I tried the packed primitives workflow with dops, and noticed that when I unpack the geometry, it loses the attributes from the simulation, including velocity.

I could try to copy the attributes myself, but I don't see a straightforward way to identify which packed primitive corresponds with the unpacked geometry, unless I add some attributes beforehand as identifiers… which sounds like an unnecessarily complicated workaround.

So… is there a recommended workflow for inheriting attributes when unpacking primitives?

See the file below for a simple demonstration of the problem.

If you just want point velocities, you can set the DOP Import SOP to “Fetch Unpacked Geometry” and then set “Point Velocities” to “Instantaneous Point Velocities”.

For more general cases, you currently need to use the AttribCopy SOP. There have been some RFEs submitted, though, to enhance the Unpack SOP to make this workflow easier.

Thanks, good to know.

For the attribcopy sop workaround, what's a good way to make sure the correct attributes are copied from the packed primitives to the unpacked ones? It looked like it stripped any useful information during the unpacking, so we can't identify which packed primitive it corresponds to…

If you're dealing with fractured geometry, you'll usually have a ‘name’ primitive attribute in the unpacked geometry, which makes matching up with the packed primitives fairly straightforward.

In your case, though, I'd suggest turning on the “Add DOP Object Name Attribute” option on the DOP Import SOP, which creates a ‘name’ primitive attribute (containing the object's name) on the unpacked geometry. You can use this to match up with the ‘name’ attribute on the packed primitives.