What is the best technique for selecting individual pieces (inside walls included) in Maya after using a voroni fracture operator?

I want to be able to select each individual broken piece from my mesh and run operations on it, such as parent to a joint. I only get the inside and outside mesh as my output, and can't think of any maya operations I could use to efficiently separate these objects into a number of separate meshes that each represent a piece.

Suggestions?

You probably want to make use of the output groups options on the voronoi fracture sop. The default settings will put the inside and outside into different groups. And the Maya plugin will, by default, split each group into its own mesh node. That's why you see the inside and outside as two separate pieces. This split by group behavior in the Maya plugin is enabled by default with the “Split Geos By Group” option on the asset node.

One way to get individual pieces would be to use the “Mesh -> Separate” menu from Maya. This requires the geometry to come in as one piece into Maya, so you have to disable “Create Output Groups” on the voronoi fracture sop. Then, you can use “Mesh -> Separate” menu to have Maya separate the mesh into pieces. However, since Maya needs to create separate nodes for each piece, if your asset later generate more pieces, you'll need to redo the “Separate” operation.

Another way is to have the asset put each piece into a separate group. Then, the Maya plugin can split each piece into its own mesh node. This is done by using the “Piece Group Prefix” option in the voronoi fracture, and clearing out the interior and exterior group. This still has the same problem as above if the asset generates more pieces later, because the asset needs to create (or delete) mesh nodes for each new piece. So you'll need to click the sync button to have the Maya plugin recreate the mesh nodes.

I'd recommend using the first way (“Mesh -> Separate”) if possible, since it doesn't rely on “Split Geos By Group” option. The option is convenient, but it's not really what groups represent in Houdini.

See the attached asset for an example.

Thanks, that does make splitting up the pieces for later operations easy. However, how should I go about creating UVs for the interior faces without using groups?

Maybe you could output all the groups from voronoi first, so that you have both the “piece” groups and the “inside/outside” groups. You can then layout UVs in your asset using the “inside/outside” groups, or do any processing that you want with those groups. After you're done with the “inside/outside” groups, you could then delete those groups so that only the “piece” groups remain.