Since the dawn of the 3D era, realistic hair has been one of the most complex and challenging materials to accurately reproduce in real-time. 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. Even more challengingly, these calculations must be updated dozens of times per second to synchronize with the motion of a character.
When AMD Gaming Evolved and Crystal Dynamics agreed to co-develop a technology to address this massive challenge, they wanted to leverage the sensational compute capabilities of the Graphics Core Next architecture to revitalize the hair of an iconic game character: Lara Croft. Well-known for her daring personality and signature ponytail, reimagining Lara Croft (and her haircut) for the 2013 release of Tomb Raider wasn’t just an opportunity to modernize the character, it was an opportunity to advance PC gaming realism.
Through painstaking collaboration between software developers at AMD and Crystal Dynamics, Tomb Raider proudly features the world’s first real-time hair lighting and physics system in a playable PC game: TressFX Hair.
“AMD Graphics and Crystal Dynamics have partnered to revitalize one of video gaming’s most iconic characters, Lara Croft of the Tomb Raider franchise,” said Matt Skynner, corporate vice president and general manager, AMD Graphics. “Developers at AMD and Crystal Dynamics collaborated tirelessly to leverage the power of AMD Radeon™ to develop the world’s first real-time hair physics system in a PC game. TressFX Hair combines advanced lighting, per-strand physics, and collision detection to bring unprecedented realism to this final frontier of image quality in PC gaming.”
Using DirectCompute to unlock the massively-parallel processing capabilities of the Graphics Core Next architecture, TressFX Hair enables the stunning image quality previously restricted to pre-rendered images. Building on AMD’s previous work on Order Independent Transparency (OIT), this method makes use of Per-Pixel Linked-List (PPLL) data structures to manage rendering complexity and memory usage.
DirectCompute is additionally utilized to perform the real-time physics simulation for TressFX Hair. This physics system treats each strand of hair as a chain with dozens of links, permitting for forces like gravity, wind and movement of the head to move and curl Lara’s hair in a realistic fashion. Further, collision detection is performed to ensure that strands do not pass through one another, or other solid surfaces such as Lara’s head, clothing and body. Finally, hair styles are simulated by gradually pulling the strands back towards their original shape after they have moved in response to an external force.
Graphics cards featuring the Graphics Core Next architecture, like the AMD Radeon™ HD 7000 Series, are particularly well-equipped to handle these types of tasks, with their combination of fast on-chip shared memory and massive processing throughput on the order of trillions of operations per second. This perfect concert between software and architecture is further enhanced by Tomb Raider’s many code optimizations that make AMD Radeon™ graphics the best solution to experience the beginning of Lara Croft’s extraordinary story.