It is always interesting to learn how a 2D cartoon has evolved throughout time - from using cels, for example, to xerography for 101 Dalmatians. But for 3D work, the approach is quite different. We must move to a realization of the sketch in three dimensions! Thus, Disney, for Tangled, had to create software for only the hair of heroin! Similarly, models were made, which are quite difficult to find on the web. Here are some pictures of steps to animate the film.
Hair is difficult enough to style, but even harder to animate! Here's a clip from the DVD bonus features.