snoopy/include/vec3.h

#pragma once

#include <iostream>

#include "math.h"

class vec3
{
public:
    static vec3 random();
    static vec3 random(double min, double max);
    static vec3 random_in_unit_disk();
    static vec3 random_unit_vector();
    static vec3 random_in_unit_sphere();
    static vec3 random_in_hemisphere(const vec3& normal);

    vec3() : e{0,0,0} {}
    vec3(double e0, double e1, double e2) : e{e0, e1, e2} {}

    double x() const { return e[0]; }
    double y() const { return e[1]; }
    double z() const { return e[2]; }
    double length() const;
    double length_squared() const;

    vec3 operator-() const { return vec3(-e[0], -e[1], -e[2]); }
    double operator[](int i) const { return e[i]; }
    double& operator[](int i) { return e[i]; }

    vec3& operator+=(const vec3 &v);
    vec3& operator*=(const double t);
    vec3& operator/=(const double t);

    friend std::ostream& operator<<(std::ostream &out, const vec3 &v);
    friend vec3 operator+(const vec3 &u, const vec3 &v);
    friend vec3 operator-(const vec3 &u, const vec3 &v);
    friend vec3 operator*(const vec3 &u, const vec3 &v);
    friend vec3 operator*(double t, const vec3 &v);
    friend vec3 operator*(const vec3 &v, double t);
    friend vec3 operator/(vec3 v, double t);

    friend vec3 lerp(const vec3 &a, const vec3 &b, double t);
    friend vec3 reflect(const vec3& v, const vec3& n);
    friend vec3 refract(const vec3& uv, const vec3& n, double etai_over_etat);
    friend double dot(const vec3 &u, const vec3 &v);
    friend vec3 cross(const vec3 &u, const vec3 &v);
    friend vec3 normalize(vec3 v);

private:
    double e[3];
};

// type aliases for vec3
using point3 = vec3; // 3D point