sbool_add_span_bin
sbool_add_span_bin<Scanline1, Scanline> add_functor1;
sbool_add_span_bin<Scanline2, Scanline> add_functor2;
sbool_add_span_bin<Scanline1, Scanline> add_functor1;
sbool_add_span_bin<Scanline2, Scanline> add_functor2;
sbool_add_span_bin<Scanline1, Scanline> add_functor;