From 2ff8f5fd4649cff554cc6afab3d92ac7efedb809 Mon Sep 17 00:00:00 2001
From: orwell96 <orwell@bleipb.de>
Date: Wed, 19 Dec 2018 17:16:13 +0100
Subject: Initial version

---
 helpers.lua    | 431 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 main.lua       | 230 ++++++++++++++++++++++++++++++
 nodedb.lua     | 163 ++++++++++++++++++++++
 serialize.lua  | 221 +++++++++++++++++++++++++++++
 track_defs.lua | 152 ++++++++++++++++++++
 tracks.lua     | 265 +++++++++++++++++++++++++++++++++++
 vector.lua     | 145 +++++++++++++++++++
 7 files changed, 1607 insertions(+)
 create mode 100644 helpers.lua
 create mode 100644 main.lua
 create mode 100644 nodedb.lua
 create mode 100755 serialize.lua
 create mode 100644 track_defs.lua
 create mode 100644 tracks.lua
 create mode 100755 vector.lua

diff --git a/helpers.lua b/helpers.lua
new file mode 100644
index 0000000..511d32e
--- /dev/null
+++ b/helpers.lua
@@ -0,0 +1,431 @@
+--advtrains by orwell96, see readme.txt
+
+local dir_trans_tbl={
+	[0]={x=0, z=1, y=0},
+	[1]={x=1, z=2, y=0},
+	[2]={x=1, z=1, y=0},
+	[3]={x=2, z=1, y=0},
+	[4]={x=1, z=0, y=0},
+	[5]={x=2, z=-1, y=0},
+	[6]={x=1, z=-1, y=0},
+	[7]={x=1, z=-2, y=0},
+	[8]={x=0, z=-1, y=0},
+	[9]={x=-1, z=-2, y=0},
+	[10]={x=-1, z=-1, y=0},
+	[11]={x=-2, z=-1, y=0},
+	[12]={x=-1, z=0, y=0},
+	[13]={x=-2, z=1, y=0},
+	[14]={x=-1, z=1, y=0},
+	[15]={x=-1, z=2, y=0},
+}
+
+local dir_angle_tbl={}
+for d,v in pairs(dir_trans_tbl) do
+	local uvec = vector.normalize(v)
+	dir_angle_tbl[d] = math.atan2(-uvec.x, uvec.z)
+end
+
+
+function advtrains.dir_to_angle(dir)
+	return dir_angle_tbl[dir] or error("advtrains: in helpers.lua/dir_to_angle() given dir="..(dir or "nil"))
+end
+
+function advtrains.dirCoordSet(coord, dir)
+	return vector.add(coord, advtrains.dirToCoord(dir))
+end
+advtrains.pos_add_dir = advtrains.dirCoordSet
+
+function advtrains.pos_add_angle(pos, ang)
+	-- 0 is +Z -> meaning of sin/cos swapped
+	return vector.add(pos, {x = -math.sin(ang), y = 0, z = math.cos(ang)})
+end
+
+function advtrains.dirToCoord(dir)
+	return dir_trans_tbl[dir] or error("advtrains: in helpers.lua/dir_to_vector() given dir="..(dir or "nil"))
+end
+advtrains.dir_to_vector = advtrains.dirToCoord
+
+function advtrains.maxN(list, expectstart)
+	local n=expectstart or 0
+	while list[n] do
+		n=n+1
+	end
+	return n-1
+end
+
+function advtrains.minN(list, expectstart)
+	local n=expectstart or 0
+	while list[n] do
+		n=n-1
+	end
+	return n+1
+end
+
+function atround(number)
+	return math.floor(number+0.5)
+end
+atfloor = math.floor
+
+
+function advtrains.round_vector_floor_y(vec)
+	return {x=math.floor(vec.x+0.5), y=math.floor(vec.y), z=math.floor(vec.z+0.5)}
+end
+
+function advtrains.yawToDirection(yaw, conn1, conn2)
+	if not conn1 or not conn2 then
+		error("given nil to yawToDirection: conn1="..(conn1 or "nil").." conn2="..(conn1 or "nil"))
+	end
+	local yaw1 = advtrains.dir_to_angle(conn1)
+	local yaw2 = advtrains.dir_to_angle(conn2)
+	local adiff1 = advtrains.minAngleDiffRad(yaw, yaw1)
+	local adiff2 = advtrains.minAngleDiffRad(yaw, yaw2)
+	
+	if math.abs(adiff2)<math.abs(adiff1) then
+		return conn2
+	else
+		return conn1
+	end
+end
+
+function advtrains.yawToAnyDir(yaw)
+	local min_conn, min_diff=0, 10
+	for conn, vec in pairs(advtrains.dir_trans_tbl) do
+		local yaw1 = advtrains.dir_to_angle(conn)
+		local diff = math.abs(advtrains.minAngleDiffRad(yaw, yaw1))
+		if diff < min_diff then
+			min_conn = conn
+			min_diff = diff
+		end
+	end
+	return min_conn
+end
+function advtrains.yawToClosestConn(yaw, conns)
+	local min_connid, min_diff=1, 10
+	for connid, conn in ipairs(conns) do
+		local yaw1 = advtrains.dir_to_angle(conn.c)
+		local diff = math.abs(advtrains.minAngleDiffRad(yaw, yaw1))
+		if diff < min_diff then
+			min_connid = connid
+			min_diff = diff
+		end
+	end
+	return min_connid
+end
+
+local pi, pi2 = math.pi, 2*math.pi
+function advtrains.minAngleDiffRad(r1, r2)
+	while r1>pi2 do
+		r1=r1-pi2
+	end
+	while r1<0 do
+		r1=r1+pi2
+	end
+	while r2>pi2 do
+		r2=r2-pi2
+	end
+	while r1<0 do
+		r2=r2+pi2
+	end
+	local try1=r2-r1
+	local try2=r2+pi2-r1
+	local try3=r2-pi2-r1
+	
+	local minabs = math.min(math.abs(try1), math.abs(try2), math.abs(try3))
+	if minabs==math.abs(try1) then
+		return try1
+	end
+	if minabs==math.abs(try2) then
+		return try2
+	end
+	if minabs==math.abs(try3) then
+		return try3
+	end
+end
+
+
+-- Takes 2 connections (0...AT_CMAX) as argument
+-- Returns the angle median of those 2 positions from the pov
+-- of standing on the cdir1 side and looking towards cdir2
+-- cdir1 - >NODE> - cdir2
+function advtrains.conn_angle_median(cdir1, cdir2)
+	local ang1 = advtrains.dir_to_angle(advtrains.oppd(cdir1))
+	local ang2 = advtrains.dir_to_angle(cdir2)
+	return ang1 + advtrains.minAngleDiffRad(ang1, ang2)/2
+end
+
+function advtrains.merge_tables(a, ...)
