@Brecht Van Lommel (brecht) , I tried this patch. Interestingly I didn't get an internal compiler error (I run on prerelease OS versions, so perhaps a compiler bug has been fixed), but it produced blank renders so something is not quite right.

A couple of thoughts:

• In master, the custom box intersectors (i.e. non trimesh) can handle thick curves and/or ribbons, and the host selects the appropriate level of specialization. I think this 2-bit approach needs to be expanded to a 3-bit one (i.e. thick curves, ribbons, pointclouds) for this to handle all possible combinations of geometry.

• I think the existing MetalRT primitive offset stuff doesn't apply to pointclouds from what I can see, although removing this didn't fix things.

I should be able to take a closer look in January.

I plan to merge this in the current non-working state, so the code doesn't go out of sync.

After D13877: Cycles: Fix bvh2 gen on Apple Silicon and use it to speed up renders this will have no effect for users.