template class Vector

#define _CRT_SECURE_NO_WARNINGS 1
#include <vector>

#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

class Vector {
public:
    explicit Vector(double x = 0, double y = 0, double z = 0) {
        data[0] = x;
        data[1] = y;
        data[2] = z;
    }
    double norm2() const {
        return data[0] * data[0] + data[1] * data[1] + data[2] * data[2];
    }
    double norm() const {
        return sqrt(norm2());
    }
    void normalize() {
        double n = norm();
        data[0] /= n;
        data[1] /= n;
        data[2] /= n;
    }
    double operator[](int i) const { return data[i]; };
    double& operator[](int i) { return data[i]; };
    double data[3];
};

Vector operator+(const Vector& a, const Vector& b) {
    return Vector(a[0] + b[0], a[1] + b[1], a[2] + b[2]);
}
Vector operator-(const Vector& a, const Vector& b) {
    return Vector(a[0] - b[0], a[1] - b[1], a[2] - b[2]);
}
Vector operator*(const double a, const Vector& b) {
    return Vector(a*b[0], a*b[1], a*b[2]);
}
Vector operator*(const Vector& a, const double b) {
    return Vector(a[0]*b, a[1]*b, a[2]*b);
}
Vector operator/(const Vector& a, const double b) {
    return Vector(a[0] / b, a[1] / b, a[2] / b);
}
double dot(const Vector& a, const Vector& b) {
    return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}
Vector cross(const Vector& a, const Vector& b) {
    return Vector(a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0]);
}

class Sphere {
public:
    // ...
};

class Ray {
public:
    // ...
};

int main() {
    int W = 512;
    int H = 512;

    std::vector<unsigned char> image(W * H * 3, 0);
    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {

            image[(i * W + j) * 3 + 0] = 255;
            image[(i * W + j) * 3 + 1] = 0;
            image[(i * W + j) * 3 + 2] = 0;
        }
    }
    stbi_write_png("image.png", W, H, 3, &image[0], 0);

    return 0;
}