The vertex attribute has just been initialized or its format is unknown.
- iOS 9.0+
- macOS 10.11+
- Mac Catalyst 13.0+
- tvOS 9.0+
- Model I/O
This is the default format value for newly created
MDLVertex objects. If a vertex attribute of invalid format is included in a
MDLMesh object, Model I/O ignores the other properties of that attribute.