Add abandoned mine shafts

mods/MAPGEN/tsm_railcorridors/README.md

@@ -0,0 +1,16 @@
+# Railway corridors for Treasurer [`tsm_railcorridors`]
+
+* Current version 0.11.0
+
+Minetest mod for adding underground corridors with rails and wood constructions with
+a few treasure chests now and then. Optional Treasurer support is available for adding
+treasures from various mods.
+
+Use the advanced settings to finetune the railway corridors.
+
+* Forum thread: https://forum.minetest.net/viewtopic.php?t=10339
+* License: MIT License.
+
+## Info for modders
+Want to include this mod in a subgame, but you hate the dependencies?
+You can edit the node names in gameconfig.lua to fit your needs. :-)

mods/MAPGEN/tsm_railcorridors/depends.txt

@@ -0,0 +1,6 @@
+mcl_init
+mcl_util
+mcl_core
+mcl_tnt
+mcl_farming
+treasurer?

mods/MAPGEN/tsm_railcorridors/description.txt

@@ -0,0 +1 @@
+Adds simple underground mines with railways and occasional treasure chests.

mods/MAPGEN/tsm_railcorridors/gameconfig.lua

@@ -0,0 +1,53 @@
+-- This file stores the various node types. This makes it easier to plug this mod into subgames
+-- in which you need to change the node names.
+
+-- Adapted for MineClone 2!
+
+-- Node names (Don't use aliases!)
+tsm_railcorridors.nodes = {
+	dirt = "mcl_core:dirt",
+	chest = "mcl_chests:chest",
+	rail = "mcl_minecarts:rail",
+	torch_floor = "mcl_torches:torch",
+	torch_wall = "mcl_torches:torch_wall",
+
+	--[[ Wood types for the corridors. Corridors are made out of full wood blocks
+	and posts. For each corridor system, a random wood type is chosen with the chance
+	specified in per mille. ]]
+	corridor_woods = {
+		{ wood = "mcl_core:wood", post = "mcl_fences:fence", chance = 900},
+		{ wood = "mcl_core:darkwood", post = "mcl_fences:dark_oak_fence", chance = 100},
+	},
+}
+
+-- Fallback function. Returns a random treasure. This function is called for chests
+-- only if the Treasurer mod is not found.
+-- pr: A PseudoRandom object
+function tsm_railcorridors.get_default_treasure(pr)
+	if pr:next(0,1000) < 30 then
+		return "mcl_farming:bread "..pr:next(1,3)
+	elseif pr:next(0,1000) < 50 then
+		if pr:next(0,1000) < 500 then
+			return "mcl_farming:pumpkin_seeds "..pr:next(1,5)
+		else
+			return "mcl_farming:melon_seeds "..pr:next(1,5)
+		end
+	elseif pr:next(0,1000) < 5 then
+		return "mcl_tools:pick_iron"
+	elseif pr:next(0,1000) < 3 then
+		local r = pr:next(0, 1000)
+		if r < 400 then
+			return "mcl_core:iron_ingot "..pr:next(1,5)
+		elseif r < 800 then
+			return "mcl_core:gold_ingot "..pr:next(1,3)
+		else
+			return "mcl_core:diamond "..pr:next(1,2)
+		end
+	elseif pr:next(0,1000) < 30 then
+		return "mcl_torches:torch "..pr:next(1,16)
+	elseif pr:next(0,1000) < 20 then
+		return "mcl_core:coal_lump "..pr:next(3,8)
+	else
+		return ""
+	end
+end

mods/MAPGEN/tsm_railcorridors/init.lua

@@ -0,0 +1,612 @@
+tsm_railcorridors = {}
+
+-- Load node names
+dofile(minetest.get_modpath(minetest.get_current_modname()).."/gameconfig.lua")
+
+-- Settings
+local setting
+
+-- Probability function
+-- TODO: Check if this is correct
+local P = function (float)
+	return math.floor(32767 * float)
+end
+
