Crafter/mods/new_functions/init.lua

local get_group = minetest.get_node_group
local registered_nodes
local get_node = minetest.get_node
--add nodes that hurt the player into the touch hurt table
local hurt_nodes = {}
minetest.register_on_mods_loaded(function()
	for _,def in pairs(minetest.registered_nodes) do
		if get_group(def.name, "touch_hurt") > 0 then
			table.insert(hurt_nodes,def.name)
		end
	end
	registered_nodes = minetest.registered_nodes
end)

--handle nodes around, inside, and above
local player_surroundings_index_table = {}

--add the player to the index table when they join and remove when they leave
minetest.register_on_joinplayer(function(player)
	local name = player:get_player_name()	
	player_surroundings_index_table[name] = {}
end)

minetest.register_on_leaveplayer(function(player)
	local name = player:get_player_name()
	player_surroundings_index_table[name] = nil
end)
--reset their drowning settings
--minetest.register_on_dieplayer(function(ObjectRef, reason))


--handle touching hurt
local player_pos

local c_pos

local temp_hurt
local x1
local y1
local z1

local xcompare
local ycompare
local zcompare

local c_player

local subval = vector.subtract

local abs_it = math.abs
local floor_it = math.floor

local heart

local function handle_hurt(player)
	if player:get_hp() > 0 then
		player_pos = player:get_pos()
		name = player:get_player_name()
		temp_hurt = player_surroundings_index_table[name].hurt
		if temp_hurt then
			c_pos = temp_hurt.pos
			x1 = floor_it(abs_it(player_pos.x-c_pos.x)*100)
			y1 = floor_it(abs_it(player_pos.y-c_pos.y)*100)
			z1 = floor_it(abs_it(player_pos.z-c_pos.z)*100)
			--we will assume the player cbox is equal as x=0.8,y=0.5,z=0.8
			if x1 <= 80 and z1 <= 80 and y1 <= 50 then
				heart = player:get_hp()
				player:set_hp(heart - player_surroundings_index_table[name].hurt.hurt_amount)
				return(true)
			end
		end
	end
	return(false)
end

--handle inside hurt
local c_player
local heart
local legs
local head
local hurt_more

local function handle_hurt_inside(player)
	if player:get_hp() > 0 then
		player_pos = player:get_pos()
		name = player:get_player_name()
		legs = player_surroundings_index_table[name].legs
		head = player_surroundings_index_table[name].head
		if legs and head then
			hurt_more = get_group(legs, "hurt_inside")
			if get_group(head, "hurt_inside") > hurt_more then
				hurt_more = get_group(head, "hurt_inside")
			end
			
			heart = player:get_hp()
			player:set_hp(heart - hurt_more)
			return(true)
		end
	end
	return(false)
end

--handle player suffocating inside solid node
local c_player
local heart
local legs
local head
local hurt_more
local drawy

local function handle_player_suffocation(player)
	if player:get_hp() > 0 then
		player_pos = player:get_pos()
		name = player:get_player_name()
		head = player_surroundings_index_table[name].head
		if head then
			drawy = registered_nodes[head].drawtype

			if drawy == "normal" then
				heart = player:get_hp()
				player:set_hp(heart - 1)
				return(true)
			end
		end
	end
	return(false)
end


--index specific things in area
--declare here for ultra extreme efficiency
local get_node = minetest.get_node
local pos
local node
local name
local damage_pos
local collisionbox
local a_min
local a_max
local v_add = vector.add
local v_sub = vector.subtract
local get_number = table.getn
local hurt_amount
local gotten_node
local function index_players_surroundings()
	for _,player in ipairs(minetest.get_connected_players()) do
		if player:get_hp() > 0 then
			--if not dead begin index
			name = player:get_player_name()
			pos = player:get_pos()
			
			--under player position (useful for walking on hot stuff)
			pos.y = pos.y - 0.1
			player_surroundings_index_table[name].under = get_node(pos).name
			
			--at legs position (useful for pushing a player up)
			pos.y = pos.y + 0.6
			player_surroundings_index_table[name].legs = get_node(pos).name
			
			--at camera/head position (useful for drowning/being trapped inside node)
			
			pos.y = pos.y + 0.940
			player_surroundings_index_table[name].head = get_node(pos).name
			
			handle_player_suffocation(player)
			handle_hurt_inside(player)

			--used for finding a damage node next to the player (centered at player's waist)
			pos.y = pos.y - 0.74
			a_min = v_sub(pos,1)
			a_max = v_add(pos,1)
			damage_pos = minetest.find_nodes_in_area(a_min, a_max, hurt_nodes)
			
			if get_number(damage_pos) > 0 then
				for _,found_location in ipairs(damage_pos) do
					gotten_node = get_node(found_location).name
					collisionbox = registered_nodes[gotten_node].collision_box
					hurt_amount = get_group(gotten_node, "touch_hurt")
					
					if not collisionbox then
						collisionbox = {-0.5,-0.5,-0.5,0.5,0.5,0.5}
					end
					player_surroundings_index_table[name].hurt = {pos=found_location,collisionbox=collisionbox,hurt_amount=hurt_amount}
					--stop doing damage on player if they got hurt
					if handle_hurt(player) == true then
						break
					end
				end
			else
				collisionbox = nil
				player_surroundings_index_table[name].hurt = nil
			end
				
		end
	end
	--4 times a second server tick
	minetest.after(0.25, function()
		index_players_surroundings()
	end)
end

index_players_surroundings() --begin

--[[ this is disabled for now
--handle water drowning - temp - will be moved to a custom function in a future update
local breath
local function handle_drowning()
	for _,player in ipairs(minetest.get_connected_players()) do
		if player:get_hp() > 0 then
			name = player:get_player_name()
			if get_group(player_surroundings_index_table[name].head, "drowning") > 0 then
				breath = player:get_breath()
				if breath > 0 then
					player:set_breath(breath - 1)
				end
			else
				breath = player:get_breath()
				if breath < 11 then
					player:set_breath(breath + 1)
				end
			end
		end
	end
	minetest.after(0.5, function()
		handle_drowning()
	end)
end

handle_drowning()
]]--