Move files to subdirectories (#6599)

* Move files around

1 files changed, 677 insertions, 0 deletions

diff --git a/src/mapgen/dungeongen.cpp b/src/mapgen/dungeongen.cpp
new file mode 100644
index 000000000..fa867b398
--- /dev/null
+++ b/src/mapgen/dungeongen.cpp
@@ -0,0 +1,677 @@
+/*
+Minetest
+Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+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 "dungeongen.h"
+#include "mapgen.h"
+#include "voxel.h"
+#include "noise.h"
+#include "mapblock.h"
+#include "mapnode.h"
+#include "map.h"
+#include "nodedef.h"
+#include "settings.h"
+
+//#define DGEN_USE_TORCHES
+
+NoiseParams nparams_dungeon_density(0.9, 0.5, v3f(500.0, 500.0, 500.0), 0, 2, 0.8, 2.0);
+NoiseParams nparams_dungeon_alt_wall(-0.4, 1.0, v3f(40.0, 40.0, 40.0), 32474, 6, 1.1, 2.0);
+
+
+///////////////////////////////////////////////////////////////////////////////
+
+
+DungeonGen::DungeonGen(INodeDefManager *ndef,
+	GenerateNotifier *gennotify, DungeonParams *dparams)
+{
+	assert(ndef);
+
+	this->ndef      = ndef;
+	this->gennotify = gennotify;
+
+#ifdef DGEN_USE_TORCHES
+	c_torch  = ndef->getId("default:torch");
+#endif
+
+	if (dparams) {
+		memcpy(&dp, dparams, sizeof(dp));
+	} else {
+		// Default dungeon parameters
+		dp.seed = 0;
+
+		dp.c_water       = ndef->getId("mapgen_water_source");
+		dp.c_river_water = ndef->getId("mapgen_river_water_source");
+		dp.c_wall        = ndef->getId("mapgen_cobble");
+		dp.c_alt_wall    = ndef->getId("mapgen_mossycobble");
+		dp.c_stair       = ndef->getId("mapgen_stair_cobble");
+
+		if (dp.c_river_water == CONTENT_IGNORE)
+			dp.c_river_water = ndef->getId("mapgen_water_source");
+
+		dp.diagonal_dirs       = false;
+		dp.only_in_ground      = true;
+		dp.holesize            = v3s16(1, 2, 1);
+		dp.corridor_len_min    = 1;
+		dp.corridor_len_max    = 13;
+		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.rooms_min           = 2;
+		dp.rooms_max           = 16;
+		dp.y_min               = -MAX_MAP_GENERATION_LIMIT;
+		dp.y_max               = MAX_MAP_GENERATION_LIMIT;
+		dp.notifytype          = GENNOTIFY_DUNGEON;
+
+		dp.np_density  = nparams_dungeon_density;
+		dp.np_alt_wall = nparams_dungeon_alt_wall;
+	}
+}
+
+
+void DungeonGen::generate(MMVManip *vm, u32 bseed, v3s16 nmin, v3s16 nmax)
+{
+	assert(vm);
+
+	//TimeTaker t("gen dungeons");
+	if (nmin.Y < dp.y_min || nmax.Y > dp.y_max)
+		return;
+
+	float nval_density = NoisePerlin3D(&dp.np_density, nmin.X, nmin.Y, nmin.Z, dp.seed);
+	if (nval_density < 1.0f)
+		return;
+
+	static const bool preserve_ignore = !g_settings->getBool("projecting_dungeons");
+
+	this->vm = vm;
+	this->blockseed = bseed;
+	random.seed(bseed + 2);
+
+	// Dungeon generator doesn't modify places which have this set
+	vm->clearFlag(VMANIP_FLAG_DUNGEON_INSIDE | VMANIP_FLAG_DUNGEON_PRESERVE);
+
+	if (dp.only_in_ground) {
+		// Set all air and water to be untouchable to make dungeons open to
+		// caves and open air. Optionally set ignore to be untouchable to
+		// prevent protruding dungeons.