+-- Wahrscheinlichkeit für jeden Chunk, solche Gänge mit Schienen zu bekommen
+-- Probability for every newly generated chunk to get corridors
+local probability_railcaves_in_chunk = P(0.33333)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_railcaves_in_chunk"))
+if setting then
+	probability_railcaves_in_chunk = P(setting)
+end
+
+-- Innerhalb welcher Parameter soll sich die Pfadlänge bewegen? (Forks heben den Maximalwert auf)
+-- Minimal and maximal value of path length (forks don't look up this value)
+local way_min = 4;
+local way_max = 7;
+setting = tonumber(minetest.setting_get("tsm_railcorridors_way_min"))
+if setting then
+	way_min = setting
+end
+setting = tonumber(minetest.setting_get("tsm_railcorridors_way_max"))
+if setting then
+	way_max = setting
+end
+
+-- Wahrsch. für jeden geraden Teil eines Korridors, Fackeln zu bekommen
+-- Probability for every horizontal part of a corridor to be with torches
+local probability_torches_in_segment = P(0.5)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_torches_in_segment"))
+if setting then
+	probability_torches_in_segment = P(setting)
+end
+
+-- Wahrsch. für jeden Teil eines Korridors, nach oben oder nach unten zu gehen
+-- Probability for every part of a corridor to go up or down
+local probability_up_or_down = P(0.2)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_up_or_down"))
+if setting then
+	probability_up_or_down = P(setting)
+end
+
+-- Wahrscheinlichkeit für jeden Teil eines Korridors, sich zu verzweigen – vorsicht, wenn fast jeder Gang sich verzweigt, kann der Algorithums unlösbar werden und MT hängt sich auf
+-- Probability for every part of a corridor to fork – caution, too high values may cause MT to hang on.
+local probability_fork = P(0.04)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_fork"))
+if setting then
+	probability_fork = P(setting)
+end
+
+-- Wahrscheinlichkeit für jeden geraden Teil eines Korridors eine Kiste zu enthalten
+-- Probability for every part of a corridor to contain a chest
+local probability_chest = P(0.05)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_chest"))
+if setting then
+	probability_chest = P(setting)
+end
+
+-- Probability for a rail corridor system to be damaged
+local probability_damage = P(0.90)
+setting = tonumber(minetest.setting_get("tsm_railcorridors_probability_damage"))
+if setting then
+	probability_damage = P(setting)
+end
+
+-- Max. and min. heights between rail corridors are generated
+local height_min = mcl_vars.mg_bedrock_overworld_max + 5 -- FIXME: Above lava layers
+local height_max = mcl_util.layer_to_y(60)
+
+-- Chaos Mode: If enabled, rail corridors don't stop generating when hitting obstacles
+local chaos_mode = minetest.setting_getbool("tsm_railcorridors_chaos") or false
+
+-- Parameter Ende
+
+-- random generator
+local pr
+local pr_initialized = false
+
+local function InitRandomizer(seed)
+	pr = PseudoRandom(seed)
+	pr_initialized = true
+end
+
+
+-- Checks if the mapgen is allowed to carve through this structure and only sets
+-- the node if it is allowed. Does never build in liquids.
+-- If check_above is true, don't build if the node above is attached (e.g. rail)
+-- or a liquid.
