Lift orientation functions from screwdriver2 mod

Ref @12Me21 https://github.com/12Me21/screwdriver2/blob/master/init.lua#L75-L79
Ref @khonkhortisan https://forum.minetest.net/viewtopic.php?p=73195&sid=1d2d2e4e76ce2ef9c84646481a4b84bc#p73195

....if either of you have an issue with this, please get in touch! The licence seems to allow this lifting and relicencing like this (given it's WTFPL as of the time of typing), but correct me if I'm wrong.

For reference, WorldEditAdditions is currently licenced under the Mozilla Public License Version 2.0.

worldeditadditions_core/init.lua

@@ -30,6 +30,7 @@ wea_c.Set = dofile(wea_c.modpath.."/utils/set.lua")
 wea_c.Vector3 = dofile(wea_c.modpath.."/utils/vector3.lua")
 wea_c.Mesh, wea_c.Face = dofile(wea_c.modpath.."/utils/mesh.lua")
 wea_c.rotation = dofile(wea_c.modpath .. "/utils/rotation.lua")
+wea_c.orientation = dofile(wea_c.modpath .. "/utils/orientation.lua")
 wea_c.param2 = dofile(wea_c.modpath .. "/utils/param2.lua")
 
 wea_c.Queue = dofile(wea_c.modpath.."/utils/queue.lua")

worldeditadditions_core/utils/orientation.lua

@@ -0,0 +1,72 @@
+
+
+-- This file is based on code from the screwdriver2 mod and a forum post on the Minetest forums. By @12Me21 and @khonkhortisan
+-- Edited by @sbrl
+-- Ref https://github.com/12Me21/screwdriver2/blob/master/init.lua#L75-L79
+-- Ref https://forum.minetest.net/viewtopic.php?p=73195&sid=1d2d2e4e76ce2ef9c84646481a4b84bc#p73195
+
+local facedir_cycles = {
+	x = { { 12, 13, 14, 15 }, { 16, 19, 18, 17 }, { 0, 4, 22, 8 }, { 1, 5, 23, 9 }, { 2, 6, 20, 10 }, { 3, 7, 21, 11 } },
+	y = { { 0, 1, 2, 3 }, { 20, 23, 22, 21 }, { 4, 13, 10, 19 }, { 8, 17, 6, 15 }, { 12, 9, 18, 7 }, { 16, 5, 14, 11 } },
+	z = { { 4, 5, 6, 7 }, { 8, 11, 10, 9 }, { 0, 16, 20, 12 }, { 1, 17, 21, 13 }, { 2, 18, 22, 14 }, { 3, 19, 23, 15 } },
+}
+local wallmounted_cycles = {
+	x = { 0, 4, 1, 5 },
+	y = { 4, 2, 5, 3 },
+	z = { 0, 3, 1, 2 },
+}
+
+-- We have standardised on radians for other rotation operations, so it wouldn't make sense for the API-facing functions in this file to use a number of times or degrees, as this would be inconsistent
+function convert_normalise_rad(rad)
+	local deg = math.deg(rad)
+	local times = worldeditadditions_core.round(deg / 90)
+	return math.floor(times) -- ensure it's an integer and not e.g. a float 1.0
+end
+
+--- Functions to rotate a facedir/wallmounted value around an axis by a certain amount
+-- 
+-- Code lifted from @12Me21 and @khonkhortisan
+-- 
+-- Ref <https://github.com/12Me21/screwdriver2/blob/master/init.lua#L75-L79> and <https://forum.minetest.net/viewtopic.php?p=73195&sid=1d2d2e4e76ce2ef9c84646481a4b84bc#p73195>
+-- @namespace worldeditadditions_core.orientation
+local orientation = {
+	--- Facedir: lower 5 bits used for direction, 0 - 23
+	-- @param	param2	number	`param2` value to rotate.
+	-- @param	axis	string	The name of the axis to rotate around. Valid values: `x`, `y`, `z`
+	-- @param	amount	The number of radians to rotate around the given `axis`. Only right angles are supported (i.e. 90° increments). Any value that isn't a 90° increment will be **rounded**!
+	-- @returns	number	A new param2 value that is rotated the given number of degrees around the given `axis`
+	facedir = function(param2, axis, amount_rad)
+		local amount = convert_normalise_rad(amount_rad)
+		print("DEBUG:core/orientation:facedir AMOUNT rad "..tostring(amount_rad).." norm "..tostring(amount))
+		local facedir = param2 % 32
+		for _, cycle in ipairs(facedir_cycles[axis]) do
+			-- Find the current facedir
+			-- Minetest adds table.indexof, but I refuse to use it because it returns -1 rather than nil
+			for i, fd in ipairs(cycle) do
+				if fd == facedir then
+					return param2 - facedir + cycle[1 + (i - 1 + amount) % 4] -- If only Lua didn't use 1 indexing...
+				end
+			end
+		end
+		return param2
+	end,
+	-- Wallmounted: lower 3 bits used, 0 - 5
+	wallmounted = function(param2, axis, amount_rad)
+		local amount = convert_normalise_rad(amount_rad)
+		print("DEBUG:core/orientation:wallmounted AMOUNT rad " .. tostring(amount_rad) .. " norm " .. tostring(amount))
+		
+		local wallmounted = param2 % 8
+		for i, wm in ipairs(wallmounted_cycles[axis]) do
+			if wm == wallmounted then
+				return param2 - wallmounted + wallmounted_cycles[axis][1 + (i - 1 + amount) % 4]
+			end
+		end
+		return param2
+	end
+}
+-- From the original codebase (linked above):
+--orientation.colorfacedir = orientation.facedir
+--orientation.colorwallmounted = orientation.wallmounted
+-- ...we'll need to know this later
+
+return orientation