add new functions?

[yangxu-debug]

Thank you for your great work!

I’m planning to extend your project by adding the functionality to generate a .ply mesh model (including vertex positions, normals, and related geometric information).

However, I’m not very familiar with Swift and Arkit. Could you please advise on where I should start ？ For example, which functions or modules are responsible for 3D data output or mesh generation? Any guidance would be greatly appreciated!