Removing hidden edges

Hi All,

Please check this video. It represents two thin sheet of metal drawn as polygons plus edges. Polygon offset is involved to avoid z-fighting between lines and polygons.

As you can see SolidWorks is able to clear hidden edges in the last drawing pass. This is not true during Zoom, Pan, Rotate.

Can you guess what are they doing in the last drawing pass to remove hidden edges?

Thanks.

Alberto