/*
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Christian Meyer
   co-programmer: Patrick Boenzli : Vector::scale()
                                    Vector::abs()

   Quaternion code borrowed from an Gamasutra article by Nick Bobick and Ken Shoemake

   2005-06-02: Benjamin Grauer: speed up, and new Functionality to Vector (mostly inline now)
*/

#define DEBUG_SPECIAL_MODULE DEBUG_MODULE_MATH

#include "quaternion.h"
#ifdef DEBUG
  #include "debug.h"
#else
  #include <stdio.h>
  #define PRINT(x) printf
#endif

using namespace std;

/////////////////
/* QUATERNIONS */
/////////////////
/**
 * @brief calculates a lookAt rotation
 * @param dir: the direction you want to look
 * @param up: specify what direction up should be
 *
 * Mathematically this determines the rotation a (0,0,1)-Vector has to undergo to point
 * the same way as dir. If you want to use this with cameras, you'll have to reverse the
 * dir Vector (Vector(0,0,0) - your viewing direction) or you'll point the wrong way. You
 * can use this for meshes as well (then you do not have to reverse the vector), but keep
 * in mind that if you do that, the model's front has to point in +z direction, and left
 * and right should be -x or +x respectively or the mesh wont rotate correctly.
 *
 * @TODO !!! OPTIMIZE THIS !!!
 */
Quaternion::Quaternion (const Vector& dir, const Vector& up)
{
  Vector z = dir.getNormalized();
  Vector x = up.cross(z).getNormalized();
  Vector y = z.cross(x);

  float m[4][4];
  m[0][0] = x.x;
  m[0][1] = x.y;
  m[0][2] = x.z;
  m[0][3] = 0;
  m[1][0] = y.x;
  m[1][1] = y.y;
  m[1][2] = y.z;
  m[1][3] = 0;
  m[2][0] = z.x;
  m[2][1] = z.y;
  m[2][2] = z.z;
  m[2][3] = 0;
  m[3][0] = 0;
  m[3][1] = 0;
  m[3][2] = 0;
  m[3][3] = 1;

  *this = Quaternion (m);
}

/**
 * @brief calculates a rotation from euler angles
 * @param roll: the roll in radians
 * @param pitch: the pitch in radians
 * @param yaw: the yaw in radians
 */
Quaternion::Quaternion (float roll, float pitch, float yaw)
{
  float cr, cp, cy, sr, sp, sy, cpcy, spsy;

  // calculate trig identities
  cr = cos(roll/2);
  cp = cos(pitch/2);
  cy = cos(yaw/2);

  sr = sin(roll/2);
  sp = sin(pitch/2);
  sy = sin(yaw/2);

  cpcy = cp * cy;
  spsy = sp * sy;

  w = cr * cpcy + sr * spsy;
  v.x = sr * cpcy - cr * spsy;
  v.y = cr * sp * cy + sr * cp * sy;
  v.z = cr * cp * sy - sr * sp * cy;
}

/**
 * @brief convert the Quaternion to a 4x4 rotational glMatrix
 * @param m: a buffer to store the Matrix in
 */
void Quaternion::matrix (float m[4][4]) const
{
  float wx, wy, wz, xx, yy, yz, xy, xz, zz, x2, y2, z2;

  // calculate coefficients
  x2 = v.x + v.x;
  y2 = v.y + v.y;
  z2 = v.z + v.z;
  xx = v.x * x2; xy = v.x * y2; xz = v.x * z2;
  yy = v.y * y2; yz = v.y * z2; zz = v.z * z2;
  wx = w * x2; wy = w * y2; wz = w * z2;

  m[0][0] = 1.0 - (yy + zz); m[1][0] = xy - wz;
  m[2][0] = xz + wy; m[3][0] = 0.0;

  m[0][1] = xy + wz; m[1][1] = 1.0 - (xx + zz);
  m[2][1] = yz - wx; m[3][1] = 0.0;

  m[0][2] = xz - wy; m[1][2] = yz + wx;
  m[2][2] = 1.0 - (xx + yy); m[3][2] = 0.0;

  m[0][3] = 0; m[1][3] = 0;
  m[2][3] = 0; m[3][3] = 1;
}


/**
 * @brief Slerps this QUaternion performs a smooth move.
 * @param toQuat to this Quaternion
 * @param t \% inth the the direction[0..1]
 */
void Quaternion::slerpTo(const Quaternion& toQuat, float t)
{
  float tol[4];
  double omega, cosom, sinom, scale0, scale1;
  //  float DELTA = 0.2;

  cosom = this->v.x * toQuat.v.x + this->v.y * toQuat.v.y + this->v.z * toQuat.v.z + this->w * toQuat.w;

  if( cosom < 0.0 )
  {
    cosom = -cosom;
    tol[0] = -toQuat.v.x;
    tol[1] = -toQuat.v.y;
    tol[2] = -toQuat.v.z;
    tol[3] = -toQuat.w;
  }
  else
  {
    tol[0] = toQuat.v.x;
    tol[1] = toQuat.v.y;
    tol[2] = toQuat.v.z;
    tol[3] = toQuat.w;
  }

  omega = acos(cosom);
  sinom = sin(omega);
  scale0 = sin((1.0 - t) * omega) / sinom;
  scale1 = sin(t * omega) / sinom;
  this->v = Vector(scale0 * this->v.x + scale1 * tol[0],
                   scale0 * this->v.y + scale1 * tol[1],
                   scale0 * this->v.z + scale1 * tol[2]);
  this->w = scale0 * this->w + scale1 * tol[3];
}


