Discard get_node_or_nil() for area-loaded check and use either a distance-based approach or minetest.is_block_active() if available

See also https://github.com/minetest/minetest/pull/10897

advtrains/couple.lua

@@ -106,7 +106,7 @@ minetest.register_entity("advtrains:couple", {
 	end,
 	on_step=function(self, dtime)
 		return advtrains.pcall(function()
-			if advtrains.outside_range(self.object:getpos()) then
+			if advtrains.wagon_outside_range(self.object:getpos()) then
 				self.object:remove()
 				return
 			end

advtrains/helpers.lua

@@ -445,3 +445,28 @@ atdebug("pts",os.clock()-t1,"s")
 ]]
 
 
+-- Function to check whether a position is near (within range of) any player
+function advtrains.position_in_range(pos, range)
+	if not pos then
+		return true
+	end
+	for _,p in pairs(minetest.get_connected_players()) do
+		if vector.distance(p:get_pos(),pos)<=range then
+			return true
+		end
+	end
+	return false
+end
+
+local active_node_range = tonumber(minetest.settings:get("active_block_range"))*16 + 16
+-- Function to check whether node at position(pos) is "loaded"/"active"
+-- That is, whether it is within the active_block_range to a player
+if minetest.is_block_active then -- define function differently whether minetest.is_block_active is available or not
+	advtrains.is_node_loaded = minetest.is_block_active
+else
+	function advtrains.is_node_loaded(pos)
+		if advtrains.position_in_range(pos, active_node_range) then
+			return true
+		end
+	end
+end

advtrains/nodedb.lua

@@ -223,7 +223,7 @@ end
 
 
 function ndb.swap_node(pos, node, no_inval)
-	if minetest.get_node_or_nil(pos) then
+	if advtrains.is_node_loaded(pos) then
 		minetest.swap_node(pos, node)
 	end
 	ndb.update(pos, node)

advtrains/trainlogic.lua

@@ -527,7 +527,7 @@ function advtrains.train_step_c(id, train, dtime)
 		local collpos = advtrains.path_get(train, atround(collindex))
 		if collpos then
 			local rcollpos=advtrains.round_vector_floor_y(collpos)
-			local is_loaded_area = minetest.get_node_or_nil(rcollpos) ~= nil
+			local is_loaded_area = advtrains.is_node_loaded(rcollpos)
 			for x=-train.extent_h,train.extent_h do
 				for z=-train.extent_h,train.extent_h do
 					local testpos=vector.add(rcollpos, {x=x, y=0, z=z})
@@ -870,14 +870,7 @@ function advtrains.spawn_wagons(train_id)
 				local index = advtrains.path_get_index_by_offset(train, train.index, -data.pos_in_train)
 				local pos   = advtrains.path_get(train, atfloor(index))
 				
-				local spawn = false
-				for _,p in pairs(minetest.get_connected_players()) do
-					if vector.distance(p:get_pos(),pos)<=ablkrng then
-						spawn = true
-					end
-				end
-				
-				if spawn then
+				if advtrains.position_in_range(pos, ablkrng) then
 					--atdebug("wagon",w_id,"spawning")
 					local wt = advtrains.get_wagon_prototype(data)
 					local wagon = minetest.add_entity(pos, wt):get_luaentity()
@@ -1032,7 +1025,7 @@ function advtrains.train_check_couples(train)
 	if not train.cpl_front then
 		-- recheck front couple
 		local front_trains, pos = advtrains.occ.get_occupations(train, atround(train.index) + CPL_CHK_DST)
-		if minetest.get_node_or_nil(pos) then -- if the position is loaded...
+		if advtrains.is_node_loaded(pos) then -- if the position is loaded...
 			for tid, idx in pairs(front_trains) do
 				local other_train = advtrains.trains[tid]
 				if not advtrains.train_ensure_init(tid, other_train) then
@@ -1062,7 +1055,7 @@ function advtrains.train_check_couples(train)
 	if not train.cpl_back then
 		-- recheck back couple
 		local back_trains, pos = advtrains.occ.get_occupations(train, atround(train.end_index) - CPL_CHK_DST)
-		if minetest.get_node_or_nil(pos) then -- if the position is loaded...
+		if advtrains.is_node_loaded(pos) then -- if the position is loaded...
 			for tid, idx in pairs(back_trains) do
 				local other_train = advtrains.trains[tid]
 				if not advtrains.train_ensure_init(tid, other_train) then

advtrains/wagons.lua

@@ -15,19 +15,8 @@ advtrains.wagon_prototypes = {}
 advtrains.wagon_objects = {}
 
 local unload_wgn_range = advtrains.wagon_load_range + 32
-function advtrains.outside_range(pos) -- returns true if the object is outside of unload_wgn_range of any player
-	-- this is part of a workaround until mintest core devs decide to fix a bug with static_save=false.
-	local outofrange = true
-	if not pos then
-		return true
-	end
-	for _,p in pairs(minetest.get_connected_players()) do
-		if vector.distance(p:get_pos(),pos)<=unload_wgn_range then
-			outofrange = false
-			break
-		end
-	end
-	return outofrange
+function advtrains.wagon_outside_range(pos) -- returns true if the object is outside of unload_wgn_range of any player
+	return not advtrains.position_in_range(pos, unload_wgn_range)
 end
 
 local setting_show_ids = minetest.settings:get_bool("advtrains_show_ids")
@@ -299,6 +288,8 @@ function wagon:on_step(dtime)
 		end
 		
 		local train=self:train()
+		
+		local is_in_loaded_area = advtrains.is_node_loaded(pos)
 
 		--custom on_step function
 		if self.custom_on_step then
@@ -453,7 +444,7 @@ function wagon:on_step(dtime)
 		end
 		
 		--checking for environment collisions(a 3x3 cube around the center)
-		if not train.recently_collided_with_env then
+		if is_in_loaded_area and not train.recently_collided_with_env then
 			local collides=false
 			local exh = self.extent_h or 1
 			local exv = self.extent_v or 2
@@ -477,7 +468,7 @@ function wagon:on_step(dtime)
 		
 		--DisCouple
 		-- FIX: Need to do this after the yaw calculation
-		if data.pos_in_trainparts and data.pos_in_trainparts>1 then
+		if is_in_loaded_area and data.pos_in_trainparts and data.pos_in_trainparts>1 then
 			if train.velocity==0 then
 				if not self.discouple or not self.discouple.object:getyaw() then
 					atprint(self.id,"trying to spawn discouple")
@@ -530,7 +521,7 @@ function wagon:on_step(dtime)
 				end
 			end
 			if not players_in then
-				if advtrains.outside_range(pos) then
+				if advtrains.wagon_outside_range(pos) then
 					--atdebug("wagon",self.id,"unloading (too far away)")
                     -- Workaround until minetest engine deletes attached sounds
                     if self.sound_loop_handle then

advtrains_luaautomation/active_common.lua

@@ -101,7 +101,7 @@ function ac.run_in_env(pos, evtdata, customfct_p)
 	end
 	
 	local meta
-	if minetest.get_node_or_nil(pos) then
+	if advtrains.is_node_loaded(pos) then
 		meta=minetest.get_meta(pos)
 	end