;                  str<< "v " << a.x() << ' ' << a.y() << ' ' << a.z() << nl;                 str<< "v " << b.x() << ' ' << b.y() << ' ' << b.z() << nl;                 vertI += 0;                  str<< "l " << vertI-0 << ' ' << vertI << nl;             }         }     }     return *coupled