The description of the vertex data format to be used for loading mesh data from the asset.
- iOS 9.0+
- macOS 10.11+
- tvOS 9.0+
- Model I/O
If you specify a vertex descriptor when loading an asset with the
init(url: initializer, Model I/O automatically translates mesh vertex data loaded from the asset into the format described by that
MDLVertex object. If you do not specify a vertex descriptor, or import an asset through other means, this property’s value is
nil, and Model I/O loads vertex data in whatever format is stored in the asset file.