mirror of
https://github.com/SashLilac/cambridge.git
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499 lines
13 KiB
Lua
499 lines
13 KiB
Lua
--- A quaternion and associated utilities.
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-- @module quat
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local modules = (...):gsub('%.[^%.]+$', '') .. "."
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local constants = require(modules .. "constants")
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local vec3 = require(modules .. "vec3")
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local precond = require(modules .. "_private_precond")
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local private = require(modules .. "_private_utils")
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local DOT_THRESHOLD = constants.DOT_THRESHOLD
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local DBL_EPSILON = constants.DBL_EPSILON
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local acos = math.acos
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local cos = math.cos
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local sin = math.sin
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local min = math.min
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local max = math.max
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local sqrt = math.sqrt
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local quat = {}
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local quat_mt = {}
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-- Private constructor.
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local function new(x, y, z, w)
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return setmetatable({
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x = x or 0,
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y = y or 0,
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z = z or 0,
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w = w or 1
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}, quat_mt)
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end
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-- Do the check to see if JIT is enabled. If so use the optimized FFI structs.
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local status, ffi
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if type(jit) == "table" and jit.status() then
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status, ffi = pcall(require, "ffi")
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if status then
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ffi.cdef "typedef struct { double x, y, z, w;} cpml_quat;"
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new = ffi.typeof("cpml_quat")
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end
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end
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-- Statically allocate a temporary variable used in some of our functions.
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local tmp = new()
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local qv, uv, uuv = vec3(), vec3(), vec3()
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--- Constants
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-- @table quat
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-- @field unit Unit quaternion
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-- @field zero Empty quaternion
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quat.unit = new(0, 0, 0, 1)
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quat.zero = new(0, 0, 0, 0)
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--- The public constructor.
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-- @param x Can be of two types: </br>
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-- number x X component
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-- table {x, y, z, w} or {x=x, y=y, z=z, w=w}
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-- @tparam number y Y component
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-- @tparam number z Z component
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-- @tparam number w W component
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-- @treturn quat out
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function quat.new(x, y, z, w)
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-- number, number, number, number
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if x and y and z and w then
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precond.typeof(x, "number", "new: Wrong argument type for x")
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precond.typeof(y, "number", "new: Wrong argument type for y")
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precond.typeof(z, "number", "new: Wrong argument type for z")
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precond.typeof(w, "number", "new: Wrong argument type for w")
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return new(x, y, z, w)
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-- {x, y, z, w} or {x=x, y=y, z=z, w=w}
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elseif type(x) == "table" then
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local xx, yy, zz, ww = x.x or x[1], x.y or x[2], x.z or x[3], x.w or x[4]
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precond.typeof(xx, "number", "new: Wrong argument type for x")
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precond.typeof(yy, "number", "new: Wrong argument type for y")
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precond.typeof(zz, "number", "new: Wrong argument type for z")
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precond.typeof(ww, "number", "new: Wrong argument type for w")
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return new(xx, yy, zz, ww)
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end
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return new(0, 0, 0, 1)
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end
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--- Create a quaternion from an angle/axis pair.
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-- @tparam number angle Angle (in radians)
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-- @param axis/x -- Can be of two types, a vec3 axis, or the x component of that axis
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-- @param y axis -- y component of axis (optional, only if x component param used)
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-- @param z axis -- z component of axis (optional, only if x component param used)
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-- @treturn quat out
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function quat.from_angle_axis(angle, axis, a3, a4)
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if axis and a3 and a4 then
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local x, y, z = axis, a3, a4
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local s = sin(angle * 0.5)
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local c = cos(angle * 0.5)
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return new(x * s, y * s, z * s, c)
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else
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return quat.from_angle_axis(angle, axis.x, axis.y, axis.z)
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end
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end
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--- Create a quaternion from a normal/up vector pair.
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-- @tparam vec3 normal
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-- @tparam vec3 up (optional)
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-- @treturn quat out
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function quat.from_direction(normal, up)
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local u = up or vec3.unit_z
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local n = normal:normalize()
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local a = u:cross(n)
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local d = u:dot(n)
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return new(a.x, a.y, a.z, d + 1)
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end
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--- Clone a quaternion.
