A “pre-release” version of PhysX 3.4 has been posted on GitHub. It will be called a pre-release until around GDC this year, but there shouldn’t be many changes going in till then - basically just bug-fixes if / when customers report issues.
So for all intents and purpose, that’s basically PhysX 3.4.0’s source code, available right now. The architecture has been completely revisited since last year, to make everything work with GPU rigid bodies. If you wanted to play with “GRB”, now is your chance: it’s now tightly integrated within the usual PhysX library.
By default everything runs on the CPU as usual. But with just a few parameters to change in the scene descriptor, things can now run on the GPU instead.
Reminder: there is no binary release anymore. You must build the code yourself (*). To get access to the source code, follow the instructions here.
After that, you get access to regular GitHub repositories for either PhysX 3.3, or now for PhysX 3.4.
Note: the links will show a 404-error until you get a registered account.
(*) EDIT: except for the GPU DLL, which is only shipped as binary for now.