+local function SetNodeIfCanBuild(pos, node, check_above)
+	if check_above then
+		local abovename = minetest.get_node({x=pos.x,y=pos.y+1,z=pos.z}).name
+		local abovedef = minetest.registered_nodes[abovename]
+		if abovename == "unknown" or abovename == "ignore" or (abovedef.groups and abovedef.groups.attached_node) or abovedef.liquidtype ~= "none" then
+			return false
+		end
+	end
+	local name = minetest.get_node(pos).name
+	local def = minetest.registered_nodes[name]
+	if name ~= "unknown" and name ~= "ignore" and def.is_ground_content and def.liquidtype == "none" then
+		minetest.set_node(pos, node)
+		return true
+	else
+		return false
+	end
+end
+
+-- Tries to place a rail, taking the damage chance into account
+local function PlaceRail(pos, damage_chance)
+	if damage_chance ~= nil and damage_chance > 0 then
+		local x = pr:next(0,100)
+		if x <= damage_chance then
+			return false
+		end
+	end
+	return SetNodeIfCanBuild(pos, {name=tsm_railcorridors.nodes.rail})
+end
+
+-- Returns true if the node as point can be considered “ground”, that is, a solid material
+-- in which mine shafts can be built into, e.g. stone, but not air or water
+local function IsGround(pos)
+	local nodename = minetest.get_node(pos).name
+	local nodedef = minetest.registered_nodes[nodename]
+	return nodename ~= "unknown" and nodename ~= "ignore" and nodedef.is_ground_content and nodedef.walkable and nodedef.liquidtype == "none"
+end
+
+-- Returns true if rails are allowed to be placed on top of this node
+local function IsRailSurface(pos)
+	local nodename = minetest.get_node(pos).name
+	local nodedef = minetest.registered_nodes[nodename]
+	return nodename ~= "unknown" and nodename ~= "ignore" and nodedef.walkable and (nodedef.node_box == nil or nodedef.node_box.type == "regular")
+end
+
+-- Checks if the node is empty space which requires to be filled by a platform
+local function NeedsPlatform(pos)
+	local node = minetest.get_node({x=pos.x,y=pos.y-1,z=pos.z})
+	local node2 = minetest.get_node({x=pos.x,y=pos.y-2,z=pos.z})
+	local nodedef = minetest.registered_nodes[node.name]
+	return node.name ~= "ignore" and node.name ~= "unknown" and nodedef.is_ground_content and ((nodedef.walkable == false and node2.name ~= tsm_railcorridors.nodes.dirt) or (nodedef.groups and nodedef.groups.falling_node))
+end
+
+-- Create a cube filled with the specified nodes
+-- Specialties:
+-- * Avoids floating rails for non-solid nodes like air
+-- Returns true if all nodes could be set
+-- Returns false if setting one or more nodes failed
+local function Cube(p, radius, node)
+	local y_top = p.y+radius
+	local nodedef = minetest.registered_nodes[node.name]
+	local solid = nodedef.walkable and (nodedef.node_box == nil or nodedef.node_box.type == "regular") and nodedef.liquidtype == "none"
+	-- Check if all the nodes could be set
+	local built_all = true
+	for zi = p.z-radius, p.z+radius do
+		for yi = y_top, p.y-radius, -1 do
+			for xi = p.x-radius, p.x+radius do
+				local ok = false
+				if not solid and yi == y_top then
+					local topdef = minetest.registered_nodes[minetest.get_node({x=xi,y=yi+1,z=zi}).name]
+					if not (topdef.groups and topdef.groups.attached_node) and topdef.liquidtype == "none" then
+						ok = true
+					end
+				else
