Is soft box-box collision supported with col_soft_enable=True?

[calumarnott]

Hi, thanks for the repository.

I’m testing diffMJX on a manipulation contact-gradient problem where the collision geometry is represented using primitive boxes.

I expected col_soft_enable=True to work for these contacts, since the SoftJAX description mentions smoothing cube-cube collision detection. However, when I try a box-box contact case in the current diffMJX fork, I get:

NotImplementedError: Soft box-box collision not implemented

Is soft box-box / cube-cube collision intended to be supported in the current diffMJX branch, or is this planned for a future release?

If box-box soft contacts are not currently supported, is there a recommended workaround? E.g. using alternative primitive geometries as a proxy representation for box-like contact.

Thanks in advance for any help you may be able to provide.

Best,
Calum