Quaternion.h

/* ============================================
 SF2 source code is placed under the MIT license
 Copyright (c) 2017 Kauai Labs

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 of this software and associated documentation files (the "Software"), to deal
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 ===============================================
 */

#ifndef SRC_ORIENTATION_QUATERNION_H_
#define SRC_ORIENTATION_QUATERNION_H_

/*----------------------------------------------------------------------------*/
/* Copyright (c) Kauai Labs 2016. All Rights Reserved.                        */
/*                                                                            */
/* Created in support of Team 2465 (Kauaibots).  Go Purple Wave!              */
/*                                                                            */
/* Open Source Software - may be modified and shared by FRC teams. Any        */
/* modifications to this code must be accompanied by the \License.txt file    */
/* in the root directory of the project.                                      */
/*----------------------------------------------------------------------------*/

#include <forward_list>
#include <vector>
using namespace std;

#include <math.h>
#include "unit/Unit.h"
#include "quantity/Scalar.h"

class Quaternion: public IInterpolate<Quaternion>, public ICopy<Quaternion>, public IQuantity {

    float w;
    float x;
    float y;
    float z;

    class FloatVectorStruct {
    public:
        float x;
        float y;
        float z;
    };

    static Unitless component_units;

public:
    Quaternion() {
        set(1, 0, 0, 0);
    }

    Quaternion(const Quaternion& src) {
        set(src);
    }

    Quaternion(float w, float x, float y, float z) {
        set(w, x, y, z);
    }

    ~Quaternion() {
    }

    void set(float w, float x, float y, float z) {
        this->w = w;
        this->x = x;
        this->y = y;
        this->z = z;
    }

    void set(const Quaternion& src) {
        set(src.w, src.x, src.y, src.z);
    }

    static void getGravity(FloatVectorStruct& v, const Quaternion& q) {
        v.x = 2 * ((q.x * q.z) - (q.w * q.y));
        v.y = 2 * ((q.w * q.x) + (q.y * q.z));
        v.z = (q.w * q.w) - (q.x * q.x) - (q.y * q.y) + (q.z * q.z);
    }

    static void getYawPitchRoll(const Quaternion& q,
            const FloatVectorStruct& gravity, FloatVectorStruct& ypr) {
        // yaw: (clockwise rotation, about Z axis)
        ypr.x = (float) atan2((2 * (q.x * q.y)) - (2 * (q.w * q.z)),
                (2 * (q.w * q.w)) + (2 * (q.x * q.x)) - 1);
        // pitch: (tilt up/down, about X axis)
        ypr.y = (float) atan(
                gravity.y
                        / sqrt(
                                (gravity.x * gravity.x)
                                        + (gravity.z * gravity.z)));
        // roll: (tilt left/right, about Y axis)
        ypr.z = (float) atan(
                gravity.x
                        / sqrt(
                                (gravity.y * gravity.y)
                                        + (gravity.z * gravity.z)));
    }

    void getYawPitchRollRadians(FloatVectorStruct& ypr) {
        FloatVectorStruct gravity;
        getGravity(gravity, *this);
        getYawPitchRoll(*this, gravity, ypr);
    }

    void getYawRadians(Scalar& yaw) {
        FloatVectorStruct ypr;
        getYawPitchRollRadians(ypr);
        yaw.set(ypr.x);
    }

    void getPitch(Scalar& pitch) {
        FloatVectorStruct ypr;
        getYawPitchRollRadians(ypr);
        pitch.set(ypr.y);
    }

    void getRoll(Scalar& roll) {
        FloatVectorStruct ypr;
        getYawPitchRollRadians(ypr);
        roll.set(ypr.z);
    }

