When quantizing the cosine term, we could have used ceil instead of floor. Doing so would have simply shifted each of the possible values up by one level. This would make the levels of shading slightly brighter.
The typical cartoon style seen in most cel animation includes black outlines around the silhouettes and along other edges of a shape. The shading model presented here does not produce those black outlines. There are several techniques for producing them, and we'll look at one later on in this book.