+		for (s16 z = nmin.Z; z <= nmax.Z; z++) {
+			for (s16 y = nmin.Y; y <= nmax.Y; y++) {
+				u32 i = vm->m_area.index(nmin.X, y, z);
+				for (s16 x = nmin.X; x <= nmax.X; x++) {
+					content_t c = vm->m_data[i].getContent();
+					if (c == CONTENT_AIR || c == dp.c_water ||
+							(preserve_ignore && c == CONTENT_IGNORE) ||
+							c == dp.c_river_water)
+						vm->m_flags[i] |= VMANIP_FLAG_DUNGEON_PRESERVE;
+					i++;
+				}
+			}
+		}
+	}
+
+	// Add them
+	for (u32 i = 0; i < floor(nval_density); i++)
+		makeDungeon(v3s16(1, 1, 1) * MAP_BLOCKSIZE);
+
+	// Optionally convert some structure to alternative structure
+	if (dp.c_alt_wall == CONTENT_IGNORE)
+		return;
+
+	for (s16 z = nmin.Z; z <= nmax.Z; z++)
+	for (s16 y = nmin.Y; y <= nmax.Y; y++) {
+		u32 i = vm->m_area.index(nmin.X, y, z);
+		for (s16 x = nmin.X; x <= nmax.X; x++) {
+			if (vm->m_data[i].getContent() == dp.c_wall) {
+				if (NoisePerlin3D(&dp.np_alt_wall, x, y, z, blockseed) > 0.0f)
+					vm->m_data[i].setContent(dp.c_alt_wall);
+			}
+			i++;
+		}
+	}
+
+	//printf("== gen dungeons: %dms\n", t.stop());
+}
+
+
+void DungeonGen::makeDungeon(v3s16 start_padding)
+{
+	const v3s16 &areasize = vm->m_area.getExtent();
+	v3s16 roomsize;
+	v3s16 roomplace;
+
+	/*
+		Find place for first room.
+		There is a 1 in 4 chance of the first room being 'large',
+		all other rooms are not 'large'.
+	*/
+	bool fits = false;
+	for (u32 i = 0; i < 100 && !fits; i++) {
+		bool is_large_room = ((random.next() & 3) == 1);
+		if (is_large_room) {
+			roomsize.Z = random.range(
+				dp.room_size_large_min.Z, dp.room_size_large_max.Z);
+			roomsize.Y = random.range(
+				dp.room_size_large_min.Y, dp.room_size_large_max.Y);
+			roomsize.X = random.range(
+				dp.room_size_large_min.X, dp.room_size_large_max.X);
+		} else {
+			roomsize.Z = random.range(dp.room_size_min.Z, dp.room_size_max.Z);
+			roomsize.Y = random.range(dp.room_size_min.Y, dp.room_size_max.Y);
+			roomsize.X = random.range(dp.room_size_min.X, dp.room_size_max.X);
+		}
+
+		// start_padding is used to disallow starting the generation of
+		// a dungeon in a neighboring generation chunk
+		roomplace = vm->m_area.MinEdge + start_padding;
+		roomplace.Z += random.range(0, areasize.Z - roomsize.Z - start_padding.Z);
+		roomplace.Y += random.range(0, areasize.Y - roomsize.Y - start_padding.Y);
+		roomplace.X += random.range(0, areasize.X - roomsize.X - start_padding.X);
+
+		/*
+			Check that we're not putting the room to an unknown place,
+			otherwise it might end up floating in the air
+		*/
+		fits = true;
+		for (s16 z = 0; z < roomsize.Z; z++)
+		for (s16 y = 0; y < roomsize.Y; y++)
+		for (s16 x = 0; x < roomsize.X; x++) {
+			v3s16 p = roomplace + v3s16(x, y, z);
+			u32 vi = vm->m_area.index(p);
+			if ((vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE) ||
+					vm->m_data[vi].getContent() == CONTENT_IGNORE) {
+				fits = false;
+				break;
+			}
+		}
+	}
+	// No place found
+	if (!fits)
+		return;
+
+	/*
+		Stores the center position of the last room made, so that
+		a new corridor can be started from the last room instead of
+		the new room, if chosen so.
