverns,nolakes,nohills,nocaverns
 
 #    Y of flat ground.
 mgflat_ground_level (Ground level) int 8
@@ -1904,6 +1904,15 @@ mgflat_hill_threshold (Hill threshold) float 0.45
 #    Controls steepness/height of hills.
 mgflat_hill_steepness (Hill steepness) float 64.0
 
+#    Y-level of cavern upper limit.
+mgflat_cavern_limit (Cavern limit) int -256
+
+#    Y-distance over which caverns expand to full size.
+mgflat_cavern_taper (Cavern taper) int 256
+
+#    Defines full size of caverns, smaller values create larger caverns.
+mgflat_cavern_threshold (Cavern threshold) float 0.7
+
 #    Lower Y limit of dungeons.
 mgflat_dungeon_ymin (Dungeon minimum Y) int -31000
 
@@ -1924,6 +1933,9 @@ mgflat_np_cave1 (Cave1 noise) noise_params_3d 0, 12, (61, 61, 61), 52534, 3, 0.5
 #    Second of two 3D noises that together define tunnels.
 mgflat_np_cave2 (Cave2 noise) noise_params_3d 0, 12, (67, 67, 67), 10325, 3, 0.5, 2.0
 
+#    3D noise defining giant caverns.
+mgflat_np_cavern (Cavern noise) noise_params_3d 0, 1, (384, 128, 384), 723, 5, 0.63, 2.0
+
 #    3D noise that determines number of dungeons per mapchunk.
 mgflat_np_dungeons (Dungeon noise) noise_params_3d 0.9, 0.5, (500, 500, 500), 0, 2, 0.8, 2.0
 

src/mapgen/mapgen_flat.cpp

@@ -1,7 +1,7 @@
 /*
 Minetest
-Copyright (C) 2015-2018 paramat
-Copyright (C) 2015-2018 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2015-2020 paramat
+Copyright (C) 2015-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
 
 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
@@ -39,8 +39,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 
 FlagDesc flagdesc_mapgen_flat[] = {
-	{"lakes", MGFLAT_LAKES},
-	{"hills", MGFLAT_HILLS},
+	{"lakes",   MGFLAT_LAKES},
+	{"hills",   MGFLAT_HILLS},
+	{"caverns", MGFLAT_CAVERNS},
 	{NULL,    0}
 };
 
@@ -52,17 +53,21 @@ MapgenFlat::MapgenFlat(MapgenFlatParams *params, EmergeParams *emerge)
 {
 	spflags            = params->spflags;
 	ground_level       = params->ground_level;
-	large_cave_depth   = params->large_cave_depth;
+	lake_threshold     = params->lake_threshold;
+	lake_steepness     = params->lake_steepness;
+	hill_threshold     = params->hill_threshold;
+	hill_steepness     = params->hill_steepness;
+
+	cave_width         = params->cave_width;
 	small_cave_num_min = params->small_cave_num_min;
 	small_cave_num_max = params->small_cave_num_max;
 	large_cave_num_min = params->large_cave_num_min;
 	large_cave_num_max = params->large_cave_num_max;
+	large_cave_depth   = params->large_cave_depth;
 	large_cave_flooded = params->large_cave_flooded;
-	cave_width         = params->cave_width;
-	lake_threshold     = params->lake_threshold;
-	lake_steepness     = params->lake_steepness;
-	hill_threshold     = params->hill_threshold;
-	hill_steepness     = params->hill_steepness;
+	cavern_limit       = params->cavern_limit;
+	cavern_taper       = params->cavern_taper;
+	cavern_threshold   = params->cavern_threshold;
 	dungeon_ymin       = params->dungeon_ymin;
 	dungeon_ymax       = params->dungeon_ymax;
 
@@ -71,9 +76,11 @@ MapgenFlat::MapgenFlat(MapgenFlatParams *params, EmergeParams *emerge)
 
 	if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
 		noise_terrain = new Noise(&params->np_terrain, seed, csize.X, csize.Z);
+
 	// 3D noise
 	MapgenBasic::np_cave1    = params->np_cave1;
 	MapgenBasic::np_cave2    = params->np_cave2;
+	MapgenBasic::np_cavern   = params->np_cavern;
 	MapgenBasic::np_dungeons = params->np_dungeons;
 }
 
@@ -88,11 +95,12 @@ MapgenFlat::~MapgenFlat()
 
 
 MapgenFlatParams::MapgenFlatParams():
-	np_terrain      (0,   1,   v3f(600, 600, 600), 7244,  5, 0.6, 2.0),
-	np_filler_depth (0,   1.2, v3f(150, 150, 150), 261,   3, 0.7, 2.0),
-	np_cave1        (0,   12,  v3f(61,  61,  61),  52534, 3, 0.5, 2.0),
-	np_cave2        (0,   12,  v3f(67,  67,  67),  10325, 3, 0.5, 2.0),
-	np_dungeons     (0.9, 0.5, v3f(500, 500, 500), 0,     2, 0.8, 2.0)
+	np_terrain      (0,   1,   v3f(600, 600, 600), 7244,  5, 0.6,  2.0),
+	np_filler_depth (0,   1.2, v3f(150, 150, 150), 261,   3, 0.7,  2.0),
+	np_cavern       (0.0, 1.0, v3f(384, 128, 384), 723,   5, 0.63, 2.0),
+	np_cave1        (0,   12,  v3f(61,  61,  61),  52534, 3, 0.5,  2.0),
+	np_cave2        (0,   12,  v3f(67,  67,  67),  10325, 3, 0.5,  2.0),
+	np_dungeons     (0.9, 0.5, v3f(500, 500, 500), 0,     2, 0.8,  2.0)
 {
 }
 
