Quaternion.h

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#pragma once

#include "math.h"
#include "Vec3.h"
#include "Mat4.h"

namespace Maths
{

    struct Quaternion
    {
        float w;
        float x;
        float y;
        float z;

        Quaternion() : w(1.0f), x(0.0f), y(0.0f), z(0.0f) {}

        Quaternion(float w, float x, float y, float z) : w(w), x(x), y(y), z(z) {}

        Quaternion(int w, int x, int y, int z) : w((float)w), x((float)x), y((float)y), z((float)z) {}

        float getLength()
        {
            return (float)sqrt((w*w) + (x*x) + (y*y) + (z*z));
        }

        float getDotProduct(Quaternion Qa, Quaternion Qb)
        {
            float dp = Qa.x*Qb.x + Qa.y*Qb.y + Qa.z*Qb.z + Qa.w * Qb.w;
            return dp;
        }

        Quaternion getNormalised()
        {
            Quaternion normalised;
            float length = getLength();
            normalised.w = w / length;
            normalised.x = x / length;
            normalised.y = y / length;
            normalised.z = z / length;
            return normalised;
        }

        void rotate(Quaternion &quat, Maths::Vec3 axis, float angle);
        
        Mat4 getMatrix();
    };

    inline Quaternion operator * (Quaternion q1, Quaternion q2)
    {
        Quaternion q3;
        q3.w = (q1.w * q2.w) - (q1.x * q2.x) - (q1.y * q2.y) - (q1.z * q2.z);
        q3.x = (q1.w * q2.x) + (q1.x * q2.w) + (q1.y * q2.z) - (q1.z * q2.y);
        q3.y = (q1.w * q2.y) - (q1.x * q2.z) + (q1.y * q2.w) + (q1.z * q2.x);
        q3.z = (q1.w * q2.z) + (q1.x * q2.y) - (q1.y * q2.x) + (q1.z * q2.w);
        return q3;
    }

}// End of Maths namespace