+	local new={}
+	for _,t in ipairs({a,...}) do
+		for k,v in pairs(t) do new[k]=v end
+	end
+	return new
+end
+function advtrains.save_keys(tbl, keys)
+	local new={}
+	for _,key in ipairs(keys) do
+		new[key] = tbl[key]
+	end
+	return new
+end
+
+function advtrains.get_real_index_position(path, index)
+	if not path or not index then return end
+	
+	local first_pos=path[math.floor(index)]
+	local second_pos=path[math.floor(index)+1]
+	
+	if not first_pos or not second_pos then return nil end
+	
+	local factor=index-math.floor(index)
+	local actual_pos={x=first_pos.x-(first_pos.x-second_pos.x)*factor, y=first_pos.y-(first_pos.y-second_pos.y)*factor, z=first_pos.z-(first_pos.z-second_pos.z)*factor,}
+	return actual_pos
+end
+function advtrains.pos_median(pos1, pos2)
+	return {x=pos1.x-(pos1.x-pos2.x)*0.5, y=pos1.y-(pos1.y-pos2.y)*0.5, z=pos1.z-(pos1.z-pos2.z)*0.5}
+end
+function advtrains.abs_ceil(i)
+	return math.ceil(math.abs(i))*math.sign(i)
+end
+
+function advtrains.serialize_inventory(inv)
+	local ser={}
+	local liszts=inv:get_lists()
+	for lisztname, liszt in pairs(liszts) do
+		ser[lisztname]={}
+		for idx, item in ipairs(liszt) do
+			local istring=item:to_string()
+			if istring~="" then
+				ser[lisztname][idx]=istring
+			end
+		end
+	end
+	return minetest.serialize(ser)
+end
+function advtrains.deserialize_inventory(sers, inv)
+	local ser=minetest.deserialize(sers)
+	if ser then
+		inv:set_lists(ser)
+		return true
+	end
+	return false
+end
+
+--is_protected wrapper that checks for protection_bypass privilege
+function advtrains.is_protected(pos, name)
+	if not name then
+		error("advtrains.is_protected() called without name parameter!")
+	end
+	if minetest.check_player_privs(name, {protection_bypass=true}) then
+		--player can bypass protection
+		return false
+	end
+	return minetest.is_protected(pos, name)
+end
+
+function advtrains.is_creative(name)
+	if not name then
+		error("advtrains.is_creative() called without name parameter!")
+	end
+	if minetest.check_player_privs(name, {creative=true}) then
+		return true
+	end
+	return minetest.settings:get_bool("creative_mode")
+end
+
+function advtrains.ms_to_kmh(speed)
+	return speed * 3.6
+end
+
+-- 4 possible inputs:
+-- integer: just do that modulo calculation
+-- table with c set: rotate c
+-- table with tables: rotate each
+-- table with integers: rotate each (probably no use case)
+function advtrains.rotate_conn_by(conn, rotate)
+	if tonumber(conn) then
+		return (conn+rotate)%AT_CMAX
+	elseif conn.c then
+		return { c = (conn.c+rotate)%AT_CMAX, y = conn.y}
+	end
+	local tmp={}
+	for connid, data in ipairs(conn) do
+		tmp[connid]=advtrains.rotate_conn_by(data, rotate)
+	end
+	return tmp
+end
+
+
+function advtrains.oppd(dir)
+	return advtrains.rotate_conn_by(dir, AT_CMAX/2)
+end
+--conn_to_match like rotate_conn_by
+--other_conns have to be a table of conn tables!
+function advtrains.conn_matches_to(conn, other_conns)
+	if tonumber(conn) then
+		for connid, data in ipairs(other_conns) do
+			if advtrains.oppd(conn) == data.c then return connid end
+		end
+		return false
+	elseif conn.c then
+		for connid, data in ipairs(other_conns) do
+			local cmp = advtrains.oppd(conn)
+			if cmp.c == data.c and (cmp.y or 0) == (data.y or 0) then return connid end
+		end
+		return false
+	end
+	local tmp={}
+	for connid, data in ipairs(conn) do
+		local backmatch = advtrains.conn_matches_to(data, other_conns)
+		if backmatch then return backmatch, connid end --returns <connid of other rail> <connid of this rail>
+	end
+	return false
+end
+
+
+-- returns: <adjacent pos>, <conn index of adjacent>, <my conn index>, <railheight of adjacent>
+function advtrains.get_adjacent_rail(this_posnr, this_conns_p, conn_idx, drives_on)
+	local this_pos = advtrains.round_vector_floor_y(this_posnr)
+	local this_conns = this_conns_p
+	if not this_conns then
+		_, this_conns = advtrains.get_rail_info_at(this_pos)
+	end
+	if not conn_idx then
+		for coni, _ in ipairs(this_conns) do
+			local adj_pos, adj_conn_idx, _, nry, nco = advtrains.get_adjacent_rail(this_pos, this_conns, coni)
+			if adj_pos then return adj_pos,adj_conn_idx,coni,nry, nco end
+		end
+		return nil
+	end
+	
+	local conn = this_conns[conn_idx]
+	local conn_y = conn.y or 0
+	local adj_pos = advtrains.dirCoordSet(this_pos, conn.c);
+	
+	while conn_y>=1 do
+		conn_y = conn_y - 1
+		adj_pos.y = adj_pos.y + 1
+	end
+	
+	local nextnode_ok, nextconns, nextrail_y=advtrains.get_rail_info_at(adj_pos, drives_on)
+	if not nextnode_ok then
+		adj_pos.y = adj_pos.y - 1
+		conn_y = conn_y + 1
+		nextnode_ok, nextconns, nextrail_y=advtrains.get_rail_info_at(adj_pos, drives_on)
+		if not nextnode_ok then
+			return nil
+		end
+	end
+	local adj_connid = advtrains.conn_matches_to({c=conn.c, y=conn_y}, nextconns)
+	if adj_connid then
+		return adj_pos, adj_connid, conn_idx, nextrail_y, nextconns
+	end
+	return nil
+end
+
+local connlku={[2]={2,1}, [3]={2,1,1}, [4]={2,1,4,3}}
+function advtrains.get_matching_conn(conn, nconns)
+	return connlku[nconns][conn]
+end
+
+function advtrains.random_id()
+	local idst=""
+	for i=0,5 do
+		idst=idst..(math.random(0,9))
+	end
+	return idst
+end
+-- Shorthand for pos_to_string and round_vector_floor_y
+function advtrains.roundfloorpts(pos)
+	return minetest.pos_to_string(advtrains.round_vector_floor_y(pos))
+end
+
+-- insert an element into a table if it does not yet exist there
+-- equalfunc is a function to compare equality, defaults to ==
+-- returns true if the element was inserted
+function advtrains.insert_once(tab, elem, equalfunc)
+	for _,e in pairs(tab) do
