32ビット単精度浮動小数3次元ベクトルクラス

#ifndef VECTOR3F_H
#define VECTOR3F_H

#include <iostream>
#include <math.h>

class Vector3f {
public:
    float x;
    float y;
    float z;
    
    Vector3f() : x(0.0f), y(0.0f), z(0.0f) {}
    
    Vector3f(float x, float y, float z) : x(x), y(y), z(z) {}
    
    Vector3f(const Vector3f& start, const Vector3f& end) {
        this->x = end.x - start.x;
        this->y = end.y - start.y;
        this->z = end.z - start.z;
    }
    
    const void set(float x, float y, float z) {
        this->x = x;
        this->y = y;
        this->z = z;
    }
    
    const void add(const Vector3f& v) {
        this->x += v.x;
        this->y += v.y;
        this->z += v.z;
    }
    
    const void sub(const Vector3f& v) {
        this->x -= v.x;
        this->y -= v.y;
        this->z -= v.z;
    }
    
    const void mul(float n) {
        this->x *= n;
        this->y *= n;
        this->z *= n;
    }
    
    const void normalize() {
        float _l = 1.0f / sqrt(
            this->x * this->x + this->y * this->y + this->z * this->z);
        this->x *= _l;
        this->y *= _l;
        this->z *= _l;
    }
    
    const void invert() {
        this->x *= -1.0f;
        this->y *= -1.0f;
        this->z *= -1.0f;
    }
    
    const float dotProduct(const Vector3f& v) const {
        return this->x * v.x + this->y * v.y + this->z * v.z;
    }
    
    const void crossProduct(const Vector3f& v1, const Vector3f& v2) {
        this->x = v1.y * v2.z - v1.z * v2.y;
        this->y = v1.z * v2.x - v1.x * v2.z;
        this->z = v1.x * v2.y - v1.y * v2.x;
    }
    
    friend std::ostream& operator << (std::ostream &stream, const Vector3f& v);
};

ostream& operator << (std::ostream &os, const Vector3f& v)
{
    os << "(" << v.x << ", " << v.y << ", " << v.z << ")";
    return os;
}

#endif

// for Unit-Test
int main (void) {
    Vector3f vec1(1, 0, 0);
    Vector3f vec2(1, 1, 1);
    Vector3f vec3(vec1, vec2);
    cout << vec1 << ", " << vec2 << ", " << vec3 << endl;
    
    vec3.crossProduct(vec1, vec2);
    cout << vec3 << endl;
    
    vec1.add(Vector3f(33, 44, 55));
    cout << vec1 << endl;
    
    vec1.sub(Vector3f(11, 22, 33));
    cout << vec1 << endl;
    
    vec3.set(1, 1, 1);
    cout << vec1.dotProduct(vec3) << endl;
    
    vec1.mul(100);
    vec1.invert();
    cout << vec1 << endl;
    
    vec1.normalize();
    cout << vec1 << endl;
    
    return 0;
}

Output:

(1, 0, 0), (1, 1, 1), (0, 1, 1)
(0, -1, 1)
(34, 44, 55)
(23, 22, 22)
67
(-2300, -2200, -2200)
(-0.594452, -0.568606, -0.568606)