Add airlike backend command, but it's nto tested or hooked up yet

worldeditadditions/lib/airapply.lua

@@ -0,0 +1,56 @@
+--  █████  ██ ██████
+-- ██   ██ ██ ██   ██
+-- ███████ ██ ██████
+-- ██   ██ ██ ██   ██
+-- ██   ██ ██ ██   ██
+-- 
+--  █████  ██████  ██████  ██   ██    ██
+-- ██   ██ ██   ██ ██   ██ ██    ██  ██
+-- ███████ ██████  ██████  ██     ████
+-- ██   ██ ██      ██      ██      ██
+-- ██   ██ ██      ██      ███████ ██
+
+--- Similar to cubeapply, except that it takes 2 positions and only keeps an ellipsoid-shaped area defined by the boundaries of the defined region.
+-- Takes a backup copy of the defined region, runs the given function, and then
+-- restores the bits around the edge that aren't inside the largest ellipsoid that will fit inside the defined region.
+-- @param	{Position}	pos1	The 1st position defining the region boundary
+-- @param	{Position}	pos2	The 2nd positioon defining the region boundary 
+-- @param	{Function}	func	The function to call that performs the action in question. It is expected that the given function will accept no arguments.
+function worldeditadditions.airapply(pos1, pos2, func)
+	local time_taken_all = worldeditadditions.get_ms_time()
+	pos1, pos2 = worldedit.sort_pos(pos1, pos2)
+	-- pos2 will always have the highest co-ordinates now
+	
+	-- Fetch the nodes in the specified area
+	local manip_before, area_before = worldedit.manip_helpers.init(pos1, pos2)
+	local data_before = manip_before:get_data()
+	
+	local time_taken_fn = worldeditadditions.get_ms_time()
+	func()
+	time_taken_fn = worldeditadditions.get_ms_time() - time_taken_fn
+	
+	local manip_after, area_after = worldedit.manip_helpers.init(pos1, pos2)
+	local data_after = manip_after:get_data()
+	
+	for z = pos2.z, pos1.z, -1 do
+		for y = pos2.y, pos1.y, -1 do
+			for x = pos2.x, pos1.x, -1 do
+				local i = area:index(x, y, z)
+				local old_is_airlike = worldeditadditions.is_airlike(data_before[i])
+				
+				-- Roll everything that replaces nodes that aren't airlike
+				if not old_is_airlike then
+					data_after[area_after:index(x, y, z)] = data_before[area_before:index(x, y, z)]
+				end
+			end
+		end
+	end
+	
+	-- Save the modified nodes back to disk & return
+	-- No need to save - this function doesn't actually change anything
+	worldedit.manip_helpers.finish(manip_after, data_after)
+	
+	
+	time_taken_all = worldeditadditions.get_ms_time() - time_taken_all
+	return true, { all = time_taken_all, fn = time_taken_fn }
+end