requestRenderMode and Gaussian Splatting

[mittermichal]

What happened?

when requestRenderMode is enabled, 3DGS is not rendered after its loaded and sorted

there doesn't seem to be an "onSorted" event that could explicitly render the scene

Reproduction steps

1. run sandcastle
2. wait few seconds, 3DGS should not be visible
3. move camera, 3DGS should appear

Sandcastle example

https://sandcastle.cesium.com/#c=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

Environment

Browser: firefox
CesiumJS Version: 1.136
Operating System: linux