+	*/
+	v3s16 last_room_center = roomplace + v3s16(roomsize.X / 2, 1, roomsize.Z / 2);
+
+	u32 room_count = random.range(dp.rooms_min, dp.rooms_max);
+	for (u32 i = 0; i < room_count; i++) {
+		// Make a room to the determined place
+		makeRoom(roomsize, roomplace);
+
+		v3s16 room_center = roomplace + v3s16(roomsize.X / 2, 1, roomsize.Z / 2);
+		if (gennotify)
+			gennotify->addEvent(dp.notifytype, room_center);
+
+#ifdef DGEN_USE_TORCHES
+		// Place torch at room center (for testing)
+		vm->m_data[vm->m_area.index(room_center)] = MapNode(c_torch);
+#endif
+
+		// Quit if last room
+		if (i == room_count - 1)
+			break;
+
+		// Determine walker start position
+
+		bool start_in_last_room = (random.range(0, 2) != 0);
+
+		v3s16 walker_start_place;
+
+		if (start_in_last_room) {
+			walker_start_place = last_room_center;
+		} else {
+			walker_start_place = room_center;
+			// Store center of current room as the last one
+			last_room_center = room_center;
+		}
+
+		// Create walker and find a place for a door
+		v3s16 doorplace;
+		v3s16 doordir;
+
+		m_pos = walker_start_place;
+		if (!findPlaceForDoor(doorplace, doordir))
+			return;
+
+		if (random.range(0, 1) == 0)
+			// Make the door
+			makeDoor(doorplace, doordir);
+		else
+			// Don't actually make a door
+			doorplace -= doordir;
+
+		// Make a random corridor starting from the door
+		v3s16 corridor_end;
+		v3s16 corridor_end_dir;
+		makeCorridor(doorplace, doordir, corridor_end, corridor_end_dir);
+
+		// Find a place for a random sized room
+		roomsize.Z = random.range(dp.room_size_min.Z, dp.room_size_max.Z);
+		roomsize.Y = random.range(dp.room_size_min.Y, dp.room_size_max.Y);
+		roomsize.X = random.range(dp.room_size_min.X, dp.room_size_max.X);
+
+		m_pos = corridor_end;
+		m_dir = corridor_end_dir;
+		if (!findPlaceForRoomDoor(roomsize, doorplace, doordir, roomplace))
+			return;
+
+		if (random.range(0, 1) == 0)
+			// Make the door
+			makeDoor(doorplace, doordir);
+		else
+			// Don't actually make a door
+			roomplace -= doordir;
+
+	}
+}
+
+
+void DungeonGen::makeRoom(v3s16 roomsize, v3s16 roomplace)
+{
+	MapNode n_wall(dp.c_wall);
+	MapNode n_air(CONTENT_AIR);
+
+	// Make +-X walls
+	for (s16 z = 0; z < roomsize.Z; z++)
+	for (s16 y = 0; y < roomsize.Y; y++) {
+		{
+			v3s16 p = roomplace + v3s16(0, y, z);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+		{
+			v3s16 p = roomplace + v3s16(roomsize.X - 1, y, z);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+	}
+
+	// Make +-Z walls
+	for (s16 x = 0; x < roomsize.X; x++)
+	for (s16 y = 0; y < roomsize.Y; y++) {
+		{
+			v3s16 p = roomplace + v3s16(x, y, 0);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+		{
+			v3s16 p = roomplace + v3s16(x, y, roomsize.Z - 1);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+	}
+
+	// Make +-Y walls (floor and ceiling)
+	for (s16 z = 0; z < roomsize.Z; z++)