+		if equalfunc and equalfunc(elem, e) or e==elem then return false end
+	end
+	tab[#tab+1] = elem
+	return true
+end
+
+local hext = { [0]="0",[1]="1",[2]="2",[3]="3",[4]="4",[5]="5",[6]="6",[7]="7",[8]="8",[9]="9",[10]="A",[11]="B",[12]="C",[13]="D",[14]="E",[15]="F"}
+local dect = { ["0"]=0,["1"]=1,["2"]=2,["3"]=3,["4"]=4,["5"]=5,["6"]=6,["7"]=7,["8"]=8,["9"]=9,["A"]=10,["B"]=11,["C"]=12,["D"]=13,["E"]=14,["F"]=15}
+
+local f = atfloor
+
+local function hex(i)
+	local x=i+32768
+	local c4 = x % 16
+	x = f(x / 16)
+	local c3 = x % 16
+	x = f(x / 16)
+	local c2 = x % 16
+	x = f(x / 16)
+	local c1 = x % 16
+	return (hext[c1]) .. (hext[c2]) .. (hext[c3]) .. (hext[c4])
+end
+
+local function c(s,i) return dect[string.sub(s,i,i)] end
+
+local function dec(s)
+	return (c(s,1)*4096 + c(s,2)*256 + c(s,3)*16 + c(s,4))-32768
+end
+-- Takes a position vector and outputs a encoded value suitable as table index
+-- This is essentially a hexadecimal representation of the position (+32768)
+-- Order (YYY)YXXXXZZZZ
+function advtrains.encode_pos(pos)
+	return hex(pos.y) .. hex(pos.x) .. hex(pos.z)
+end
+
+-- decodes a position encoded with encode_pos
+function advtrains.decode_pos(pts)
+	local stry = string.sub(pts, 1,4)
+	local strx = string.sub(pts, 5,8)
+	local strz = string.sub(pts, 9,12)
+	return vector.new(dec(strx), dec(stry), dec(strz))
+end
+
+--[[ Benchmarking code
+local tdt = {}
+local tlt = {}
+local tet = {}
+
+for i=1,1000000 do
+	tdt[i] = vector.new(math.random(-65536, 65535), math.random(-65536, 65535), math.random(-65536, 65535))
+	if i%1000 == 0 then
+		tlt[#tlt+1] = tdt[i]
+	end
+end
+
+local t1=os.clock()
+for i=1,1000000 do
+	local pe = advtrains.encode_pos(tdt[i])
+	local pb = advtrains.decode_pos(pe)
+	tet[pe] = i
+end
+for i,v in ipairs(tlt) do
+	local lk = tet[advtrains.encode_pos(v)]
+end
+atdebug("endec",os.clock()-t1,"s")
+
+tet = {}
+
+t1=os.clock()
+for i=1,1000000 do
+	local pe = minetest.pos_to_string(tdt[i])
+	local pb = minetest.string_to_pos(pe)
+	tet[pe] = i
+end
+for i,v in ipairs(tlt) do
+	local lk = tet[minetest.pos_to_string(v)]
+end
+atdebug("pts",os.clock()-t1,"s")
+
+--Results:
+--2018-11-29 16:57:08: ACTION[Main]: [advtrains]endec 1.786451 s 
+--2018-11-29 16:57:10: ACTION[Main]: [advtrains]pts 2.566377 s 
+]]
+
+
diff --git a/main.lua b/main.lua
new file mode 100644
index 0000000..460c29d
--- /dev/null
+++ b/main.lua
@@ -0,0 +1,230 @@
+-- advtrains track map generator
+-- Usage:...
+
+-- Viewport maximum coordinate in all directions
+local maxc = 5000
+
+-- embed an image called "world.png"
+local wimg = false
+-- image file resolution (not world resolution!)
+local wimresx = 3000
+local wimresy = 3000
+-- one pixel is ... nodes
+local wimscale = 4
+
+
+
+--Constant for maximum connection value/division of the circle
+AT_CMAX = 16
+
+advtrains = {}
+minetest = {}
+core = minetest
+
+--table for track nodes/connections
+trackconns = {}
+
+-- math library seems to be missing this function
+math.hypot = function(a,b) return math.sqrt(a*a + b*b) end
+
+-- need to declare this for trackdefs
+function attrans(str) return str end
+
+-- pos to string
+local function pts(pos)
+	return pos.x .. "," .. pos.y .. "," .. pos.z
+end
+
+--Advtrains dump (special treatment of pos and sigd)
+function atdump(t, intend)
+	local str
+	if type(t)=="table" then
+		if t.x and t.y and t.z then
+			str=minetest.pos_to_string(t)
+		elseif t.p and t.s then -- interlocking sigd
+			str="S["..minetest.pos_to_string(t.p).."/"..t.s.."]"
+		else
+			str="{"
+			local intd = (intend or "") .. "  "
+			for k,v in pairs(t) do
+				if type(k)~="string" or not string.match(k, "^path[_]?") then
+					-- do not print anything path-related
+					str = str .. "\n" .. intd .. atdump(k, intd) .. " = " ..atdump(v, intd)
+				end
+			end
+			str = str .. "\n" .. (intend or "") .. "}"
+		end
+	elseif type(t)=="boolean" then
+		if t then
+			str="true"
+		else
+			str="false"
+		end
+	elseif type(t)=="function" then
+		str="<function>"
+	elseif type(t)=="userdata" then
+		str="<userdata>"
+	else
+		str=""..t
+	end
+	return str
+end
+
+dofile("vector.lua")
+dofile("serialize.lua")
+dofile("helpers.lua")
+dofile("tracks.lua")
+dofile("track_defs.lua")
+
+dofile("nodedb.lua")
+
+
+-- Load saves
+local file, err = io.open("advtrains", "r")
+local tbl = minetest.deserialize(file:read("*a"))
+if type(tbl) ~= "table" then
+	error("not a table")
+end
+if tbl.version then
+	
+	advtrains.ndb.load_data(tbl.ndb)
+	
+else
+	error("Incompatible save format!")
+end
+file:close()
+
+-- open svg file
+
+local svgfile = io.open("out.svg", "w")
+
+svgfile:write([[
+<?xml version="1.0" standalone="no" ?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
+  "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
+<svg width="1024" height="800" xmlns="http://www.w3.org/2000/svg"
+  xmlns:xlink="http://www.w3.org/1999/xlink" ]])
+
+
+svgfile:write('viewBox="'..(-maxc)..' '..(-maxc)..' '..(2*maxc)..' '..(2*maxc)..'" >')
+
+
+svgfile:write([[
+<circle cx="0" cy="0" r="2" stroke="red" stroke-width="1" />
+]])
+
+if wimg then
+	local wimx = -(wimresx*wimscale/2)
+	local wimy = -(wimresy*wimscale/2)
+	local wimw = wimresx*wimscale
+	local wimh = wimresy*wimscale
+	
+	svgfile:write('<image xlink:href="world.png" x="'..wimx..'" y="'..wimy..'" height="'..wimh..'px" width="'..wimw..'px"/>')
+end
+
+local function writec(text)
+	print(text)
+	svgfile:write("<!-- " .. text .. " -->\n")
+end
+
+
+-- everything set up. Start generating an SVG
+-- All nodes that have been fit into a polyline are removed from the NDB, in order to not draw them again.
