Improved grates - water flowing IN from the side can now flow OUT downwards.

grate.lua

@@ -14,17 +14,12 @@ local function grate_step(pos, offset)
 	if neigh_node then neigh_name = neigh_node.name else return end
 	local neigh_def = minetest.registered_nodes[neigh_name]
 	if not neigh_def then return end -- Unknown nodes can't flow.
-	if not neigh_def.liquidtype then return end -- Non-liquids can't flow at all.
-	
-	--print("Neighbor is liquid.")
+	if neigh_def.liquidtype ~= "source" and neigh_def.liquidtype ~= "flowing" then return end -- Non-liquids can't flow at all.
 	
 	-- Check its level.
 	local level = neigh_node.param2 % 16
-	if level < 8 then level = level * 2 end
+	if level < 8 then level = level * 2 else level = (level - 8) * 2 end
 	if neigh_def.liquidtype == "source" then level = 16 end
-	if level < 2 then return end -- Level < 2 water stops flowing within two blocks.
-	
-	--print("Neighbor is high enough level.")
 	
 	-- Check the opposing neighbor.
 	local opposite = vector.subtract(pos, offset)
@@ -44,18 +39,45 @@ local function grate_step(pos, offset)
 		
 		if opposite_level > level - 2 or opposite_def.liquidtype == "source" then return end
 	end -- Liquids can't flow into higher level liquids.
-	
-	--print("Opposite is floodable.")
-	
 	local neigh_flowing = neigh_def.liquid_alternative_flowing
 	if not neigh_flowing then return end -- Improperly configured liquids can't flow.
 	
-	--print("Liquid is configured properly.")
+	local flow_to = opposite
 	
-	minetest.set_node(opposite, {
+	if vector.equals(offset, {x=0, y=-1, z=0}) then
+		-- Silly code, water can't flow UP!
+		return
+	elseif vector.equals(offset, {x=0, y=1, z=0}) then
+		-- Water is very good at flowing down. Set to a high value.
+		minetest.set_node(flow_to, {
+			name = neigh_flowing,
+			param1 = neigh_node.param1,
+			param2 = 6
+		})
+		return
+	else
+		-- Great, water is flowing from the side, but what if the grate is above air?
+		-- We should check if the water can flow down, first.
+		local grav = vector.subtract(pos, {x=0, y=1, z=0})
+		local grav_node = minetest.get_node(grav)
+		local grav_name
+		if grav_node then grav_name = grav_node.name end
+		
+		-- Meet the grav_node - the node that's below the grate.
+		-- If liquids can flow into this node, we can forget about the opposite_node.
+		
+		if grav_node and grav_name == "air" then
+			-- OOP! Sudden course change!
+			flow_to = grav
+		end
+	end
+	
+	local new_param2 = neigh_def.liquidtype == "source" and 6 or neigh_node.param2 - 2
+	if new_param2 < 1 then return end
+	minetest.set_node(flow_to, {
 		name = neigh_flowing,
 		param1 = neigh_node.param1,
-		param2 = --[[neigh_node.param2 == 0]]neigh_def.liquidtype == "source" and 6 or neigh_node.param2 - 2
+		param2 = new_param2
 	})
 end
 
@@ -66,15 +88,15 @@ minetest.register_abm({
 	interval = 1,
 	chance = 1,
 	action = function (pos, node)
-		for i=1,6 do -- For each of our 6 neighbors,
+		for i=1,5 do -- For each of our 5 neighbors, (excluding the node from below, of course)
 			-- Calculate where our neighbor is
 			local offset = {x=0,y=0,z=0}
 			if i == 1 then offset.y = 1 end
-			if i == 2 then offset.y = -1 end
-			if i == 3 then offset.x = 1 end
-			if i == 4 then offset.x = -1 end
-			if i == 5 then offset.z = 1 end
-			if i == 6 then offset.z = -1 end
+			--if i == 2 then offset.y = -1 end
+			if i == 2 then offset.x = 1 end
+			if i == 3 then offset.x = -1 end
+			if i == 4 then offset.z = 1 end
+			if i == 5 then offset.z = -1 end
 			 -- Then run the checking code
 			grate_step(pos, offset)
 		end