+	for (s16 x = 0; x < roomsize.X; x++) {
+		{
+			v3s16 p = roomplace + v3s16(x, 0, z);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+		{
+			v3s16 p = roomplace + v3s16(x,roomsize. Y - 1, z);
+			if (!vm->m_area.contains(p))
+				continue;
+			u32 vi = vm->m_area.index(p);
+			if (vm->m_flags[vi] & VMANIP_FLAG_DUNGEON_UNTOUCHABLE)
+				continue;
+			vm->m_data[vi] = n_wall;
+		}
+	}
+
+	// Fill with air
+	for (s16 z = 1; z < roomsize.Z - 1; z++)
+	for (s16 y = 1; y < roomsize.Y - 1; y++)
+	for (s16 x = 1; x < roomsize.X - 1; x++) {
+		v3s16 p = roomplace + v3s16(x, y, z);
+		if (!vm->m_area.contains(p))
+			continue;
+		u32 vi = vm->m_area.index(p);
+		vm->m_flags[vi] |= VMANIP_FLAG_DUNGEON_UNTOUCHABLE;
+		vm->m_data[vi] = n_air;
+	}
+}
+
+
+void DungeonGen::makeFill(v3s16 place, v3s16 size,
+	u8 avoid_flags, MapNode n, u8 or_flags)
+{
+	for (s16 z = 0; z < size.Z; z++)
+	for (s16 y = 0; y < size.Y; y++)
+	for (s16 x = 0; x < size.X; x++) {
+		v3s16 p = place + v3s16(x, y, z);
+		if (!vm->m_area.contains(p))
+			continue;
+		u32 vi = vm->m_area.index(p);
+		if (vm->m_flags[vi] & avoid_flags)
+			continue;
+		vm->m_flags[vi] |= or_flags;
+		vm->m_data[vi] = n;
+	}
+}
+
+
+void DungeonGen::makeHole(v3s16 place)
+{
+	makeFill(place, dp.holesize, 0, MapNode(CONTENT_AIR),
+		VMANIP_FLAG_DUNGEON_INSIDE);
+}
+
+
+void DungeonGen::makeDoor(v3s16 doorplace, v3s16 doordir)
+{
+	makeHole(doorplace);
+
+#ifdef DGEN_USE_TORCHES
+	// Place torch (for testing)
+	vm->m_data[vm->m_area.index(doorplace)] = MapNode(c_torch);
+#endif
+}
+
+
+void DungeonGen::makeCorridor(v3s16 doorplace, v3s16 doordir,
+	v3s16 &result_place, v3s16 &result_dir)
+{
+	makeHole(doorplace);
+	v3s16 p0 = doorplace;
+	v3s16 dir = doordir;
+	u32 length = random.range(dp.corridor_len_min, dp.corridor_len_max);
+	u32 partlength = random.range(dp.corridor_len_min, dp.corridor_len_max);
+	u32 partcount = 0;
+	s16 make_stairs = 0;
+
+	if (random.next() % 2 == 0 && partlength >= 3)
+		make_stairs = random.next() % 2 ? 1 : -1;
+
+	for (u32 i = 0; i < length; i++) {
+		v3s16 p = p0 + dir;
+		if (partcount != 0)
+			p.Y += make_stairs;
+
+		// Check segment of minimum size corridor is in voxelmanip
+		if (vm->m_area.contains(p) && vm->m_area.contains(p + v3s16(0, 1, 0))) {
+			if (make_stairs) {
+				makeFill(p + v3s16(-1, -1, -1),
+					dp.holesize + v3s16(2, 3, 2),
+					VMANIP_FLAG_DUNGEON_UNTOUCHABLE,
+					MapNode(dp.c_wall),
+					0);
+				makeHole(p);
+				makeHole(p - dir);
+
+				// TODO: fix stairs code so it works 100%
+				// (quite difficult)
+
+				// exclude stairs from the bottom step
+				// exclude stairs from diagonal steps
+				if (((dir.X ^ dir.Z) & 1) &&
+						(((make_stairs ==  1) && i != 0) ||
+						((make_stairs == -1) && i != length - 1))) {
+					// rotate face 180 deg if
+					// making stairs backwards
+					int facedir = dir_to_facedir(dir * make_stairs);
+					v3s16 ps = p;