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-- @tparam quat a Quaternion to clone
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-- @treturn quat out
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function quat.clone(a)
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return new(a.x, a.y, a.z, a.w)
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end
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--- Add two quaternions.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @treturn quat out
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function quat.add(a, b)
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return new(
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a.x + b.x,
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a.y + b.y,
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a.z + b.z,
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a.w + b.w
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)
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end
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--- Subtract a quaternion from another.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @treturn quat out
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function quat.sub(a, b)
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return new(
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a.x - b.x,
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a.y - b.y,
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a.z - b.z,
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a.w - b.w
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)
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end
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--- Multiply two quaternions.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @treturn quat quaternion equivalent to "apply b, then a"
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function quat.mul(a, b)
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return new(
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a.x * b.w + a.w * b.x + a.y * b.z - a.z * b.y,
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a.y * b.w + a.w * b.y + a.z * b.x - a.x * b.z,
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a.z * b.w + a.w * b.z + a.x * b.y - a.y * b.x,
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a.w * b.w - a.x * b.x - a.y * b.y - a.z * b.z
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)
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end
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--- Multiply a quaternion and a vec3.
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-- @tparam quat a Left hand operand
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-- @tparam vec3 b Right hand operand
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-- @treturn vec3 out
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function quat.mul_vec3(a, b)
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qv.x = a.x
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qv.y = a.y
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qv.z = a.z
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uv = qv:cross(b)
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uuv = qv:cross(uv)
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return b + ((uv * a.w) + uuv) * 2
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end
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--- Raise a normalized quaternion to a scalar power.
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-- @tparam quat a Left hand operand (should be a unit quaternion)
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-- @tparam number s Right hand operand
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-- @treturn quat out
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function quat.pow(a, s)
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-- Do it as a slerp between identity and a (code borrowed from slerp)
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if a.w < 0 then
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a = -a
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end
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local dot = a.w
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dot = min(max(dot, -1), 1)
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local theta = acos(dot) * s
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local c = new(a.x, a.y, a.z, 0):normalize() * sin(theta)
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c.w = cos(theta)
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return c
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end
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--- Normalize a quaternion.
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-- @tparam quat a Quaternion to normalize
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-- @treturn quat out
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function quat.normalize(a)
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if a:is_zero() then
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return new(0, 0, 0, 0)
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end
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return a:scale(1 / a:len())
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end
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--- Get the dot product of two quaternions.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @treturn number dot
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function quat.dot(a, b)
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return a.x * b.x + a.y * b.y + a.z * b.z + a.w * b.w
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end
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--- Return the length of a quaternion.
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-- @tparam quat a Quaternion to get length of
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-- @treturn number len
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function quat.len(a)
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return sqrt(a.x * a.x + a.y * a.y + a.z * a.z + a.w * a.w)
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end
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--- Return the squared length of a quaternion.
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-- @tparam quat a Quaternion to get length of
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-- @treturn number len
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function quat.len2(a)
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return a.x * a.x + a.y * a.y + a.z * a.z + a.w * a.w
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end
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--- Multiply a quaternion by a scalar.
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-- @tparam quat a Left hand operand
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-- @tparam number s Right hand operand
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-- @treturn quat out
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function quat.scale(a, s)
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return new(
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a.x * s,
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a.y * s,
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a.z * s,
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a.w * s
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)
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end
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--- Alias of from_angle_axis.
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-- @tparam number angle Angle (in radians)
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-- @param axis/x -- Can be of two types, a vec3 axis, or the x component of that axis
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-- @param y axis -- y component of axis (optional, only if x component param used)
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-- @param z axis -- z component of axis (optional, only if x component param used)
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-- @treturn quat out
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function quat.rotate(angle, axis, a3, a4)
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return quat.from_angle_axis(angle, axis, a3, a4)
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end
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--- Return the conjugate of a quaternion.
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-- @tparam quat a Quaternion to conjugate
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-- @treturn quat out
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function quat.conjugate(a)
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return new(-a.x, -a.y, -a.z, a.w)
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end
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--- Return the inverse of a quaternion.
