Add mod real_suffocation with custom tweaks for CTF (#693)

* add mod 'real_suffocation'

* tiny nitpick, please squash

* remove deprecated description, move to mod.conf

* change license

* fix luacheck error

mods/other/real_suffocation/README.md

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+# Real Suffocation [`real_suffocation`]
+Version: 1.0.0
+
+This mod adds suffocation. Suffocation is basically the same as drowning, but it
+is for being stuck inside solid blocks. If you're inside a solid block, you lose
+breath. If you lost your breath completely and you're still inside, you suffer
+10 HP (=5 “hearts”) of damage every 2 seconds.
+
+Specifically, suffocation is added to all blocks which:
+
+* Are solid
+* Are full cubes
+* Don't already have built-in damage or drowning damage
+* Are not excluded from suffocations by mods
+
+## Info for modders
+This mod will not add suffocation to all nodes with the group
+`disable_suffocation=1`.
+
+This mod adds the group `real_suffocation=1` to all nodes it has modified,
+this is mostly done for informational purposes.
+
+## License
+Everything is under the MIT license. Forked from https://repo.or.cz/minetest_real_suffocation.git.

mods/other/real_suffocation/init.lua

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+-- Load setting
+local suffocation_damage = 2
+local setting = minetest.settings:get("real_suffocation_damage")
+if tonumber(setting) ~= nil then
+	suffocation_damage = tonumber(setting)
+end
+
+-- Skip the rest if suffocation damage is 0, no point in overwriting stuff
+if suffocation_damage > 0 then
+
+-- Checks all nodes and adds suffocation (drowning damage) for suitable nodes
+local function add_suffocation()
+	-- For debugging output
+	local suffocate_nodes = {}
+	local no_suffocate_nodes = {}
+	-- Check ALL the nodes!
+	for itemstring, def in pairs(minetest.registered_nodes) do
+		--[[ Here comes the HUGE conditional deciding whether we use suffocation. We want to catch as many nodes as possible
+		while avoiding bad nodes. We care mostly about physical properties, we don't care about visual appearance.
+		Here's what it checks and why:
+		- Walkable: Must be walkable, which means player can get stuck inside. If player can move freely, suffocation does not make sense
+		- Drowning and damage: If node has set any of those explicitly, it probably knows why. We don't want to mess with it.
+		- collision_box, node_box: Checks whether we deal with full-sized standard cubes, since only care about those.
+			Everything else is probably too small for suffocation to seem real.
+		- disable_suffocation group: If set to 1, we bail out. This makes it possible for nodes to defend themselves against hacking. :-)
+		]]
+		if (def.walkable == nil or def.walkable == true)
+		and (def.drowning == nil or def.drowning == 0)
+		and (def.damage_per_second == nil or def.damage_per_second <= 0)
+		and (def.collision_box == nil or def.collision_box.type == "regular")
+		and (def.node_box == nil or def.node_box.type == "regular")
+		and (def.groups.disable_suffocation ~= 1)
+		then
+			-- Add “real_suffocation” group so other mods know this node was touched by this mod
+			local marked_groups = def.groups
+			marked_groups.real_suffocation = 1
+			-- Let's hack the node!
+			minetest.override_item(itemstring, { drowning = suffocation_damage, groups = marked_groups })
+			table.insert(suffocate_nodes, itemstring)
+		else
+			table.insert(no_suffocate_nodes, itemstring)
+		end
+	end
+	minetest.log("info", "[real_suffocation] Suffocation has been hacked into "..#suffocate_nodes.." nodes.")
+	minetest.log("verbose", "[real_suffocation] Nodes with suffocation: "..dump(suffocate_nodes))
+	minetest.log("verbose", "[real_suffocation] Suffocation has not been hacked into "..#no_suffocate_nodes.." nodes: "..dump(no_suffocate_nodes))
+end
+
+-- This is a minor hack to make sure our loop runs after all nodes have been registered
+minetest.after(0, add_suffocation)
+
+end
+
+minetest.register_on_joinplayer(function(player)
+    player:set_properties({max_breath = 10})
+end)

mods/other/real_suffocation/mod.conf

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+name = real_suffocation
+description = The player will lose breath inside solid blocks.

mods/other/real_suffocation/settingtypes.txt

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+# How much damage is caused by “suffocation” by default, that is, running
+# out of breath while being inside solid blocks like dirt, gravel, sand,
+# etc. Like for drowning, damage is caused every 2 seconds.
+real_suffocation_damage (Suffocation damage) int 2 0