Add mod to fix Minetest's unsafe spawn positions

mods/hades_safespawn/init.lua

@@ -0,0 +1,82 @@
+local function find_safe_nearby_pos(data)
+	local player = data.player
+	if not player or not player:is_player() then
+		return false
+	end
+	local attempt = data.attempt or 0
+	local pos = player:get_pos()
+	local safe = false
+	local node = minetest.get_node(pos)
+	if node.name == "ignore" then
+		attempt = attempt + 1
+		if attempt >= 5 then
+			-- Give up after too many attempts
+			minetest.log("action", "Safe spawn check for "..player:get_player_name().." failed. Got 'ignore' nodes too many times in row")
+			return false
+		end
+		-- Area is not loaded yet... Try again later
+		minetest.log("info", "Safe spawn check for "..player:get_player_name().." not possible due to unloaded area (attempt #"..attempt.."). Trying again ...")
+		minetest.after(1, find_safe_nearby_pos, {player=player, attempt=attempt+1})
+		return false
+	elseif attempt > 0 then
+		minetest.log("info", "Safe spawn check for "..player:get_player_name().." is now possible (attempt #"..attempt.."). Starting check ...")
+	end
+	-- First check if we have solid land to walk on
+	for b=1, 6 do
+		local below = minetest.get_node({x=pos.x, y=pos.y-b, z=pos.z})
+		if minetest.get_item_group(below.name, "lava") ~= 0 then
+			break
+		end
+		local bdef = minetest.registered_nodes[below.name]
+		if bdef.walkable then
+			safe = true
+			break
+		end
+	end
+	if safe then
+		-- Lava below, in or above player = unsafe (obviously)
+		local p1 = {x=pos.x, y=pos.y-1, z=pos.z}
+		local p2 = {x=pos.x, y=pos.y+2, z=pos.z}
+		local lavas = minetest.find_nodes_in_area(p1, p2, {"group:lava"})
+		if #lavas > 0 then
+			safe = false
+		end
+	end
+	-- It's not safe to spawn here ...
+	if not safe then
+		-- Activate safety teleport!
+		local p1 = {x=pos.x-8, y=pos.y, z=pos.z-8}
+		local p2 = {x=pos.x+8, y=pos.y+8, z=pos.z+8}
+
+		-- TODO: Generalize to any "solid" node
+		local nodes = minetest.find_nodes_in_area_under_air(p1, p2, {"group:ash", "group:sand", "group:stone", "group:dirt", "group:gravel"})
+		-- TODO: Check nodes in random order
+		for n=1, #nodes do
+			local tpos = nodes[n]
+			tpos.y = tpos.y + 1
+			local tpos_above = {x=tpos.x, y=tpos.y+1, z=tpos.z}
+			local n_above = minetest.get_node(tpos_above)
+			if n_above.name == "air" then
+				player:set_pos(tpos)
+				minetest.log("action", player:get_player_name().." got a spawn safety teleportion from "..minetest.pos_to_string(pos, 1).." to "..minetest.pos_to_string(tpos, 1))
+				return true
+			end
+		end
+		if #nodes == 0 then
+			minetest.log("action", player:get_player_name().." had an unsafe spawn at "..minetest.pos_to_string(pos, 1).." but no safe alternative spawn spot could be found.")
+			return true
+		end
+	end
+	minetest.log("verbose", "Safe spawn check for "..player:get_player_name().." thinks this spawn is safe. Nothing to do")
+end
+
+local on_spawn = function(player)
+	minetest.after(0, find_safe_nearby_pos, {player=player})
+end
+
+minetest.register_on_newplayer(function(player)
+	on_spawn(player)
+end)
+minetest.register_on_respawnplayer(function(player)
+	on_spawn(player)
+end)

mods/hades_safespawn/mod.conf

@@ -0,0 +1,2 @@
+name = hades_safespawn
+description = This mod detects unsafe spawn positions and tries to place the player at a safe one instead