+					u16 stair_width = (dir.Z != 0) ? dp.holesize.X : dp.holesize.Z;
+					// Stair width direction vector
+					v3s16 swv = (dir.Z != 0) ? v3s16(1, 0, 0) : v3s16(0, 0, 1);
+
+					for (u16 st = 0; st < stair_width; st++) {
+						u32 vi = vm->m_area.index(ps.X - dir.X, ps.Y - 1, ps.Z - dir.Z);
+						if (vm->m_area.contains(ps + v3s16(-dir.X, -1, -dir.Z)) &&
+								vm->m_data[vi].getContent() == dp.c_wall)
+							vm->m_data[vi] = MapNode(dp.c_stair, 0, facedir);
+
+						vi = vm->m_area.index(ps.X, ps.Y, ps.Z);
+						if (vm->m_area.contains(ps) &&
+								vm->m_data[vi].getContent() == dp.c_wall)
+							vm->m_data[vi] = MapNode(dp.c_stair, 0, facedir);
+
+						ps += swv;
+					}
+				}
+			} else {
+				makeFill(p + v3s16(-1, -1, -1),
+					dp.holesize + v3s16(2, 2, 2),
+					VMANIP_FLAG_DUNGEON_UNTOUCHABLE,
+					MapNode(dp.c_wall),
+					0);
+				makeHole(p);
+			}
+
+			p0 = p;
+		} else {
+			// Can't go here, turn away
+			dir = turn_xz(dir, random.range(0, 1));
+			make_stairs = -make_stairs;
+			partcount = 0;
+			partlength = random.range(1, length);
+			continue;
+		}
+
+		partcount++;
+		if (partcount >= partlength) {
+			partcount = 0;
+
+			dir = random_turn(random, dir);
+
+			partlength = random.range(1, length);
+
+			make_stairs = 0;
+			if (random.next() % 2 == 0 && partlength >= 3)
+				make_stairs = random.next() % 2 ? 1 : -1;
+		}
+	}
+	result_place = p0;
+	result_dir = dir;
+}
+
+
+bool DungeonGen::findPlaceForDoor(v3s16 &result_place, v3s16 &result_dir)
+{
+	for (u32 i = 0; i < 100; i++) {
+		v3s16 p = m_pos + m_dir;
+		v3s16 p1 = p + v3s16(0, 1, 0);
+		if (!vm->m_area.contains(p) || !vm->m_area.contains(p1) || i % 4 == 0) {
+			randomizeDir();
+			continue;
+		}
+		if (vm->getNodeNoExNoEmerge(p).getContent() == dp.c_wall &&
+				vm->getNodeNoExNoEmerge(p1).getContent() == dp.c_wall) {
+			// Found wall, this is a good place!
+			result_place = p;
+			result_dir = m_dir;
+			// Randomize next direction
+			randomizeDir();
+			return true;
+		}
+		/*
+			Determine where to move next
+		*/
+		// Jump one up if the actual space is there
+		if (vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 0, 0)).getContent() == dp.c_wall &&
+				vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 1, 0)).getContent() == CONTENT_AIR &&
+				vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 2, 0)).getContent() == CONTENT_AIR)
+			p += v3s16(0,1,0);
+		// Jump one down if the actual space is there
+		if (vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 1, 0)).getContent() == dp.c_wall &&
+				vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 0, 0)).getContent() == CONTENT_AIR &&
+				vm->getNodeNoExNoEmerge(p +
+				v3s16(0, -1, 0)).getContent() == CONTENT_AIR)
+			p += v3s16(0, -1, 0);
+		// Check if walking is now possible
+		if (vm->getNodeNoExNoEmerge(p).getContent() != CONTENT_AIR ||
+				vm->getNodeNoExNoEmerge(p +
