one of the major breakthroughs of "monsters, inc." was the simulated movement of sulley's fur and boo's shirt. the animators would animate the characters "bald and naked". once the animation was finished, a computer program aided by the "simulation department" would apply the hair and cloth onto the characters. if sulley moved the hair would react to the movement just like it would in nature. the same goes for boo's t-shirt that would produce wrinkles in the fabric. this would save the animators from animating the three million hairs on sullivan individually.