Hidden Face Removal

Hidden Face Removal (HFR) is an optimization technique, which improves rendering speed. This technique determines whether an arbitrary polygon is facing forward or backward, and if enabled, backward-facing polygons are not drawn. This method can be used with closed-surface shapes, for example a Sphere. However, under certain circumstances it is necessary to view the inside of an object, which means backward-facing polygons should be drawn. For such objects to be drawn correctly, hidden Face Removal property should be disabled.