From 4efec1ef58ba4afe4692a22a361079b5026a7de3 Mon Sep 17 00:00:00 2001
From: jordan4ibanez <jordan4ibanez@users.noreply.github.com>
Date: Fri, 23 Apr 2021 12:55:11 -0400
Subject: [PATCH] Add in chicken slow falling

---
 mods/ENTITIES/mcl_mobs/api/api.lua            |  1 +
 .../mcl_mobs/api/mob_functions/ai.lua         | 23 +++++++++++++++
 .../mcl_mobs/api/mob_functions/movement.lua   | 28 +++++++++++++++++++
 mods/ENTITIES/mobs_mc/chicken.lua             |  1 +
 4 files changed, 53 insertions(+)

diff --git a/mods/ENTITIES/mcl_mobs/api/api.lua b/mods/ENTITIES/mcl_mobs/api/api.lua
index 307a180903..fc153a5fe1 100644
--- a/mods/ENTITIES/mcl_mobs/api/api.lua
+++ b/mods/ENTITIES/mcl_mobs/api/api.lua
@@ -355,6 +355,7 @@ function mobs:register_mob(name, def)
 		hostile_cooldown = def.hostile_cooldown or 15,
 		tilt_fly = def.tilt_fly,
 		tilt_swim = def.tilt_swim,
+		fall_slow = def.fall_slow,
 		-- End of MCL2 extensions
 
 		on_spawn = def.on_spawn,
diff --git a/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua b/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
index d6d51b8deb..e883a36702 100644
--- a/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
+++ b/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
@@ -1,5 +1,7 @@
 local math_random = math.random
 local math_pi     = math.pi
+local math_floor  = math.floor
+local math_round  = math.round
 
 local vector_multiply = vector.multiply
 local vector_add      = vector.add
@@ -22,6 +24,12 @@ local quick_rotate = function(self,dtime)
 	end
 end
 
+--a simple helper function for rounding
+--http://lua-users.org/wiki/SimpleRound
+function round2(num, numDecimalPlaces)
+	return tonumber(string.format("%." .. (numDecimalPlaces or 0) .. "f", num))
+end
+
 
 --[[
  _                     _ 
@@ -89,6 +97,21 @@ local land_state_execution = function(self,dtime)
 		float_now = true
 	end
 
+	--make slow falling mobs fall slow
+	if self.fall_slow then
+		if self.object:get_velocity().y < 0 then
+			--lua is acting really weird so we have to help it
+			if round2(self.object:get_acceleration().y, 1) == -self.gravity then
+				self.object:set_acceleration(vector_new(0,0,0))
+				mobs.mob_fall_slow(self)
+			end
+		else
+			if round2(self.object:get_acceleration().y, 1) == 0 then
+				self.object:set_acceleration(vector_new(0,-self.gravity,0))
+			end
+		end
+	end
+
 	if self.state == "stand" then
 
 		--do animation
diff --git a/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua b/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
index 811488396f..819df63533 100644
--- a/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
+++ b/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
@@ -113,8 +113,36 @@ mobs.jump = function(self, velocity)
     self.object:add_velocity(vector_new(0,velocity,0))    
 end
 
+--make mobs fall slowly
+mobs.mob_fall_slow = function(self)
+
+	local current_velocity = self.object:get_velocity()
+
+	local goal_velocity = {
+		x = 0,
+		y = -2,
+		z = 0,
+	}
 
 
+	local new_velocity_addition = vector.subtract(goal_velocity,current_velocity)
+
+	new_velocity_addition.x = 0
+	new_velocity_addition.z = 0
+
+	if vector_length(new_velocity_addition) > vector_length(goal_velocity) then
+		vector.multiply(new_velocity_addition, (vector_length(goal_velocity) / vector_length(new_velocity_addition)))
+	end
+
+	new_velocity_addition.x = 0
+	new_velocity_addition.z = 0
+
+	--smooths out mobs a bit
+	if vector_length(new_velocity_addition) >= 0.0001 then
+		self.object:add_velocity(new_velocity_addition)
+	end
+
+end
 
 
 --[[
diff --git a/mods/ENTITIES/mobs_mc/chicken.lua b/mods/ENTITIES/mobs_mc/chicken.lua
index 2fe82293e3..2e1a2e5245 100644
--- a/mods/ENTITIES/mobs_mc/chicken.lua
+++ b/mods/ENTITIES/mobs_mc/chicken.lua
@@ -18,6 +18,7 @@ mobs:register_mob("mobs_mc:chicken", {
 	xp_max = 3,
 	collisionbox = {-0.2, -0.01, -0.2, 0.2, 0.69, 0.2},
 	runaway = true,
+	fall_slow = true,
 	floats = 1,
 	visual = "mesh",
 	mesh = "mobs_mc_chicken.b3d",