mat3: nml::mat3& operator[](size_t index)

Return a reference to x if index is 0, a reference to y if index is 1 or a reference to z if index is 2, else, throw an exception.

Example

#include "include/mat3.h"
#include <iostream>

int main() {
        nml::mat3 m(1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f, 8.0f, 9.0f);
        m[0] = nml::vec3(5.0f, 6.0f, 7.0f);
        m[1][1] = 12.0f;
        m[2][2] = 25.0f;
        std::cout << nml::to_string(m) << std::endl;
        m[3][0] = 2.0; // Error

        return 0;
}

Result:

[[5.000000, 6.000000, 7.000000], [4.000000, 12.000000, 6.000000], [7.000000, 8.000000, 25.000000]]
terminate called after throwing an instance of 'std::out_of_range'
        what():  mat3::operator[]: index is out of range.
Aborted