Merge pull request 'Optimize finding lightning rods' (#4665) from optimize-lightning into master

Reviewed-on: https://git.minetest.land/VoxeLibre/VoxeLibre/pulls/4665
Reviewed-by: Mikita Wiśniewski <rudzik8@protonmail.com>

.luarc.json

@@ -3,6 +3,7 @@
   "diagnostics": { "disable": ["lowercase-global"] },
   "diagnostics.globals": [
     "minetest",
+    "core",
     "dump",
     "dump2",
     "Raycast",
@@ -18,5 +19,6 @@
     "AreaStore",
     "vector"
   ],
+  "workspace.library": ["/usr/share/luanti/luanti-lls-definitions/library", "/usr/share/luanti/builtin"],
   "workspace.ignoreDir": [".luacheckrc"]
 }

mods/ITEMS/mcl_lightning_rods/api.lua

@@ -0,0 +1,194 @@
+local storage = minetest.get_mod_storage()
+local mod = mcl_lightning_rods
+local BLOCK_SIZE = 64
+
+-- Helper functions
+function vector_floor(v)
+	return vector.new( math.floor(v.x), math.floor(v.y), math.floor(v.z) )
+end
+function vector_min(a,b)
+	return vector.new( math.min(a.x,b.x), math.min(a.y,b.y), math.min(a.z,b.z) )
+end
+function vector_max(a,b)
+	return vector.new( math.max(a.x,b.x), math.max(a.y,b.y), math.max(a.z,b.z) )
+end
+
+local function read_voxel_area(pos1, pos2)
+	local vm = minetest.get_voxel_manip()
+	local minp, maxp = vm:read_from_map(pos1, pos2)
+	local data = vm:get_data()
+	local area = VoxelArea:new({MinEdge = minp, MaxEdge = maxp})
+
+	return vm,data,area
+end
+
+local function load_index(x,y,z)
+	local idx_key = string.format("%d-%d,%d,%d",BLOCK_SIZE,x,y,z)
+	local idx_str = storage:get_string(idx_key)
+	if idx_str and idx_str ~= "" then
+		local idx = minetest.deserialize(idx_str)
+		return idx or {}
+	end
+
+	return {}
+end
+local function load_index_vector(pos)
+	return load_index(pos.x,pos.y,pos.z)
+end
+
+local function save_index(x,y,z, idx)
+	local idx_str = minetest.serialize(idx)
+	local idx_key = string.format("%d-%d,%d,%d",BLOCK_SIZE,x,y,z)
+	storage:set_string(idx_key, idx_str)
+end
+local function save_index_vector(pos, idx)
+	return save_index(pos.x,pos.y,pos.z, idx)
+end
+
+-- Remove duplicates and verify all locations have a lightning attractor present
+local function clean_index(idx, drop)
+	local new_idx = {}
+	local exists = {}
+	for _,p in ipairs(idx) do
+		local key = string.format("%d,%d,%d",p.x,p.y,p.z)
+		if not exists[key] then
+			exists[key] = true
+
+			local node = minetest.get_node(p)
+			if minetest.get_item_group(node.name, "attracts_lightning") ~= 0 or (drop and vector.distance(p,drop) < 0.1 ) then
+				new_idx[#new_idx + 1] = p
+			end
+		end
+	end
+	return new_idx
+end
+
+function mod.find_attractors_in_area(pos1, pos2)
+	-- Normalize the search area into large, regular blocks
+	local pos1_r = vector_floor(pos1 / BLOCK_SIZE)
+	local pos2_r = vector_floor(pos2 / BLOCK_SIZE)
+	local min = vector_min(pos1_r, pos2_r)
+	local max = vector_max(pos1_r, pos2_r)
+
+	local results = {}
+	for z = min.z,max.z do
+		for y = min.y,max.y do
+			for x = min.x,max.x do
+				local idx = load_index(x,y,z)
+
+				-- Make sure every indexed position actually has a lightning attractor present
+				for _,pos in ipairs(idx) do
+					local node = minetest.get_node(pos)
+					if minetest.get_item_group(node.name, "attracts_lightning") ~= 0 then
+						results[#results + 1] = pos
+					end
+				end
+			end
+		end
+	end