/**
 * @brief performs a smooth move.
 * @param from  where
 * @param to where
 * @param t the time this transformation should take value [0..1]
 * @returns the Result of the smooth move
 */
Quaternion Quaternion::quatSlerp(const Quaternion& from, const Quaternion& to, float t)
{
  float tol[4];
  double omega, cosom, sinom, scale0, scale1;
  //  float DELTA = 0.2;

  cosom = from.v.x * to.v.x + from.v.y * to.v.y + from.v.z * to.v.z + from.w * to.w;

  if( cosom < 0.0 )
  {
    cosom = -cosom;
    tol[0] = -to.v.x;
    tol[1] = -to.v.y;
    tol[2] = -to.v.z;
    tol[3] = -to.w;
  }
  else
  {
    tol[0] = to.v.x;
    tol[1] = to.v.y;
    tol[2] = to.v.z;
    tol[3] = to.w;
  }

  omega = acos(cosom);
  sinom = sin(omega);
  scale0 = sin((1.0 - t) * omega) / sinom;
  scale1 = sin(t * omega) / sinom;
  return Quaternion(Vector(scale0 * from.v.x + scale1 * tol[0],
                           scale0 * from.v.y + scale1 * tol[1],
                           scale0 * from.v.z + scale1 * tol[2]),
                    scale0 * from.w + scale1 * tol[3]);
}

/**
 * @returns the heading
 */
float Quaternion::getHeading() const
{
  float pole = this->v.x*this->v.y + this->v.z*this->w;
  if (fabsf(pole) != 0.5)
    return atan2(2.0* (v.y*w - v.x*v.z), 1 - 2.0*(v.y*v.y - v.z*v.z));
  else if (pole == .5) // North Pole
    return 2.0 * atan2(v.x, w);
  else // South Pole
    return -2.0 * atan2(v.x, w);
}

/**
 * @returns the Attitude
 */
float Quaternion::getAttitude() const
{
  return asin(2.0 * (v.x*v.y + v.z*w));
}

/**
 * @returns the Bank
 */
float Quaternion::getBank() const
{
  if (fabsf(this->v.x*this->v.y + this->v.z*this->w) != 0.5)
    return atan2(2.0*(v.x*w-v.y*v.z) , 1 - 2.0*(v.x*v.x - v.z*v.z));
  else
    return 0.0f;
}


/**
 * @brief convert a rotational 4x4 glMatrix into a Quaternion
 * @param m: a 4x4 matrix in glMatrix order
 */
Quaternion::Quaternion (float m[4][4])
{

  float  tr, s, q[4];
  int    i, j, k;

  int nxt[3] = {1, 2, 0};

  tr = m[0][0] + m[1][1] + m[2][2];

  // check the diagonal
  if (tr > 0.0)
  {
    s = sqrt (tr + 1.0);
    w = s / 2.0;
    s = 0.5 / s;
    v.x = (m[1][2] - m[2][1]) * s;
    v.y = (m[2][0] - m[0][2]) * s;
    v.z = (m[0][1] - m[1][0]) * s;
  }
  else
  {
    // diagonal is negative
    i = 0;
    if (m[1][1] > m[0][0]) i = 1;
    if (m[2][2] > m[i][i]) i = 2;
    j = nxt[i];
    k = nxt[j];

    s = sqrt ((m[i][i] - (m[j][j] + m[k][k])) + 1.0);

    q[i] = s * 0.5;

    if (s != 0.0) s = 0.5 / s;

    q[3] = (m[j][k] - m[k][j]) * s;
    q[j] = (m[i][j] + m[j][i]) * s;
    q[k] = (m[i][k] + m[k][i]) * s;

    v.x = q[0];
    v.y = q[1];
    v.z = q[2];
    w = q[3];
  }
}

/**
 * @brief outputs some nice formated debug information about this quaternion
*/
void Quaternion::debug() const
{
  PRINT(0)("real a=%f; imag: x=%f y=%f z=%f\n", w, v.x, v.y, v.z);
}

/**
 * @brief another better Quaternion Debug Function.
 */
void Quaternion::debug2() const
{
  Vector axis = this->getSpacialAxis();
  PRINT(0)("angle = %f, axis: ax=%f, ay=%f, az=%f\n", this->getSpacialAxisAngle(), axis.x, axis.y, axis.z );
}