pressure logic: add horizontally-rotating directional flowable helper

pressure_logic/flowable_node_registry_install.lua

@@ -66,6 +66,43 @@ register.directional_vertical_fixed = function(nodename, topside)
 	register.directional(nodename, neighbourfn, directionfn)
 end
 
+-- register a node as a directional flowable whose accepting sides depends upon param2 rotation.
+-- used for entry panels, valves, flow sensors and spigots,
+-- whose facing axis is always upwards and can only rotate horizontally.
+local iseastwest = function(node)
+	local data = node.param2
+	local rotation = data % 4
+	-- rotation 0 and 2 is the same axis, as is 1 and 3.
+	-- 0-3 starts at north and proceeds clockwise.
+	local axis = rotation % 2
+	--pipeworks.logger("iseastwest() rotation="..tostring(rotation).." axis="..tostring(axis))
+	return (axis == 1)
+end
+register.directional_horizonal_rotate = function(nodename)
+	local north = {x= 0,y= 0,z= 1}
+	local south = {x= 0,y= 0,z=-1}
+	local east =  {x= 1,y= 0,z= 0}
+	local west =  {x=-1,y= 0,z= 0}
+	local neighbourfn = function(node)
+		if iseastwest(node) then
+			return { east, west }
+		else
+			return { north, south }
+		end
+	end
+	local directionfn = function(node, direction)
+		local result = false
+		if iseastwest(node) then
+			--pipeworks.logger("horizontal rotate directionfn() eastwest=true")
+			result = vector.equals(direction, east) or vector.equals(direction, west)
+		else
+			result = vector.equals(direction, north) or vector.equals(direction, south)
+		end
+		return result
+	end
+	register.directional(nodename, neighbourfn, directionfn)
+end
+
 
 
 local checkbase = function(nodename)