IECoreVDB : Python bindings renamed from pyopenvdb to openvdb in later versions

[boberfly]

Generally describe what this PR will do, and why it is needed.

• If pyopenvdb fails, try the renamed openvdb in later versions in a try/except.

Related Issues

• NA

Dependencies

• OpenVDB 12 (maybe 11?) but this change just adds support for the module rename, the old one will work.

Breaking Changes

• NA

Checklist

• I have read the contribution guidelines.
• I have updated the documentation, if applicable.
• I have tested my change(s) in the test suite, and added new test cases where necessary.
• My code follows the Cortex project's prevailing coding style and conventions.

[johnhaddon]

Thanks Alex! It looks like OpenVDB 12 also switches the Python bindings from pybind11 to nano bind - do you know how that affects our interoperability bindings in https://github.com/ImageEngine/cortex/blob/main/src/IECoreVDB/bindings/IECoreVDBModule.cpp?

[boberfly]

Good question, I can tell you it still compiled fine but I'll do some closer testing here or run the unit tests.

[boberfly]

Turns out Cortex just silently didn't build OpenVDB from the logs. I started to make a NanoBindConverter.h and some plumbing for nanobind however I can't quite get the casting right and the porting guide from their documentation isn't too clear to me (I've made comments to those parts).

https://nanobind.readthedocs.io/en/latest/porting.html#type-casters

[murraystevenson]

Closing in favour of #1531.