Add configurable globalstep interval (#32)

* Add configurable globalstep interval

* Add warning for high globalstep interval

* Lower maximum globalstep interval

With no accelerator tubes, 0.8 can handle item movement speeds even
with lag.

default_settings.lua

@@ -28,6 +28,7 @@ local settings = {
 	drop_on_routing_fail = false,
 	delete_item_on_clearobject = true,
 	use_real_entities = true,
+	entity_update_interval = 0,
 }
 
 pipeworks.toggles = {}
@@ -63,10 +64,9 @@ pipeworks.toggles.finite_water = nil
 for name, value in pairs(settings) do
 	local setting_type = type(value)
 	if setting_type == "boolean" then
-		pipeworks[name] = minetest.settings:get_bool(prefix..name)
-		if pipeworks[name] == nil then
-			pipeworks[name] = value
-		end
+		pipeworks[name] = minetest.settings:get_bool(prefix..name, value)
+	elseif setting_type == "number" then
+		pipeworks[name] = tonumber(minetest.settings:get(prefix..name) or value)
 	else
 		pipeworks[name] = value
 	end

init.lua

@@ -32,6 +32,9 @@ end
 if pipeworks.toggles.pipe_mode == "pressure" then
 	minetest.log("warning", "pipeworks pressure logic mode comes with caveats and differences in behaviour, you have been warned!")
 end
+if pipeworks.entity_update_interval >= 0.2 and pipeworks.enable_accelerator_tube then
+	minetest.log("warning", "pipeworks accelerator tubes will not entirely work with an entity update interval 0.2 or above.")
+end
 
 -- Random variables
 

luaentity.lua

@@ -382,13 +382,36 @@ local move_entities_globalstep_part2 = function(dtime)
 	end
 end
 
-local handle_active_blocks_timer = 0.1
+-- dtime after which there is an update (or skip).
+local dtime_threshold = pipeworks.entity_update_interval
+-- Accumulated dtime since last update (or skip).
+local dtime_accum = 0
+-- Delayed dtime accumulated due to skipped updates.
+local dtime_delayed = 0
+local skip_update = false
 
 minetest.register_globalstep(function(dtime)
-	handle_active_blocks_timer = handle_active_blocks_timer + dtime
-	if dtime < 0.2 or handle_active_blocks_timer >= (dtime * 3) then
-		handle_active_blocks_timer = 0.1
-		move_entities_globalstep_part1(dtime)
-		move_entities_globalstep_part2(dtime)
+	if dtime >= 0.2 and dtime_delayed < 1 then
+		-- Reduce activity when the server is lagging.
+		skip_update = true
 	end
+
+	dtime_accum = dtime_accum + dtime
+	if dtime_accum < dtime_threshold then
+		return
+	end
+
+	if skip_update then
+		dtime_delayed = dtime_delayed + dtime_accum
+		skip_update = false
+	else
+		move_entities_globalstep_part1(dtime_accum + dtime_delayed)
+		move_entities_globalstep_part2(dtime_accum + dtime_delayed)
+		dtime_delayed = 0
+	end
+
+	-- Tune the threshold so that the average interval is pipeworks.entity_update_interval.
+	dtime_threshold = math.max(dtime_threshold + (pipeworks.entity_update_interval - dtime_accum) / 10, 0)
+
+	dtime_accum = 0
 end)

settingtypes.txt

@@ -78,4 +78,9 @@ pipeworks_delete_item_on_clearobject (Delete Item On Clearobject) bool true
 
 #Use real visible entities in tubes within active areas.
 #When disabled, tubes are made opaque.
-pipeworks_use_real_entities (Use real entities) bool true
+pipeworks_use_real_entities (Use Real Entities) bool true
+
+#Target interval between tube entity steps.
+#A high value may cause issues with tube entity visuals.
+#A value 0.2 or above may cause issues with accelerator tubes.
+pipeworks_entity_update_interval (Entity Update Interval) float 0 0 0.8