NVIDIA announces that the source code for PhysX is now available to developers for free, saying this will "will accelerate the adoption of PhysX," the physics middleware (thanks HARDOCP). Here's word:

Used in more than 500 games on multiple platforms, NVIDIA PhysX is one of the most popular physics engines for game development.

The PhysX software development kit (SDK) is already free on Windows platforms. We’re now extending this to include PhysX Clothing and PhysX Destruction, enabling game developers to easily create a more interactive gaming environment.

And starting this month, the PhysX SDK is available free with full source code for Windows, Linux, OSx and Android on https://github.com/NVIDIAGameWorks/PhysX.

The PhysX SDK is a proven solution for gameplay physics and simulation-driven effects. It is integrated into major game engines such as Unreal Engine 3 and 4, Unity, AnvilNext Engine, Bitsquid Engine, Dunia 2 Engine and REDengine.

NVIDIA PhysX Clothing and Destruction are integrated into the Unreal Engine 4. PhysX Clothing and Destruction effects can be seen in games such as: Batman: Arkham Asylum, Batman: Arkham City, Bioshock Infinite, Borderlands 2, Lords of the Fallen, Monster Hunter Online, Daylight, as well as upcoming titles such as The Witcher 3.

A major component of the NVIDIA GameWorks library, the latest PhysX version (3.3.3) is our best ever, with improved stability and performance. Features include constrained rigid body dynamics, collision detection, scene queries, character controller, particles, vehicles and much more.