> Pixar developed and internally released a new simulator, which is multi-threaded. The new code does computation before it sends hair off to the simulator to determine how other hairs would relate. This means that a cluster of hairs would all be dealt with as one group, and the Hair simulation could be multi-threaded. In one sequence Merida flicks her hair from one side of her face to the other, but even such high level gross spatial changes were able to be automatically accommodated.
Fascinating. You know that Pixar designed the character like they did just so they would have the challenge of doing her hair.
(via [The Loop](http://www.loopinsight.com/2012/08/21/how-pixar-made-meridas-hair/))