IOS Metal error with DotLottie when adding vello plugin

[AngeloMateus]

Updated from v0.3.3 to 0.5.1 Lottie animations were working perfectly on IOS pre update.
Now when adding VelloPlugin, it still builds fine, but the app crashes on launch with:

-[MTLDebugComputeCommandEncoder dispatchThreadgroups:threadsPerThreadgroup:]:1054: failed assertion `(threadgroupsPerGrid.width(0) * threadgroupsPerGrid.y(1) * threadgroupsPerGrid.depth(1))(0) must not be 0.'

The only useful thread I found on this was this post

[simbleau]

This sounds like a bug of Vello, not bevy_vello. Vello uses a heuristic to determine the appropriate thread count. It might not be correct for iOS. Perhaps bring it up with them?

[DJMcNab]

This would appear to be linebender/vello#537 (comment)

Can you confirm which shader this is failing on?

[AngeloMateus]

I'm not sure where I would find this, the error above is all I get from the crash, could you point me in the right direction?

Edit: I'm not using wgls shaders with Vello I'm using it with Lottie animations

[simbleau]

The error distinctly mentions Compute, which would point to either 1) the hardware not supporting compute, or 2) an change to compute shaders caused a bug, which is what @DJMcNab was pointing out.

A little bit of context here, bevy_vello doesn't have or use any compute shaders, but its underlying render backend vello does.

You can file an issue here, where this should be tracked: https://github.com/linebender/vello/issues

Once Vello updates with a bug fix, I can update bevy_vello with that patch.