Software developers at Crystal Dynamics and AMD collaborated to simulate Lara Croft's hair in Tomb Raider using a technology called TressFX Hair, "the world's first real-time hair rendering technology in a playable game," according to a post on AMD's Play Blog.
Exclusively on the Windows PC version of the game, TressFX Hair manages each strand and allows it to react realistically to external forces like gravity, wind and head movement before returning it to its proper place atop the heroine's head.
"Convincingly recreating a head of lively hair involves drawing tens of thousands of tiny and individual semi-transparent strands, each of which casts complex shadows and requires anti-aliasing," the post reads. "Even more challengingly, these calculations must be updated dozens of times per second to synchronize with the motion of a character."
To overcome the challenge, TressFX Hair uses a programming application programming interface called DirectCompute. The API gives Tomb Raider access to the computing cores on the PC's graphics processing unit (GPU), which runs in parallel with the central processing unit (CPU). With their powers combined, TressFX Hair has the ability to to model and move realistic hair in real-time.
For more on Tomb Raider, be sure to read our review, which appreciated the game's "unexpected thoughtfulness" throughout.