+ cout << "sizeof(Sphere): " << sizeof(Sphere) << endl;
+ cout << "Nb of spheres: " << NB_SPHERES << endl;
+ cout << "sizeof(spheres): " << NB_SPHERES * sizeof(Sphere) << endl;
+ cout << "dg: " << this->dg.x << " x " << this->dg.y << endl;
+ cout << "db: " << this->db.x << " x " << this->db.y << endl;