For this project I implemented the hatching method
described in "Real-time Hatching" by Praun, et al.
The aim of the technique is to make objects appear as if they
have been shaded with strokes of a pencil or pen.
This image shows an example of depth peeling. Outward faces are
colored green and inward faces are colored red. The image on
the left shows the original object. The middle image shows the
object with the first layer peeled off. In the right image
the object has had a second layer removed and now shows what
one would normally think of as the "inside" of the flask.