Hair is the only thing it has been used for.
However, according to AMD it is an physics engine for rendering soft body objects.
It can be used for hair, grass, cloth, etc.
And from what I've seen in Bioshock so far cloth is the only physics element in the game.
Nothing else in the environment even moves...
So TressFX certainly could have been used.
So how is AMD foolish?
They are foolish by slapping their name on a game running on a nVidia engine instead of their own.
Again theres only 2 options for Physics
why use Tress FX when it covers only 1 thing? that does not constitute a Physics Library for use in a game
Bullet Physics would have been the AMD alternative to use, considering again they HIRED the guy that originally created it works for AMD, and has for the last 3 years. Tress FX from what I can tell is work of trying to make Bullet Physics GPU Accelerated. So what they have shown = all they have managed to accomplish in three years.
that leaves again just Havok or PhysX as viable alternatives.
Regardless of which way you look at it niether AMD nor Nvidia really give great performance in Bioshock Infinite, frame rates may go as high as 150-200 but due to runts and drops on BOTH brands the way the game feels its runn much much lower. Drivers have begun correcting that but I digress thats something for another time.
PhysX is essentially a seperate entity now from NVIDIA, they own it yes they license it yes. But it has no bearing on GeForce products. because regardless of GPU acceleration or not it is one of only two viable middleware physics engines widely used.
and how is it an Nvidia engine? when its CPU only. Nvidia doesnt prioritize development for Nvidia CPUs cause Nvidia cpus dont exist in the x86 space. Their PhysX library is agnostic in that it sucks on all CPUs, but regardless of that fact, it works on every platform
360 / PS3 / 720 / PS4 / Wii U / PC / iOS / Android etc etc etc.
You are too hung up on it being Nvidia PhysX. When only running on the CPU drop the Nvidia from that its seperate its middleware, it is no different in this regard than Sapphire TriXX for overclocking. Its a middleware software package that serves a purpose.
Other Examples of Middleware for games include but are not limited to.
Speed Tree
Havok
PhysX
Bink Video
Game Spy
Emotion FX
RAD Game Tools Miles Sound
Simul Weather
Umbra Software
Geomerics
etc etc
these are all Middleware
Slap Nvidia in front of those and people would bitch about it.