src/Quaternion.h

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#pragma once

#include "Vector.h"

// Unit quaternion class
class Quaternion
{
public:
        Quaternion()
        {
                Set(Vector(0.0f,0.0f,0.0f),0.0f);
        };

        Quaternion(const Vector &vecV, const float fS)
        {
                Set(vecV,fS);
        };

        Quaternion(const Vector &vecV)
        {
                Set(vecV,0.0f);
        };

        Quaternion(const float fAngle, const Vector &vecAxis)
        {
                float fD = fAngle * 0.5f;
                Set(vecAxis.GetNormalized() * sinf(fD),cosf(fD));
        };

        Quaternion(const Vector &vecFrom, const Vector &vecTo)
        {
                const float fAngle = acosf(vecFrom.GetNormalized().GetDot(vecTo.GetNormalized()));
                const Vector vecAxis = vecFrom.GetNormalized().GetCross(vecTo.GetNormalized());
                (*this) = Quaternion(fAngle,vecAxis);
        };

        ~Quaternion()
        {
        };

        void Set(const Vector &vecV, const float fS)
        {
                m_vecVector = vecV;
                m_fScalar = fS;
                normalize();
        };

        void SetVector(const Vector &vecV)
        {
                Set(vecV,GetScalar());
        };

        void SetScalar(const float fS)
        {
                Set(GetVector(),fS);
        };

        const Vector & GetVector() const
        {
                return m_vecVector;
        };

        const float & GetScalar() const
        {
                return m_fScalar;
        };

        const float GetMagnitude() const
        {
                return sqrtf( GetScalar()*GetScalar() + GetVector().GetMagnitude() * GetVector().GetMagnitude());
        };

        const Quaternion GetNormalized() const
        {
                Quaternion quaNew = *this;
                float fMagnitude = quaNew.GetMagnitude();

                if (fMagnitude > 0.0f)
                {
                        quaNew.m_vecVector /= fMagnitude;
                        quaNew.m_fScalar /= fMagnitude;
                }

                return quaNew;
        };

        const Quaternion GetInverse() const
        {
                return Quaternion(GetVector()*-1.0f,GetScalar()).GetNormalized();
        };

        void normalize()
        {
                (*this) = GetNormalized();
        };

        void invert()
        {
                (*this) = GetInverse();
        };

        const bool operator==(const Quaternion & quaOther) const
        {
                return (GetVector() == quaOther.GetVector()) && (GetScalar() == quaOther.GetScalar());
        };

        const bool operator!=(const Quaternion & quaOther) const
        {
                return !(*this == quaOther);
        };

        const Quaternion & operator*=(const float & fOther)
        {
                Set(GetVector() * fOther,GetScalar() * fOther);
                return *this;
        };

        const Quaternion & operator/=(const float & fOther)
        {
                Set(GetVector() / fOther,GetScalar() / fOther);
                return *this;
        };

        const Quaternion & operator+=(const Quaternion & quaOther)
        {
                Set(GetVector() + quaOther.GetVector(),GetScalar() + quaOther.GetScalar());
                return *this;
        };

        const Quaternion & operator-=(const Quaternion & quaOther)
        {
                Set(GetVector() - quaOther.GetVector(),GetScalar() - quaOther.GetScalar());
                return *this;
        };

        const Quaternion & operator*=(const Quaternion& quaOther)
        {
                Set(
                        GetVector().GetCross(quaOther.GetVector()) + GetVector() * quaOther.GetScalar()  + quaOther.GetVector() * GetScalar(),
                        GetScalar() * quaOther.GetScalar() - GetVector().GetDot(quaOther.GetVector()));
                return *this;
        };

        const Quaternion operator*(const float fOther) const
        {
                Quaternion quaNew = *this;
                quaNew *= fOther;
                return quaNew;
        };

        const Quaternion operator/(const float fOther) const
        {
                Quaternion quaNew = *this;
                quaNew *= fOther;
                return quaNew;
        };

        const Quaternion operator+(const Quaternion & quaOther) const
        {
                Quaternion quaNew = *this;
                quaNew += quaOther;
                return quaNew;
        };

        const Quaternion operator-(const Quaternion & quaOther) const
        {
                Quaternion quaNew = *this;
                quaNew += quaOther;
                return quaNew;
        };

        const Quaternion operator*(const Quaternion & quaOther) const
        {
                Quaternion quaNew = *this;
                quaNew *= quaOther;
                return quaNew;
        };

        const Vector operator*(const Vector &vecOther) const
        {
                Quaternion quaRotated = (*this * Quaternion(vecOther) * GetInverse());
                return quaRotated.GetVector() * vecOther.GetMagnitude();
        };

private:
        Vector m_vecVector;
        float m_fScalar;
};


inline std::ostream & operator << (std::ostream & os, const Quaternion & quaQuaternion)
{
        os << "(" << quaQuaternion.GetVector() << ";" << quaQuaternion.GetScalar() << ")";
        return os;
}

inline std::istream & operator>> (std::istream & is, Quaternion & quaQuaternion)
{
        Vector vecV;
        float fS;

        if (is >> eat("(") >> vecV >> eat(";") >> fS >> eat(")"))
                quaQuaternion.Set(vecV,fS);

        return is;
}

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