Multi-File Assets

Unity's support for Multi-file USD assets allows you to import assets composed from multiple layers, where the layers are stored in separate files.

Using multi-file assets makes it easier for multiple artists to collaborate on the same assets and scenes, and provides smaller change deltas when committing changes to these files in a version control system (VCS). See Why use USD? for more detail.

Import multi-file assets

To import a multi-file USD asset, add all the files to your Unity project, then enable the Import setting on the root file only of your composite USD asset. The other files are imported automatically by the USD importer if the root file correctly references them.

When you import a multi-file asset, all the assets contained in each of the child files become sub-assets of the root file asset.

Notes for exporting your multi-file assets

• When exporting your USD stage as multiple files, you must specify that the root file refers to the child files using a relative path.

• You must ensure that all the USD assets in a given composition exist in the assets folder. You cannot add some files from a multi-file composition and omit others.

• If you have more than one multi-file composition in your project, it's possible for more than one root file to reference the same child file.

  If you do this, the shared child file will not be a shared reference. Instead it becomes duplicated into each root asset.

  Here Root file A and Root file E both reference child file D, which means the assets inside File D are duplicated as sub assets inside the import result for both A and E.