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//

// Copyright (c) 2002-2012, Industrial Light & Magic, a division of Lucas

// Digital Ltd. LLC

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///////////////////////////////////////////////////////////////////////////

#ifndef INCLUDED_IMATHQUAT_H

#define INCLUDED_IMATHQUAT_H

//----------------------------------------------------------------------

//

//  template class Quat<T>

//

//  "Quaternions came from Hamilton ... and have been an unmixed

//  evil to those who have touched them in any way. Vector is a

//  useless survival ... and has never been of the slightest use

//  to any creature."

//

//      - Lord Kelvin

//

//  This class implements the quaternion numerical type -- you

//      will probably want to use this class to represent orientations

//  in R3 and to convert between various euler angle reps. You

//  should probably use Imath::Euler<> for that.

//

//----------------------------------------------------------------------

#include "ImathExc.h"

#include "ImathMatrix.h"

#include "ImathNamespace.h"

#include <iostream>

IMATH_INTERNAL_NAMESPACE_HEADER_ENTER

#if (defined _WIN32 || defined _WIN64) && defined _MSC_VER

// Disable MS VC++ warnings about conversion from double to float

#pragma warning(disable:4244)

#endif

template <class T>

class Quat

{

  public:

    T     r;      // real part

    Vec3<T>   v;      // imaginary vector

    //-----------------------------------------------------

    //  Constructors - default constructor is identity quat

    //-----------------------------------------------------

    Quat ();

    template <class S>

    Quat (const Quat<S> &q);

    Quat (T s, T i, T j, T k);

    Quat (T s, Vec3<T> d);

    static Quat<T> identity ();

    //-------------------------------------------------

    //  Basic Algebra - Operators and Methods

    //  The operator return values are *NOT* normalized

    //

    //  operator^ and euclideanInnnerProduct() both

    //            implement the 4D dot product

    //

    //  operator/ uses the inverse() quaternion

    //

    //  operator~ is conjugate -- if (S+V) is quat then

    //      the conjugate (S+V)* == (S-V)

    //

    //  some operators (*,/,*=,/=) treat the quat as

    //  a 4D vector when one of the operands is scalar

    //-------------------------------------------------

    const Quat<T> & operator =  (const Quat<T> &q);

    const Quat<T> & operator *= (const Quat<T> &q);

    const Quat<T> & operator *= (T t);

    const Quat<T> & operator /= (const Quat<T> &q);

    const Quat<T> & operator /= (T t);

    const Quat<T> & operator += (const Quat<T> &q);

    const Quat<T> & operator -= (const Quat<T> &q);

    T &     operator [] (int index);  // as 4D vector

    T     operator [] (int index) const;

    template <class S> bool operator == (const Quat<S> &q) const;

    template <class S> bool operator != (const Quat<S> &q) const;

    Quat<T> &   invert ();    // this -> 1 / this

    Quat<T>   inverse () const;

    Quat<T> &   normalize ();   // returns this

    Quat<T>   normalized () const;

    T     length () const;  // in R4

    Vec3<T>             rotateVector(const Vec3<T> &original) const;

    T                   euclideanInnerProduct(const Quat<T> &q) const;

    //-----------------------

    //  Rotation conversion

    //-----------------------

    Quat<T> &   setAxisAngle (const Vec3<T> &axis, T radians);

    Quat<T> &   setRotation (const Vec3<T> &fromDirection,

             const Vec3<T> &toDirection);

    T     angle () const;

    Vec3<T>   axis () const;

    Matrix33<T>   toMatrix33 () const;

    Matrix44<T>   toMatrix44 () const;

    Quat<T>   log () const;

    Quat<T>   exp () const;

  private:

    void    setRotationInternal (const Vec3<T> &f0,

               const Vec3<T> &t0,

               Quat<T> &q);

};

template<class T>

Quat<T>     slerp (const Quat<T> &q1, const Quat<T> &q2, T t);

template<class T>

Quat<T>     slerpShortestArc

                              (const Quat<T> &q1, const Quat<T> &q2, T t);

template<class T>

Quat<T>     squad (const Quat<T> &q1, const Quat<T> &q2, 

             const Quat<T> &qa, const Quat<T> &qb, T t);

template<class T>

void      intermediate (const Quat<T> &q0, const Quat<T> &q1, 

              const Quat<T> &q2, const Quat<T> &q3,

              Quat<T> &qa, Quat<T> &qb);

template<class T>

Matrix33<T>   operator * (const Matrix33<T> &M, const Quat<T> &q);

template<class T>

Matrix33<T>   operator * (const Quat<T> &q, const Matrix33<T> &M);