    static void slerp(const Quaternion& qa, const Quaternion& qb, double t,
            Quaternion& out) {
        // Calculate angle between them.
        double cosHalfTheta = qa.w * qb.w + qa.x * qb.x + qa.y * qb.y
                + qa.z * qb.z;
        // if qa=qb or qa=-qb then theta = 0 and we can return qa
        if (fabs(cosHalfTheta) >= 1.0) {
            out.w = qa.w;
            out.x = qa.x;
            out.y = qa.y;
            out.z = qa.z;
            return;
        }
        // Calculate temporary values.
        double halfTheta = acos(cosHalfTheta);
        double sinHalfTheta = sqrt(1.0 - cosHalfTheta * cosHalfTheta);
        // if theta = 180 degrees then result is not fully defined
        // we could rotate around any axis normal to qa or qb
        if (fabs(sinHalfTheta) < 0.001) {
            out.w = (qa.w * 0.5f + qb.w * 0.5f);
            out.x = (qa.x * 0.5f + qb.x * 0.5f);
            out.y = (qa.y * 0.5f + qb.y * 0.5f);
            out.z = (qa.z * 0.5f + qb.z * 0.5f);
            return;
        }
        float ratioA = (float) (sin((1 - t) * halfTheta) / sinHalfTheta);
        float ratioB = (float) (sin(t * halfTheta) / sinHalfTheta);
        //calculate Quaternion.
        out.w = (qa.w * ratioA + qb.w * ratioB);
        out.x = (qa.x * ratioA + qb.x * ratioB);
        out.y = (qa.y * ratioA + qb.y * ratioB);
        out.z = (qa.z * ratioA + qb.z * ratioB);
        return;
    }

    void conjugate() {
        this->x = -this->x;
        this->y = -this->y;
        this->z = -this->z;
    }

    void inverse() {
        this->conjugate();
        this->divide(dotProduct(*this, *this));
    }

    void multiply(const Quaternion& q) {
        float w, x, y, z;

        x = this->w * q.x + this->x * q.w + this->y * q.z - this->z * q.y;
        y = this->w * q.y + this->y * q.w + this->z * q.x - this->x * q.z;
        z = this->w * q.z + this->z * q.w + this->x * q.y - this->y * q.x;
        w = this->w * q.w - this->x * q.x - this->y * q.y - this->z * q.z;

        this->w = w;
        this->x = x;
        this->y = y;
        this->z = z;
    }

    void divide(float s) {
        this->w = this->w / s;
        this->x = this->x / s;
        this->y = this->y / s;
        this->z = this->z / s;
    }

    float dotProduct(const Quaternion& q1, const Quaternion& q2) {
        return q1.x * q2.x + q1.y * q2.y + q1.z * q2.z + q1.w * q2.w;
    }

    static void difference(const Quaternion& qa, const Quaternion& qb,
            Quaternion& q_diff) {
        q_diff.set(qa.w, qa.x, qa.y, qa.z);
        q_diff.inverse();
        q_diff.multiply(qb);
    }

    float getW() {
        return w;
    }

    float getX() {
        return x;
    }

    float getY() {
        return y;
    }

    float getZ() {
        return z;
    }

    void interpolate(const Quaternion& to, double time_ratio, Quaternion& out) {
        Quaternion::slerp(*this, to, time_ratio, out);
    }

    void copy(Quaternion& t) {
        this->w = t.w;
        this->x = t.x;
        this->y = t.y;
        this->z = t.z;
    }

    Quaternion* instantiate_copy() {
        return new Quaternion(*this);
    }

    static void getUnits(vector<IUnit *>& units) {
        units.clear();
        units.push_back(&Quaternion::component_units);
        units.push_back(&Quaternion::component_units);
        units.push_back(&Quaternion::component_units);
        units.push_back(&Quaternion::component_units);
    }

    bool getPrintableString(vector<string>& printable_string) {
        return false;
    }

    bool getContainedQuantities(vector<IQuantity *>& quantities) {
        quantities.push_back(new Scalar(w));
        quantities.push_back(new Scalar(x));
        quantities.push_back(new Scalar(y));
        quantities.push_back(new Scalar(z));
        return true;
    }

    bool getContainedQuantityNames(vector<string>& quantity_names) {
        quantity_names.push_back("W");
        quantity_names.push_back("X");
        quantity_names.push_back("Y");
        quantity_names.push_back("Z");
        return true;
    }
};

#endif /* SRC_ORIENTATION_QUATERNION_H_ */