Fix mobs able to swim in plants

mods/ENTITIES/mcl_mobs/api.lua

@@ -344,27 +344,22 @@ local flight_check = function(self)
 
 	if not def then return false end -- nil check
 
-	if type(self.fly_in) == "string"
-	and nod == self.fly_in then
-
-		return true
-
+	local fly_in
+	if type(self.fly_in) == "string" then
+		fly_in = { self.fly_in }
 	elseif type(self.fly_in) == "table" then
-
-		for _,fly_in in pairs(self.fly_in) do
-
-			if nod == fly_in then
-
-				return true
-			end
-		end
+		fly_in = self.fly_in
+	else
+		return false
 	end
 
-	-- stops mobs getting stuck inside stairs and plantlike nodes
-	if def.drawtype ~= "airlike"
-	and def.drawtype ~= "liquid"
-	and def.drawtype ~= "flowingliquid" then
-		return true
+	for _,checknode in pairs(fly_in) do
+		if nod == checknode then
+			return true
+		elseif checknode == "__airlike" and def.walkable == false and
+				(def.liquidtype == "none" or minetest.get_item_group(nod, "fake_liquid") == 1) then
+			return true
+		end
 	end
 
 	return false
@@ -3173,7 +3168,7 @@ minetest.register_entity(name, {
 	type = def.type,
 	attack_type = def.attack_type,
 	fly = def.fly,
-	fly_in = def.fly_in or "air",
+	fly_in = def.fly_in or {"air", "__airlike"},
 	owner = def.owner or "",
 	order = def.order or "",
 	on_die = def.on_die,

mods/ENTITIES/mcl_mobs/api.txt

@@ -52,8 +52,10 @@ functions needed for the mob to work properly which contains the following:
    'stepheight'    height of a block that your mob can easily walk up onto,
                    defaults to 1.1.
    'fly'           when true allows your mob to fly around instead of walking.
-   'fly_in'        holds the node name that the mob flies (or swims) around
-                   in e.g. "air" or "default:water_source".
+   'fly_in'        holds the node name or a table of node names in which the
+                   mob flies (or swims) around in. The special name
+                   '__airlike' stands for all nodes with 'walkable=false'
+                   that are not liquids
    'runaway'       if true causes animals to turn and run away when hit.
    'view_range'    how many nodes in distance the mob can see a player.
    'damage'        how many health points the mob does to a player or another

mods/ENTITIES/mobs_mc/bat.lua

@@ -44,7 +44,6 @@ mobs:register_mob("mobs_mc:bat", {
 	view_range = 16,
 
 	fly = true,
-	fly_in = "air",
 })
 
 

mods/ENTITIES/mobs_mc/ender_dragon.lua

@@ -34,7 +34,6 @@ mobs:register_mob("mobs_mc:enderdragon", {
 	jump_height = 14,
 	stepheight = 1.2,
 	fly = true,
-	fly_in = {"air"},
 	dogshoot_switch = 1,
 	dogshoot_count_max =5,
 	dogshoot_count2_max = 5,

mods/ENTITIES/mobs_mc/ghast.lua

@@ -66,7 +66,6 @@ mobs:register_mob("mobs_mc:ghast", {
 	jump_height = 4,
 	floats=1,
 	fly = true,
-	fly_in = {"air"},
 })
 
 

mods/ENTITIES/mobs_mc/parrot.lua

@@ -52,7 +52,6 @@ mobs:register_mob("mobs_mc:parrot", {
 	floats = 1,
 	physical = true,
 	fly = true,
-	fly_in = {"air"},
 	fear_height = 4,
 	view_range = 16,
 	follow = mobs_mc.follow.parrot,

mods/ENTITIES/mobs_mc/vex.lua

@@ -85,7 +85,6 @@ mobs:register_mob("mobs_mc:vex", {
 		end
 	end,
 	fly = true,
-	fly_in = {"air"},
 })