Change villager spawning algorithm

Now the entity spawners regularily check if another object is nearby, only then they spawn.
This should make entity spawns more reliable.

mods/village/generate.lua

@@ -429,7 +429,6 @@ function village.spawn_chunk(pos, orient, replace, pr, chunktype, nofill, dont_c
 	    "village:entity_spawner",
 	    function(pos)
 	       table.insert(ent_spawns, pos)
-	       minetest.remove_node(pos)
 	    end, true)
 
 	 if #ent_spawns > 0 then
@@ -440,14 +439,19 @@ function village.spawn_chunk(pos, orient, replace, pr, chunktype, nofill, dont_c
                   end
 		  local spawn, index = util.choice_element(ent_spawns, pr)
 		  if spawn ~= nil then
-		     spawn.y = spawn.y + 1.6
-		     minetest.add_entity(spawn, ent)
+                     local meta = minetest.get_meta(spawn)
+	             meta:set_string("entity", ent)
+	             minetest.get_node_timer(spawn):start(1)
                      -- Prevent spawning on same tile
                      table.remove(ent_spawns, index)
 		  end
 	       end
 	    end
 	 end
+         -- Remove unused entity spawners
+         for e=1, #ent_spawns do
+             minetest.remove_node(ent_spawns[e])
+         end
       end
    end
 

mods/village/mapgen.lua

@@ -25,18 +25,39 @@ minetest.register_node(
    "village:entity_spawner",
    {
       description = S("Village Entity Spawner"),
-      tiles = {
-          "village_entity.png", "village_entity.png", "village_entity.png",
-          "village_entity.png", "village_entity.png^[transformFX", "village_entity.png^[transformFX"
-      },
-      is_ground_content = false,
+      drawtype = "airlike",
+      pointable = false,
+      inventory_image = "village_entity.png",
+      wield_image = "village_entity.png",
+      is_ground_content = true,
       sunlight_propagates = true,
       paramtype = "light",
       post_effect_color = { a = 0x40, r = 0x8D, g = 0x75, b = 0x97 },
       walkable = false,
+      floodable = true,
+      buildable_to = true,
       drop = "",
       groups = {dig_immediate = 3, not_in_creative_inventory = 1},
-      sounds = default.node_sound_defaults()
+      sounds = default.node_sound_defaults(),
+      on_timer = function(pos, elapsed)
+          -- Wait until some objects are nearby ...
+          local objs_around = minetest.get_objects_inside_radius(pos, 12)
+          -- ... but not TOO nearby (occupying the pos)
+          local objs_near = minetest.get_objects_inside_radius(pos, 1.2)
+          if #objs_around > 0 and #objs_near == 0 then
+              local ent = minetest.get_meta(pos):get_string("entity")
+              if ent ~= "" then
+                  minetest.add_entity({x=pos.x, y=pos.y+0.6, z=pos.z}, ent)
+              else
+                  minetest.log("error", "[village] Entity spawner without 'entity' in meta set @ "..minetest.pos_to_string(pos))
+              end
+              minetest.remove_node(pos)
+              return
+          else
+              -- Don't spawn and try again later
+              minetest.get_node_timer(pos):start(5)
+          end
+      end,
 })
 
 minetest.register_node(