+
+-- "Restart points" for the breadth-first traverser (set when more than 2 conns present)
+-- {pos = <position>, connid = <int>, conn = <conndef>}
+-- Note that the node at "pos" is already deleted from the NDB at the time of recall, therefore "conn" is specified
+local bfs_rsp = {}
+
+
+-- Points of the current polyline. Inserted as xyz vectors, maybe we'll use the y value one day
+local current_polyline = {}
+
+-- Traverser function from interlocking, highly modified
+local function gen_rsp_polyline(rsp)
+
+	-- trick a bit
+	local pos, connid, conns = rsp.pos, 1, {rsp.conn}
+	current_polyline[#current_polyline+1] = pos
+	
+	while true do
+		local adj_pos, adj_connid, conn_idx, nextrail_y, next_conns = advtrains.get_adjacent_rail(pos, conns, connid)
+		if not adj_pos then
+			return
+		end
+		-- continue traversing
+		local conn_mainbranch
+		for nconnid, nconn in ipairs(next_conns) do
+			if adj_connid ~= nconnid then
+				if not conn_mainbranch then
+					--use the first one found to continue
+					conn_mainbranch = nconnid
+					--writec(nconnid.." nconn mainbranch")
+				else
+					-- insert bfs reminders for other conns
+					table.insert(bfs_rsp, {pos = adj_pos, connid = nconnid, conn = nconn})
+					--writec(nconnid.." nconn bfs")
+				end
+			end
+		end
+		
+		-- save in polyline and delete from ndb
+		--writec("Saved pos: "..pts(adj_pos).." mainbranch cont "..conn_mainbranch.." nextconns "..atdump(next_conns))
+		current_polyline[#current_polyline+1] = adj_pos
+		advtrains.ndb.clear(adj_pos)
+		
+		pos, connid, conns = adj_pos, conn_mainbranch, next_conns
+		
+	end
+end
+
+
+local function polyline_write(pl)
+	local str = {'<polyline style="fill:none;stroke:black;stroke-width:1" points="'}
+	
+	local i
+	local e
+	local lastldir = {x=0, y=0}
+	for i=1,#pl do
+		e = pl[i]
+		-- Note that we mirror y, so positive z is up
+		table.insert(str, e.x .. "," .. -(e.z) .. " ")
+	end
+	
+	table.insert(str, '" />\n')
+	
+	svgfile:write(table.concat(str))
+end
+
+
+-- while there are entries in the nodedb
+-- 1. find a starting point
+	local stpos, conns = advtrains.ndb.mapper_find_starting_point()
+while stpos do
+	
+	writec("Restart at position "..pts(stpos))
+	for connid, conn in ipairs(conns) do
+		table.insert(bfs_rsp, {pos = stpos, connid = connid, conn = conn})
+	end
+	advtrains.ndb.clear(stpos)
+	
+	-- 2. while there are BFS entries
+	while #bfs_rsp > 0 do
+		-- make polylines
+		local current_rsp = bfs_rsp[#bfs_rsp]
+		bfs_rsp[#bfs_rsp] = nil
+		--print("Starting polyline at "..pts(current_rsp.pos).."/"..current_rsp.connid)
+		
+		
+		current_polyline = {}
+		
+		gen_rsp_polyline(current_rsp)
+		
+		polyline_write(current_polyline)
+	end
+	stpos, conns = advtrains.ndb.mapper_find_starting_point()
+end
+
+svgfile:write("</svg>")
+svgfile:close()
+
diff --git a/nodedb.lua b/nodedb.lua
new file mode 100644
index 0000000..f79dbbd
--- /dev/null
+++ b/nodedb.lua
@@ -0,0 +1,163 @@
+--nodedb.lua
+--database of all nodes that have 'save_in_at_nodedb' field set to true in node definition
+
+
+--serialization format:
+--(2byte z) (2byte y) (2byte x) (2byte contentid)
+--contentid := (14bit nodeid, 2bit param2)
+
+local function int_to_bytes(i)
+	local x=i+32768--clip to positive integers
+	local cH = math.floor(x /           256) % 256;
+	local cL = math.floor(x                ) % 256;
+	return(string.char(cH, cL));
+end
+local function bytes_to_int(bytes)
+	local t={string.byte(bytes,1,-1)}
+	local n = 
+		t[1] *           256 +
+		t[2]
+    return n-32768
+end
+local function l2b(x)
+	return x%4
+end
+local function u14b(x)
+	return math.floor(x/4)
+end
+local ndb={}
+
+--local variables for performance
+local ndb_nodeids={}
+local ndb_nodes={}
+
+local function ndbget(x,y,z)
+	local ny=ndb_nodes[y]
+	if ny then
+		local nx=ny[x]
+		if nx then
+			return nx[z]
+		end
+	end
+	return nil
+end
+local function ndbset(x,y,z,v)
+	if not ndb_nodes[y] then
+		ndb_nodes[y]={}
+	end
+	if not ndb_nodes[y][x] then
+		ndb_nodes[y][x]={}
+	end
+	ndb_nodes[y][x][z]=v
+end
+
+
+local path="advtrains_ndb2"
+--load
+--nodeids get loaded by advtrains init.lua and passed here
+function ndb.load_data(data)
+	ndb_nodeids = data and data.nodeids or {}
+	local file, err = io.open(path, "rb")
+	if not file then
+		print("Couldn't load the node database: ", err or "Unknown Error")
+	else
+		local cnt=0
+		local hst_z=file:read(2)
+		local hst_y=file:read(2)
+		local hst_x=file:read(2)
+		local cid=file:read(2)
+		while hst_z and hst_y and hst_x and cid and #hst_z==2 and #hst_y==2 and #hst_x==2 and #cid==2 do
+			ndbset(bytes_to_int(hst_x), bytes_to_int(hst_y), bytes_to_int(hst_z), bytes_to_int(cid))
+			cnt=cnt+1
+			hst_z=file:read(2)
+			hst_y=file:read(2)
+			hst_x=file:read(2)
+			cid=file:read(2)
+		end
+		print("nodedb: read", cnt, "nodes.")
+		file:close()
+	end
+end
+
+--function to get node. track database is not helpful here.
+function ndb.get_node_or_nil(pos)
+	-- FIX for bug found on linuxworks server:
+	-- a loaded node might get read before the LBM has updated its state, resulting in wrongly set signals and switches
+	-- -> Using the saved node prioritarily.