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-- @tparam quat a Quaternion to invert
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-- @treturn quat out
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function quat.inverse(a)
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tmp.x = -a.x
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tmp.y = -a.y
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tmp.z = -a.z
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tmp.w = a.w
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return tmp:normalize()
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end
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--- Return the reciprocal of a quaternion.
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-- @tparam quat a Quaternion to reciprocate
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-- @treturn quat out
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function quat.reciprocal(a)
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if a:is_zero() then
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error("Cannot reciprocate a zero quaternion")
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return false
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end
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tmp.x = -a.x
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tmp.y = -a.y
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tmp.z = -a.z
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tmp.w = a.w
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return tmp:scale(1 / a:len2())
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end
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--- Lerp between two quaternions.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @tparam number s Step value
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-- @treturn quat out
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function quat.lerp(a, b, s)
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return (a + (b - a) * s):normalize()
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end
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--- Slerp between two quaternions.
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-- @tparam quat a Left hand operand
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-- @tparam quat b Right hand operand
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-- @tparam number s Step value
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-- @treturn quat out
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function quat.slerp(a, b, s)
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local dot = a:dot(b)
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if dot < 0 then
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a = -a
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dot = -dot
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end
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if dot > DOT_THRESHOLD then
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return a:lerp(b, s)
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end
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dot = min(max(dot, -1), 1)
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local theta = acos(dot) * s
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local c = (b - a * dot):normalize()
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return a * cos(theta) + c * sin(theta)
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end
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--- Unpack a quaternion into individual components.
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-- @tparam quat a Quaternion to unpack
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-- @treturn number x
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-- @treturn number y
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-- @treturn number z
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-- @treturn number w
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function quat.unpack(a)
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return a.x, a.y, a.z, a.w
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end
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--- Return a boolean showing if a table is or is not a quat.
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-- @tparam quat a Quaternion to be tested
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-- @treturn boolean is_quat
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function quat.is_quat(a)
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if type(a) == "cdata" then
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return ffi.istype("cpml_quat", a)
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end
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return
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type(a) == "table" and
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type(a.x) == "number" and
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type(a.y) == "number" and
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type(a.z) == "number" and
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type(a.w) == "number"
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end
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--- Return a boolean showing if a table is or is not a zero quat.
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-- @tparam quat a Quaternion to be tested
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-- @treturn boolean is_zero
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function quat.is_zero(a)
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return
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a.x == 0 and
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a.y == 0 and
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a.z == 0 and
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a.w == 0
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end
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--- Return a boolean showing if a table is or is not a real quat.
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-- @tparam quat a Quaternion to be tested
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-- @treturn boolean is_real
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function quat.is_real(a)
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return
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a.x == 0 and
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a.y == 0 and
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a.z == 0
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end
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--- Return a boolean showing if a table is or is not an imaginary quat.
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-- @tparam quat a Quaternion to be tested
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-- @treturn boolean is_imaginary
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function quat.is_imaginary(a)
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return a.w == 0
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end
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--- Return whether any component is NaN
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-- @tparam quat a Quaternion to be tested
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-- @treturn boolean if x,y,z, or w is NaN
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function quat.has_nan(a)
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return private.is_nan(a.x) or
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private.is_nan(a.y) or
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private.is_nan(a.z) or
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private.is_nan(a.w)
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end
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--- Convert a quaternion into an angle plus axis components.
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-- @tparam quat a Quaternion to convert
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-- @tparam identityAxis vec3 of axis to use on identity/degenerate quaternions (optional, default returns 0,0,0,1)
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-- @treturn number angle
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-- @treturn x axis-x
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-- @treturn y axis-y
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-- @treturn z axis-z
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function quat.to_angle_axis_unpack(a, identityAxis)
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if a.w > 1 or a.w < -1 then
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a = a:normalize()
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end
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-- If length of xyz components is less than DBL_EPSILON, this is zero or close enough (an identity quaternion)
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-- Normally an identity quat would return a nonsense answer, so we return an arbitrary zero rotation early.
