какие зависимости есть у этого кода? --------------------------------------------------------------------------------
--      Copyright (c) 2015 , 蒙占志(topameng) <PRESIDIO_ANONYMIZED_EMAIL_ADDRESS>
--      All rights reserved.
--
--      Use, modification and distribution are subject to the "New BSD License"
--      as listed at <url: http://www.opensource.org/licenses/bsd-license.php >.
--------------------------------------------------------------------------------

local sin 	= math.sin
local cos 	= math.cos
local acos 	= math.acos
local asin 	= math.asin
local sqrt 	= math.sqrt
local min	= math.min
local max 	= math.max
local sign	= math.sign
local atan2 = math.atan2
local clamp = math.clamp
local abs	= math.abs
local setmetatable = setmetatable
local getmetatable = getmetatable
local rawget = rawget
local rawset = rawset

local rad2Deg = math.rad2Deg
local halfDegToRad = 0.5 * math.deg2Rad
local _forward = Vector3.forward
local _up = Vector3.up
local _next = { 2, 3, 1 }

Quaternion = 
{
	class = "Quaternion", 
}

setmetatable(Quaternion, Quaternion)

Quaternion.__index = function(t, name)		
	local var = rawget(Quaternion, name)
	
	if var then
		return var	
	end
	
	if name == "identity" then
		return Quaternion.New(0, 0, 0, 1)
	elseif name == "eulerAngles" then
		return t:ToEulerAngles()
	end
	
	return nil
end

Quaternion.__newindex = function(t, name, k)	
	if name == "eulerAngles" then
		t:SetEuler(k)
	else
		rawset(t, name, k)
	end	
end

function Quaternion.New(x, y, z, w)	
	local quat = {x = x or 0, y = y or 0, z = z or 0, w = w or 0}
	setmetatable(quat, Quaternion)	
	return quat
end

function Quaternion:Set(x,y,z,w)
	self.x = x or 0
	self.y = y or 0
	self.z = z or 0
	self.w = w or 0
end

function Quaternion:Clone()
	return Quaternion.New(self.x, self.y, self.z, self.w)
end

function Quaternion:Get()
	return self.x, self.y, self.z, self.w
end

function Quaternion.Dot(a, b)
	return a.x * b.x + a.y * b.y + a.z * b.z + a.w * b.w
end

function Quaternion.Angle(a, b)
	local dot = Quaternion.Dot(a, b)
	if dot < 0 then dot = -dot end
	return acos(min(dot, 1)) * 2 * 57.29578	
end

function Quaternion.AngleAxis(angle, axis)
	local normAxis = axis:Normalize()
    angle = angle * halfDegToRad
    local s = sin(angle)    
    
    local w = cos(angle)
    local x = normAxis.x * s
    local y = normAxis.y * s
    local z = normAxis.z * s
	
	return Quaternion.New(x,y,z,w)
end

function Quaternion.Equals(a, b)
	return a.x == b.x and a.y == b.y and a.z == b.z and a.w == b.w
end

function Quaternion.Euler(x, y, z)		
	local quat = Quaternion.New()	
	quat:SetEuler(x,y,z)
	return quat
end

function Quaternion:SetEuler(x, y, z)		
	if y == nil and z == nil then		
		y = x.y
		z = x.z	
		x = x.x
	end
		
	x = x * halfDegToRad
    y = y * halfDegToRad
    z = z * halfDegToRad
	
	local sinX = sin(x)
    local cosX = cos(x)
    local sinY = sin(y)
    local cosY = cos(y)
    local sinZ = sin(z)
    local cosZ = cos(z)
    
    self.w = cosY * cosX * cosZ + sinY * sinX * sinZ
    self.x = cosY * sinX * cosZ + sinY * cosX * sinZ
    self.y = sinY * cosX * cosZ - cosY * sinX * sinZ
    self.z = cosY * cosX * sinZ - sinY * sinX * cosZ
	
	return self
end

function Quaternion:Normalize()
	local quat = self:Clone()
	quat:SetNormalize()
	return quat
end

function Quaternion:SetNormalize()
	local n = self.x * self.x + self.y * self.y + self.z * self.z + self.w * self.w
	
	if n ~= 1 and n > 0 then
		n = 1 / sqrt(n)
		self.x = self.x * n
		self.y = self.y * n
		self.z = self.z * n
		self.w = self.w * n		
	end
end

--产生一个新的从from到to的四元数
function Quaternion.FromToRotation(from, to)
	local quat = Quaternion.New()
	quat:SetFromToRotation(from, to)
	return quat
end

