`.rad` files causing stutter during animation

[teddy-at-schemata]

Hi, thank you for all the work you've put into Spark! I'm working on animating splats (all .rad files) by parenting them to a GLTF and animating it. However, I'm noticing some stutter when running an animation for the first few runs:

I switched out the splat files for .plys and a .spz, and the animation runs smoothly. I've experimented by only having one .rad and the rest be other types, and the stutter gets reintroduced even with one .rad file.

[mrxz]

Since it only happens the first few runs, it might be related to allocations taking place. The .rad format allows for both LoD and streaming/paged splats, so these systems might play a role as well, assuming you're using these features. It would be good to know more about the exact setup. A minimal reproduction of the issue would be ideal.

Which browser version, OS and graphics card are you using?

[teddy-at-schemata]

I'm using Vivaldi (7.9.3970.64), a Chromium-based browser (Chromium version 146.0.7680.226). I'm on a Macbook Pro with the Apple M5 chip, running Tahoe 26.3.

The stutter also gets reintroduced after orbiting the camera, but it smooths out after a few runs. I'll try to provide a .glb and .rad file to help reproduce the issue.

[teddy-at-schemata]

Was able to reproduce the issue, it seems that LOD is the problem. See the full reproduction at this repo: https://github.com/teddy-at-schemata/spark-bug-report/tree/main

The repo loads a .glb with three nodes: a cube, sphere, and torus. It loads in three splat files and parents them to the glb nodes. The glb has one animation called 'test' that transforms the three nodes. Observe the stutter after moving the camera when you load in .rad files, or when you load in the .spz files and set lod: true. Observe that stutter disappears when you load in the .spz files and remove lod: true.