+	return results
+end
+local function find_closest_position_in_list(pos, list)
+	local dist = nil
+	local best = nil
+	for _,p in ipairs(list) do
+		local p_dist = vector.distance(p,pos)
+		if not dist or p_dist < dist then
+			dist = p_dist
+			best = p
+		end
+	end
+	return best
+end
+
+function mod.find_closest_attractor(pos, search_size)
+	local attractor_positions = mod.find_attractors_in_area(
+		vector.offset(pos, -search_size, -search_size, -search_size),
+		vector.offset(pos,  search_size,  search_size,  search_size)
+	)
+	return find_closest_position_in_list(pos, attractor_positions)
+end
+
+function mod.unregister_lightning_attractor(pos)
+	-- Verify the node no longer attracts lightning
+	local node = minetest.get_node(pos)
+	if minetest.get_item_group(node.name, "attracts_lightning") ~= 0 then return end
+
+	-- Get the existing index data (if any)
+	local pos_r = vector_floor(pos / BLOCK_SIZE)
+	local idx = load_index_vector(pos_r)
+
+	-- Clean the index and drop this node
+	idx = clean_index(idx, pos)
+	save_index_vector(pos_r, idx)
+end
+function mod.register_lightning_attractor(pos)
+	-- Verify the node attracts lightning
+	local node = minetest.get_node(pos)
+	if minetest.get_item_group(node.name, "attracts_lightning") == 0 then return end
+
+	-- Get the existing index data (if any)
+	local pos_r = vector_floor(pos / BLOCK_SIZE)
+	local idx = load_index_vector(pos_r)
+	for _,p in ipairs(idx) do
+		-- Don't need to change anything if the rod is already registered
+		if vector.distance(p,pos) < 0.1 then return end
+	end
+
+	-- Add and save the rod position
+	idx[#idx + 1] = pos
+
+	-- Clean and save the index data
+	clean_index(idx)
+	save_index_vector(pos_r, idx)
+end
+
+-- Constants used for content id index
+local IS_ATTRACTOR = {}
+local IS_NOT_ATTRACTOR = {}
+function mod.index_block(pos)
+	local pos_r = vector_floor(pos1 / BLOCK_SIZE)
+	local pos1 = vector.multiply(pos_r,BLOCK_SIZE)
+	local pos2 = vector.offset(pos,BLOCK_SIZE - 1,BLOCK_SIZE - 1,BLOCK_SIZE - 1)
+
+	-- We are completely rebuilding the index data so there is no nead to load
+	-- the existing data
+	local idx = {}
+
+	-- Setup voxel manipulator
+	local _,data,area = read_voxel_area()
+
+	-- Indexes to speed things up
+	local cid_attractors = {}
+
+	-- Iterate over the area and look for lightning attractors
+	local minx = pos1.x
+	local maxx = pos1.x
+	for z = pos1.z,pos2.z do
+		for y = pos1.y,pos2.y do
+			for x = minx,maxx do
+				local vi = area:index(x,y,z)
+				local cid = data[vi]
+				local attr = cid_attractors[cid]
+				if attr then
+					if attr == IS_ATTRACTOR then
+						idx[#idx + 1] = vector.new(x,y,z)
+					end
+				else
+					-- Lookup data and cache for later
+					local name = minetest.get_name_from_content_id(cid)
+					if minetest.get_item_group(name, "attracts_lightning") then
+						cid_attractors = IS_ATTRACTOR
+						idx[#idx + 1] = vector.new(x,y,z)
+					else
+						cid_attractors = IS_NOT_ATTRACTOR
+					end
+				end
+			end
+		end
+	end
+
+	-- Save for later use
+	save_index_vector(pos_r, idx)
+end
+

mods/ITEMS/mcl_lightning_rods/init.lua

@@ -1,6 +1,16 @@
+local modname = minetest.get_current_modname()
+local modpath = minetest.get_modpath(modname)
 local S = minetest.get_translator("mcl_lightning_rods")
 