+				v3s16(0, 1, 0)).getContent() != CONTENT_AIR) {
+			// Cannot continue walking here
+			randomizeDir();
+			continue;
+		}
+		// Move there
+		m_pos = p;
+	}
+	return false;
+}
+
+
+bool DungeonGen::findPlaceForRoomDoor(v3s16 roomsize, v3s16 &result_doorplace,
+	v3s16 &result_doordir, v3s16 &result_roomplace)
+{
+	for (s16 trycount = 0; trycount < 30; trycount++) {
+		v3s16 doorplace;
+		v3s16 doordir;
+		bool r = findPlaceForDoor(doorplace, doordir);
+		if (!r)
+			continue;
+		v3s16 roomplace;
+		// X east, Z north, Y up
+		if (doordir == v3s16(1, 0, 0)) // X+
+			roomplace = doorplace +
+				v3s16(0, -1, random.range(-roomsize.Z + 2, -2));
+		if (doordir == v3s16(-1, 0, 0)) // X-
+			roomplace = doorplace +
+				v3s16(-roomsize.X + 1, -1, random.range(-roomsize.Z + 2, -2));
+		if (doordir == v3s16(0, 0, 1)) // Z+
+			roomplace = doorplace +
+				v3s16(random.range(-roomsize.X + 2, -2), -1, 0);
+		if (doordir == v3s16(0, 0, -1)) // Z-
+			roomplace = doorplace +
+				v3s16(random.range(-roomsize.X + 2, -2), -1, -roomsize.Z + 1);
+
+		// Check fit
+		bool fits = true;
+		for (s16 z = 1; z < roomsize.Z - 1; z++)
+		for (s16 y = 1; y < roomsize.Y - 1; y++)
+		for (s16 x = 1; x < roomsize.X - 1; x++) {
+			v3s16 p = roomplace + v3s16(x, y, z);
+			if (!vm->m_area.contains(p)) {
+				fits = false;
+				break;
+			}
+			if (vm->m_flags[vm->m_area.index(p)] & VMANIP_FLAG_DUNGEON_INSIDE) {
+				fits = false;
+				break;
+			}
+		}
+		if (!fits) {
+			// Find new place
+			continue;
+		}
+		result_doorplace = doorplace;
+		result_doordir   = doordir;
+		result_roomplace = roomplace;
+		return true;
+	}
+	return false;
+}
+
+
+v3s16 rand_ortho_dir(PseudoRandom &random, bool diagonal_dirs)
+{
+	// Make diagonal directions somewhat rare
+	if (diagonal_dirs && (random.next() % 4 == 0)) {
+		v3s16 dir;
+		int trycount = 0;
+
+		do {
+			trycount++;
+
+			dir.Z = random.next() % 3 - 1;
+			dir.Y = 0;
+			dir.X = random.next() % 3 - 1;
+		} while ((dir.X == 0 || dir.Z == 0) && trycount < 10);
+
+		return dir;
+	}
+
+	if (random.next() % 2 == 0)
+		return random.next() % 2 ? v3s16(-1, 0, 0) : v3s16(1, 0, 0);
+
+	return random.next() % 2 ? v3s16(0, 0, -1) : v3s16(0, 0, 1);
+}
+
+
+v3s16 turn_xz(v3s16 olddir, int t)
+{
+	v3s16 dir;
+	if (t == 0) {
+		// Turn right
+		dir.X = olddir.Z;
+		dir.Z = -olddir.X;
+		dir.Y = olddir.Y;
+	} else {
+		// Turn left
+		dir.X = -olddir.Z;
+		dir.Z = olddir.X;
+		dir.Y = olddir.Y;
+	}
+	return dir;
+}
+
+
+v3s16 random_turn(PseudoRandom &random, v3s16 olddir)
+{
+	int turn = random.range(0, 2);
+	v3s16 dir;
+	if (turn == 0)
+		// Go straight
+		dir = olddir;
+	else if (turn == 1)
+		// Turn right
+		dir = turn_xz(olddir, 0);
+	else
+		// Turn left
+		dir = turn_xz(olddir, 1);
+	return dir;
+}
+
+
+int dir_to_facedir(v3s16 d)
+{
+	if (abs(d.X) > abs(d.Z))
+		return d.X < 0 ? 3 : 1;
+
+	return d.Z < 0 ? 2 : 0;
+}