Why might macOS Preview successfully play animation in a USDZ file, but a RealityKit on visionOS cannot play the same animation?

The issue where macOS Preview successfully plays animation in a USDZ file, but RealityKit on visionOS cannot, could be due to several factors:

1. File Format and Dependencies: USDZ files are great for publishing and distributing assets because they package all dependencies such as textures into a single file. However, they can't be edited without unzipping. If the animation relies on certain dependencies or specific configurations that are not correctly interpreted by RealityKit, this could cause issues. (Optimize your 3D assets for spatial computing)

2. Coordinate Systems and Transformations: RealityKit uses a specific coordinate system (negative Z is forward, Y is up, and positive X is right). If the animation in the USDZ file does not align with this coordinate system, it might not play correctly in RealityKit. (Optimize your 3D assets for spatial computing)

3. Rendering Engines: RealityKit and macOS Preview might handle rendering differently. RealityKit is a real-time engine optimized for spatial experiences, while macOS Preview might use different rendering techniques that are more forgiving or handle certain aspects of the USDZ file differently. (What’s new in USD and MaterialX)

4. Variants and API Support: RealityKit supports the ability to specify variants when loading a USD file. If the animation relies on specific variants that are not correctly specified or supported in RealityKit, this could cause the animation to fail. (What’s new in USD and MaterialX)

5. Debugging Tools: Using the RealityKit debugger can help identify issues with the animation. The debugger allows you to inspect the entity hierarchy and transformations, which can help pinpoint where the animation might be failing. (Break into the RealityKit debugger)

Relevant Sessions

• Optimize your 3D assets for spatial computing
• What’s new in USD and MaterialX
• Break into the RealityKit debugger

If you need more specific details or a deeper dive into any of these aspects, please let me know!