+					ok = true
+				end
+				local built = false
+				if ok then
+					built = SetNodeIfCanBuild({x=xi,y=yi,z=zi}, node)
+				end
+				if not built then
+					built_all = false
+				end
+			end
+		end
+	end
+	return built_all
+end
+
+local function Platform(p, radius, node)
+	for zi = p.z-radius, p.z+radius do
+		for xi = p.x-radius, p.x+radius do
+			local np = NeedsPlatform({x=xi,y=p.y,z=zi})
+			if np then
+				minetest.set_node({x=xi,y=p.y-1,z=zi}, node)
+			end
+		end
+	end
+end
+
+
+-- Random chest items
+-- Zufälliger Kisteninhalt
+local function rci()
+	if(minetest.get_modpath("treasurer") ~= nil) then
+		local treasures
+		if pr:next(0,100) < 3 then
+			treasures = treasurer.select_random_treasures(1,2,4)
+		elseif pr:next(0,100) < 5 then
+			if pr:next(0,100) < 50 then
+				treasures = treasurer.select_random_treasures(1,2,4,"seed")
+			else
+				treasures = treasurer.select_random_treasures(1,2,4,"seed")
+			end
+		elseif pr:next(0,1000) < 5 then
+			if minetest.get_modpath("tnt") then
+				return "tnt:tnt "..pr:next(1,3)
+			end
+		elseif pr:next(0,1000) < 3 then
+			if pr:next(0,1000) < 800 then
+				treasures = treasurer.select_random_treasures(1,3,6,"mineral")
+			else
+				treasures = treasurer.select_random_treasures(1,5,9,"mineral")
+			end
+		end
+
+		if(treasures ~= nil) then
+			if(#treasures>=1) then
+				return treasures[1]:get_name()
+			else
+				return ""
+			end
+		else
+			return ""
+		end
+	else
+		return tsm_railcorridors.get_default_treasure(pr)
+	end
+end
+-- chests
+local function Place_Chest(pos, param2)
+	if SetNodeIfCanBuild(pos, {name=tsm_railcorridors.nodes.chest, param2=param2}) then
+		local meta = minetest.get_meta(pos)
+		local inv = meta:get_inventory()
+		for i=1, inv:get_size("main") do
+			inv:set_stack("main", i, ItemStack(rci()))
+		end
+	end
+end
+	
+local function WoodBulk(pos, wood)
+	SetNodeIfCanBuild({x=pos.x+1, y=pos.y, z=pos.z+1}, {name=wood})
+	SetNodeIfCanBuild({x=pos.x-1, y=pos.y, z=pos.z+1}, {name=wood})
+	SetNodeIfCanBuild({x=pos.x+1, y=pos.y, z=pos.z-1}, {name=wood})
+	SetNodeIfCanBuild({x=pos.x-1, y=pos.y, z=pos.z-1}, {name=wood})
+end
+
+-- Gänge mit Schienen
+-- Corridors with rails
+
+-- Returns <success>, <segments>
+-- success: true if corridor could be placed entirely
+-- segments: Number of segments successfully placed
+local function corridor_part(start_point, segment_vector, segment_count, wood, post, is_final)
+	local p = {x=start_point.x, y=start_point.y, z=start_point.z}
+	local torches = pr:next() < probability_torches_in_segment
+	local dir = {0, 0}
+	local torchdir = {1, 1}
+	local node_wood = {name=wood}
+	local node_fence = {name=post}
+	if segment_vector.x == 0 and segment_vector.z ~= 0 then
+		dir = {1, 0}
+		torchdir = {5, 4}
+	elseif segment_vector.x ~= 0 and segment_vector.z == 0 then
+		dir = {0, 1}
+		torchdir = {3, 2}
+	end
+	for segmentindex = 0, segment_count-1 do
+		local dug = Cube(p, 1, {name="air"})
+		if not chaos_mode and segmentindex > 0 and not dug then return false, segmentindex end
+		-- Add wooden platform, if neccessary. To avoid floating rails
+		if segment_vector.y == 0 then
+			Platform({x=p.x, y=p.y-1, z=p.z}, 1, node_wood)
+		end
+		-- Diese komischen Holz-Konstruktionen
+		-- These strange wood structs
