Initial commit.

README.md

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+Depth Finder [depth\_finder]
+============================
+Help find the deep passages in caves.
+
+By David G (kestral246@gmail.com)
+
+![Depth Finder Screenshot](screenshot.png "Depth Finder")
+
+With my Quarry Mechanics mod, it's necessary to find iron to do any stone construction, but digging stone is also more difficult. I would try to find deep caves to avoid digging, but I was wasting a lot of time exploring shallow caves. Also, it's easy to miss some of the deep passages without spending a lot of time systematically exploring.
+
+To make it easier to reach iron (which will work equally well without the quarry mod), I've created this depth\_finder mod. It scans air nodes in front of the player and reports the deepest point found. Checking different directions will help determine if a cave goes very deep, and which direction to find these deep spots.
+
+For efficiency it just searches a cylindrical sector in the direction pointed, so it could miss finding particularly winding passages. *(Based on my wand\_of\_illumination mod.)*
+
+Now as to my choice of tool provided—since I needed something that could be crafted before a lot of digging, my choices were limited. My thought with two flints was that they could be banged together, and the return echo would indicate depth.
+
+This is obviously a silly idea, so if someone can come up with a better idea, please let me know.
+
+
+Dependencies
+------------
+
+- Craft recipe optionally depends on default.
+
+
+Craft Recipe
+------------
+
+Simple Depth Finder
+
+![Simple Depth Finder](images/crafting1.png "Simple Depth Finder Craft Recipe")
+
+Licenses
+--------
+
+Source code
+
+> The MIT License (MIT)
+
+Media (textures)
+
+> Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
+
+Current texture copied from default\_flint.png by Gambit

init.lua

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+-- Depth Finder [depth_finder]
+-- by David G (kestral246@gmail.com)
+-- 2020-03-15
+
+-- Currently just two flints--bang them together and the return echo indicates depth.
+
+local scan_angle = math.pi/4  -- corresponds to 90°
+
+-- Maximum number of nodes to check
+local maxcount = 150000
+
+-- The wear and radius can now be set independently for each lamp tool.
+
+-- Set to true to print debug statistics.
+local debug = false
+
+local scanned = {}  -- Set containing scanned nodes, so they don't get scanned multiple times.
+local tocheck = {}  -- Table of nodes to check.
+local max_depth = {}  -- Deepest node scanned.
+
+minetest.register_on_joinplayer(function(player)
+	local pname = player:get_player_name()
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	max_depth[pname] = 0
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	local pname = player:get_player_name()
+	scanned[pname] = nil
+	tocheck[pname] = nil
+	max_depth[pname] = nil
+end)
+
+-- Determine number of elements in table, for summary output.
+local tlength = function(T)
+	local count = 0
+	for _ in pairs(T) do count = count + 1 end
+	return count
+end
+
+-- Scan neighboring nodes, flag for checking if air.
+local scan_node = function(pname, pos, origin, vdir, maxdist)
+	-- Update to search a cone pattern in direction pointed.
+	-- Need small sphere to get cone out.
+	local origin2d = {x=origin.x, y=0, z=origin.z}
+	local pos2d = {x=pos.x, y=0, z=pos.z}
+	local radius = vector.distance(origin2d, pos2d)
+	if radius <= 2 or (radius <= maxdist and vector.angle(vdir, vector.direction(origin2d, pos2d)) < scan_angle) then
+		local enc_pos = minetest.hash_node_position(pos)
+		if scanned[pname][enc_pos] ~= true then  -- hasn't been scanned
+			local name = minetest.get_node(pos).name
+			if name == "air" then  -- checkable
+				table.insert(tocheck[pname], enc_pos)  -- add to check list
+			end
+			scanned[pname][enc_pos] = true  -- don't scan again
+		end
+	end
+end
+
+-- To check, scan all neighbors and determine if this node needs to be converted to light.
+local check_node = function(pname, pos, origin, vdir, maxdist, height, depth)
+	local enc_pos = minetest.hash_node_position(pos)
+	local name = minetest.get_node(pos).name
+	scan_node(pname, vector.add(pos, {x=0,y=0,z=1}), origin, vdir, maxdist)  -- north
+	scan_node(pname, vector.add(pos, {x=1,y=0,z=0}), origin, vdir, maxdist)  -- east
+	scan_node(pname, vector.add(pos, {x=0,y=0,z=-1}), origin, vdir, maxdist)  -- south
+	scan_node(pname, vector.add(pos, {x=-1,y=0,z=0}), origin, vdir, maxdist)  -- west
+	if pos.y > origin.y - depth then
+		scan_node(pname, vector.add(pos, {x=0,y=-1,z=0}), origin, vdir, maxdist)  -- down
+	end
+	if pos.y < origin.y + height then
+		scan_node(pname, vector.add(pos, {x=0,y=1,z=0}), origin, vdir, maxdist)  -- up
+	end
+	if pos.y < max_depth[pname] then
+		max_depth[pname] = pos.y
+	end
+end
+
+local use_finder = function(player, itemstack, radius, height, depth, wear)
+	local pname = player:get_player_name()
+	local pos = vector.add(vector.round(player:get_pos()), {x=0,y=0,z=0})  -- position of wand
+	local theta = math.fmod(player:get_look_horizontal() + math.pi/2, 2*math.pi)
+	local vdir = vector.normalize({x=math.cos(theta), y=0, z=math.sin(theta)})
+	local key_stats = player:get_player_control()
+	local wear_cost = wear
+
+	-- Initialize temporary tables for safety.
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	max_depth[pname] = pos.y
+	-- Search starts at finder position.
+	table.insert(tocheck[pname], minetest.hash_node_position(pos))
+	local count = 1
+	while count <= table.getn(tocheck[pname]) and count <= maxcount do
+		check_node(pname, minetest.get_position_from_hash(tocheck[pname][count]), pos, vdir, radius, height, depth)
+		count = count + 1
+	end
+	count = count - 1 
+	if debug then  -- print statistics
+		minetest.debug("depth_finder: y = "..tostring(pos.y)..", scan = "..
+			tostring(tlength(scanned[pname]))..", check = "..tostring(count)..", depth = "..
+			tostring(max_depth[pname]))
+	end
+	--minetest.chat_send_player(pname, "pdir = "..tostring(minetest.serialize(vdir)))
+	minetest.chat_send_player(pname, "depth = "..tostring(max_depth[pname] - pos.y))
+	-- Clear temporary tables, which could be large.
+	scanned[pname] = {}
+	tocheck[pname] = {}
+	max_depth[pname] = 0
+	-- Add wear to finder
+	itemstack:add_wear(wear_cost)
+	return itemstack
+end
+
+minetest.register_tool("depth_finder:simple", {
+	description = "Simple Depth Finder",
+	inventory_image = "depth_finder_simple.png",
+	stack_max = 1,
+	on_use = function(itemstack, player, pointed_thing)
+		local radius = 50
+		local height = 10
+		local depth = 80
+		local wear = math.floor(65535/25)
+		local worn_item = use_finder(player, itemstack, radius, height, depth, wear)
+		return worn_item
+	end,
+})
+
+-- Need default for crafting recipe.
+-- Example craft recipe.
+if minetest.get_modpath("default") ~= nil then
+	minetest.register_craft({
+		output = "depth_finder:simple",
+		recipe = {
+			{"default:flint", "default:flint"}
+		}
+	})
+end

mod.conf

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+name = depth_finder
+description = Help find the deep passages in caves.
+optional_depends = default