template<class T>

std::ostream &    operator << (std::ostream &o, const Quat<T> &q);

template<class T>

Quat<T>     operator * (const Quat<T> &q1, const Quat<T> &q2);

template<class T>

Quat<T>     operator / (const Quat<T> &q1, const Quat<T> &q2);

template<class T>

Quat<T>     operator / (const Quat<T> &q, T t);

template<class T>

Quat<T>     operator * (const Quat<T> &q, T t);

template<class T>

Quat<T>     operator * (T t, const Quat<T> &q);

template<class T>

Quat<T>     operator + (const Quat<T> &q1, const Quat<T> &q2);

template<class T>

Quat<T>     operator - (const Quat<T> &q1, const Quat<T> &q2);

template<class T>

Quat<T>     operator ~ (const Quat<T> &q);

template<class T>

Quat<T>     operator - (const Quat<T> &q);

template<class T>

Vec3<T>     operator * (const Vec3<T> &v, const Quat<T> &q);

//--------------------

// Convenient typedefs

//--------------------

typedef Quat<float> Quatf;

typedef Quat<double>  Quatd;

//---------------

// Implementation

//---------------

template<class T>

inline

Quat<T>::Quat (): r (1), v (0, 0, 0)

{

    // empty

}

template<class T>

template <class S>

inline

Quat<T>::Quat (const Quat<S> &q): r (q.r), v (q.v)

{

    // empty

}

template<class T>

inline

Quat<T>::Quat (T s, T i, T j, T k): r (s), v (i, j, k)

{

    // empty

}

template<class T>

inline

Quat<T>::Quat (T s, Vec3<T> d): r (s), v (d)

{

    // empty

}

template<class T>

inline Quat<T>

Quat<T>::identity ()

{

    return Quat<T>();

}

template<class T>

inline const Quat<T> &

Quat<T>::operator = (const Quat<T> &q)

{

    r = q.r;

    v = q.v;

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator *= (const Quat<T> &q)

{

    T rtmp = r * q.r - (v ^ q.v);

    v = r * q.v + v * q.r + v % q.v;

    r = rtmp;

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator *= (T t)

{

    r *= t;

    v *= t;

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator /= (const Quat<T> &q)

{

    *this = *this * q.inverse();

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator /= (T t)

{

    r /= t;

    v /= t;

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator += (const Quat<T> &q)

{

    r += q.r;

    v += q.v;

    return *this;

}

template<class T>

inline const Quat<T> &

Quat<T>::operator -= (const Quat<T> &q)

{

    r -= q.r;

    v -= q.v;

    return *this;

}

template<class T>

inline T &

Quat<T>::operator [] (int index)

{

    return index ? v[index - 1] : r;

}

template<class T>

inline T

Quat<T>::operator [] (int index) const

{

    return index ? v[index - 1] : r;

}

template <class T>

template <class S>

inline bool

Quat<T>::operator == (const Quat<S> &q) const

{

    return r == q.r && v == q.v;

}

template <class T>

template <class S>

inline bool

Quat<T>::operator != (const Quat<S> &q) const

{

    return r != q.r || v != q.v;

}

template<class T>

inline T

operator ^ (const Quat<T>& q1 ,const Quat<T>& q2)

{

    return q1.r * q2.r + (q1.v ^ q2.v);

}

template <class T>

inline T

Quat<T>::length () const

{

    return Math<T>::sqrt (r * r + (v ^ v));

}

template <class T>

inline Quat<T> &

Quat<T>::normalize ()

{

    if (T l = length())

    {

  r /= l;

  v /= l;

    }

    else

    {

  r = 1;

  v = Vec3<T> (0);

    }

    return *this;

}

template <class T>

inline Quat<T>

Quat<T>::normalized () const

{

    if (T l = length())

  return Quat (r / l, v / l);

    return Quat();

}

template<class T>

inline Quat<T>

Quat<T>::inverse () const

{

    //

    // 1    Q*

    // - = ----   where Q* is conjugate (operator~)

    // Q   Q* Q   and (Q* Q) == Q ^ Q (4D dot)

    //

    T qdot = *this ^ *this;

    return Quat (r / qdot, -v / qdot);

}

template<class T>

inline Quat<T> &

Quat<T>::invert ()

{

    T qdot = (*this) ^ (*this);

    r /= qdot;

    v = -v / qdot;

    return *this;

}

template<class T>

inline Vec3<T>

Quat<T>::rotateVector(const Vec3<T>& original) const

{

    //

    // Given a vector p and a quaternion q (aka this),

    // calculate p' = qpq*

    //

    // Assumes unit quaternions (because non-unit

    // quaternions cannot be used to rotate vectors

    // anyway).