+	local node = ndb.get_node_raw(pos)
+	if node then
+		return node
+	else
+		-- no minetest here
+		return nil
+	end
+end
+function ndb.get_node(pos)
+	local n=ndb.get_node_or_nil(pos)
+	if not n then
+		return {name="ignore", param2=0}
+	end
+	return n
+end
+function ndb.get_node_raw(pos)
+	local cid=ndbget(pos.x, pos.y, pos.z)
+	if cid then
+		local nodeid = ndb_nodeids[u14b(cid)]
+		if nodeid then
+			return {name=nodeid, param2 = l2b(cid)}
+		end
+	end
+	return nil
+end
+
+function ndb.clear(pos)
+	ndbset(pos.x, pos.y, pos.z, nil)
+end
+
+
+--get_node with pseudoload. now we only need track data, so we can use the trackdb as second fallback
+--nothing new will be saved inside the trackdb.
+--returns:
+--true, conn1, conn2, rely1, rely2, railheight   in case everything's right.
+--false  if it's not a rail or the train does not drive on this rail, but it is loaded or
+--nil    if the node is neither loaded nor in trackdb
+--the distraction between false and nil will be needed only in special cases.(train initpos)
+function advtrains.get_rail_info_at(pos)
+	local rdp=advtrains.round_vector_floor_y(pos)
+	
+	local node=ndb.get_node_or_nil(rdp)
+	if not node then return end
+	
+	local nodename=node.name
+	
+	local conns, railheight, tracktype=advtrains.get_track_connections(node.name, node.param2)
+	
+	if not conns then
+		return false
+	end
+	
+	return true, conns, railheight
+end
+
+
+-- mapper-specific
+
+function ndb.mapper_find_starting_point()
+	for y, ty in pairs(ndb_nodes) do
+		for x, tx in pairs(ty) do
+			for z, v in pairs(tx) do
+				local pos = {x=x, y=y, z=z}
+				local node_ok, conns, _ = advtrains.get_rail_info_at(pos)
+				if node_ok then
+					return pos, conns
+				else
+					-- this is a signal or something similar, ignore.
+					tx[z]=nil
+				end
+			end
+		end
+	end
+end
+
+
+advtrains.ndb = ndb
diff --git a/serialize.lua b/serialize.lua
new file mode 100755
index 0000000..692ddd5
--- /dev/null
+++ b/serialize.lua
@@ -0,0 +1,221 @@
+--- Lua module to serialize values as Lua code.
+-- From: https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
+-- License: MIT
+-- @copyright 2006-2997 Fabien Fleutot <metalua@gmail.com>
+-- @author Fabien Fleutot <metalua@gmail.com>
+-- @author ShadowNinja <shadowninja@minetest.net>
+--------------------------------------------------------------------------------
+
+--- Serialize an object into a source code string. This string, when passed as
+-- an argument to deserialize(), returns an object structurally identical to
+-- the original one.  The following are currently supported:
+--   * Booleans, numbers, strings, and nil.
+--   * Functions; uses interpreter-dependent (and sometimes platform-dependent) bytecode!
+--   * Tables; they can cantain multiple references and can be recursive, but metatables aren't saved.
+-- This works in two phases:
+--   1. Recursively find and record multiple references and recursion.
+--   2. Recursively dump the value into a string.
+-- @param x Value to serialize (nil is allowed).
+-- @return load()able string containing the value.
+function core.serialize(x)
+	local local_index  = 1  -- Top index of the "_" local table in the dump
+	-- table->nil/1/2 set of tables seen.
+	-- nil = not seen, 1 = seen once, 2 = seen multiple times.
+	local seen = {}
+
+	-- nest_points are places where a table appears within itself, directly
+	-- or not.  For instance, all of these chunks create nest points in
+	-- table x: "x = {}; x[x] = 1", "x = {}; x[1] = x",
+	-- "x = {}; x[1] = {y = {x}}".
+	-- To handle those, two tables are used by mark_nest_point:
+	-- * nested - Transient set of tables being currently traversed.
+	--   Used for detecting nested tables.
+	-- * nest_points - parent->{key=value, ...} table cantaining the nested
+	--   keys and values in the parent.  They're all dumped after all the
+	--   other table operations have been performed.
+	--
+	-- mark_nest_point(p, k, v) fills nest_points with information required
+	-- to remember that key/value (k, v) creates a nest point  in table
+	-- parent. It also marks "parent" and the nested item(s) as occuring
+	-- multiple times, since several references to it will be required in
+	-- order to patch the nest points.
+	local nest_points  = {}
+	local nested = {}
+	local function mark_nest_point(parent, k, v)
+		local nk, nv = nested[k], nested[v]
+		local np = nest_points[parent]
+		if not np then
+			np = {}
+			nest_points[parent] = np
+		end
+		np[k] = v
+		seen[parent] = 2
+		if nk then seen[k] = 2 end
+		if nv then seen[v] = 2 end
+	end
+
+	-- First phase, list the tables and functions which appear more than
+	-- once in x.
+	local function mark_multiple_occurences(x)
+		local tp = type(x)
+		if tp ~= "table" and tp ~= "function" then
+			-- No identity (comparison is done by value, not by instance)
+			return
+		end
+		if seen[x] == 1 then
+			seen[x] = 2
+		elseif seen[x] ~= 2 then
+			seen[x] = 1
+		end
+
+		if tp == "table" then
+			nested[x] = true
+			for k, v in pairs(x) do
+				if nested[k] or nested[v] then
+					mark_nest_point(x, k, v)
+				else
+					mark_multiple_occurences(k)
+					mark_multiple_occurences(v)
+				end
+			end
+			nested[x] = nil
+		end
+	end
+
+	local dumped     = {}  -- object->varname set
+	local local_defs = {}  -- Dumped local definitions as source code lines
+
+	-- Mutually recursive local functions:
+	local dump_val, dump_or_ref_val
+
+	-- If x occurs multiple times, dump the local variable rather than
+	-- the value. If it's the first time it's dumped, also dump the
+	-- content in local_defs.
+	function dump_or_ref_val(x)
+		if seen[x] ~= 2 then
+			return dump_val(x)
+		end
+		local var = dumped[x]
+		if var then  -- Already referenced
+			return var
+		end
+		-- First occurence, create and register reference
+		local val = dump_val(x)
+		local i = local_index
+		local_index = local_index + 1
+		var = "_["..i.."]"
+		local_defs[#local_defs + 1] = var.." = "..val
+		dumped[x] = var
+		return var
+	end
+
+	-- Second phase.  Dump the object; subparts occuring multiple times
+	-- are dumped in local variables which can be referenced multiple
+	-- times.  Care is taken to dump local vars in a sensible order.
+	function dump_val(x)
+		local  tp = type(x)
+		if     x  == nil        then return "nil"
+		elseif tp == "string"   then return string.format("%q", x)
+		elseif tp == "boolean"  then return x and "true" or "false"
+		elseif tp == "function" then
+			return string.format("loadstring(%q)", string.dump(x))
+		elseif tp == "number"   then
+			-- Serialize integers with string.format to prevent
+			-- scientific notation, which doesn't preserve
+			-- precision and breaks things like node position
+			-- hashes.  Serialize floats normally.
