local pole_texture = "advtrains_signals_japan_mast.png"
local signal_face_texture = "advtrains_hud_bg.png^[colorize:#000000:255"
local pole_radius = 1/16
local pole_box = {-pole_radius,-1/2,-pole_radius,pole_radius,1/2,pole_radius}
local light_radius = 1/20
local signal_width = 6*light_radius
local signal_thickness = pole_radius*3
local signal_height = {}
local signal_box = {}
local light_red = "advtrains_hud_bg.png^[colorize:red:255"
local light_yellow = "advtrains_hud_bg.png^[colorize:orange:255"
local light_green = "advtrains_hud_bg.png^[colorize:lime:255"
local light_purple = "advtrains_hud_bg.png^[colorize:purple:255"
local light_distant = light_purple
local light_off = signal_face_texture

do
	local model_dir = core.get_modpath("advtrains_signals_japan") .. DIR_DELIM .. "models"
	local function add_model(name, content)
		local fn = "advtrains_signals_japan_" .. name
		if core.features.dynamic_add_media_startup then
			core.dynamic_add_media {
				filename = fn,
				filedata = content,
			}
		else
			core.mkdir(model_dir)
			core.safe_file_write(model_dir .. DIR_DELIM .. fn, content)
		end
	end
	local model_path_prefix = table.concat({minetest.get_modpath("advtrains_signals_japan"), "models", "advtrains_signals_japan_"}, DIR_DELIM)

	local function vertex(x, y, z)
		return string.format("v %f %f %f", x, y, z)
	end
	local function texture(u, v)
		return string.format("vt %f %f", u, v)
	end
	local function face_element(v, vt)
		if vt then
			return string.format("%d/%d", v, vt)
		end
		return tonumber(v)
	end
	local function face_elements(...)
		local st = {"f"}
		local args = {...}
		local len = #args
		for i = 1, len, 2 do
			st[(i+3)/2] = face_element(args[i], args[i+1])
		end
		return table.concat(st, " ")
	end
	local function sequential_elements(v0, vt0, count)
		local st = {}
		for i = 1, count do
			st[i] = face_element(v0+i, vt0+i)
		end
		return table.concat(st, " ")
	end
	local function mod_lower(min, a, b)
		return min + (a-min)%b
	end
	local function connect_circular(v0, vt0, count)
		return "f " .. sequential_elements(v0, vt0, count)
	end
	local function connect_cylindrical(v0, vt0, count)
		local st = {}
		for i = 0, count-1 do
			local j = (i+1)%count
			local v1 = v0+i+1
			local v2 = v1+count
			local v3 = v0+j+1
			local v4 = v3+count
			local vt1 = vt0+i+1
			local vt2 = vt1+count+1
			st[i+1] = face_elements(v1, vt1, v3, vt1+1, v4, vt2+1, v2, vt2)
		end
		return table.concat(st, "\n")
	end
	local function circular_textures(u0, v0, r, count, total, angular_offset, direction)
		local st = {}
		if not angular_offset then
			angular_offset = 0
		end
		if not total then
			total = count
		end