--设置当前四元数为 from 到 to的旋转, 注意from和to同 forward平行会同unity不一致
function Quaternion:SetFromToRotation1(from, to)
	local v0 = from:Normalize()
	local v1 = to:Normalize()
	local d = Vector3.Dot(v0, v1)

	if d > -1 + 1e-6 then	
		local s = sqrt((1+d) * 2)
		local invs = 1 / s
		local c = Vector3.Cross(v0, v1) * invs
		self:Set(c.x, c.y, c.z, s * 0.5)	
	elseif d > 1 - 1e-6 then
		return Quaternion.New(0, 0, 0, 1)
	else
		local axis = Vector3.Cross(Vector3.right, v0)
		
		if axis:SqrMagnitude() < 1e-6 then
			axis = Vector3.Cross(Vector3.forward, v0)
		end

		self:Set(axis.x, axis.y, axis.z, 0)		
		return self
	end
	
	return self
end

local function MatrixToQuaternion(rot, quat)
	local trace = rot[1][1] + rot[2][2] + rot[3][3]
	
	if trace > 0 then		
		local s = sqrt(trace + 1)
		quat.w = 0.5 * s
		s = 0.5 / s
		quat.x = (rot[3][2] - rot[2][3]) * s
		quat.y = (rot[1][3] - rot[3][1]) * s
		quat.z = (rot[2][1] - rot[1][2]) * s--]]
		quat:SetNormalize()
	else
		local i = 1		
		local q = {0, 0, 0}
		
		if rot[2][2] > rot[1][1] then			
			i = 2			
		end
		
		if rot[3][3] > rot[i][i] then
			i = 3			
		end
		
		local j = _next[i]
		local k = _next[j]
		
		local t = rot[i][i] - rot[j][j] - rot[k][k] + 1
		local s = 0.5 / sqrt(t)
		q[i] = s * t
		local w = (rot[k][j] - rot[j][k]) * s
		q[j] = (rot[j][i] + rot[i][j]) * s
		q[k] = (rot[k][i] + rot[i][k]) * s
		
		quat:Set(q[1], q[2], q[3], w)			
		quat:SetNormalize()		
	end
end

function Quaternion:SetFromToRotation(from, to)
	from = from:Normalize()
	to = to:Normalize()
	
	local e = Vector3.Dot(from, to)
	
	if e > 1 - 1e-6 then
		self:Set(0, 0, 0, 1)
	elseif e < -1 + 1e-6 then		
		local left = {0, from.z, from.y}	
		local mag = left[2] * left[2] + left[3] * left[3]  --+ left[1] * left[1] = 0
		
		if mag < 1e-6 then		
			left[1] = -from.z
			left[2] = 0
			left[3] = from.x
			mag = left[1] * left[1] + left[3] * left[3]
		end
				
		local invlen = 1/sqrt(mag)
		left[1] = left[1] * invlen
		left[2] = left[2] * invlen
		left[3] = left[3] * invlen
		
		local up = {0, 0, 0}
		up[1] = left[2] * from.z - left[3] * from.y
		up[2] = left[3] * from.x - left[1] * from.z
		up[3] = left[1] * from.y - left[2] * from.x
				

		local fxx = -from.x * from.x
		local fyy = -from.y * from.y
		local fzz = -from.z * from.z
		
		local fxy = -from.x * from.y
		local fxz = -from.x * from.z
		local fyz = -from.y * from.z

		local uxx = up[1] * up[1]
		local uyy = up[2] * up[2]
		local uzz = up[3] * up[3]
		local uxy = up[1] * up[2]
		local uxz = up[1] * up[3]
		local uyz = up[2] * up[3]

		local lxx = -left[1] * left[1]
		local lyy = -left[2] * left[2]
		local lzz = -left[3] * left[3]
		local lxy = -left[1] * left[2]
		local lxz = -left[1] * left[3]
		local lyz = -left[2] * left[3]
		
		local rot = 
		{
			{fxx + uxx + lxx, fxy + uxy + lxy, fxz + uxz + lxz},
			{fxy + uxy + lxy, fyy + uyy + lyy, fyz + uyz + lyz},
			{fxz + uxz + lxz, fyz + uyz + lyz, fzz + uzz + lzz},
		}
		
		MatrixToQuaternion(rot, self)		
	else
		local v = Vector3.Cross(from, to)
		local h = (1 - e) / Vector3.Dot(v, v) 
		
		local hx = h * v.x
		local hz = h * v.z
		local hxy = hx * v.y
		local hxz = hx * v.z
		local hyz = hz * v.y
		
		local rot = 
		{ 					
			{e + hx*v.x, 	hxy - v.z, 		hxz + v.y},
			{hxy + v.z,  	e + h*v.y*v.y, 	hyz-v.x},
			{hxz - v.y,  	hyz + v.x,    	e + hz*v.z},
		}
		