+			if math.floor(x) == x then
+				return string.format("%d", x)
+			else
+				return tostring(x)
+			end
+		elseif tp == "table" then
+			local vals = {}
+			local idx_dumped = {}
+			local np = nest_points[x]
+			for i, v in ipairs(x) do
+				if not np or not np[i] then
+					vals[#vals + 1] = dump_or_ref_val(v)
+				end
+				idx_dumped[i] = true
+			end
+			for k, v in pairs(x) do
+				if (not np or not np[k]) and
+						not idx_dumped[k] then
+					vals[#vals + 1] = "["..dump_or_ref_val(k).."] = "
+						..dump_or_ref_val(v)
+				end
+			end
+			return "{"..table.concat(vals, ", ").."}"
+		else
+			error("Can't serialize data of type "..tp)
+		end
+	end
+
+	local function dump_nest_points()
+		for parent, vals in pairs(nest_points) do
+			for k, v in pairs(vals) do
+				local_defs[#local_defs + 1] = dump_or_ref_val(parent)
+					.."["..dump_or_ref_val(k).."] = "
+					..dump_or_ref_val(v)
+			end
+		end
+	end
+
+	mark_multiple_occurences(x)
+	local top_level = dump_or_ref_val(x)
+	dump_nest_points()
+
+	if next(local_defs) then
+		return "local _ = {}\n"
+			..table.concat(local_defs, "\n")
+			.."\nreturn "..top_level
+	else
+		return "return "..top_level
+	end
+end
+
+-- Deserialization
+
+local env = {
+	loadstring = loadstring,
+}
+
+local safe_env = {
+	loadstring = function() end,
+}
+
+function core.deserialize(str, safe)
+	if type(str) ~= "string" then
+		return nil, "Cannot deserialize type '"..type(str)
+			.."'. Argument must be a string."
+	end
+	if str:byte(1) == 0x1B then
+		return nil, "Bytecode prohibited"
+	end
+	local f, err = loadstring(str)
+	if not f then return nil, err end
+	setfenv(f, safe and safe_env or env)
+
+	local good, data = pcall(f)
+	if good then
+		return data
+	else
+		return nil, data
+	end
+end
+
+
+-- Unit tests
+local test_in = {cat={sound="nyan", speed=400}, dog={sound="woof"}}
+local test_out = core.deserialize(core.serialize(test_in))
+
+assert(test_in.cat.sound == test_out.cat.sound)
+assert(test_in.cat.speed == test_out.cat.speed)
+assert(test_in.dog.sound == test_out.dog.sound)
+
+test_in = {escape_chars="\n\r\t\v\\\"\'", non_european="θשׁ٩∂"}
+test_out = core.deserialize(core.serialize(test_in))
+assert(test_in.escape_chars == test_out.escape_chars)
+assert(test_in.non_european == test_out.non_european)
+
diff --git a/track_defs.lua b/track_defs.lua
new file mode 100644
index 0000000..aac2ebf
--- /dev/null
+++ b/track_defs.lua
@@ -0,0 +1,152 @@
+--== Insert track defs here! ==--
+-- Default tracks for advtrains
+-- (c) orwell96 and contributors
+
+--flat
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack",
+	texture_prefix="advtrains_dtrack",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_shared.png",
+	description=attrans("Track"),
+	formats={},
+}, advtrains.ap.t_30deg_flat)
+--slopes
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack",
+	texture_prefix="advtrains_dtrack",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".obj",
+	shared_texture="advtrains_dtrack_shared.png",
+	second_texture="default_gravel.png",
+	description=attrans("Track"),
+	formats={vst1={true, false, true}, vst2={true, false, true}, vst31={true}, vst32={true}, vst33={true}},
+}, advtrains.ap.t_30deg_slope)
+
+--bumpers
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack_bumper",
+	texture_prefix="advtrains_dtrack_bumper",
+	models_prefix="advtrains_dtrack_bumper",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_rail.png",
+	--bumpers still use the old texture until the models are redone.
+	description=attrans("Bumper"),
+	formats={},
+}, advtrains.ap.t_30deg_straightonly)
+
+
+
+-- atc track
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack_atc",
+	texture_prefix="advtrains_dtrack_atc",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_shared_atc.png",
+	description=attrans("ATC controller"),
+	formats={},
+	get_additional_definiton = advtrains.atc_function
+}, advtrains.trackpresets.t_30deg_straightonly)
+
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack_unload",
+	texture_prefix="advtrains_dtrack_unload",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_shared_unload.png",
+	description=attrans("Unloading Track"),
+	formats={},
+	get_additional_definiton = function(def, preset, suffix, rotation)
+		return {
+		   after_dig_node=function(pos)
+		      advtrains.invalidate_all_paths()
+		      advtrains.ndb.clear(pos)
+		   end,
+		   advtrains = {
+		      on_train_enter = function(pos, train_id)
+			 train_load(pos, train_id, true)
+		      end,
+		   },
+		}
+	end
+				     }, advtrains.trackpresets.t_30deg_straightonly)
+advtrains.register_tracks("default", {
+	nodename_prefix="advtrains:dtrack_load",
+	texture_prefix="advtrains_dtrack_load",
+	models_prefix="advtrains_dtrack",
+	models_suffix=".b3d",
+	shared_texture="advtrains_dtrack_shared_load.png",
+	description=attrans("Loading Track"),
+	formats={},
+	get_additional_definiton = function(def, preset, suffix, rotation)
+		return {
+		   after_dig_node=function(pos)
+		      advtrains.invalidate_all_paths()
+		      advtrains.ndb.clear(pos)
+		   end,
+
+		   advtrains = {
+		      on_train_enter = function(pos, train_id)
+			 train_load(pos, train_id, false)
+		      end,
+		   },
+		}
+	end
+				     }, advtrains.trackpresets.t_30deg_straightonly)
+
+
+	advtrains.register_tracks("default", {
+		nodename_prefix="advtrains:dtrack_detector_off",
+		texture_prefix="advtrains_dtrack_detector",
+		models_prefix="advtrains_dtrack",
+		models_suffix=".b3d",
+		shared_texture="advtrains_dtrack_shared_detector_off.png",
+		description=attrans("Detector Rail"),
+		formats={},
+		get_additional_definiton = function(def, preset, suffix, rotation)
+			return {
+				mesecons = {
+					receptor = {
+						state = mesecon.state.off,
+						rules = advtrains.meseconrules
+					}
+				},
+				advtrains = {
+					on_train_enter=function(pos, train_id)
+						advtrains.ndb.swap_node(pos, {name="advtrains:dtrack_detector_on".."_"..suffix..rotation, param2=advtrains.ndb.get_node(pos).param2})
+						mesecon.receptor_on(pos, advtrains.meseconrules)
+					end
+				}
+			}
+		end
+	}, advtrains.ap.t_30deg_straightonly)
+	advtrains.register_tracks("default", {
+		nodename_prefix="advtrains:dtrack_detector_on",
+		texture_prefix="advtrains_dtrack",
+		models_prefix="advtrains_dtrack",
+		models_suffix=".b3d",
+		shared_texture="advtrains_dtrack_shared_detector_on.png",
+		description="Detector(on)(you hacker you)",
+		formats={},
+		get_additional_definiton = function(def, preset, suffix, rotation)
+			return {
+				mesecons = {
+					receptor = {
+						state = mesecon.state.on,
+						rules = advtrains.meseconrules
+					}
+				},
+				advtrains = {
+					on_train_leave=function(pos, train_id)
+						advtrains.ndb.swap_node(pos, {name="advtrains:dtrack_detector_off".."_"..suffix..rotation, param2=advtrains.ndb.get_node(pos).param2})
+						mesecon.receptor_off(pos, advtrains.meseconrules)
+					end
+				}
+			}
+		end
+	}, advtrains.ap.t_30deg_straightonly_noplacer)
+	
+	
+--== END insert track defs ==--
diff --git a/tracks.lua b/tracks.lua
new file mode 100644
index 0000000..b04c585
--- /dev/null
+++ b/tracks.lua
@@ -0,0 +1,265 @@
+--advtrains by orwell96, see readme.txt
+
+--dev-time settings:
+--EDIT HERE
+--If the old non-model rails on straight tracks should be replaced by the new...