    //

    Quat<T> vec (0, original);  // temporarily promote grade of original

    Quat<T> inv (*this);

    inv.v *= -1;                // unit multiplicative inverse

    Quat<T> result = *this * vec * inv;

    return result.v;

}

template<class T>

inline T 

Quat<T>::euclideanInnerProduct (const Quat<T> &q) const

{

    return r * q.r + v.x * q.v.x + v.y * q.v.y + v.z * q.v.z;

}

template<class T>

T

angle4D (const Quat<T> &q1, const Quat<T> &q2)

{

    //

    // Compute the angle between two quaternions,

    // interpreting the quaternions as 4D vectors.

    //

    Quat<T> d = q1 - q2;

    T lengthD = Math<T>::sqrt (d ^ d);

    Quat<T> s = q1 + q2;

    T lengthS = Math<T>::sqrt (s ^ s);

    return 2 * Math<T>::atan2 (lengthD, lengthS);

}

template<class T>

Quat<T>

slerp (const Quat<T> &q1, const Quat<T> &q2, T t)

{

    //

    // Spherical linear interpolation.

    // Assumes q1 and q2 are normalized and that q1 != -q2.

    //

    // This method does *not* interpolate along the shortest

    // arc between q1 and q2.  If you desire interpolation

    // along the shortest arc, and q1^q2 is negative, then

    // consider calling slerpShortestArc(), below, or flipping

    // the second quaternion explicitly.

    //

    // The implementation of squad() depends on a slerp()

    // that interpolates as is, without the automatic

    // flipping.

    //

    // Don Hatch explains the method we use here on his

    // web page, The Right Way to Calculate Stuff, at

    // http://www.plunk.org/~hatch/rightway.php

    //

    T a = angle4D (q1, q2);

    T s = 1 - t;

    Quat<T> q = sinx_over_x (s * a) / sinx_over_x (a) * s * q1 +

          sinx_over_x (t * a) / sinx_over_x (a) * t * q2;

    return q.normalized();

}

template<class T>

Quat<T>

slerpShortestArc (const Quat<T> &q1, const Quat<T> &q2, T t)

{

    //

    // Spherical linear interpolation along the shortest

    // arc from q1 to either q2 or -q2, whichever is closer.

    // Assumes q1 and q2 are unit quaternions.

    //

    if ((q1 ^ q2) >= 0)

        return slerp (q1, q2, t);

    else

        return slerp (q1, -q2, t);

}

template<class T>

Quat<T>

spline (const Quat<T> &q0, const Quat<T> &q1,

        const Quat<T> &q2, const Quat<T> &q3,

  T t)

{

    //

    // Spherical Cubic Spline Interpolation -

    // from Advanced Animation and Rendering

    // Techniques by Watt and Watt, Page 366:

    // A spherical curve is constructed using three

    // spherical linear interpolations of a quadrangle

    // of unit quaternions: q1, qa, qb, q2.

    // Given a set of quaternion keys: q0, q1, q2, q3,

    // this routine does the interpolation between

    // q1 and q2 by constructing two intermediate

    // quaternions: qa and qb. The qa and qb are 

    // computed by the intermediate function to 

    // guarantee the continuity of tangents across

    // adjacent cubic segments. The qa represents in-tangent

    // for q1 and the qb represents the out-tangent for q2.

    // 

    // The q1 q2 is the cubic segment being interpolated. 

    // The q0 is from the previous adjacent segment and q3 is 

    // from the next adjacent segment. The q0 and q3 are used

    // in computing qa and qb.

    // 

    Quat<T> qa = intermediate (q0, q1, q2);

    Quat<T> qb = intermediate (q1, q2, q3);

    Quat<T> result = squad (q1, qa, qb, q2, t);

    return result;

}

template<class T>

Quat<T>

squad (const Quat<T> &q1, const Quat<T> &qa,

       const Quat<T> &qb, const Quat<T> &q2,

       T t)

{

    //

    // Spherical Quadrangle Interpolation -

    // from Advanced Animation and Rendering

    // Techniques by Watt and Watt, Page 366:

    // It constructs a spherical cubic interpolation as 

    // a series of three spherical linear interpolations 

    // of a quadrangle of unit quaternions. 

    //     

    Quat<T> r1 = slerp (q1, q2, t);

    Quat<T> r2 = slerp (qa, qb, t);

    Quat<T> result = slerp (r1, r2, 2 * t * (1 - t));

    return result;

}

template<class T>

Quat<T>

intermediate (const Quat<T> &q0, const Quat<T> &q1, const Quat<T> &q2)

{

    //

    // From advanced Animation and Rendering

    // Techniques by Watt and Watt, Page 366:

    // computing the inner quadrangle 

    // points (qa and qb) to guarantee tangent

    // continuity.

