If I were a game programmer, I'd be salivating at the bounty of cutting-edge souce code that's available free of charge. Unreal Engine 4 and Unity 5 are open books for anyone who wants to take a peek, and they've now been joined by PhysX. Nvidia has put the full source for PhysX 3.3.3 and its clothing and destruction components on GitHub.

The release appears to be related to Unreal Engine 4's recent liberation. PhysX powers Unreal's "core game physics," according to Epic co-founder and programming guru Tim Sweeney, and the code is accessible via the engine's repository. Interestingly, Sweeney says Nvidia is providing the "CPU-based implementation" of PhysX. GPU-specific source may remain under wraps.

Nvidia will be accepting changes to the code, Sweeney adds, and it may roll modifications into the "main PhysX branch." PhysX updates then will be shared with the community through future Unreal Engine iterations.

In an apparently separate effort, the PhysX SDK has been expanded from its Windows roots to cover Android, OS X, and Linux. The SDK and source have been released through Nvidia's GameWorks repository, as well. Instructions to gain access are available here.