+--false: no
+--true: yes
+advtrains.register_replacement_lbms=false
+
+--[[TracksDefinition
+nodename_prefix
+texture_prefix
+description
+common={}
+straight={}
+straight45={}
+curve={}
+curve45={}
+lswitchst={}
+lswitchst45={}
+rswitchst={}
+rswitchst45={}
+lswitchcr={}
+lswitchcr45={}
+rswitchcr={}
+rswitchcr45={}
+vert1={
+	--you'll probably want to override mesh here
+}
+vert2={
+	--you'll probably want to override mesh here
+}
+]]--
+advtrains.all_tracktypes={}
+
+--definition preparation
+local function conns(c1, c2, r1, r2) return {{c=c1, y=r1}, {c=c2, y=r2}} end
+local function conns3(c1, c2, c3, r1, r2, r3) return {{c=c1, y=r1}, {c=c2, y=r2}, {c=c3, y=r3}} end
+
+advtrains.ap={}
+advtrains.ap.t_30deg_flat={
+	regstep=1,
+	variant={
+		st={
+			conns = conns(0,8),
+			desc = "straight",
+			tpdouble = true,
+			tpsingle = true,
+			trackworker = "cr",
+		},
+		cr={
+			conns = conns(0,7),
+			desc = "curve",
+			tpdouble = true,
+			trackworker = "swlst",
+		},
+		swlst={
+			conns = conns3(0,8,7),
+			desc = "left switch (straight)",
+			trackworker = "swrst",
+			switchalt = "swlcr",
+			switchmc = "on",
+			switchst = "st",
+		},
+		swlcr={
+			conns = conns3(0,7,8),
+			desc = "left switch (curve)",
+			trackworker = "swrcr",
+			switchalt = "swlst",
+			switchmc = "off",
+			switchst = "cr",
+		},
+		swrst={
+			conns = conns3(0,8,9),
+			desc = "right switch (straight)",
+			trackworker = "st",
+			switchalt = "swrcr",
+			switchmc = "on",
+			switchst = "st",
+		},
+		swrcr={
+			conns = conns3(0,9,8),
+			desc = "right switch (curve)",
+			trackworker = "st",
+			switchalt = "swrst",
+			switchmc = "off",
+			switchst = "cr",
+		},
+	},
+	regtp=true,
+	tpdefault="st",
+	trackworker={
+		["swrcr"]="st",
+		["swrst"]="st",
+		["cr"]="swlst",
+		["swlcr"]="swrcr",
+		["swlst"]="swrst",
+	},
+	rotation={"", "_30", "_45", "_60"},
+}
+advtrains.ap.t_30deg_slope={
+	regstep=1,
+	variant={
+		vst1={conns = conns(8,0,0,0.5), rail_y = 0.25, desc = "steep uphill 1/2", slope=true},
+		vst2={conns = conns(8,0,0.5,1), rail_y = 0.75, desc = "steep uphill 2/2", slope=true},
+		vst31={conns = conns(8,0,0,0.33), rail_y = 0.16, desc = "uphill 1/3", slope=true},
+		vst32={conns = conns(8,0,0.33,0.66), rail_y = 0.5, desc = "uphill 2/3", slope=true},
+		vst33={conns = conns(8,0,0.66,1), rail_y = 0.83, desc = "uphill 3/3", slope=true},
+	},
+	regsp=true,
+	slopeplacer={
+		[2]={"vst1", "vst2"},
+		[3]={"vst31", "vst32", "vst33"},
+		max=3,--highest entry
+	},
+	slopeplacer_45={
+		[2]={"vst1_45", "vst2_45"},
+		max=2,
+	},
+	rotation={"", "_30", "_45", "_60"},
+	trackworker={},
+	increativeinv={},
+}
+advtrains.ap.t_30deg_straightonly={
+	regstep=1,
+	variant={
+		st={
+			conns = conns(0,8),
+			desc = "straight",
+			tpdouble = true,
+			tpsingle = true,
+			trackworker = "st",
+		},
+	},
+	regtp=true,
+	tpdefault="st",
+	rotation={"", "_30", "_45", "_60"},
+}
+advtrains.ap.t_30deg_straightonly_noplacer={
+	regstep=1,
+	variant={
+		st={
+			conns = conns(0,8),
+			desc = "straight",
+			tpdouble = true,
+			tpsingle = true,
+			trackworker = "st",
+		},
+	},
+	tpdefault="st",
+	rotation={"", "_30", "_45", "_60"},
+}
+advtrains.ap.t_45deg={
+	regstep=2,
+	variant={
+		st={
+			conns = conns(0,8),
+			desc = "straight",
+			tpdouble = true,
+			tpsingle = true,
+			trackworker = "cr",
+		},
+		cr={
+			conns = conns(0,6),
+			desc = "curve",
+			tpdouble = true,
+			trackworker = "swlst",
+		},
+		swlst={
+			conns = conns3(0,8,6),
+			desc = "left switch (straight)",
+			trackworker = "swrst",
+			switchalt = "swlcr",
+			switchmc = "on",
+			switchst = "st",
+		},
+		swlcr={
+			conns = conns3(0,6,8),
+			desc = "left switch (curve)",
+			trackworker = "swrcr",
+			switchalt = "swlst",
+			switchmc = "off",
+			switchst = "cr",
+		},
+		swrst={
+			conns = conns3(0,8,10),
+			desc = "right switch (straight)",
+			trackworker = "st",
+			switchalt = "swrcr",
+			switchmc = "on",
+			switchst = "st",
+		},
+		swrcr={
+			conns = conns3(0,10,8),
+			desc = "right switch (curve)",
+			trackworker = "st",
+			switchalt = "swrst",
+			switchmc = "off",
+			switchst = "cr",
+		},
+	},
+	regtp=true,
+	tpdefault="st",
+	trackworker={
+		["swrcr"]="st",
+		["swrst"]="st",
+		["cr"]="swlst",
+		["swlcr"]="swrcr",
+		["swlst"]="swrst",
+	},
+	rotation={"", "_30", "_45", "_60"},
+}
+advtrains.trackpresets = advtrains.ap
+
+--definition format: ([] optional)
+--[[{
+	nodename_prefix
+	texture_prefix
+	[shared_texture]
+	models_prefix
+	models_suffix (with dot)
+	[shared_model]
+	formats={
+		st,cr,swlst,swlcr,swrst,swrcr,vst1,vst2
+		(each a table with indices 0-3, for if to register a rail with this 'rotation' table entry. nil is assumed as 'all', set {} to not register at all)
+	}
+	common={} change something on common rail appearance
+}
+[18.12.17] Note on new connection system:
+In order to support real rail crossing nodes and finally make the trackplacer respect switches, I changed the connection system.