@@ -112,11 +120,15 @@ void MapgenFlatParams::readParams(const Settings *settings)
 	settings->getFloatNoEx("mgflat_lake_steepness",     lake_steepness);
 	settings->getFloatNoEx("mgflat_hill_threshold",     hill_threshold);
 	settings->getFloatNoEx("mgflat_hill_steepness",     hill_steepness);
+	settings->getS16NoEx("mgflat_cavern_limit",         cavern_limit);
+	settings->getS16NoEx("mgflat_cavern_taper",         cavern_taper);
+	settings->getFloatNoEx("mgflat_cavern_threshold",   cavern_threshold);
 	settings->getS16NoEx("mgflat_dungeon_ymin",         dungeon_ymin);
 	settings->getS16NoEx("mgflat_dungeon_ymax",         dungeon_ymax);
 
 	settings->getNoiseParams("mgflat_np_terrain",      np_terrain);
 	settings->getNoiseParams("mgflat_np_filler_depth", np_filler_depth);
+	settings->getNoiseParams("mgflat_np_cavern",       np_cavern);
 	settings->getNoiseParams("mgflat_np_cave1",        np_cave1);
 	settings->getNoiseParams("mgflat_np_cave2",        np_cave2);
 	settings->getNoiseParams("mgflat_np_dungeons",     np_dungeons);
@@ -138,11 +150,15 @@ void MapgenFlatParams::writeParams(Settings *settings) const
 	settings->setFloat("mgflat_lake_steepness",     lake_steepness);
 	settings->setFloat("mgflat_hill_threshold",     hill_threshold);
 	settings->setFloat("mgflat_hill_steepness",     hill_steepness);
+	settings->setS16("mgflat_cavern_limit",         cavern_limit);
+	settings->setS16("mgflat_cavern_taper",         cavern_taper);
+	settings->setFloat("mgflat_cavern_threshold",   cavern_threshold);
 	settings->setS16("mgflat_dungeon_ymin",         dungeon_ymin);
 	settings->setS16("mgflat_dungeon_ymax",         dungeon_ymax);
 
 	settings->setNoiseParams("mgflat_np_terrain",      np_terrain);
 	settings->setNoiseParams("mgflat_np_filler_depth", np_filler_depth);
+	settings->setNoiseParams("mgflat_np_cavern",       np_cavern);
 	settings->setNoiseParams("mgflat_np_cave1",        np_cave1);
 	settings->setNoiseParams("mgflat_np_cave2",        np_cave2);
 	settings->setNoiseParams("mgflat_np_dungeons",     np_dungeons);
@@ -226,11 +242,25 @@ void MapgenFlat::makeChunk(BlockMakeData *data)
 		generateBiomes();
 	}
 
+	// Generate tunnels, caverns and large randomwalk caves
 	if (flags & MG_CAVES) {
-		// Generate tunnels
+		// Generate tunnels first as caverns confuse them
 		generateCavesNoiseIntersection(stone_surface_max_y);
+
+		// Generate caverns
+		bool near_cavern = false;
+		if (spflags & MGFLAT_CAVERNS)
+			near_cavern = generateCavernsNoise(stone_surface_max_y);
+
 		// Generate large randomwalk caves
-		generateCavesRandomWalk(stone_surface_max_y, large_cave_depth);
+		if (near_cavern)
+			// Disable large randomwalk caves in this mapchunk by setting
+			// 'large cave depth' to world base. Avoids excessive liquid in
+			// large caverns and floating blobs of overgenerated liquid.
+			generateCavesRandomWalk(stone_surface_max_y,
+				-MAX_MAP_GENERATION_LIMIT);
+		else
+			generateCavesRandomWalk(stone_surface_max_y, large_cave_depth);
 	}
 
 	// Generate the registered ores

src/mapgen/mapgen_flat.h

@@ -1,7 +1,7 @@
 /*
 Minetest
-Copyright (C) 2015-2018 paramat
-Copyright (C) 2015-2018 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
+Copyright (C) 2015-2020 paramat
+Copyright (C) 2015-2016 kwolekr, Ryan Kwolek <kwolekr@minetest.net>
 
 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
@@ -25,6 +25,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 /////// Mapgen Flat flags
 #define MGFLAT_LAKES 0x01
 #define MGFLAT_HILLS 0x02
+#define MGFLAT_CAVERNS 0x04
 
 class BiomeManager;
 
@@ -33,22 +34,27 @@ extern FlagDesc flagdesc_mapgen_flat[];
 struct MapgenFlatParams : public MapgenParams
 {
 	s16 ground_level = 8;
-	s16 large_cave_depth = -33;
+	float lake_threshold = -0.45f;
+	float lake_steepness = 48.0f;
+	float hill_threshold = 0.45f;
+	float hill_steepness = 64.0f;
+
+	float cave_width = 0.09f;
 	u16 small_cave_num_min = 0;
 	u16 small_cave_num_max = 0;
 	u16 large_cave_num_min = 0;
 	u16 large_cave_num_max = 2;
+	s16 large_cave_depth = -33;
 	float large_cave_flooded = 0.5f;
-	float cave_width = 0.09f;
-	float lake_threshold = -0.45f;
-	float lake_steepness = 48.0f;
-	float hill_threshold = 0.45f;
-	float hill_steepness = 64.0f;
+	s16 cavern_limit = -256;
+	s16 cavern_taper = 256;
+	float cavern_threshold = 0.7f;
 	s16 dungeon_ymin = -31000;
 	s16 dungeon_ymax = 31000;
 
 	NoiseParams np_terrain;
 	NoiseParams np_filler_depth;
+	NoiseParams np_cavern;
 	NoiseParams np_cave1;
 	NoiseParams np_cave2;
 	NoiseParams np_dungeons;