    // 

    Quat<T> q1inv = q1.inverse();

    Quat<T> c1 = q1inv * q2;

    Quat<T> c2 = q1inv * q0;

    Quat<T> c3 = (T) (-0.25) * (c2.log() + c1.log());

    Quat<T> qa = q1 * c3.exp();

    qa.normalize();

    return qa;

}

template <class T>

inline Quat<T>

Quat<T>::log () const

{

    //

    // For unit quaternion, from Advanced Animation and 

    // Rendering Techniques by Watt and Watt, Page 366:

    //

    T theta = Math<T>::acos (std::min (r, (T) 1.0));

    if (theta == 0)

  return Quat<T> (0, v);

    T sintheta = Math<T>::sin (theta);

    T k;

    if (abs (sintheta) < 1 && abs (theta) >= limits<T>::max() * abs (sintheta))

  k = 1;

    else

  k = theta / sintheta;

    return Quat<T> ((T) 0, v.x * k, v.y * k, v.z * k);

}

template <class T>

inline Quat<T>

Quat<T>::exp () const

{

    //

    // For pure quaternion (zero scalar part):

    // from Advanced Animation and Rendering

    // Techniques by Watt and Watt, Page 366:

    //

    T theta = v.length();

    T sintheta = Math<T>::sin (theta);

    T k;

    if (abs (theta) < 1 && abs (sintheta) >= limits<T>::max() * abs (theta))

  k = 1;

    else

  k = sintheta / theta;

    T costheta = Math<T>::cos (theta);

    return Quat<T> (costheta, v.x * k, v.y * k, v.z * k);

}

template <class T>

inline T

Quat<T>::angle () const

{

    return 2 * Math<T>::atan2 (v.length(), r);

}

template <class T>

inline Vec3<T>

Quat<T>::axis () const

{

    return v.normalized();

}

template <class T>

inline Quat<T> &

Quat<T>::setAxisAngle (const Vec3<T> &axis, T radians)

{

    r = Math<T>::cos (radians / 2);

    v = axis.normalized() * Math<T>::sin (radians / 2);

    return *this;

}

template <class T>

Quat<T> &

Quat<T>::setRotation (const Vec3<T> &from, const Vec3<T> &to)

{

    //

    // Create a quaternion that rotates vector from into vector to,

    // such that the rotation is around an axis that is the cross

    // product of from and to.

    //

    // This function calls function setRotationInternal(), which is

    // numerically accurate only for rotation angles that are not much

    // greater than pi/2.  In order to achieve good accuracy for angles

    // greater than pi/2, we split large angles in half, and rotate in

    // two steps.

    //

    //

    // Normalize from and to, yielding f0 and t0.

    //

    Vec3<T> f0 = from.normalized();

    Vec3<T> t0 = to.normalized();

    if ((f0 ^ t0) >= 0)

    {

  //

  // The rotation angle is less than or equal to pi/2.

  //

  setRotationInternal (f0, t0, *this);

    }

    else

    {

  //

  // The angle is greater than pi/2.  After computing h0,

  // which is halfway between f0 and t0, we rotate first

  // from f0 to h0, then from h0 to t0.

  //

  Vec3<T> h0 = (f0 + t0).normalized();

  if ((h0 ^ h0) != 0)

  {

      setRotationInternal (f0, h0, *this);

      Quat<T> q;

      setRotationInternal (h0, t0, q);

      *this *= q;

  }

  else

  {

      //

      // f0 and t0 point in exactly opposite directions.

      // Pick an arbitrary axis that is orthogonal to f0,

      // and rotate by pi.

      //

      r = T (0);

      Vec3<T> f02 = f0 * f0;

      if (f02.x <= f02.y && f02.x <= f02.z)

    v = (f0 % Vec3<T> (1, 0, 0)).normalized();

      else if (f02.y <= f02.z)

    v = (f0 % Vec3<T> (0, 1, 0)).normalized();

      else

    v = (f0 % Vec3<T> (0, 0, 1)).normalized();

  }

    }

    return *this;

}

template <class T>

void

Quat<T>::setRotationInternal (const Vec3<T> &f0, const Vec3<T> &t0, Quat<T> &q)

{

    //

    // The following is equivalent to setAxisAngle(n,2*phi),

    // where the rotation axis, n, is orthogonal to the f0 and

    // t0 vectors, and 2*phi is the angle between f0 and t0.