+There can be a variable number of connections available. These are specified as tuples {c=<connection>, y=<rely>}
+The table "at_conns" consists of {<conn1>, <conn2>...}
+the "at_rail_y" property holds the value that was previously called "railheight"
+Depending on the number of connections:
+2 conns: regular rail
+3 conns: switch:
+	- when train passes in at conn1, will move out of conn2
+	- when train passes in at conn2 or conn3, will move out of conn1
+4 conns: cross (or cross switch, depending on arrangement of conns):
+	- conn1 <> conn2
+	- conn3 <> conn4
+]]
+
+function advtrains.register_tracks(tracktype, def, preset)
+	for suffix, var in pairs(preset.variant) do
+		for rotid, rotation in ipairs(preset.rotation) do
+			if not def.formats[suffix] or def.formats[suffix][rotid] then
+				
+				--connections
+				local at_conns = advtrains.rotate_conn_by(var.conns, (rotid-1)*preset.regstep)
+
+				trackconns[def.nodename_prefix.."_"..suffix..rotation] = at_conns
+				
+			end
+		end
+	end
+end
+
+
+function advtrains.get_track_connections(name, param2)
+	
+	if not trackconns[name] then return end
+	
+	return advtrains.rotate_conn_by(trackconns[name], param2*AT_CMAX/4), nil, nil
+end
diff --git a/vector.lua b/vector.lua
new file mode 100755
index 0000000..0549f9a
--- /dev/null
+++ b/vector.lua
@@ -0,0 +1,145 @@
+
+vector = {}
+
+function vector.new(a, b, c)
+	if type(a) == "table" then
+		assert(a.x and a.y and a.z, "Invalid vector passed to vector.new()")
+		return {x=a.x, y=a.y, z=a.z}
+	elseif a then
+		assert(b and c, "Invalid arguments for vector.new()")
+		return {x=a, y=b, z=c}
+	end
+	return {x=0, y=0, z=0}
+end
+
+function vector.equals(a, b)
+	return a.x == b.x and
+	       a.y == b.y and
+	       a.z == b.z
+end
+
+function vector.length(v)
+	return math.hypot(v.x, math.hypot(v.y, v.z))
+end
+
+function vector.normalize(v)
+	local len = vector.length(v)
+	if len == 0 then
+		return {x=0, y=0, z=0}
+	else
+		return vector.divide(v, len)
+	end
+end
+
+function vector.floor(v)
+	return {
+		x = math.floor(v.x),
+		y = math.floor(v.y),
+		z = math.floor(v.z)
+	}
+end
+
+function vector.round(v)
+	return {
+		x = math.floor(v.x + 0.5),
+		y = math.floor(v.y + 0.5),
+		z = math.floor(v.z + 0.5)
+	}
+end
+
+function vector.apply(v, func)
+	return {
+		x = func(v.x),
+		y = func(v.y),
+		z = func(v.z)
+	}
+end
+
+function vector.distance(a, b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return math.hypot(x, math.hypot(y, z))
+end
+
+function vector.direction(pos1, pos2)
+	local x_raw = pos2.x - pos1.x
+	local y_raw = pos2.y - pos1.y
+	local z_raw = pos2.z - pos1.z
+	local x_abs = math.abs(x_raw)
+	local y_abs = math.abs(y_raw)
+	local z_abs = math.abs(z_raw)
+	if x_abs >= y_abs and
+	   x_abs >= z_abs then
+		y_raw = y_raw * (1 / x_abs)
+		z_raw = z_raw * (1 / x_abs)
+		x_raw = x_raw / x_abs
+	end
+	if y_abs >= x_abs and
+	   y_abs >= z_abs then
+		x_raw = x_raw * (1 / y_abs)
+		z_raw = z_raw * (1 / y_abs)
+		y_raw = y_raw / y_abs
+	end
+	if z_abs >= y_abs and
+	   z_abs >= x_abs then
+		x_raw = x_raw * (1 / z_abs)
+		y_raw = y_raw * (1 / z_abs)
+		z_raw = z_raw / z_abs
+	end
+	return {x=x_raw, y=y_raw, z=z_raw}
+end
+
+
+function vector.add(a, b)
+	if type(b) == "table" then
+		return {x = a.x + b.x,
+			y = a.y + b.y,
+			z = a.z + b.z}
+	else
+		return {x = a.x + b,
+			y = a.y + b,
+			z = a.z + b}
+	end
+end
+
+function vector.subtract(a, b)
+	if type(b) == "table" then
+		return {x = a.x - b.x,
+			y = a.y - b.y,
+			z = a.z - b.z}
+	else
+		return {x = a.x - b,
+			y = a.y - b,
+			z = a.z - b}
+	end
+end
+
+function vector.multiply(a, b)
+	if type(b) == "table" then
+		return {x = a.x * b.x,
+			y = a.y * b.y,
+			z = a.z * b.z}
+	else
+		return {x = a.x * b,
+			y = a.y * b,
+			z = a.z * b}
+	end
+end
+
+function vector.divide(a, b)
+	if type(b) == "table" then
+		return {x = a.x / b.x,
+			y = a.y / b.y,
+			z = a.z / b.z}
+	else
+		return {x = a.x / b,
+			y = a.y / b,
+			z = a.z / b}
+	end
+end
+
+function vector.sort(a, b)
+	return {x = math.min(a.x, b.x), y = math.min(a.y, b.y), z = math.min(a.z, b.z)},
+		{x = math.max(a.x, b.x), y = math.max(a.y, b.y), z = math.max(a.z, b.z)}
+end
-- 
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