Make furnace work even when unloaded

mods/default/furnace.lua

@@ -163,6 +163,7 @@ minetest.register_abm({
 		local fuel_time = meta:get_float("fuel_time") or 0
 		local src_time = meta:get_float("src_time") or 0
 		local fuel_totaltime = meta:get_float("fuel_totaltime") or 0
+		local last_gametime = meta:get_float("last_gametime") or minetest.get_gametime()
 		
 		--
 		-- Inizialize inventory
@@ -185,57 +186,83 @@ minetest.register_abm({
 		-- Cooking
 		--
 
-		-- Check if we have cookable content
+		local cooked, aftercooked, cookable
-		local cooked, aftercooked = minetest.get_craft_result({method = "cooking", width = 1, items = srclist})
-		local cookable = true
 
-		if cooked.time == 0 then
+		-- Get the time delta between last run
-			cookable = false
+		local delta = minetest.get_gametime() - last_gametime
-		end
+		last_gametime = minetest.get_gametime()
 
-		-- Check if we have enough fuel to burn
+		-- Simulate the furnace for delta seconds
-		if fuel_time < fuel_totaltime then
+		repeat
-			-- The furnace is currently active and has enough fuel
+			-- Check if we still have cookable content
-			fuel_time = fuel_time + 1
+			cooked, aftercooked = minetest.get_craft_result({method = "cooking", width = 1, items = srclist})
+			cookable = cooked.time ~= 0
 
-			-- If there is a cookable item then check if it is ready yet
+			-- Determine appropriate time step size
-			if cookable then
+			local step = delta
-				src_time = src_time + 1
+			local fuel_left = fuel_totaltime - fuel_time
-				if src_time >= cooked.time then
+			if fuel_totaltime ~= 0 then
-					-- Place result in dst list if possible
+				if fuel_left > 0 then
-					if inv:room_for_item("dst", cooked.item) then
+					-- There is fuel left, step to the time when the cookable item is ready OR when the fuel dies, whichever is nearest
-						inv:add_item("dst", cooked.item)
+					if cookable then
-						inv:set_stack("src", 1, aftercooked.items[1])
+						local src_left = cooked.time - src_time
-						src_time = 0
+						step = math.min(delta, fuel_left, src_left)
+					else
+						step = math.min(delta, fuel_left)
 					end
+				elseif cookable then
+					-- No fuel left, replacing costs 1 second
+					step = 1
 				end
 			end
-		else
+			delta = delta - step
-			-- Furnace ran out of fuel
-			if cookable then
-				-- We need to get new fuel
-				local fuel, afterfuel = minetest.get_craft_result({method = "fuel", width = 1, items = fuellist})
 
-				if fuel.time == 0 then
+			-- Check if we have enough fuel to burn
-					-- No valid fuel in fuel list
+			if fuel_time < fuel_totaltime then
+				-- The furnace is currently active and has enough fuel
+				fuel_time = fuel_time + step
+				
+				-- If there is a cookable item then check if it is ready yet
+				if cookable then
+					src_time = src_time + step
+					if src_time >= cooked.time then
+						-- Place result in dst list if possible
+						if inv:room_for_item("dst", cooked.item) then
+							inv:add_item("dst", cooked.item)
+							inv:set_stack("src", 1, aftercooked.items[1])
+							srclist = inv:get_list("src")
+							src_time = 0
+						end
+					end
+				end
+			else
+				-- Furnace ran out of fuel
+				if cookable then
+					-- We need to get new fuel
+					local fuel, afterfuel = minetest.get_craft_result({method = "fuel", width = 1, items = fuellist})
+					
+					if fuel.time == 0 then
+						-- No valid fuel in fuel list
+						fuel_totaltime = 0
+						fuel_time = 0
+						src_time = 0
+					else
+						-- Take fuel from fuel list
+						inv:set_stack("fuel", 1, afterfuel.items[1])
+						fuellist = inv:get_list("fuel")
+						
+						fuel_totaltime = fuel.time
+						fuel_time = 0
+						
+					end
+				else
+					-- We don't need to get new fuel since there is no cookable item
 					fuel_totaltime = 0
 					fuel_time = 0
 					src_time = 0
-				else
-					-- Take fuel from fuel list
-					inv:set_stack("fuel", 1, afterfuel.items[1])
-					
-					fuel_totaltime = fuel.time
-					fuel_time = 0
-					
 				end
-			else
-				-- We don't need to get new fuel since there is no cookable item
-				fuel_totaltime = 0
-				fuel_time = 0
-				src_time = 0
 			end
-		end
+		until delta <= 0
 		
 		--
 		-- Update formspec, infotext and node
@@ -274,6 +301,7 @@ minetest.register_abm({
 		--
 		-- Set meta values
 		--
+		meta:set_float("last_gametime", last_gametime)
 		meta:set_float("fuel_totaltime", fuel_totaltime)
 		meta:set_float("fuel_time", fuel_time)
 		meta:set_float("src_time", src_time)