if (!beam
|| !Beam::has_interface (beam)
|| !Beam::visible_stem_count (beam))
return gh_double2scm (0.0);
Drul_array<Real> pos (0, 0);
if (!beam
|| !Beam::has_interface (beam)
|| !Beam::visible_stem_count (beam))
return gh_double2scm (0.0);
Drul_array<Real> pos (0, 0);