From dda7839d8c4c2292e9c8d6472faf38372654d886 Mon Sep 17 00:00:00 2001
From: jordan4ibanez <jordan4ibanez@users.noreply.github.com>
Date: Fri, 16 Apr 2021 21:43:02 -0400
Subject: [PATCH] Add in prototype swimming

---
 .../mcl_mobs/api/mob_functions/ai.lua         | 44 ++++++++++++++++++-
 .../mcl_mobs/api/mob_functions/movement.lua   | 32 ++++++++++++++
 mods/ENTITIES/mobs_mc/squid.lua               |  1 +
 3 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua b/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
index c77e0b1a5..4a19d0067 100644
--- a/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
+++ b/mods/ENTITIES/mcl_mobs/api/mob_functions/ai.lua
@@ -2,6 +2,7 @@ local math_random = math.random
 
 local vector_multiply = vector.multiply
 local vector_add      = vector.add
+local vector_new      = vector.new
 
 local minetest_yaw_to_dir                   = minetest.yaw_to_dir
 local minetest_get_item_group               = minetest.get_item_group
@@ -201,11 +202,32 @@ local flop = function(self,dtime)
 	mobs.flop(self)
 end
 
+--this is to swap the built in engine acceleration modifier
+local fly_physics_swapper = function(self,inside_fly_node)
 
+	--push non-existing physics switch to new mobs
+	self.fly_physics_switch = self.fly_physics_switch or not inside_fly_node
+
+	--should be flying, gravity is applied, switch to floating
+	if inside_fly_node and not self.fly_physics_switch then
+		self.object:set_acceleration(vector_new(0,0,0))
+		self.fly_physics_switch = true
+	--not be flying, gravity isn't applied, switch to falling
+	elseif not inside_fly_node and self.fly_physics_switch then
+		self.pitch = 0
+		self.object:set_acceleration(vector_new(0,-self.gravity,0))
+		self.fly_physics_switch = false
+	end
+end
+
+
+local random_pitch_multiplier = {-1,1}
 -- states are executed here
 local fly_state_execution = function(self,dtime)
 
 	local pos = self.object:get_pos()
+
+	pos.y = pos.y + self.object:get_properties().collisionbox[5]
 	local current_node = minetest_get_node(pos).name
 	local inside_fly_node = false
 
@@ -217,10 +239,12 @@ local fly_state_execution = function(self,dtime)
 		end
 	end
 
-	
+	--turn gravity on or off
+	fly_physics_swapper(self,inside_fly_node)
 
 	--fly properly if inside fly node
 	if inside_fly_node then
+
 		if self.state == "stand" then
 
 			--do animation
@@ -231,11 +255,27 @@ local fly_state_execution = function(self,dtime)
 
 			--print("standing")
 
+			mobs.set_fly_velocity(self,0)
+
 		elseif self.state == "fly" then
 
+			self.walk_timer = self.walk_timer - dtime
 
-			--print("flying")
+			--reset the walk timer
+			if self.walk_timer <= 0 then
+	
+				--re-randomize the walk timer
+				self.walk_timer = math.random(1,6) + math.random()
+	
+				--set the mob into a random direction
+				self.yaw = (math_random() * (math.pi * 2))
 
+				--create a truly random pitch, since there is no easy access to pitch math that I can find
+				self.pitch = math_random() * random_pitch_multiplier[math_random(1,2)]
+			end
+			
+
+			mobs.set_fly_velocity(self,self.walk_velocity)
 		end
 	--flop around if not inside fly node
 	else
diff --git a/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua b/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
index 09e21f470..681d97a1e 100644
--- a/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
+++ b/mods/ENTITIES/mcl_mobs/api/mob_functions/movement.lua
@@ -98,4 +98,36 @@ mobs.flop = function(self, velocity)
     self.object:add_velocity(final_additional_force)
 
 	return true
+end
+
+
+
+-- move mob in facing direction
+--this has been modified to be internal
+--internal = lua (self.yaw)
+--engine = c++ (self.object:get_yaw())
+mobs.set_fly_velocity = function(self, v)
+	
+	local yaw = (self.yaw or 0)
+	local pitch = (self.pitch or 0)
+
+	local current_velocity = self.object:get_velocity()
+
+	local goal_velocity = {
+		x = (math_sin(yaw) * -v),
+		y = pitch,
+		z = (math_cos(yaw) * v),
+	}
+
+
+	local new_velocity_addition = vector.subtract(goal_velocity,current_velocity)
+
+	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
+
+	--smooths out mobs a bit
+	if vector_length(new_velocity_addition) >= 0.0001 then
+		self.object:add_velocity(new_velocity_addition)
+	end
 end
\ No newline at end of file
diff --git a/mods/ENTITIES/mobs_mc/squid.lua b/mods/ENTITIES/mobs_mc/squid.lua
index fbec650dd..f650472fc 100644
--- a/mods/ENTITIES/mobs_mc/squid.lua
+++ b/mods/ENTITIES/mobs_mc/squid.lua
@@ -16,6 +16,7 @@ mobs:register_mob("mobs_mc:squid", {
     xp_min = 1,
     xp_max = 3,
     armor = 100,
+    rotate = 270,
     -- FIXME: If the squid is near the floor, it turns black
     collisionbox = {-0.4, 0.0, -0.4, 0.4, 0.9, 0.4},
     visual = "mesh",