Mobs drown instead of taking direct water damage

mods/mobs/api.lua

@@ -168,6 +168,8 @@ function mobs:register_mob(name, def)
 	 lifetimer = def.lifetimer or 180, -- 3 minutes
 	 hp_min = def.hp_min or 5,
 	 hp_max = def.hp_max or 10,
+	 breath_max = def.breath_max or -1, -- how many seconds the mob can breathe in drowning nodes. -1 = no drowning damage
+	 breath = def.breath_max,
 	 physical = true,
 	 collides_with_objects = def.collides_with_objects or true,
 	 collisionbox = def.collisionbox,
@@ -517,22 +519,6 @@ function mobs:register_mob(name, def)
                local nodef = minetest.registered_nodes[nod.name]
                pos.y = pos.y + 1
 
-               -- water
-               if self.water_damage ~= 0
-               and nodef.groups.water then
-                  self.object:set_hp(self.object:get_hp() - self.water_damage)
-                  effect(pos, 5, "bubble.png")
-                  if check_for_death(self) then return end
-               end
-
-               -- lava or fire
-               if self.lava_damage ~= 0
-               and nodef.groups.lava then
-                  self.object:set_hp(self.object:get_hp() - self.lava_damage)
-                  effect(pos, 5, "mobs_flame.png", 8)
-                  if check_for_death(self) then return end
-               end
-
                -- node damage
                if self.takes_node_damage == true
                and nodef.damage_per_second > 0 then
@@ -545,6 +531,43 @@ function mobs:register_mob(name, def)
                   if check_for_death(self) then return end
                end
 
+               -- drowning damage
+               if self.breath_max ~= - 1 then
+                  if not self.breath then
+                      self.breath = self.breath_max
+                  end
+                  if nodef.drowning > 0 then
+                      self.breath = self.breath - 1
+                      if self.breath < 0 then
+                          self.breath = 0
+                          self.object:set_hp(self.object:get_hp() - nodef.drowning)
+                          effect(pos, 5, "bubble.png")
+                      end
+                      if check_for_death(self) then return end
+                  else
+                      self.breath = self.breath + 1
+                      if self.breath > self.breath_max then
+                         self.breath = self.breath_max
+                      end
+                  end
+               end
+
+               -- water damage
+               if self.water_damage ~= 0
+               and nodef.groups.water then
+                  self.object:set_hp(self.object:get_hp() - self.water_damage)
+                  effect(pos, 5, "bubble.png")
+                  if check_for_death(self) then return end
+               end
+
+               -- lava damage
+               if self.lava_damage ~= 0
+               and nodef.groups.lava then
+                  self.object:set_hp(self.object:get_hp() - self.lava_damage)
+                  effect(pos, 5, "mobs_flame.png", 8)
+                  if check_for_death(self) then return end
+               end
+
             end
 
             local do_jump = function(self)

mods/mobs/mob_boar.lua

@@ -13,6 +13,7 @@ mobs:register_mob(
       damage = 2,
       hp_min = 16,
       hp_max = 20,
+      breath_max = 5,
       armor = 200,
       collisionbox = {-0.5, -1, -0.5, 0.5, 0.1, 0.5},
       visual = "mesh",
@@ -37,7 +38,7 @@ mobs:register_mob(
 	 {name = "mobs:pork_raw",
 	  chance = 1, min = 1, max = 4},
       },
-      water_damage = 1,
+      water_damage = 0,
       lava_damage = 5,
       light_damage = 0,
       animation = {

mods/mobs/mob_mineturtle.lua

@@ -11,6 +11,7 @@ mobs:register_mob(
       attack_type = "explode",
       hp_min = 10,
       hp_max = 15,
+      breath_max = 20,
       armor = 200,
       collisionbox = {-0.4, 0, -0.4, 0.4, 0.7, 0.4},
       visual = "mesh",
@@ -34,7 +35,7 @@ mobs:register_mob(
 	 {name = "tnt:tnt",
 	  chance = 1, min = 1, max = 3},
       },
-      water_damage = 1,
+      water_damage = 0,
       lava_damage = 5,
       light_damage = 0,
       takes_node_damage = false,

mods/mobs/mob_npc.lua

@@ -90,6 +90,7 @@ for _, npc_type_table in pairs(npc_types) do
 	 attacks_monsters = true,
 	 hp_min = 10,
 	 hp_max = 20,
+	 breath_max = 11,
 	 armor = 80,
 	 collisionbox = {-0.35,-1.0,-0.35, 0.35,0.8,0.35},
 	 visual = "mesh",

mods/mobs/mob_sheep.lua

@@ -10,6 +10,7 @@ mobs:register_mob(
       passive = true,
       hp_min = 10,
       hp_max = 14,
+      breath_max = 5,
       armor = 200,
       collisionbox = {-0.5, -1, -0.5, 0.5, 0.1, 0.5},
       visual = "mesh",
@@ -37,7 +38,7 @@ mobs:register_mob(
 	 {name = "mobs:wool",
 	  chance = 1, min = 1, max = 2},
       },
-      water_damage = 1,
+      water_damage = 0,
       lava_damage = 5,
       light_damage = 0,
       animation = {

mods/mobs/mob_skunk.lua

@@ -9,6 +9,7 @@ mobs:register_mob(
       passive = false,
       attack_type = "dogfight",
       damage = 1,
+      breath_max = 7,
       hp_min = 16,
       hp_max = 22,
       armor = 130,
@@ -34,7 +35,7 @@ mobs:register_mob(
 	 {name = "mobs:meat_raw",
 	  chance = 1, min = 1, max = 2},
       },
-      water_damage = 1,
+      water_damage = 0,
       lava_damage = 7,
       light_damage = 0,
       animation = {

mods/mobs/mob_walker.lua

@@ -11,6 +11,7 @@ mobs:register_mob(
       damage = 3,
       hp_min = 8,
       hp_max = 16,
+      breath_max = -1,
       armor = 200,
       collisionbox = {-0.3, 0, -0.3, 0.3, 1.5, 0.3},
       visual = "mesh",