builtin/game/forceloading.lua

   1 -- Prevent anyone else accessing those functions
   2 local forceload_block = core.forceload_block
   3 local forceload_free_block = core.forceload_free_block
   4 core.forceload_block = nil
   5 core.forceload_free_block = nil
   6
   7 local blocks_forceloaded
   8 local blocks_temploaded = {}
   9 local total_forceloaded = 0
  10
  11 local BLOCKSIZE = core.MAP_BLOCKSIZE
  12 local function get_blockpos(pos)
  13         return {
  14                 x = math.floor(pos.x/BLOCKSIZE),
  15                 y = math.floor(pos.y/BLOCKSIZE),
  16                 z = math.floor(pos.z/BLOCKSIZE)}
  17 end
  18
  19 -- When we create/free a forceload, it's either transient or persistent. We want
  20 -- to add to/remove from the table that corresponds to the type of forceload, but
  21 -- we also need the other table because whether we forceload a block depends on
  22 -- both tables.
  23 -- This function returns the "primary" table we are adding to/removing from, and
  24 -- the other table.
  25 local function get_relevant_tables(transient)
  26         if transient then
  27                 return blocks_temploaded, blocks_forceloaded
  28         else
  29                 return blocks_forceloaded, blocks_temploaded
  30         end
  31 end
  32
  33 function core.forceload_block(pos, transient)
  34         local blockpos = get_blockpos(pos)
  35         local hash = core.hash_node_position(blockpos)
  36         local relevant_table, other_table = get_relevant_tables(transient)
  37         if relevant_table[hash] ~= nil then
  38                 relevant_table[hash] = relevant_table[hash] + 1
  39                 return true
  40         elseif other_table[hash] ~= nil then
  41                 relevant_table[hash] = 1
  42         else
  43                 if total_forceloaded >= (tonumber(core.settings:get("max_forceloaded_blocks")) or 16) then
  44                         return false
  45                 end
  46                 total_forceloaded = total_forceloaded+1
  47                 relevant_table[hash] = 1
  48                 forceload_block(blockpos)
  49                 return true
  50         end
  51 end
  52
  53 function core.forceload_free_block(pos, transient)
  54         local blockpos = get_blockpos(pos)
  55         local hash = core.hash_node_position(blockpos)
  56         local relevant_table, other_table = get_relevant_tables(transient)
  57         if relevant_table[hash] == nil then return end
  58         if relevant_table[hash] > 1 then
  59                 relevant_table[hash] = relevant_table[hash] - 1
  60         elseif other_table[hash] ~= nil then
  61                 relevant_table[hash] = nil
  62         else
  63                 total_forceloaded = total_forceloaded-1
  64                 relevant_table[hash] = nil
  65                 forceload_free_block(blockpos)
  66         end
  67 end
  68
  69 -- Keep the forceloaded areas after restart
  70 local wpath = core.get_worldpath()
  71 local function read_file(filename)
  72         local f = io.open(filename, "r")
  73         if f==nil then return {} end
  74         local t = f:read("*all")
  75         f:close()
  76         if t=="" or t==nil then return {} end
  77         return core.deserialize(t) or {}
  78 end
  79
  80 local function write_file(filename, table)
  81         local f = io.open(filename, "w")
  82         f:write(core.serialize(table))
  83         f:close()
  84 end
  85
  86 blocks_forceloaded = read_file(wpath.."/force_loaded.txt")
  87 for _, __ in pairs(blocks_forceloaded) do
  88         total_forceloaded = total_forceloaded + 1
  89 end
  90
  91 core.after(5, function()
  92         for hash, _ in pairs(blocks_forceloaded) do
  93                 local blockpos = core.get_position_from_hash(hash)
  94                 forceload_block(blockpos)
  95         end
  96 end)
  97
  98 core.register_on_shutdown(function()
  99         write_file(wpath.."/force_loaded.txt", blocks_forceloaded)
 100 end)