Box creation & entry demo, quite hacky for now

mods/boxes/init.lua

@@ -1,7 +1,7 @@
 boxes = {}
 
 local function bytes_to_string(bytes)
-	s = {}
+	local s = {}
 	for i = 1, #bytes do
 		s[i] = string.char(bytes[i])
 	end
@@ -9,7 +9,7 @@ local function bytes_to_string(bytes)
 end
 
 local function string_to_bytes(str)
-	s = {}
+	local s = {}
 	for i = 1, string.len(str) do
 		s[i] = string.byte(str, i)
 	end
@@ -423,9 +423,180 @@ function boxes.vfree(minp)
 	update_alloc_sizes(node.parent)
 end
 
+function boxes.read_box(box_data)
+	local data_index = 1
+	local function read_u8()
+		local c = string.byte(box_data, data_index)
+		data_index = data_index + 1
+		return c
+	end
+	local function read_u16()
+		local a = read_u8()
+		local b = read_u8()
+		return 256 * a + b
+	end
+	local function read_pos()
+		local x = read_u16()
+		local y = read_u16()
+		local z = read_u16()
+		return {x = x, y = y, z = z}
+	end
+	local size = read_pos()
+	local entry = read_pos()
+	local exit = read_pos()
+	return {
+		size = size,
+		entry = entry,
+		exit = exit,
+		data = string.sub(box_data, data_index)
+	}
+end
+
+function boxes.write_box(box)
+	local data_index = 1
+	local data = {}
+	local function write_u8(x)
+		data[data_index] = x
+		data_index = data_index + 1
+	end
+	local function write_u16(x)
+		write_u8(math.floor(x / 256))
+		write_u8(x % 256)
+	end
+	local function write_pos(p)
+		write_u16(p.x)
+		write_u16(p.y)
+		write_u16(p.z)
+	end
+	write_pos(box.size)
+	write_pos(box.entry)
+	write_pos(box.exit)
+	return bytes_to_string(data) .. box.data
+end
+
+function vector.min(a, b)
+	return {
+		x = math.min(a.x, b.x),
+		y = math.min(a.y, b.y),
+		z = math.min(a.z, b.z),
+	}
+end
+
+function vector.max(a, b)
+	return {
+		x = math.max(a.x, b.x),
+		y = math.max(a.y, b.y),
+		z = math.max(a.z, b.z),
+	}
+end
+
+local players_in_boxes = {}
+
+local function read_file(filename)
+	local file = io.open(filename, "r")
+	if file ~= nil then
+		local file_content = file:read("*all")
+		io.close(file)
+		return file_content
+	end
+	return ""
+end
+
+local function write_file(filename, data)
+	local file, err = io.open(filename, "w")
+	if file then
+		file:write(data)
+		io.close(file)
+	else
+		error(err)
+	end
+end
+
+local entry_lobby_data = read_file(minetest.get_modpath(minetest.get_current_modname()) .. "/entry.box")
+local exit_lobby_data = read_file(minetest.get_modpath(minetest.get_current_modname()) .. "/exit.box")
+local box_data = read_file(minetest.get_modpath(minetest.get_current_modname()) .. "/box.box")
+
+local function pop_node(pos)
+	local node = minetest.get_node(pos)
+	local meta = minetest.get_meta(pos)
+	local r = {pos = pos, node = node, meta = meta:to_table()}
+	minetest.remove_node(pos)
+	return r
+end
+
+local function unpop_node(data)
+	minetest.set_node(data.pos, data.node)
+	local meta = minetest.get_meta(data.pos)
+	meta:from_table(data.meta)
+end
+
+local function open_door(player, pos)
+	local nds = {
+		pop_node(pos),
+		pop_node(vector.add(pos, {x = -1, y = 0, z = 0})),
+		pop_node(vector.add(pos, {x =  0, y = 1, z = 0})),
+		pop_node(vector.add(pos, {x = -1, y = 1, z = 0})),
+	}
+	local od = players_in_boxes[player:get_player_name()].open_doors
+	od[#od + 1] = { minx = pos.x + 0.5, nodes = nds }
+end
+
+minetest.register_globalstep(function(dtime)
