Add workaround to unload wagons that are too far away from players

advtrains/init.lua

@@ -39,6 +39,12 @@ AT_CMAX = 16
 
 advtrains = {trains={}, player_to_train_mapping={}}
 
+-- get wagon loading range
+advtrains.wagon_load_range = tonumber(minetest.settings:get("advtrains_wagon_load_range"))
+if not advtrains.wagon_load_range then
+	advtrains.wagon_load_range = tonumber(minetest.settings:get("active_block_range"))*16
+end
+
 --pcall
 local no_action=false
 

advtrains/settingtypes.txt

@@ -39,3 +39,9 @@ advtrains_prot_range_down (Track protection range [down]) int 1 0 10
 #    drop: Player is killed, all items are dropped as items on the tracks.
 #    normal: Player is killed, game-defined behavior is applied as if the player died by other means.
 advtrains_overrun_mode (Overrun mode) enum drop none,drop,normal
+
+#    Wagon entity loading/unloading range, in nodes
+#    When a wagon is within this range to a player, it is loaded
+#    When a wagon leaves this range + 32 nodes, it is unloaded
+#    If unset, defaults to active_block_range*16
+advtrains_wagon_load_range (Wagon Entity Load/Unload Range) int 96 32 512

advtrains/trainlogic.lua

@@ -851,7 +851,7 @@ function advtrains.update_trainpart_properties(train_id, invert_flipstate)
 end
 
 
-local ablkrng = minetest.settings:get("active_block_range")*16
+local ablkrng = advtrains.wagon_load_range
 -- This function checks whether entities need to be spawned for certain wagons, and spawns them.
 -- Called from train_step_*(), not required to check init.
 function advtrains.spawn_wagons(train_id)
@@ -862,7 +862,7 @@ function advtrains.spawn_wagons(train_id)
 		local data = advtrains.wagons[w_id]
 		if data then
 			if data.train_id ~= train_id then
-				atwarn("Train",train_id,"Wagon #",1,": Saved train ID",data.train_id,"did not match!")
+				atwarn("Train",train_id,"Wagon #",i,": Saved train ID",data.train_id,"did not match!")
 				data.train_id = train_id
 			end
 			if not advtrains.wagon_objects[w_id] or not advtrains.wagon_objects[w_id]:getyaw() then
@@ -878,6 +878,7 @@ function advtrains.spawn_wagons(train_id)
 				end
 				
 				if spawn then
+					--atdebug("wagon",w_id,"spawning")
 					local wt = advtrains.get_wagon_prototype(data)
 					local wagon = minetest.add_entity(pos, wt):get_luaentity()
 					wagon:set_id(w_id)

advtrains/wagons.lua

@@ -14,6 +14,8 @@ advtrains.wagons = {}
 advtrains.wagon_prototypes = {}
 advtrains.wagon_objects = {}
 
+local unload_wgn_range = advtrains.wagon_load_range + 32
+
 local setting_show_ids = minetest.settings:get_bool("advtrains_show_ids")
 
 --
@@ -473,8 +475,29 @@ function wagon:on_step(dtime)
 			yaw=yaw+math.pi
 		end
 		
+		-- this timer runs off every 2 seconds.
 		self.updatepct_timer=(self.updatepct_timer or 0)-dtime
 		local updatepct_timer_elapsed = self.updatepct_timer<=0
+		
+		if updatepct_timer_elapsed then
+			--restart timer
+			self.updatepct_timer=2
+			-- perform checks that are not frequently needed
+			
+			-- unload entity if out of range (because relevant pr won't be merged in engine)
+			-- This is a WORKAROUND!
+			local outofrange = false
+			for _,p in pairs(minetest.get_connected_players()) do
+				if vector.distance(p:get_pos(),pos)>=unload_wgn_range then
+					outofrange = true
+				end
+			end
+			if outofrange then
+				--atdebug("wagon",self.id,"unloading (too far away)")
+				self.object:remove()
+			end
+		end
+		
 		if not self.old_velocity_vector 
 				or not vector.equals(velocityvec, self.old_velocity_vector)
 				or not self.old_acceleration_vector 
@@ -520,7 +543,6 @@ function wagon:on_step(dtime)
                 self.object:setyaw(yaw)
             end
 			
-			self.updatepct_timer=2
 			if self.update_animation then
 				self:update_animation(train.velocity, self.old_velocity)
 			end