AMD unveils TressFX Hair simulation technology

February 26, 2013 | 09:52

Tags: #directcompute #directx #radeon #radeon-hd #tressfx

Companies: #amd #crystal-dynamics #square-enix

AMD has announced a partnership with Square Enix studio Crystal Dynamics under the Gaming Evolved programme that promises to bring gamers unprecedented realism in a hitherto neglected aspect of gaming: hair simulation.

No, really.

Announced this week, AMD's deal with Crystal Dynamics sees the company working to increase the realism of hair rendering in games to a level previously only possible with pre-rendered footage, by offloading the heavy lifting to the graphics processor using the DirectCompute offload language. The result is undeniably impressive: compared to the often solid-block hair of most game characters, hair rendered using the TressFX Hair engine - for that is the technology's name - is considerably more complex and dangles in an alarmingly realistic manner.

While we'd possibly question AMD's claim that the result is something previously only available to renderfarms creating pre-rendered video footage for cinema and cutscenes, there's no denying it's pretty. Sample shots posted to AMD's blog showcase the technology being used in the new Tomb Raider reboot to great effect, with the underlying promise being that hair fans are going to need AMD graphics hardware to experience the game to its full potential.

Of course, DirectCompute - part of Microsoft's DirectX package - isn't an AMD exclusive, but while Nvidia's latest graphics boards support the offload language in addition to the company's own CUDA early indications are that TressFX Hair is to be exclusive to AMD's Radeon boards. The reason, AMD claims, is utilisation of AMD-specific technologies, including order-independent transparency using per-pixel linked-list data structures to reduce the memory required for the simulation - an important aspect to allowing the rendering to be performed in real-time.

The DirectCompute portion of the TressFX system, meanwhile, performs the real-time physics calculations, treating each hair as a chain of links that allows the hair to move in a reasonably realistic manner - curving to fall over Lara Croft's shoulder, for example, or impacting on other strands rather than passing straight through. The engine also supports custom hairstyles, deforming the hair back to its original shape when the external force - a surface, gravity or wind - is removed.

Neither of those things, however, should prevent TressFX Hair from being compatible with rival Nvidia's graphics boards - and the company's PR-heavy unveil is notable in its lack of clarity. We've reached out to AMD in search of a simple answer to the question "is TressFX Hair exclusive to AMD Radeon hardware" and will keep you updated.

One thing, however, is clear: AMD is massively keen to push TressFX Hair as a big thing, and while we'd question how important realistic hair is to the overall gameplay experience - even in a third-person game, which by its very nature has you spending the majority of your experience staring at the lead character's ponytail - there's little doubt that extra realism is always welcomed.

As we suspected, AMD's press release has been very carefully worded. 'TressFX is not exclusive to AMD,' a spokesperson for the company has told us. 'It works on any DirectX11 card, similar to some other AMD-built technologies - for example Order-Independent Transparency (OIT) or High Definition Ambient Occlusion (HDAO).' Thus is the truth revealed: any DirectX11-capable graphics hardware, including those from rival Nvidia, will be able to make use of AMD's hair-rendering know-how.

Devon Nekechuck, product manager for high-end discrete desktop graphics at AMD, offers a bit more detail - and a sneaky plug for his company's GCN-based Radeon HD products: 'TressFX will definitely work on any DirectCompute-enabled device. This has roots in the core of Gaming Evolved, where we want to enable technology for all gamers, and not create proprietary features that lock out gamers that use our competitor's products. That said, TressFX is very computationally intensive, and hence games that use TressFX will really be able to benefit from high DirectCompute performance. Because of that, you will see Graphics Core Next-based GPUs excel when it's enabled.'
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