    //

    // This function is called by setRotation(), above; it assumes

    // that f0 and t0 are normalized and that the angle between

    // them is not much greater than pi/2.  This function becomes

    // numerically inaccurate if f0 and t0 point into nearly

    // opposite directions.

    //

    //

    // Find a normalized vector, h0, that is halfway between f0 and t0.

    // The angle between f0 and h0 is phi.

    //

    Vec3<T> h0 = (f0 + t0).normalized();

    //

    // Store the rotation axis and rotation angle.

    //

    q.r = f0 ^ h0;  //  f0 ^ h0 == cos (phi)

    q.v = f0 % h0;  // (f0 % h0).length() == sin (phi)

}

template<class T>

Matrix33<T>

Quat<T>::toMatrix33() const

{

    return Matrix33<T> (1 - 2 * (v.y * v.y + v.z * v.z),

          2 * (v.x * v.y + v.z * r),

          2 * (v.z * v.x - v.y * r),

          2 * (v.x * v.y - v.z * r),

            1 - 2 * (v.z * v.z + v.x * v.x),

          2 * (v.y * v.z + v.x * r),

          2 * (v.z * v.x + v.y * r),

          2 * (v.y * v.z - v.x * r),

            1 - 2 * (v.y * v.y + v.x * v.x));

}

template<class T>

Matrix44<T>

Quat<T>::toMatrix44() const

{

    return Matrix44<T> (1 - 2 * (v.y * v.y + v.z * v.z),

          2 * (v.x * v.y + v.z * r),

          2 * (v.z * v.x - v.y * r),

          0,

          2 * (v.x * v.y - v.z * r),

            1 - 2 * (v.z * v.z + v.x * v.x),

          2 * (v.y * v.z + v.x * r),

          0,

          2 * (v.z * v.x + v.y * r),

          2 * (v.y * v.z - v.x * r),

            1 - 2 * (v.y * v.y + v.x * v.x),

          0,

          0,

          0,

          0,

          1);

}

template<class T>

inline Matrix33<T>

operator * (const Matrix33<T> &M, const Quat<T> &q)

{

    return M * q.toMatrix33();

}

template<class T>

inline Matrix33<T>

operator * (const Quat<T> &q, const Matrix33<T> &M)

{

    return q.toMatrix33() * M;

}

template<class T>

std::ostream &

operator << (std::ostream &o, const Quat<T> &q)

{

    return o << "(" << q.r

       << " " << q.v.x

       << " " << q.v.y

       << " " << q.v.z

       << ")";

}

template<class T>

inline Quat<T>

operator * (const Quat<T> &q1, const Quat<T> &q2)

{

    return Quat<T> (q1.r * q2.r - (q1.v ^ q2.v),

        q1.r * q2.v + q1.v * q2.r + q1.v % q2.v);

}

template<class T>

inline Quat<T>

operator / (const Quat<T> &q1, const Quat<T> &q2)

{

    return q1 * q2.inverse();

}

template<class T>

inline Quat<T>

operator / (const Quat<T> &q, T t)

{

    return Quat<T> (q.r / t, q.v / t);

}

template<class T>

inline Quat<T>

operator * (const Quat<T> &q, T t)

{

    return Quat<T> (q.r * t, q.v * t);

}

template<class T>

inline Quat<T>

operator * (T t, const Quat<T> &q)

{

    return Quat<T> (q.r * t, q.v * t);

}

template<class T>

inline Quat<T>

operator + (const Quat<T> &q1, const Quat<T> &q2)

{

    return Quat<T> (q1.r + q2.r, q1.v + q2.v);

}

template<class T>

inline Quat<T>

operator - (const Quat<T> &q1, const Quat<T> &q2)

{

    return Quat<T> (q1.r - q2.r, q1.v - q2.v);

}

template<class T>

inline Quat<T>

operator ~ (const Quat<T> &q)

{

    return Quat<T> (q.r, -q.v);

}

template<class T>

inline Quat<T>

operator - (const Quat<T> &q)

{

    return Quat<T> (-q.r, -q.v);

}

template<class T>

inline Vec3<T>

operator * (const Vec3<T> &v, const Quat<T> &q)

{

    Vec3<T> a = q.v % v;

    Vec3<T> b = q.v % a;

    return v + T (2) * (q.r * a + b);

}

#if (defined _WIN32 || defined _WIN64) && defined _MSC_VER

#pragma warning(default:4244)

#endif

IMATH_INTERNAL_NAMESPACE_HEADER_EXIT

#endif // INCLUDED_IMATHQUAT_H