Drawing Order.
For purposes of making features overlap correctly, three kinds of special-case polygons are used. Hole polygons, pupils and the face polygon. Hole polygons are the insides of the eyes and mouth. When the face is drawn, the hole polygons are drawn first, then the pupils, then the face polygonÑ except for the regions defined by the hole polygonsÑthen the free polygons, then point-attached polygons, and lastly the feature-attached polygons: