quaternions.h

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/*******************************************************************************
 * \file quaternions.h
 * 
 * \author MAV'RIC Team
 * \author Felix Schill
 * \author Geraud L'Eplattenier
 *   
 * \brief Useful functions for quaternions
 *
 ******************************************************************************/


#ifndef QUATERNIONS_H_
#define QUATERNIONS_H_

#ifdef __cplusplus
extern "C"
{
#endif

#include <stdint.h>
#include "maths.h"
#include "vectors.h"


typedef struct 
{
    float s;            
    float v[3];         
} quat_t;


#define QI(q, out) \
    out.s = q.s;\
    out.v[0] = -q.v[0];\
    out.v[1] = -q.v[1];\
    out.v[2] = -q.v[2];


#define QUAT(q, s, v0, v1, v2) \
    q.s = s;\
    q.v[0] = v0;\
    q.v[1] = v1;\
    q.v[2] = v2;


quat_t static inline quaternions_create_from_vector(float v[3])
{
    quat_t q;   
    q.s = 0; 
    q.v[0] = v[0]; 
    q.v[1] = v[1]; 
    q.v[2] = v[2];
    return q;
}


#define QMUL(q1,q2,out) \
    tmp[0] = q1.v[1] * q2.v[2] - q1.v[2] * q2.v[1];\
    tmp[1] = q1.v[2] * q2.v[0] - q1.v[0] * q2.v[2];\
    tmp[2] = q1.v[0] * q2.v[1] - q1.v[1] * q2.v[0];\
    out.v[0] = q2.s* q1.v[0] + q1.s * q2.v[0] + tmp[0];\
    out.v[1] = q2.s* q1.v[1] + q1.s * q2.v[1] + tmp[1];\
    out.v[2] = q2.s* q1.v[2] + q1.s * q2.v[2] + tmp[2];\
    out.s= q1.s * q2.s - SCP(q1.v, q2.v);


quat_t static inline quaternions_multiply(const quat_t q1, const quat_t q2)
{
    float tmp[3];
    quat_t out;

    tmp[0] = q1.v[1] * q2.v[2] - q1.v[2] * q2.v[1];
    tmp[1] = q1.v[2] * q2.v[0] - q1.v[0] * q2.v[2];
    tmp[2] = q1.v[0] * q2.v[1] - q1.v[1] * q2.v[0];
    
    out.v[0] = q2.s * q1.v[0] + q1.s * q2.v[0] + tmp[0];
    out.v[1] = q2.s * q1.v[1] + q1.s * q2.v[1] + tmp[1];
    out.v[2] = q2.s * q1.v[2] + q1.s * q2.v[2] + tmp[2];
    out.s = q1.s * q2.s - vectors_scalar_product(q1.v, q2.v);
    
    return out;
}


quat_t static inline quaternions_inverse(const quat_t q)
{
    quat_t qinv;
    qinv.s = q.s;
    
    for( int32_t  i = 0; i < 3; i++)
    {
        qinv.v[i] = -q.v[i];
    }
    
    return qinv;
}


quat_t static inline quaternions_global_to_local(const quat_t qe, const quat_t qvect)
{
    quat_t qinv, qtmp;
    
    qinv = quaternions_inverse(qe);
    qtmp = quaternions_multiply(qinv,qvect);
    qtmp = quaternions_multiply(qtmp,qe);

    return qtmp;
}


quat_t static inline quaternions_local_to_global(const quat_t qe, const quat_t qvect)
{
    quat_t qinv, qtmp;
    
    qinv = quaternions_inverse(qe);
    qtmp = quaternions_multiply(qe, qvect);
    qtmp = quaternions_multiply(qtmp, qinv);
    
    return qtmp;
}


void static inline quaternions_rotate_vector(const quat_t q, const float u[3], float v[3])
{
    float tmp1[3], tmp2[3];

    vectors_cross_product(q.v, u, tmp1);
    tmp1[0] = 2 * tmp1[0];
    tmp1[1] = 2 * tmp1[1];
    tmp1[2] = 2 * tmp1[2];

    vectors_cross_product(q.v, tmp1, tmp2);
    
    v[0] = u[0] + q.s * tmp1[0] + tmp2[0];
    v[1] = u[1] + q.s * tmp1[1] + tmp2[1];
    v[2] = u[2] + q.s * tmp1[2] + tmp2[2];
}


static inline quat_t quaternions_normalise(const quat_t q)
{
    quat_t result;
    
    float snorm = SQR(q.s) + SQR(q.v[0]) + SQR(q.v[1]) + SQR(q.v[2]);

    if (snorm > 0.0000001f) 
    {
        float norm = maths_fast_sqrt(snorm);
        result.s = q.s / norm;
        result.v[0] = q.v[0] / norm;        
        result.v[1] = q.v[1] / norm;        
        result.v[2] = q.v[2] / norm;
    }
    else
    {
        result.s = 1.0f;
        result.v[0] = 0.0f;
        result.v[1] = 0.0f;
        result.v[2] = 0.0f;
    }

    return result;
}


#ifdef __cplusplus
}
#endif

#endif /* QUATERNIONS_H_ */