add mapblock calc function / fix entity spawning in inactive areas

blocks/send_mapblock.lua

@@ -66,11 +66,7 @@ minetest.register_node("epic:send_mapblock", {
     on_enter = function(pos, meta, player, ctx)
 			local rel_pos = minetest.string_to_pos(meta:get_string("pos"))
 			local target_pos = epic.to_absolute_pos(pos, rel_pos)
-			local block_pos = {
-				x = math.floor(target_pos.x / 16),
-				y = math.floor(target_pos.y / 16),
-				z = math.floor(target_pos.z / 16)
-			}
+			local block_pos = epic.get_mapblock_pos(target_pos)
 			player:send_mapblock(block_pos)
 			ctx.next()
     end

blocks/spawn_mob.lua

@@ -48,19 +48,28 @@ local function do_spawn(pos, meta)
 	local target_pos = epic.to_absolute_pos(pos, minetest.string_to_pos(meta:get_string("pos")))
 	local mobname = meta:get_string("mobname")
 
-	local objs = minetest.get_objects_inside_radius(target_pos, 9)
-	local count = 0
-	for _ in ipairs(objs) do
-		count = count + 1
-	end
+	if mobname and mobname ~= "" then
+		local mapblock_pos = epic.get_mapblock_pos(target_pos)
+		-- start a transient forceload
+		-- entities can only operate in active mapblocks
+		minetest.forceload_block(mapblock_pos, true)
+
+		-- spawn mob and free forceload in the next server step
+		minetest.after(0.1, function()
+			local objs = minetest.get_objects_inside_radius(target_pos, 9)
+			local count = 0
+			for _ in ipairs(objs) do
+				count = count + 1
+			end
 
-	if count > 16 then
-		-- too many objects
-		return
-	end
+			if count < 16 then
+				-- only spawn new entities if not too much objects in that area already
+				minetest.add_entity(target_pos, mobname)
+			end
 
-	if mobname and mobname ~= "" then
-		minetest.add_entity(target_pos, mobname)
+			-- release forceload
+			minetest.forceload_free_block(mapblock_pos, true)
+		end)
 	end
 end
 

common.lua

@@ -196,3 +196,11 @@ epic.execute_epic = function(player, main_pos, name)
 	epic.run_hook("on_execute_epic", { player, main_pos, state })
 
 end
+
+function epic.get_mapblock_pos(pos)
+	return {
+		x = math.floor(pos.x / 16),
+		y = math.floor(pos.y / 16),
+		z = math.floor(pos.z / 16)
+	}
+end