is there any API/Lib I can use to access devices across multiple platforms (Win, Linux and Mac OS X to start with) from C?
I'd prefer not to have different APIs under different platforms. What's the way to do it? Is it really just doing HID directly and thus maybe not benefiting from future enhancements (of soft- and hardware)?
Going straight to HID is certainly a possibility but you would have rely on a third-party framework that abstracts the OS-dependant HID manager service.
All 3Dconnexion USB hardware are standard HID multi-axis devices.