+		if segmentindex % 2 == 1 and segment_vector.y == 0 then
+			local calc = {
+				p.x+dir[1], p.z+dir[2], -- X and Z, added by direction
+				p.x-dir[1], p.z-dir[2], -- subtracted
+				p.x+dir[2], p.z+dir[1], -- orthogonal
+				p.x-dir[2], p.z-dir[1], -- orthogonal, the other way
+			}
+			--[[ Shape:
+				WWW
+				P.P
+				PrP
+				pfp
+			W = wood
+			P = post (above floor level)
+			p = post (in floor level, only placed if no floor)
+			
+			From previous generation (for reference):
+			f = floor
+			r = rail
+			. = air
+			]]
+
+			-- Don't place those wood structs below open air
+			if not (minetest.get_node({x=calc[1], y=p.y+2, z=calc[2]}).name == "air" and
+				minetest.get_node({x=calc[3], y=p.y+2, z=calc[4]}).name == "air" and
+				minetest.get_node({x=p.x, y=p.y+2, z=p.z}).name == "air") then
+
+				-- Left post and planks
+				local left_ok = true
+				left_ok = SetNodeIfCanBuild({x=calc[1], y=p.y-1, z=calc[2]}, node_fence)
+				if left_ok then left_ok = SetNodeIfCanBuild({x=calc[1], y=p.y  , z=calc[2]}, node_fence) end
+				if left_ok then left_ok = SetNodeIfCanBuild({x=calc[1], y=p.y+1, z=calc[2]}, node_wood) end
+
+				-- Right post and planks
+				local right_ok = true
+				right_ok = SetNodeIfCanBuild({x=calc[3], y=p.y-1, z=calc[4]}, node_fence)
+				if right_ok then right_ok = SetNodeIfCanBuild({x=calc[3], y=p.y  , z=calc[4]}, node_fence) end
+				if right_ok then right_ok = SetNodeIfCanBuild({x=calc[3], y=p.y+1, z=calc[4]}, node_wood) end
+
+				-- Middle planks
+				local top_planks_ok = false
+				if left_ok and right_ok then top_planks_ok = SetNodeIfCanBuild({x=p.x, y=p.y+1, z=p.z}, node_wood) end
+
+				if minetest.get_node({x=p.x,y=p.y-2,z=p.z}).name=="air" then
+					if left_ok then SetNodeIfCanBuild({x=calc[1], y=p.y-2, z=calc[2]}, node_fence) end
+					if right_ok then SetNodeIfCanBuild({x=calc[3], y=p.y-2, z=calc[4]}, node_fence) end
+				end
+				-- Torches on the middle planks
+				if torches and top_planks_ok then
+					-- Place torches at horizontal sides
+					SetNodeIfCanBuild({x=calc[5], y=p.y+1, z=calc[6]}, {name=tsm_railcorridors.nodes.torch_wall, param2=torchdir[1]}, true)
+					SetNodeIfCanBuild({x=calc[7], y=p.y+1, z=calc[8]}, {name=tsm_railcorridors.nodes.torch_wall, param2=torchdir[2]}, true)
+				end
+			elseif torches then
+				-- Try to build torches instead of the wood structs
+				local node = {name=tsm_railcorridors.nodes.torch_floor, param2=minetest.dir_to_wallmounted({x=0,y=-1,z=0})}
+
+				-- Try two different height levels
+				local pos1 = {x=calc[1], y=p.y-2, z=calc[2]}
+				local pos2 = {x=calc[3], y=p.y-2, z=calc[4]}
+				local nodedef1 = minetest.registered_nodes[minetest.get_node(pos1).name]
+				local nodedef2 = minetest.registered_nodes[minetest.get_node(pos2).name]
+
+				if nodedef1.walkable then
+					pos1.y = pos1.y + 1
+				end
+				SetNodeIfCanBuild(pos1, node, true)
+
+				if nodedef2.walkable then
+					pos2.y = pos2.y + 1
+				end
+				SetNodeIfCanBuild(pos2, node, true)
+
+			end
+		end
+		
+		-- nächster Punkt durch Vektoraddition
+		-- next way point
+		p = vector.add(p, segment_vector)
+	end
+
+	-- End of the corridor; create the final piece
+	if is_final then
+		local dug = Cube(p, 1, {name="air"})