+		for playername, info in pairs(players_in_boxes) do
+			local i = 1
+			local player = minetest.get_player_by_name(playername)
+			local pos = player:get_pos()
+			local od = info.open_doors
+			local n = #od
+			while od[i] do
+				if pos.x >= od[i].minx then
+					for _, dt in ipairs(od[i].nodes) do
+						unpop_node(dt)
+					end
+					od[i] = od[n]
+					n = n - 1
+				else
+					i = i + 1
+				end
+			end
+		end
+end)
+
+function boxes.start_box(player, box_data)
+	local name = player:get_player_name()
+	assert(players_in_boxes[name] == nil)
+	local box = boxes.read_box(box_data)
+	local lobby_spawn = boxes.read_box(entry_lobby_data)
+	local lobby_exit = boxes.read_box(exit_lobby_data)
+	local lobby_spawn_offset = vector.subtract(box.entry, lobby_spawn.exit)
+	local lobby_exit_offset = vector.subtract(box.exit, lobby_exit.entry)
+	local pmin = vector.min({x = 0, y = 0, z = 0}, vector.min(lobby_spawn_offset,
+		lobby_exit_offset))
+	local box_offset = {x = -pmin.x, y = -pmin.y, z = -pmin.z}
+	local spawn_offset = vector.add(box_offset, lobby_spawn_offset)
+	local exit_offset = vector.add(box_offset, lobby_exit_offset)
+	local pmax = vector.max(vector.add(box_offset, box.size),
+	             vector.max(vector.add(spawn_offset, lobby_spawn.size),
+	                        vector.add(exit_offset, lobby_exit.size)))
+	local request_size = math.max(pmax.x, pmax.z)
+	local minp = boxes.valloc(request_size)
+	boxes.load(vector.add(minp, box_offset), box.data)
+	boxes.load(vector.add(minp, spawn_offset), lobby_spawn.data)
+	boxes.load(vector.add(minp, exit_offset), lobby_exit.data)
+
+	player:set_pos(vector.add(minp, vector.add(spawn_offset, lobby_spawn.entry)))
+	players_in_boxes[name] = {
+		minp = minp,
+		open_doors = {},
+	}
+	open_door(player, vector.add(minp, vector.add(box_offset, box.entry)))
+	open_door(player, vector.add(minp, vector.add(box_offset, box.exit)))
+end
+
 -- test code
---[[
+
 minetest.after(5, function()
+--[[
 	local data = boxes.save({x = -1, y = -4, z = -1},
 	                        {x =  1, y = -2, z =  1})
 	print(string.len(data))
@@ -437,6 +608,42 @@ minetest.after(5, function()
 	print(dump(boxes_tree))
 	boxes.vfree(minp)
 	print(dump(boxes_tree))
-
-end)
 ]]
+
+--[[
+	local data_spawn = boxes.save({x = -35, y = -32, z = 56},
+	                              {x = -33, y = -29, z = 64})
+	local data_exit = boxes.save({x = -10, y = -32, z = 53},
+	                             {x =  -8, y = -29, z = 61})
+	local sp = {
+		size = boxes.extent(data_spawn),
+		entry = {x = 0, y = 2, z = 4},
+		exit = {x = 3, y = 1, z = 4},
+		data = data_spawn,
+	}
+	local ex = {
+		size = boxes.extent(data_exit),
+		entry = {x = 0, y = 1, z = 4},
+		exit = {x = 3, y = 1, z = 4},
+		data = data_exit,
+	}
+
+	local data_box = boxes.save({x = -32, y = -32, z = 48},
+	                            {x = -11, y = -27, z = 69})
+	local bx = {
+		size = boxes.extent(data_box),
+		entry = {x = 0, y = 1, z = 10},
+		exit = {x = 22, y = 1, z = 10},
+		data = data_box,
+	}
+
+	local path = minetest.get_worldpath()
+	write_file(path .. "/entry.box", boxes.write_box(sp))
+	write_file(path .. "/exit.box", boxes.write_box(ex))
+	write_file(path .. "/box.box", boxes.write_box(bx))
+]]
+
+	local player = minetest.get_player_by_name("singleplayer")
+	boxes.start_box(player, box_data)
+end)
+