From c504577227409218aa80722dc1b222e2bb74efa0 Mon Sep 17 00:00:00 2001
From: OldCoder <me@minetest.org>
Date: Sun, 4 Sep 2022 22:03:06 -0700
Subject: [PATCH] Imported from trollstream "ContentDB"

---
 README.md      | 30 +++++++++++++++++++
 init.lua       | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++
 mod.conf       |  1 +
 twmlib_api.txt | 33 +++++++++++++++++++++
 4 files changed, 144 insertions(+)
 create mode 100644 README.md
 create mode 100644 init.lua
 create mode 100644 mod.conf
 create mode 100644 twmlib_api.txt

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..974ce76
--- /dev/null
+++ b/README.md
@@ -0,0 +1,30 @@
+Timed World Modifiers library
+=============================
+
+* Version 0.1
+* Licence LGPLv2 or, at your discretion, any later version.
+
+Twmlib (Timed World Modifier) adds a kind of environmental ABM that could be triggered on a very wide range of nodes but only a few at a time.
+See twmlib_api.txt for documentation.
+
+
+Licence
+-------
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation, either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+https://www.gnu.org/licenses/licenses.html#LGPL
+
+
+Authors of source code
+----------------------
+
+Karamel
diff --git a/init.lua b/init.lua
new file mode 100644
index 0000000..cc9e0d7
--- /dev/null
+++ b/init.lua
@@ -0,0 +1,80 @@
+
+twmlib = {}
+twmlib.registered_twm = {}
+function twmlib.next_interval()
+	return tonumber(minetest.settings:get("twmlib.interval")) or 2
+end
+local mod_path = minetest.get_modpath(minetest.get_current_modname())
+
+function twmlib.register_twm(twm_definition)
+	for _, nodename in ipairs(twm_definition.nodenames) do
+		if twmlib.registered_twm[nodename] == nil then
+			twmlib.registered_twm[nodename] = {}
+		end
+		table.insert(twmlib.registered_twm[nodename], twm_definition)
+	end
+end
+
+
+local range = (minetest.settings:get("active_block_range") or 3) * 16
+local function loop()
+	-- Take one player at random
+	local players = minetest.get_connected_players()
+	if #players == 0 then return end -- players not loaded yet
+	local picked = players[math.random(1, #players)]
+	-- Take a random position around
+	local pos = picked:get_pos()
+	if not pos then return end -- player not positioned yet
+	pos.y = pos.y + math.random(-range, range)
+	pos.x = pos.x + math.random(-range, range)
+	pos.z = pos.z + math.random(-range, range)
+	local rand_pos = vector.new(pos.x, pos.y, pos.z)
+	local node = minetest.get_node(rand_pos)
+	if node.name == "air" then
+		-- go up or down a few times until something is found
+		local dy = (math.random() > 0.5)
+		if dy then
+			dy = 1
+		else
+			dy = -1
+		end
+		local i = 0
+		while i < range / 2 and node.name == "air" do
+			rand_pos = vector.add(rand_pos, vector.new(0, dy, 0))
+			node = minetest.get_node(rand_pos)
+			i = i + 1
+		end
+	end
+	if node.name == "air" or node.name == "ignore" then return end
+	-- look for a registered twm for the node or group
+	if twmlib.registered_twm[node.name] then
+		-- trigger twm by node
+		for _, def in ipairs(twmlib.registered_twm[node.name]) do
+			if def.chance then
+				if math.random(1, def.chance) == 1 then
+					def.action(rand_pos, node)
+				end
+			else
+				def.action(rand_pos, node)
+			end
+		end
+	end
+	local node_def = minetest.registered_nodes[node.name]
+	for group, level in ipairs(node_def.groups) do
+		local str_group = "group:" .. group
+		if twmlib.registered_twm[str_group] then
+			-- trigger twm by group
+			for _, def in ipairs(twmlib.registered_twm[str_group]) do
+				if def.chance then
+					if math.random(1, def.chance) == 1 then
+						def.action(rand_pos, node)
+					end
+				else
+					def.action(rand_pos, node)
+				end
+			end
+		end
+	end
+	minetest.after(twmlib.next_interval(), loop)
+end
+minetest.after(twmlib.next_interval(), loop)
diff --git a/mod.conf b/mod.conf
new file mode 100644
index 0000000..d59c36d
--- /dev/null
+++ b/mod.conf
@@ -0,0 +1 @@
+description = Timed World Modifiers, triggers on random nodes library
diff --git a/twmlib_api.txt b/twmlib_api.txt
new file mode 100644
index 0000000..092b08a
--- /dev/null
+++ b/twmlib_api.txt
@@ -0,0 +1,33 @@
+Twmlib Lua API
+==============
+
+Table of contents
+-- Introduction
+-- API
+---- twmlib.register_twm
+-- TWM definition
+
+
+Introduction
+------------
+
+Twmlib (Timed World Modifier) adds a kind of environmental ABM that could be triggered on a very wide range of nodes but only a few at a time.
+
+On a regular and rather short interval, a random node is picked around a player. If this node has a registered TWM, it can be triggered.
+
+
+API
+---
+
+### twmlib.register_twm(twm_definition)
+
+* `twm_definition` see below
+
+TWM definition
+--------------
+
+A TWM definition is like an ABM definition.
+
+* `nodenames` a table of node names, that can include groups with "group:<name>" rather than simple node name.
+* `chance` optional inverted chance of the TWM to be triggered. Default it 1.
+* `action` the function(pos, node) to be called when the TWM is triggered.