new line_of_sight function by BrunoMine and flight_check by taikedz

api.lua

@@ -1,5 +1,5 @@
 
--- Mobs Api (7th January 2017)
+-- Mobs Api (17th January 2017)
 
 mobs = {}
 mobs.mod = "redo"
@@ -208,6 +208,96 @@ set_animation = function(self, type)
 	end
 end
 
+-- Get distance
+local get_distance = function(a, b)
+
+	local x, y, z = a.x - b.x, a.y - b.y, a.z - b.z
+
+	return square(x * x + y * y + z * z)
+end
+
+
+-- check line of sight (BrunoMine)
+function line_of_sight(self, pos1, pos2, stepsize)
+
+	stepsize = stepsize or 1
+
+	local s, pos = minetest.line_of_sight(pos1, pos2, stepsize)
+
+	-- normal walking and flying mobs can see you through air
+	if s == true then
+		return true
+	end
+
+	-- New pos1 to be analyzed
+	local npos1 = {x = pos1.x, y = pos1.y, z = pos1.z}
+
+	local r, pos = minetest.line_of_sight(npos1, pos2, stepsize)
+
+	-- Checks the return
+	if r == true then return true end
+
+	-- Nodename found
+	local nn = minetest.get_node(pos).name
+
+	-- Target Distance (td) to travel
+	local td = get_distance(pos1, pos2)
+
+	-- Actual Distance (ad) traveled
+	local ad = 0
+
+	-- It continues to advance in the line of sight in search of a real obstruction.
+	while minetest.registered_nodes[nn]
+	and minetest.registered_nodes[nn].walkable == false do
+
+		-- Check if you can still move forward
+		if td < ad + stepsize then
+			return true -- Reached the target
+		end
+
+		-- Moves the analyzed pos
+		local d = get_distance(pos1, pos2)
+		npos1.x = ((pos2.x - pos1.x) / d * stepsize) + pos1.x
+		npos1.y = ((pos2.y - pos1.y) / d * stepsize) + pos1.y
+		npos1.z = ((pos2.z - pos1.z) / d * stepsize) + pos1.z
+
+		ad = ad + stepsize
+
+		-- scan again
+		r, pos = minetest.line_of_sight(npos1, pos2, stepsize)
+
+		if r == true then return true end
+
+		-- New Nodename found
+		nn = minetest.get_node(pos).name
+
+	end
+
+	return false
+end
+
+
+-- are we flying in what we are suppose to? (taikedz)
+local function flight_check(self, pos_w)
+
+	local nod = minetest.get_node(pos_w).name
+
+	if type(self.fly_in) == "string"
+	and ( nod == self.fly_in or nod == self.fly_in:gsub("_source", "_flowing") ) then
+
+		return true
+
+	elseif type(self.fly_in) == "table" then
+
+		for _,fly_in in pairs(self.fly_in) do
+
+			if nod == fly_in or nod == fly_in:gsub("_source", "_flowing") then
+				return true
+			end
+		end
+	end
+end
+
 
 -- check line of sight for walkers and swimmers alike
 function line_of_sight_water(self, pos1, pos2, stepsize)
@@ -235,13 +325,8 @@ function line_of_sight_water(self, pos1, pos2, stepsize)
 	-- just incase we have a special node for flying/swimming mobs
 	elseif s == false
 	and self.fly
-	and self.fly_in then
-
-		local nod = minetest.get_node(pos_w).name
-
-		if nod == self.fly_in then
-			return true
-		end
+	and flight_check(self, pos_w) then
+		return true
 	end
 
 	return false
@@ -1063,7 +1148,8 @@ local monster_attack = function(self)
 			-- field of view check goes here
 
 				-- choose closest player to attack
-				if line_of_sight_water(self, sp, p, 2) == true
+--				if line_of_sight_water(self, sp, p, 2) == true
+				if line_of_sight(self, sp, p, 2) == true
 				and dist < min_dist then
 					min_dist = dist
 					min_player = player
@@ -1222,17 +1308,20 @@ local follow_flop = function(self)
 		end
 	end
 
-	-- water swimmers flop when on land
-	if self.fly
-	and self.fly_in == "default:water_source"
-	and self.standing_in ~= self.fly_in then
+	-- swimmers flop when out of their element, and swim again when back in
+	if self.fly then
+		local s = self.object:getpos()
+		if not flight_check(self, s) then
 
-		self.state = "flop"
-		self.object:setvelocity({x = 0, y = -5, z = 0})
+			self.state = "flop"
+			self.object:setvelocity({x = 0, y = -5, z = 0})
 
-		set_animation(self, "stand")
+			set_animation(self, "stand")
 
-		return
+			return
+		elseif self.state == "flop" then
+			self.state = "stand"
+		end
 	end
 end
 
@@ -1554,7 +1643,8 @@ local do_states = function(self, dtime)
 				local p_y = floor(p2.y + 1)
 				local v = self.object:getvelocity()
 
-				if nod.name == self.fly_in then
+--				if nod.name == self.fly_in then
+				if flight_check(self, s) then
 
 					if me_y < p_y then
 
@@ -1692,7 +1782,8 @@ local do_states = function(self, dtime)
 						p2.y = p2.y + .5--1.5
 						s2.y = s2.y + .5--1.5
 
-						if line_of_sight_water(self, p2, s2) == true then
+--						if line_of_sight_water(self, p2, s2) == true then
+						if line_of_sight(self, p2, s2) == true then
 
 							-- play attack sound
 							mob_sound(self, self.sounds.attack)