+		if not chaos_mode and not dug then return false, segment_count end
+		Platform({x=p.x, y=p.y-1, z=p.z}, 1, node_wood)
+	end
+	return true, segment_count
+end
+
+local function corridor_func(waypoint, coord, sign, up_or_down, up, wood, post, is_final, up_or_down_next, damage)
+	local segamount = 3
+	if up_or_down then
+		segamount = 1
+	end
+	if sign then
+		segamount = 0-segamount
+	end
+	local vek = {x=0,y=0,z=0};
+	local start = table.copy(waypoint)
+	if coord == "x" then
+		vek.x=segamount
+		if up_or_down and up == false then
+			start.x=start.x+segamount
+		end
+	elseif coord == "z" then
+		vek.z=segamount
+		if up_or_down and up == false then
+			start.z=start.z+segamount
+		end
+	end
+	if up_or_down then
+		if up then
+			vek.y = 1
+		else
+			vek.y = -1
+		end
+	end
+	local segcount = pr:next(4,6)
+	if up_or_down and up == false then
+		Cube(waypoint, 1, {name="air"})
+	end
+	local corridor_dug, corridor_segments_dug = corridor_part(start, vek, segcount, wood, post, is_final)
+	local corridor_vek = {x=vek.x*segcount, y=vek.y*segcount, z=vek.z*segcount}
+
+	-- nachträglich Schienen legen
+	-- after this: rails
+	segamount = 1
+	if sign then
+		segamount = 0-segamount
+	end
+	if coord == "x" then
+		vek.x=segamount
+	elseif coord == "z" then
+		vek.z=segamount
+	end
+	if up_or_down then
+		if up then
+			vek.y = 1
+		else
+			vek.y = -1
+		end
+	end
+	local chestplace = -1
+	if corridor_dug and not up_or_down and pr:next() < probability_chest then
+		chestplace = pr:next(1,segcount+1)
+	end
+	local railsegcount
+	if not chaos_mode and not corridor_dug then
+		railsegcount = corridor_segments_dug * 3
+	elseif not up_or_down then
+		railsegcount = segcount * 3
+	else
+		railsegcount = segcount
+	end
+	for i=1,railsegcount do
+		local p = {x=waypoint.x+vek.x*i, y=waypoint.y+vek.y*i-1, z=waypoint.z+vek.z*i}
+		if (minetest.get_node({x=p.x,y=p.y-1,z=p.z}).name=="air" and minetest.get_node({x=p.x,y=p.y-3,z=p.z}).name~=tsm_railcorridors.nodes.rail) then
+			p.y = p.y - 1;
+			if i == chestplace then
+				chestplace = chestplace + 1
+			end
+		end
+		if IsRailSurface({x=p.x,y=p.y-1,z=p.z}) then
+			PlaceRail(p, damage)
+		end
+		if i == chestplace then
+			if minetest.get_node({x=p.x+vek.z,y=p.y-1,z=p.z-vek.x}).name == post then
+				chestplace = chestplace + 1
+			else
+				Place_Chest({x=p.x+vek.z,y=p.y,z=p.z-vek.x}, minetest.dir_to_facedir(vek))
+			end
+		end
+	end
+	
+	local offset = table.copy(corridor_vek)
+	local final_point = vector.add(waypoint, offset)
+	if up_or_down then
+		if up then
+			offset.y = offset.y - 1
+			final_point = vector.add(waypoint, offset)
+		else
+			offset[coord] = offset[coord] + segamount
+			final_point = vector.add(waypoint, offset)
+			if IsRailSurface({x=final_point.x,y=final_point.y-2,z=final_point.z}) then
+				PlaceRail({x=final_point.x,y=final_point.y-1,z=final_point.z}, damage)
+			end
+		end
+	end
+	if not corridor_dug then
+		return false
+	else
+		return final_point
+	end
+end
+
+local function start_corridor(waypoint, coord, sign, length, psra, wood, post, damage)
+	local wp = waypoint
+	local c = coord
+	local s = sign
+	local ud = false -- up or down
+	local udn = false -- up or down is next
+	local up
+	for i=1,length do
+		local needs_platform
+		-- Up or down?
