MPUQuaternion.cpp

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//
//  This file is part of MPU9150Lib
//
//  Copyright (c) 2013 Pansenti, LLC
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy of 
//  this software and associated documentation files (the "Software"), to deal in 
//  the Software without restriction, including without limitation the rights to use, 
//  copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the 
//  Software, and to permit persons to whom the Software is furnished to do so, 
//  subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in all 
//  copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
//  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 
//  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 
//  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 
//  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#include "MPUQuaternion.h"

void MPUQuaternionNormalize(MPUQuaternion q)
{
  float length = MPUQuaternionNorm(q);
  
  if (length == 0)
    return;
  q[QUAT_W] /= length;
  q[QUAT_X] /= length;
  q[QUAT_Y] /= length;
  q[QUAT_Z] /= length;
}

void MPUQuaternionQuaternionToEuler(const MPUQuaternion q, MPUVector3 v)
{
  float pole = M_PI/2.0f - 0.05f;                           // fix roll near poles with this tolerance

  v[VEC3_Y] = asin(2.0f * (q[QUAT_W] * q[QUAT_Y] - q[QUAT_X] * q[QUAT_Z]));

  if ((v[VEC3_Y] < pole) && (v[VEC3_Y] > -pole))
          v[VEC3_X] = atan2(2.0f * (q[QUAT_Y] * q[QUAT_Z] + q[QUAT_W] * q[QUAT_X]),
                    1.0f - 2.0f * (q[QUAT_X] * q[QUAT_X] + q[QUAT_Y] * q[QUAT_Y]));
        
  v[VEC3_Z] = atan2(2.0f * (q[QUAT_X] * q[QUAT_Y] + q[QUAT_W] * q[QUAT_Z]),
                    1.0f - 2.0f * (q[QUAT_Y] * q[QUAT_Y] + q[QUAT_Z] * q[QUAT_Z]));
}

void MPUQuaternionEulerToQuaternion(const MPUVector3 v, MPUQuaternion q)
{
  float cosX2 = cos(v[VEC3_X] / 2.0f);
  float sinX2 = sin(v[VEC3_X] / 2.0f);
  float cosY2 = cos(v[VEC3_Y] / 2.0f);
  float sinY2 = sin(v[VEC3_Y] / 2.0f);
  float cosZ2 = cos(v[VEC3_Z] / 2.0f);
  float sinZ2 = sin(v[VEC3_Z] / 2.0f);

  q[QUAT_W] = cosX2 * cosY2 * cosZ2 + sinX2 * sinY2 * sinZ2;
  q[QUAT_X] = sinX2 * cosY2 * cosZ2 - cosX2 * sinY2 * sinZ2;
  q[QUAT_Y] = cosX2 * sinY2 * cosZ2 + sinX2 * cosY2 * sinZ2;
  q[QUAT_Z] = cosX2 * cosY2 * sinZ2 - sinX2 * sinY2 * cosZ2;
  MPUQuaternionNormalize(q);
}

void MPUQuaternionConjugate(const MPUQuaternion s, MPUQuaternion d) 
{
  d[QUAT_W] = s[QUAT_W];
  d[QUAT_X] = -s[QUAT_X];
  d[QUAT_Y] = -s[QUAT_Y];
  d[QUAT_Z] = -s[QUAT_Z];
}
        
void MPUQuaternionMultiply(const MPUQuaternion qa, const MPUQuaternion qb, MPUQuaternion qd) 
{
  MPUVector3 va;
  MPUVector3 vb;
  float dotAB;
  MPUVector3 crossAB;
                
  va[VEC3_X] = qa[QUAT_X];
  va[VEC3_Y] = qa[QUAT_Y];
  va[VEC3_Z] = qa[QUAT_Z];
        
  vb[VEC3_X] = qb[QUAT_X];
  vb[VEC3_Y] = qb[QUAT_Y];
  vb[VEC3_Z] = qb[QUAT_Z];
        
  MPUVector3DotProduct(va, vb, &dotAB);
  MPUVector3CrossProduct(va, vb, crossAB);
                
  qd[QUAT_W] = qa[QUAT_W] * qb[QUAT_W] - dotAB;
  qd[QUAT_X] = qa[QUAT_W] * vb[VEC3_X] + qb[QUAT_W] * va[VEC3_X] + crossAB[VEC3_X];
  qd[QUAT_Y] = qa[QUAT_W] * vb[VEC3_Y] + qb[QUAT_W] * va[VEC3_Y] + crossAB[VEC3_Y];
  qd[QUAT_Z] = qa[QUAT_W] * vb[VEC3_Z] + qb[QUAT_W] * va[VEC3_Z] + crossAB[VEC3_Z];
}