Remove redundancy in ONB constructor

In the branch pathtracing, there are two implementations of ONB::ONB (lines 222–257 in geometry.h), which are essentially the same but accept either a Vec or a Normal.

It would be better to create a constructor that takes the three parameters x, y, and z:

class ONB {
    // …
    ONB(float x, float y, float x) {
        // Put here your implementation of the OBN algorithm
    }
    // …
};

and then call it from the other two constructors:

class ONB {
    // …
    ONB(Vec normal) : ONB{normal.x, normal.y, normal.z} {}
    ONB(Normal normal) : ONB{normal.x, normal.y, normal.z} {}
};

In this way you have just one implementation of the algorithm and it is easier to catch bugs.

ElisaLegnani / PhotorealisticRendering

Remove redundancy in ONB constructor #15