_pts->SetPoint( 0 , xInic , yInic , zInic ) ;
_pts->SetPoint( 1 , mid , yFin , zInic ) ;
_pts->SetPoint( 2 , xFin , yInic , zFin ) ;
_pts->SetPoint( 0 , xInic , yInic , zInic ) ;
_pts->SetPoint( 1 , mid , yFin , zInic ) ;
_pts->SetPoint( 2 , xFin , yInic , zFin ) ;