+		if udn then
+			needs_platform = NeedsPlatform(wp)
+			if needs_platform then
+				ud = false
+			end
+			ud = true
+			-- Force direction near the height limits
+			if wp.y >= height_max - 12 then
+				up = false
+			elseif wp.y <= height_min + 12 then
+				up = true
+			else
+				-- Chose random direction in between
+				up = pr:next(0, 2) < 1
+			end
+		else
+			ud = false
+		end
+		-- Update up/down next
+		if pr:next() < probability_up_or_down and i~=1 and not udn and not needs_platform then
+			udn = i < length
+		elseif udn and not needs_platform then
+			udn = false
+		end
+		-- Make corridor / Korridor graben
+		wp = corridor_func(wp,c,s, ud, up, wood, post, i == length, udn, damage)
+		if wp == false then return end
+		-- Verzweigung?
+		-- Fork?
+		if pr:next() < probability_fork then
+			local p = {x=wp.x, y=wp.y, z=wp.z}
+			start_corridor(wp, c, s, pr:next(way_min,way_max), psra, wood, post, damage)
+			if c == "x" then c="z" else c="x" end
+			start_corridor(wp, c, s, pr:next(way_min,way_max), psra, wood, post, damage)
+			start_corridor(wp, c, not s, pr:next(way_min,way_max), psra, wood, post, damage)
+			WoodBulk({x=p.x, y=p.y-1, z=p.z}, wood)
+			WoodBulk({x=p.x, y=p.y,   z=p.z}, wood)
+			WoodBulk({x=p.x, y=p.y+1, z=p.z}, wood)
+			WoodBulk({x=p.x, y=p.y+2, z=p.z}, wood)
+			return
+		end
+		-- coord und sign verändern
+		-- randomly change sign and coord
+		if c=="x" then
+			c="z"
+		elseif c=="z" then
+			c="x"
+	 	end;
+		s = pr:next(0, 2) < 1
+	end
+end
+
+local function place_corridors(main_cave_coords, psra)
+	--[[ ALWAYS start building in the ground. Prevents corridors starting
+	in mid-air or in liquids. ]]
+	if not IsGround(main_cave_coords) then
+		return
+	end
+
+	-- Determine if this corridor system is “damaged” (some rails removed) and to which extent
+	local damage = 0
+	if pr:next() > probability_damage then
+		damage = pr:next(10, 50)
+	end
+	--[[ Starter cube: A big hollow dirt cube from which the corridors will extend.
+	Corridor generation starts here. ]]
+	if pr:next(0, 100) < 50 then
+		Cube(main_cave_coords, 4, {name=tsm_railcorridors.nodes.dirt})
+		Cube(main_cave_coords, 3, {name="air"})
+		PlaceRail({x=main_cave_coords.x, y=main_cave_coords.y-3, z=main_cave_coords.z}, damage)
+		main_cave_coords.y =main_cave_coords.y - 1
+	else
+		Cube(main_cave_coords, 3, {name=tsm_railcorridors.nodes.dirt})
+		Cube(main_cave_coords, 2, {name="air"})
+		PlaceRail({x=main_cave_coords.x, y=main_cave_coords.y-2, z=main_cave_coords.z}, damage)
+	end
+	local xs = pr:next(0, 2) < 1
+	local zs = pr:next(0, 2) < 1;
+
+	-- Select random wood type (found in gameconfig.lua)
+	local rnd = pr:next(1,1000)
+
+	local woodtype = 1
+	local accumulated_chance = 0
+	for w=1, #tsm_railcorridors.nodes.corridor_woods do
+		local woodtable = tsm_railcorridors.nodes.corridor_woods[w]
+		accumulated_chance = accumulated_chance + woodtable.chance
+		if accumulated_chance > 1000 then
+			minetest.log("warning", "[tsm_railcorridors] Warning: Wood chances add up to over 100%!")