		MatrixToQuaternion(rot, self)
	end
end

function Quaternion:Inverse()
	local quat = Quaternion.New()
		
	quat.x = -self.x
	quat.y = -self.y
	quat.z = -self.z
	quat.w = self.w
	
	return quat
end

function Quaternion.Lerp(q1, q2, t)
	t = clamp(t, 0, 1)
	local q = Quaternion.New()	
	
	if Quaternion.Dot(q1, q2) < 0 then
		q.x = q1.x + t * (-q2.x -q1.x)
		q.y = q1.y + t * (-q2.y -q1.y)
		q.z = q1.z + t * (-q2.z -q1.z)
		q.w = q1.w + t * (-q2.w -q1.w)
	else
		q.x = q1.x + (q2.x - q1.x) * t
		q.y = q1.y + (q2.y - q1.y) * t
		q.z = q1.z + (q2.z - q1.z) * t
		q.w = q1.w + (q2.w - q1.w) * t
	end	
	
	q:SetNormalize()
	return q
end


function Quaternion.LookRotation(forward, up)
	local mag = forward:Magnitude()
	if mag < 1e-6 then
		error("error input forward to Quaternion.LookRotation" + tostring(forward))
		return nil
	end
	
	forward = forward / mag
	up = up or _up				
	local right = Vector3.Cross(up, forward)
	right:SetNormalize()    
    up = Vector3.Cross(forward, right)
    right = Vector3.Cross(up, forward)	
	
--[[	local quat = Quaternion.New(0,0,0,1)
	local rot = 
	{ 					
		{right.x, up.x, forward.x},
		{right.y, up.y, forward.y},
		{right.z, up.z, forward.z},
	}
	
	MatrixToQuaternion(rot, quat)
	return quat--]]
		
	local t = right.x + up.y + forward.z
    
	if t > 0 then		
		local x, y, z, w
		t = t + 1
		local s = 0.5 / sqrt(t)		
		w = s * t
		x = (up.z - forward.y) * s		
		y = (forward.x - right.z) * s
		z = (right.y - up.x) * s
		
		local ret = Quaternion.New(x, y, z, w)	
		ret:SetNormalize()
		return ret
	else
		local rot = 
		{ 					
			{right.x, up.x, forward.x},
			{right.y, up.y, forward.y},
			{right.z, up.z, forward.z},
		}
	
		local q = {0, 0, 0}
		local i = 1		
		
		if up.y > right.x then			
			i = 2			
		end
		
		if forward.z > rot[i][i] then
			i = 3			
		end
		
		local j = _next[i]
		local k = _next[j]
		
		local t = rot[i][i] - rot[j][j] - rot[k][k] + 1
		local s = 0.5 / sqrt(t)
		q[i] = s * t
		local w = (rot[k][j] - rot[j][k]) * s
		q[j] = (rot[j][i] + rot[i][j]) * s
		q[k] = (rot[k][i] + rot[i][k]) * s
		
		local ret = Quaternion.New(q[1], q[2], q[3], w)			
		ret:SetNormalize()
		return ret
	end
end

function Quaternion:SetIdentity()
	self.x = 0
	self.y = 0
	self.z = 0
	self.w = 1
end

local function UnclampedSlerp(from, to, t)		
	local cosAngle = Quaternion.Dot(from, to)
	
    if cosAngle < 0 then    
        cosAngle = -cosAngle
        to = Quaternion.New(-to.x, -to.y, -to.z, -to.w)
    end
    
    local t1, t2
    
    if cosAngle < 0.95 then    
	    local angle 	= acos(cosAngle)
		local sinAngle 	= sin(angle)
        local invSinAngle = 1 / sinAngle
        t1 = sin((1 - t) * angle) * invSinAngle
        t2 = sin(t * angle) * invSinAngle    
		local quat = Quaternion.New(from.x * t1 + to.x * t2, from.y * t1 + to.y * t2, from.z * t1 + to.z * t2, from.w * t1 + to.w * t2)
		return quat
    else    
		return Quaternion.Lerp(from, to, t)
    end   	
end


function Quaternion.Slerp(from, to, t)	
	t = clamp(t, 0, 1)
	return UnclampedSlerp(from, to, t)
end

function Quaternion.RotateTowards(from, to, maxDegreesDelta)   	
	local angle = Quaternion.Angle(from, to)
	
	if angle == 0 then
		return to
	end
	
	local t = min(1, maxDegreesDelta / angle)
	return UnclampedSlerp(from, to, t)
end

