From a7aaac904c18e52b988f0517ce7b1bc2097d42b4 Mon Sep 17 00:00:00 2001
From: Wuzzy <almikes@aol.com>
Date: Sun, 19 Feb 2017 23:32:54 +0100
Subject: [PATCH] Import flowlib by Qwertymine

---
 mods/CORE/flowlib/README.txt |   7 ++
 mods/CORE/flowlib/init.lua   | 146 +++++++++++++++++++++++++++++++++++
 mods/CORE/flowlib/mod.conf   |   1 +
 3 files changed, 154 insertions(+)
 create mode 100644 mods/CORE/flowlib/README.txt
 create mode 100644 mods/CORE/flowlib/init.lua
 create mode 100644 mods/CORE/flowlib/mod.conf

diff --git a/mods/CORE/flowlib/README.txt b/mods/CORE/flowlib/README.txt
new file mode 100644
index 0000000000..5425ce96e8
--- /dev/null
+++ b/mods/CORE/flowlib/README.txt
@@ -0,0 +1,7 @@
+Waterlib
+================
+Simple flow functions for use in Minetest mods by Qwertymine3
+
+License of source code:
+-----------------------
+WTFPL
diff --git a/mods/CORE/flowlib/init.lua b/mods/CORE/flowlib/init.lua
new file mode 100644
index 0000000000..96baf99b44
--- /dev/null
+++ b/mods/CORE/flowlib/init.lua
@@ -0,0 +1,146 @@
+flowlib = {}
+
+--sum of direction vectors must match an array index
+local function to_unit_vector(dir_vector)
+	--(sum,root)
+	-- (0,1), (1,1+0=1), (2,1+1=2), (3,1+2^2=5), (4,2^2+2^2=8)
+	local inv_roots = {[0] = 1, [1] = 1, [2] = 0.70710678118655, [4] = 0.5
+		, [5] = 0.44721359549996, [8] = 0.35355339059327}
+	local sum = dir_vector.x*dir_vector.x + dir_vector.z*dir_vector.z
+	return {x=dir_vector.x*inv_roots[sum],y=dir_vector.y
+		,z=dir_vector.z*inv_roots[sum]}
+end
+
+local is_touching = function(realpos,nodepos,radius)
+	local boarder = 0.5 - radius
+	return (math.abs(realpos - nodepos) > (boarder))
+end
+
+flowlib.is_touching = is_touching
+
+local is_water = function(pos)
+	return (minetest.get_item_group(minetest.get_node(
+			{x=pos.x,y=pos.y,z=pos.z}).name
+		, "water") ~= 0)
+end
+
+flowlib.is_water = is_water
+
+local node_is_water = function(node)
+	return (minetest.get_item_group(node.name, "water") ~= 0)
+end
+
+flowlib.node_is_water = node_is_water
+
+local is_lava = function(pos)
+	return (minetest.get_item_group(minetest.get_node(
+			{x=pos.x,y=pos.y,z=pos.z}).name
+		, "lava") ~= 0)
+end
+
+flowlib.is_lava = is_lava
+
+local node_is_lava = function(node)
+	return (minetest.get_item_group(node.name, "lava") ~= 0)
+end
+
+flowlib.node_is_lava = node_is_lava
+
+
+local is_liquid = function(pos)
+	return (minetest.get_item_group(minetest.get_node(
+			{x=pos.x,y=pos.y,z=pos.z}).name
+		, "liquid") ~= 0)
+end
+
+flowlib.is_liquid = is_liquid
+
+local node_is_liquid = function(node)
+	return (minetest.get_item_group(node.name, "liquid") ~= 0)
+end
+
+flowlib.node_is_liquid = node_is_liquid
+
+--This code is more efficient
+local function quick_flow_logic(node,pos_testing,direction)
+	local name = node.name
+	if minetest.registered_nodes[name].liquidtype == "source" then
+		local node_testing = minetest.get_node(pos_testing)
+		local param2_testing = node_testing.param2
+		if minetest.registered_nodes[node_testing.name].liquidtype 
+		~= "flowing" then
+			return 0
+		else
+			return direction
+		end
+	elseif minetest.registered_nodes[name].liquidtype == "flowing" then
+		local node_testing = minetest.get_node(pos_testing)
+		local param2_testing = node_testing.param2
+		if minetest.registered_nodes[node_testing.name].liquidtype 
+		== "source" then
+			return -direction
+		elseif minetest.registered_nodes[node_testing.name].liquidtype 
+		== "flowing" then
+			if param2_testing < node.param2 then
+				if (node.param2 - param2_testing) > 6 then
+					return -direction
+				else
+					return direction
+				end
+			elseif param2_testing > node.param2 then
+				if (param2_testing - node.param2) > 6 then
+					return direction
+				else
+					return -direction
+				end
+			end
+		end
+	end
+	return 0
+end
+
+local quick_flow = function(pos,node)
+	local x = 0
+	local z = 0
+	
+	if not node_is_liquid(node)  then
+		return {x=0,y=0,z=0}
+	end
+	
+	x = x + quick_flow_logic(node,{x=pos.x-1,y=pos.y,z=pos.z},-1)
+	x = x + quick_flow_logic(node,{x=pos.x+1,y=pos.y,z=pos.z}, 1)
+	z = z + quick_flow_logic(node,{x=pos.x,y=pos.y,z=pos.z-1},-1)
+	z = z + quick_flow_logic(node,{x=pos.x,y=pos.y,z=pos.z+1}, 1)
+	
+	return to_unit_vector({x=x,y=0,z=z})
+end
+
+flowlib.quick_flow = quick_flow
+
+
+	--if not in water but touching, move centre to touching block
+	--x has higher precedence than z
+	--if pos changes with x, it affects z
+local move_centre = function(pos,realpos,node,radius)
+	if is_touching(realpos.x,pos.x,radius) then
+		if is_liquid({x=pos.x-1,y=pos.y,z=pos.z}) then
+			node = minetest.get_node({x=pos.x-1,y=pos.y,z=pos.z})
+			pos = {x=pos.x-1,y=pos.y,z=pos.z}
+		elseif is_liquid({x=pos.x+1,y=pos.y,z=pos.z}) then
+			node = minetest.get_node({x=pos.x+1,y=pos.y,z=pos.z})
+			pos = {x=pos.x+1,y=pos.y,z=pos.z}
+		end
+	end
+	if is_touching(realpos.z,pos.z,radius) then
+		if is_liquid({x=pos.x,y=pos.y,z=pos.z-1}) then
+			node = minetest.get_node({x=pos.x,y=pos.y,z=pos.z-1})
+			pos = {x=pos.x,y=pos.y,z=pos.z-1}
+		elseif is_liquid({x=pos.x,y=pos.y,z=pos.z+1}) then
+			node = minetest.get_node({x=pos.x,y=pos.y,z=pos.z+1})
+			pos = {x=pos.x,y=pos.y,z=pos.z+1}
+		end
+	end
+	return pos,node
+end
+
+flowlib.move_centre = move_centre
diff --git a/mods/CORE/flowlib/mod.conf b/mods/CORE/flowlib/mod.conf
new file mode 100644
index 0000000000..0d982481c4
--- /dev/null
+++ b/mods/CORE/flowlib/mod.conf
@@ -0,0 +1 @@
+name = flowlib