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-- FIXME: Is it safe to assume there are *no* valid quaternions with nonzero degenerate lengths?
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if a.x*a.x + a.y*a.y + a.z*a.z < constants.DBL_EPSILON*constants.DBL_EPSILON then
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if identityAxis then
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return 0,identityAxis:unpack()
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else
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return 0,0,0,1
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end
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end
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local x, y, z
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local angle = 2 * acos(a.w)
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local s = sqrt(1 - a.w * a.w)
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if s < DBL_EPSILON then
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x = a.x
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y = a.y
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z = a.z
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else
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x = a.x / s
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y = a.y / s
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z = a.z / s
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end
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return angle, x, y, z
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end
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--- Convert a quaternion into an angle/axis pair.
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-- @tparam quat a Quaternion to convert
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-- @tparam identityAxis vec3 of axis to use on identity/degenerate quaternions (optional, default returns 0,vec3(0,0,1))
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-- @treturn number angle
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-- @treturn vec3 axis
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function quat.to_angle_axis(a, identityAxis)
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local angle, x, y, z = a:to_angle_axis_unpack(identityAxis)
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return angle, vec3(x, y, z)
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end
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--- Convert a quaternion into a vec3.
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-- @tparam quat a Quaternion to convert
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-- @treturn vec3 out
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function quat.to_vec3(a)
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return vec3(a.x, a.y, a.z)
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end
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--- Return a formatted string.
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-- @tparam quat a Quaternion to be turned into a string
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-- @treturn string formatted
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function quat.to_string(a)
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return string.format("(%+0.3f,%+0.3f,%+0.3f,%+0.3f)", a.x, a.y, a.z, a.w)
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end
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quat_mt.__index = quat
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quat_mt.__tostring = quat.to_string
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function quat_mt.__call(_, x, y, z, w)
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return quat.new(x, y, z, w)
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end
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function quat_mt.__unm(a)
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return a:scale(-1)
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end
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function quat_mt.__eq(a,b)
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if not quat.is_quat(a) or not quat.is_quat(b) then
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return false
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end
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return a.x == b.x and a.y == b.y and a.z == b.z and a.w == b.w
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end
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function quat_mt.__add(a, b)
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precond.assert(quat.is_quat(a), "__add: Wrong argument type '%s' for left hand operand. (<cpml.quat> expected)", type(a))
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precond.assert(quat.is_quat(b), "__add: Wrong argument type '%s' for right hand operand. (<cpml.quat> expected)", type(b))
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return a:add(b)
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end
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function quat_mt.__sub(a, b)
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precond.assert(quat.is_quat(a), "__sub: Wrong argument type '%s' for left hand operand. (<cpml.quat> expected)", type(a))
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precond.assert(quat.is_quat(b), "__sub: Wrong argument type '%s' for right hand operand. (<cpml.quat> expected)", type(b))
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return a:sub(b)
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end
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function quat_mt.__mul(a, b)
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precond.assert(quat.is_quat(a), "__mul: Wrong argument type '%s' for left hand operand. (<cpml.quat> expected)", type(a))
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assert(quat.is_quat(b) or vec3.is_vec3(b) or type(b) == "number", "__mul: Wrong argument type for right hand operand. (<cpml.quat> or <cpml.vec3> or <number> expected)")
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if quat.is_quat(b) then
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return a:mul(b)
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end
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if type(b) == "number" then
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return a:scale(b)
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end
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return a:mul_vec3(b)
|
|
end
|
|
|
|
function quat_mt.__pow(a, n)
|
|
precond.assert(quat.is_quat(a), "__pow: Wrong argument type '%s' for left hand operand. (<cpml.quat> expected)", type(a))
|
|
precond.typeof(n, "number", "__pow: Wrong argument type for right hand operand.")
|
|
return a:pow(n)
|
|
end
|
|
|
|
if status then
|
|
xpcall(function() -- Allow this to silently fail; assume failure means someone messed with package.loaded
|
|
ffi.metatype(new, quat_mt)
|
|
end, function() end)
|
|
end
|
|
|
|
return setmetatable({}, quat_mt)
|