+			break
+		end
+		if rnd <= accumulated_chance then
+			woodtype = w
+			break
+		end
+	end
+	local wood = tsm_railcorridors.nodes.corridor_woods[woodtype].wood
+	local post = tsm_railcorridors.nodes.corridor_woods[woodtype].post
+	start_corridor(main_cave_coords, "x", xs, pr:next(way_min,way_max), psra, wood, post, damage)
+	start_corridor(main_cave_coords, "z", zs, pr:next(way_min,way_max), psra, wood, post, damage)
+	-- Auch mal die andere Richtung?
+	-- Try the other direction?
+	if pr:next(0, 100) < 70 then
+		start_corridor(main_cave_coords, "x", not xs, pr:next(way_min,way_max), psra, wood, post, damage)
+	end
+	if pr:next(0, 100) < 70 then
+		start_corridor(main_cave_coords, "z", not zs, pr:next(way_min,way_max), psra, wood, post, damage)
+	end
+end
+
+minetest.register_on_generated(function(minp, maxp, blockseed)
+	InitRandomizer(blockseed)
+	if minp.y < height_max and maxp.y > height_min and pr:next() < probability_railcaves_in_chunk then
+		-- Get semi-random height in chunk
+
+		local buffer = 5
+		local y = pr:next(minp.y + buffer, maxp.y - buffer)
+		y = math.floor(math.max(height_min, math.min(height_max, y)))
+		local p = {x=minp.x+(maxp.x-minp.x)/2, y=y, z=minp.z+(maxp.z-minp.z)/2}
+		-- Haupthöhle und alle weiteren
+		-- Corridors; starting with main cave out of dirt
+		place_corridors(p, pr)
+	end
+end)

mods/MAPGEN/tsm_railcorridors/mod.conf

@@ -0,0 +1 @@
+name = tsm_railcorridors

mods/MAPGEN/tsm_railcorridors/settingtypes.txt

@@ -0,0 +1,30 @@
+#Probability (0.0 to 1.0) for every newly generated chunk to get rail corridors.
+tsm_railcorridors_probability_railcaves_in_chunk (Rail corridor probability) float 0.33333 0.0 1.0
+
+#Minimum rail corridor path length (excludes forks).
+tsm_railcorridors_way_min (Minimum rail corridor length) int 4 1
+
+#Maximum rail corridor path length (excludes forks).
+tsm_railcorridors_way_max (Maximum rail corridor length) int 7 1
+
+#Probability (0.0 to 1.0) for every horizontal part of a rail corridor to have torches.
+tsm_railcorridors_probability_torches_in_segment (Torch probability) float 0.5 0.0 1.0
+
+#Probability (0.0 to 1.0) for every part of a rail corridor to go up or down.
+tsm_railcorridors_probability_up_or_down (Stairway probability) float 0.2 0.0 1.0
+
+#Probability (0.0 to 1.0) for every part of a rail corridor to fork.
+#Caution! Too high values may cause Minetest to hang.
+tsm_railcorridors_probability_fork (Fork probability) float 0.04 0.0 1.0
+
+#Probability (0.0 to 1.0) for every part of a rail corridor to contain a treasure chest.
+tsm_railcorridors_probability_chest (Chest probability) float 0.05 0.0 1.0
+
+#Probability (0.0 to 1.0) for a rail corridor system to have damaged/incomplete railways
+tsm_railcorridors_probability_damage (Damaged railway probability) float 0.90 0.0 1.0
+
+#If enabled, rail corridors continue to generate through obstacles such
+#as other rail corridors (without destroying them, mostly). This may lead
+#to pretty chaotic rail corridors, but they are also more free to spread.
+#If disabled, rail corridors spread in a orderly fashion.
+tsm_railcorridors_chaos (Chaos Mode) bool false