local function Approximately(f0, f1)
	return abs(f0 - f1) < 1e-6	
end

function Quaternion:ToAngleAxis()		
	local angle = 2 * acos(self.w)
	
	if Approximately(angle, 0) then
		return angle * 57.29578, Vector3.New(1, 0, 0)
	end
	
	local div = 1 / sqrt(1 - sqrt(self.w))
	return angle * 57.29578, Vector3.New(q.x * div, q.y * div, q.z * div)
end

local pi = math.pi
local half_pi = pi * 0.5
local two_pi = 2 * pi
local negativeFlip = -0.0001
local positiveFlip = two_pi - 0.0001
	
local function SanitizeEuler(euler)	
	if euler.x < negativeFlip then
		euler.x = euler.x + two_pi
	elseif euler.x > positiveFlip then
		euler.x = euler.x - two_pi
	end

	if euler.y < negativeFlip then
		euler.y = euler.y + two_pi
	elseif euler.y > positiveFlip then
		euler.y = euler.y - two_pi
	end

	if euler.z < negativeFlip then
		euler.z = euler.z + two_pi
	elseif euler.z > positiveFlip then
		euler.z = euler.z + two_pi
	end
end

--from http://www.geometrictools.com/Documentation/EulerAngles.pdf
--Order of rotations: YXZ, 原来的ZXY顺序
function Quaternion:ToEulerAngles()
	local x = self.x
	local y = self.y
	local z = self.z
	local w = self.w
		
	local check = 2 * (y * z - w * x)
	
	if check < 0.999 then
		if check > -0.999 then
			local v = Vector3.New( -asin(check), 
						atan2(2 * (x * z + w * y), 1 - 2 * (x * x + y * y)), 
						atan2(2 * (x * y + w * z), 1 - 2 * (x * x + z * z)))
			SanitizeEuler(v)
			v:Mul(rad2Deg)
			return v
		else
			local v = Vector3.New(half_pi, atan2(2 * (x * y - w * z), 1 - 2 * (y * y + z * z)), 0)
			SanitizeEuler(v)
			v:Mul(rad2Deg)
			return v
		end
	else
		local v = Vector3.New(-half_pi, atan2(-2 * (x * y - w * z), 1 - 2 * (y * y + z * z)), 0)
		SanitizeEuler(v)
		v:Mul(rad2Deg)
		return v		
	end
end

function Quaternion:Forward()
	return self:MulVec3(_forward)
end


function Quaternion.MulVec3(self, point)
	local vec = Vector3.New()
    
	local num 	= self.x * 2
	local num2 	= self.y * 2
	local num3 	= self.z * 2
	local num4 	= self.x * num
	local num5 	= self.y * num2
	local num6 	= self.z * num3
	local num7 	= self.x * num2
	local num8 	= self.x * num3
	local num9 	= self.y * num3
	local num10 = self.w * num
	local num11 = self.w * num2
	local num12 = self.w * num3
	
	vec.x = (((1 - (num5 + num6)) * point.x) + ((num7 - num12) * point.y)) + ((num8 + num11) * point.z)
	vec.y = (((num7 + num12) * point.x) + ((1 - (num4 + num6)) * point.y)) + ((num9 - num10) * point.z)
	vec.z = (((num8 - num11) * point.x) + ((num9 + num10) * point.y)) + ((1 - (num4 + num5)) * point.z)
	
	return vec
end

Quaternion.__mul = function(lhs, rhs)
	if Quaternion == getmetatable(rhs) then
		return Quaternion.New((((lhs.w * rhs.x) + (lhs.x * rhs.w)) + (lhs.y * rhs.z)) - (lhs.z * rhs.y), (((lhs.w * rhs.y) + (lhs.y * rhs.w)) + (lhs.z * rhs.x)) - (lhs.x * rhs.z), (((lhs.w * rhs.z) + (lhs.z * rhs.w)) + (lhs.x * rhs.y)) - (lhs.y * rhs.x), (((lhs.w * rhs.w) - (lhs.x * rhs.x)) - (lhs.y * rhs.y)) - (lhs.z * rhs.z))	
	elseif Vector3 == getmetatable(rhs) then
		return lhs:MulVec3(rhs)
	end
end

Quaternion.__unm = function(q)
	return Quaternion.New(-q.x, -q.y, -q.z, -q.w)
end

Quaternion.__eq = function(lhs,rhs)
	return Quaternion.Dot(lhs, rhs) > 0.999999
end

Quaternion.__tostring = function(self)
	return "["..self.x..","..self.y..","..self.z..","..self.w.."]"
end