----@type nodebox
+mcl_lightning_rods = {}
+local mod = mcl_lightning_rods
+
+---@class core.NodeDef
+---@field _on_lightning_strike? fun(pos : vector.Vector, node : core.Node)
+
+dofile(modpath.."/api.lua")
+
+---@type core.NodeBox
 local cbox = {
 	type = "fixed",
 	fixed = {
@@ -9,7 +19,7 @@ local cbox = {
 	},
 }
 
----@type node_definition
+---@type core.NodeDef
 local rod_def = {
 	description = S("Lightning Rod"),
 	_doc_items_longdesc = S("A block that attracts lightning"),
@@ -59,6 +69,17 @@ local rod_def = {
 
 		return minetest.item_place(itemstack, placer, pointed_thing, param2)
 	end,
+	after_place_node = function(pos)
+		mod.register_lightning_attractor(pos)
+	end,
+	after_destruct = function(pos)
+		mod.unregister_lightning_attractor(pos)
+	end,
+	_on_lightning_strike = function(pos, node)
+		minetest.set_node(pos, { name = "mcl_lightning_rods:rod_powered", param2 = node.param2 })
+		mesecon.receptor_on(pos, mesecon.rules.alldirs)
+		minetest.get_node_timer(pos):start(0.4)
+	end,
 
 	_mcl_blast_resistance = 6,
 	_mcl_hardness = 3,
@@ -79,7 +100,7 @@ rod_def_a.mesecons = {
 	},
 }
 
-rod_def_a.on_timer = function(pos, elapsed)
+rod_def_a.on_timer = function(pos)
 	local node = minetest.get_node(pos)
 
 	if node.name == "mcl_lightning_rods:rod_powered" then --has not been dug
@@ -92,21 +113,21 @@ end
 
 minetest.register_node("mcl_lightning_rods:rod_powered", rod_def_a)
 
+lightning.register_on_strike(function(pos)
+	local lr = mod.find_closest_attractor(pos, 64)
+	if not lr then return end
 
-lightning.register_on_strike(function(pos, pos2, objects)
-	local lr = minetest.find_node_near(pos, 128, { "group:attracts_lightning" }, true)
+	-- Make sure this possition attracts lightning
+	local node = minetest.get_node(lr)
+	if minetest.get_item_group(node.name, "attracts_lightning") == 0 then return end
 
-	if lr then
-		local node = minetest.get_node(lr)
-
-		if node.name == "mcl_lightning_rods:rod" then
-			minetest.set_node(lr, { name = "mcl_lightning_rods:rod_powered", param2 = node.param2 })
-			mesecon.receptor_on(lr, mesecon.rules.alldirs)
-			minetest.get_node_timer(lr):start(0.4)
-		end
+	-- Allow the node to process a lightning strike
+	local nodedef = minetest.registered_nodes[node.name]
+	if nodedef and nodedef._on_lightning_strike then
+		nodedef._on_lightning_strike(lr, node)
 	end
 
-	return lr, nil
+	return lr
 end)
 
 minetest.register_craft({
@@ -117,3 +138,10 @@ minetest.register_craft({
 		{ "", "mcl_copper:copper_ingot", "" },
 	},
 })
+minetest.register_lbm({
+	name = "mcl_lightning_rods:index_rods",
+	nodenames = {"mcl_lightning_rods:rod","mcl_lightning_rods:rod_powered"},
+	action = function(pos)
+		mod.register_lightning_attractor(pos)
+	end
+})