Add forceloading

3 files changed, 90 insertions, 0 deletions

diff --git a/builtin/builtin.lua b/builtin/builtin.lua
index 99242f3d2..dc428220a 100644
--- a/builtin/builtin.lua
+++ b/builtin/builtin.lua
@@ -34,3 +34,4 @@ dofile(modpath.."/falling.lua")
 dofile(modpath.."/features.lua")
 dofile(modpath.."/voxelarea.lua")
 dofile(modpath.."/vector.lua")
+dofile(modpath.."/forceloading.lua")
diff --git a/builtin/forceloading.lua b/builtin/forceloading.lua
new file mode 100644
index 000000000..021de075b
--- /dev/null
+++ b/builtin/forceloading.lua
@@ -0,0 +1,79 @@
+-- Prevent anyone else accessing those functions
+local forceload_block = minetest.forceload_block
+local forceload_free_block = minetest.forceload_free_block
+minetest.forceload_block = nil
+minetest.forceload_free_block = nil
+
+local blocks_forceloaded
+local total_forceloaded = 0
+
+local BLOCKSIZE = 16
+local function get_blockpos(pos)
+	return {
+		x = math.floor(pos.x/BLOCKSIZE),
+		y = math.floor(pos.y/BLOCKSIZE),
+		z = math.floor(pos.z/BLOCKSIZE)}
+end
+
+function minetest.forceload_block(pos)
+	local blockpos = get_blockpos(pos)
+	local hash = minetest.hash_node_position(blockpos)
+	if blocks_forceloaded[hash] ~= nil then
+		blocks_forceloaded[hash] = blocks_forceloaded[hash] + 1
+		return true
+	else
+		if total_forceloaded >= (minetest.setting_get("max_forceloaded_blocks") or 16) then
+			return false
+		end
+		total_forceloaded = total_forceloaded+1
+		blocks_forceloaded[hash] = 1
+		forceload_block(blockpos)
+		return true
+	end
+end
+
+function minetest.forceload_free_block(pos)
+	local blockpos = get_blockpos(pos)
+	local hash = minetest.hash_node_position(blockpos)
+	if blocks_forceloaded[hash] == nil then return end
+	if blocks_forceloaded[hash] > 1 then
+		blocks_forceloaded[hash] = blocks_forceloaded[hash] - 1
+	else
+		total_forceloaded = total_forceloaded-1
+		blocks_forceloaded[hash] = nil
+		forceload_free_block(blockpos)
+	end
+end
+
+-- Keep the forceloaded areas after restart
+local wpath = minetest.get_worldpath()
+local function read_file(filename)
+	local f = io.open(filename, "r")
+	if f==nil then return {} end
+	local t = f:read("*all")
+	f:close()
+	if t=="" or t==nil then return {} end
+	return minetest.deserialize(t)
+end
+
+local function write_file(filename, table)
+	local f = io.open(filename, "w")
+	f:write(minetest.serialize(table))
+	f:close()
+end
+
+blocks_forceloaded = read_file(wpath.."/force_loaded.txt")
+for _, __ in pairs(blocks_forceloaded) do
+	total_forceloaded = total_forceloaded + 1
+end
+
+minetest.after(5, function()
+	for hash, _ in pairs(blocks_forceloaded) do
+		local blockpos = minetest.get_position_from_hash(hash)
+		forceload_block(blockpos)
+	end
+end)
+
+minetest.register_on_shutdown(function()
+	write_file(wpath.."/force_loaded.txt", blocks_forceloaded)
+end)
diff --git a/builtin/misc.lua b/builtin/misc.lua
index fd80aacf6..1d5e146c6 100644
--- a/builtin/misc.lua
+++ b/builtin/misc.lua
@@ -64,6 +64,16 @@ function minetest.hash_node_position(pos)
 	return (pos.z+32768)*65536*65536 + (pos.y+32768)*65536 + pos.x+32768
 end
 
+function minetest.get_position_from_hash(hash)
+	local pos = {}
+	pos.x = (hash%65536) - 32768
+	hash = math.floor(hash/65536)
+	pos.y = (hash%65536) - 32768
+	hash = math.floor(hash/65536)
+	pos.z = (hash%65536) - 32768
+	return pos
+end
+
 function minetest.get_item_group(name, group)
 	if not minetest.registered_items[name] or not
 			minetest.registered_items[name].groups[group] then