add random planar velocity when stopped

this seems to almost solve the problem of random standing.

mods/ENTITIES/mcl_mobs/api.lua

@@ -2244,7 +2244,14 @@ local follow_flop = function(self)
 
 			return
 		elseif self.state == "flop" then
+			if not is_glider(self) then
 				self.state = "stand"
+				set_animation(self, "stand")
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+				return
+			end
 			self.object:set_acceleration({x = 0, y = 0, z = 0})
 			set_velocity(self, 0)
 		end
@@ -2487,11 +2494,17 @@ local do_states = function(self, dtime)
 		end
 		if self.facing_fence == true
 		or cliff_or_danger
-		or random(1, 100) <= 30 then
+		or random(1, 100) <= 30
-
+		or ( (self.fly and not self.keep_flying)
-			set_velocity(self, 0)
+		or not self.fly ) then
+			if not is_glider(self) then
 				self.state = "stand"
 				set_animation(self, "stand")
+				set_velocity(self, 0)
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+			end
 			local yaw = self.object:get_yaw() or 0
 			yaw = set_yaw(self, yaw + 0.78, 8)
 		else
@@ -2517,9 +2530,14 @@ local do_states = function(self, dtime)
 		if self.runaway_timer > 5
 		or is_at_cliff_or_danger(self) then
 			self.runaway_timer = 0
-			set_velocity(self, 0)
+			if not is_glider(self) then
 				self.state = "stand"
 				set_animation(self, "stand")
+				set_velocity(self, 0)
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+			end
 			local yaw = self.object:get_yaw() or 0
 			yaw = set_yaw(self, yaw + 0.78, 8)
 		else
@@ -2540,9 +2558,14 @@ local do_states = function(self, dtime)
 		or self.attack:get_hp() <= 0
 		or (self.attack:is_player() and mcl_mobs.invis[ self.attack:get_player_name() ]) then
 
+			if not is_glider(self) then
 				self.state = "stand"
-			set_velocity(self, 0)
 				set_animation(self, "stand")
+				set_velocity(self, 0)
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+			end
 			self.attack = nil
 			self.v_start = false
 			self.timer = 0
@@ -3389,7 +3412,11 @@ local mob_staticdata = function(self)
 	self.remove_ok = true
 	self.attack = nil
 	self.following = nil
+	if not is_glider(self) then
 		self.state = "stand"
+	else
+		self.state = "walk"
+	end
 
 	local tmp = {}
 
@@ -3559,6 +3586,9 @@ local mob_activate = function(self, staticdata, def, dtime)
 
 	-- run on_spawn function if found
 	if self.on_spawn and not self.on_spawn_run then
+		if self.fly then
+			self.desired_altitude = self.desired_altitude + math.random(-5,10)
+		end
 		if self.on_spawn(self) then
 			self.on_spawn_run = true --  if true, set flag to run once only
 		end
@@ -3570,10 +3600,73 @@ local mob_activate = function(self, staticdata, def, dtime)
 	end
 end
 
+local function get_speed_over_ground(self)
+	local p = self.object:get_velocity()
+	return vector.length(vector.new(p.x,0,p.z))
+end
+
+local function check_ground(self) --return true if too close to the ground
+	local p = self.object:get_pos()
+	local n = minetest.find_nodes_in_area_under_air(vector.offset(p,0,-self.desired_altitude-1,0),vector.offset(p,0,0,0),{"group:solid","group:liquid"})
+	if #n > 0 then
+		return true
+	end
+end
+
+local function get_random_velocity(self)
+	local v = self.object:get_velocity()
+	return vector.new(math.random(self.walk_velocity),v.y,math.random(self.walk_velocity))
+end
+
+local function descend(self)
+	local v = self.object:get_velocity()
+	local gs = get_speed_over_ground(self)
+	local r = math.max(math.abs(self.fall_speed) - gs,1)
+	--minetest.log("descend "..tostring(r) .. " vel "..tostring(v.y).. " rate "..tostring(r))
+	if v.y > self.fall_speed then
+		--self.object:set_velocity(vector.new(v.x,-r,v.z))
+		self.object:add_velocity(vector.new(0,-r/10,0))
+	end
+end
+
+local function climb(self)
+	local v = self.object:get_velocity()
+	local gs = get_speed_over_ground(self)
+	local r = self.run_velocity + gs
+	--minetest.log("climb "..tostring(r) .. " vel "..tostring(v.y).. " rate "..tostring(r))
+	if v.y < self.walk_velocity then
+		self.object:add_velocity(vector.new(0,r/10,0))
+	end
+end
+--self.floater
+--self.desired altitude (above ground)
+local function check_flight(self,dtime)
+	if self.floater or not self.fly then return end --floaters don't need altitdude adjustment
+	--self.state = "walk"
+	local gs = get_speed_over_ground(self)
+	if gs < 1 then
+		local y = self.object:get_yaw()
+		self.object:set_yaw((y + math.random(-30,30)) % 360)
+		set_velocity(self,math.random(1,self.walk_velocity))
+	end
+	if not self.flap_timer and check_ground(self) then
+		climb(self)
+		self.flap_timer = 0
+	elseif self.flap_timer then
+		if self.flap_timer > self.flap_time then
+			self.flap_timer = nil
+		else
+			self.flap_timer = self.flap_timer + dtime
+		end
+	else
+		descend(self)
+	end	
+end
 
