# Chapter2. The vec3 class

First include math.h, stdlib.h and iostream on top of this code.

``` class vec3 {```

``` public: vec3() {} vec3(float e0, float e1, float e2) { e[0] = e0; e[1] = e1; e[2] = e2; } inline float x() const { return e[0]; } inline float y() const { return e[1]; } inline float z() const { return e[2]; } inline float r() const { return e[0]; } inline float g() const { return e[1]; } inline float b() const { return e[2]; } //unary operator inline const vec3& operator+() const { return *this; } inline vec3 operator-() const { return vec3(-e[0], -e[1], -e[2]); } inline float operator[] (int i) const{ return e[i]; } inline float& operator[] (int i) { return e[i]; } inline vec3& operator+=(const vec3 &v2); inline vec3& operator-=(const vec3 &v2); inline vec3& operator*=(const vec3 &v2); inline vec3& operator/=(const vec3 &v2); inline vec3& operator*=(const float t); inline vec3& operator/=(const float t); inline float length() const { return sqrt(e[0] * e[0] + e[1] * e[1] + e[2] * e[2]); } inline float squared_length() const { return e[0] * e[0] + e[1] * e[1] + e[2] * e[2]; } inline void make_unit_vector(); float e[3]; }; inline std::istream& operator >> (std::istream &is, vec3 &t) { is >> t.e[0] >> t.e[1] >> t.e[2]; return is; } inline std::ostream& operator<<(std::ostream &os, const vec3 &t) { os << t.e[0] << " " << t.e[1] << " " << t.e[2]; return os; } inline void vec3::make_unit_vector() { float k = 1.0 / sqrt(e[0] * e[0] + e[1] * e[1] + e[2] * e[2]); e[0] *= k; e[1] *= k; e[2] *= k; } inline vec3 operator+(const vec3 &v1, const vec3 &v2) { return vec3(v1.e[0] + v2.e[0], v1.e[1] + v2.e[1], v1.e[2] + v2.e[2]); } inline vec3 operator-(const vec3 &v1, const vec3 &v2) { return vec3(v1.e[0] - v2.e[0], v1.e[1] - v2.e[1], v1.e[2] - v2.e[2]); } inline vec3 operator*(const vec3 &v1, const vec3 &v2) { return vec3(v1.e[0] * v2.e[0], v1.e[1] * v2.e[1], v1.e[2] * v2.e[2]); } inline vec3 operator/(const vec3 &v1, const vec3 &v2) { return vec3(v1.e[0] / v2.e[0], v1.e[1] / v2.e[1], v1.e[2] / v2.e[2]); } inline vec3 operator*(float t, const vec3 &v) { return vec3(t * v.e[0], t * v.e[1], t * v.e[2]); } inline vec3 operator/(vec3 v, float t) { return vec3(v.e[0] / t, v.e[1] / t, v.e[2] / t); } inline vec3 operator*(const vec3 &v, float t) { return vec3(t * v.e[0], t * v.e[1], t * v.e[2]); } inline float dot(const vec3 & v1, const vec3 &v2) { return v1.e[0] * v2.e[0] + v1.e[1] * v2.e[1] + v1.e[2] * v2.e[2]; } inline vec3 cross(const vec3 &v1, const vec3 &v2) { return vec3((v1.e[1] * v2.e[2] - v1.e[2] * v2.e[1]), (-(v1.e[0] * v2.e[2] - v1.e[2] * v2.e[0])), (v1.e[0] * v2.e[1] - v1.e[1] * v2.e[0])); } inline vec3& vec3::operator+=(const vec3 &v) { e[0] += v.e[0]; e[1] += v.e[1]; e[2] += v.e[2]; return *this; } inline vec3& vec3::operator*=(const vec3 &v) { e[0] *= v.e[0]; e[1] *= v.e[1]; e[2] *= v.e[2]; return *this; } inline vec3& vec3::operator/=(const vec3 &v) { e[0] /= v.e[0]; e[1] /= v.e[1]; e[2] /= v.e[2]; return *this; } inline vec3& vec3::operator-=(const vec3& v) { e[0] -= v.e[0]; e[1] -= v.e[1]; e[2] -= v.e[2]; return *this; } inline vec3& vec3::operator*=(const float t) { e[0] *= t; e[1] *= t; e[2] *= t; return *this; } inline vec3& vec3::operator/=(const float t) { float k = 1.0 / t; e[0] *= k; e[1] *= k; e[2] *= k; return *this; } inline vec3 unit_vector(vec3 v) { return v / v.length(); } ```