 -- main mob function
 local mob_step = function(self, dtime)
 	check_item_pickup(self)
+	check_flight(self,dtime)
 	if not self.fire_resistant then
 		mcl_burning.tick(self.object, dtime, self)
 	end
@@ -3720,8 +3813,13 @@ local mob_step = function(self, dtime)
 	if is_at_water_danger(self) and self.state ~= "attack" then
 		if random(1, 10) <= 6 then
 			set_velocity(self, 0)
+			if not is_glider(self) then
 				self.state = "stand"
 				set_animation(self, "stand")
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+			end
 			yaw = yaw + random(-0.5, 0.5)
 			yaw = set_yaw(self, yaw, 8)
 		end
@@ -3770,9 +3868,14 @@ local mob_step = function(self, dtime)
 	follow_flop(self)
 
 	if is_at_cliff_or_danger(self) then
+			if not is_glider(self) then
 				set_velocity(self, 0)
 				self.state = "stand"
 				set_animation(self, "stand")
+			else
+				self.state = "walk"
+				set_animation(self, "walk")
+			end
 			local yaw = self.object:get_yaw() or 0
 			yaw = set_yaw(self, yaw + 0.78, 8)
 	end
@@ -3915,6 +4018,9 @@ minetest.register_entity(name, {
 	view_range = def.view_range or 16,
 	walk_velocity = def.walk_velocity or 1,
 	run_velocity = def.run_velocity or 2,
+	desired_altitude = def.desired_altitude or 12, --over ground
+	flap_time = def.flap_time or 2, --time between wing glap / climb events
+	keep_flying = def.keep_flying or false,
 	damage = scale_difficulty(def.damage, 0, 0),
 	light_damage = def.light_damage or 0,
 	sunlight_damage = def.sunlight_damage or 0,

mods/ENTITIES/mobs_mc/init.lua

@@ -142,3 +142,5 @@ dofile(path .. "/slime+magma_cube.lua") -- Wuzzy
 dofile(path .. "/spider.lua") -- Spider by AspireMint (fishyWET (CC-BY-SA 3.0 license for texture)
 dofile(path .. "/vex.lua") -- KrupnoPavel
 dofile(path .. "/wither.lua") -- Mesh and animation by toby109tt  / https://github.com/22i
+
+dofile(path .. "/phantom.lua") -- Mesh and animation by toby109tt  / https://github.com/22i

mods/ENTITIES/mobs_mc/phantom.lua

@@ -0,0 +1,62 @@
+--Phantom for mcl2
+--cora
+--License for code WTFPL, cc0
+
+local S = minetest.get_translator("mobs_mc")
+
+mcl_mobs:register_mob("mobs_mc:phantom", {
+	description = S("Phantom"),
+	type = "monster",
+	spawn_class = "passive",
+	pathfinding = 1,
+	hp_min = 6,
+	hp_max = 6,
+	xp_min = 1,
+	xp_max = 3,
+	collisionbox = {-0.25, -0.01, -0.25, 0.25, 0.89, 0.25},
+	visual = "mesh",
+	mesh = "mobs_mc_phantom.b3d",
+	textures = {{"mobs_mc_phantom.png","mobs_mc_phantom_e.png","mobs_mc_phantom_e_s.png"}},
+	visual_size = {x=3, y=3},
+	walk_velocity = 3,
+	run_velocity = 5,
+	desired_altitude = 19,
+	keep_flying = true,
+	sounds = {
+		random = "mobs_mc_phantom_random",
+		damage = {name="mobs_mc_phantom_hurt", gain=0.3},
+		death = {name="mobs_mc_phantom_death", gain=0.6},
+		eat = "mobs_mc_animal_eat_generic",
+		distance = 16,
+	},
+	drops = {
+		{name = "mcl_mobitems:leather", --TODO: phantom membrane
+		chance = 1,
+		min = 1,
+		max = 2,
+		looting = "common",},
+	},
+    	animation = {
+		stand_speed = 50,
+		walk_speed = 50,
+		fly_speed = 50,
+		stand_start = 0,
+		stand_end = 0,
+		fly_start = 0,
+		fly_end = 30,
+		walk_start = 0,
+		walk_end = 30,
+	},
+	fall_damage = 0,
+	fall_speed = -2.25,
+	attack_type = "dogfight",
+	floats = 1,
+	physical = true,
+	fly = true,
+	makes_footstep_sound = false,
+	fear_height = 0,
+	view_range = 16,
+})
+
+-- spawn eggs
+mcl_mobs:register_egg("mobs_mc:phantom", S("Phantom"), "mobs_mc_spawn_icon_phantom.png", 0)