Translucent meshes randomly flicker when using VSM

Flickering can occur on translucent materials, usually in the distance when there is at least one directional light and when using VSM. Flickering seems highly dependent on framerate and timing.

Limiting the framerate with t.MaxFPS or turning off TLV batching usually seems to make the flickering stop (r.TranslucencyLightingVolume.Batch 0)

• The flickering is from TLV only (not happening with forward translucent shading)
• It seems it also happens without Lumen enabled
• The issue may not happen with older Nvidia drivers, eg, 551.86
• {{r.TranslucencyLightingVolume.Blur 0 }} doesn’t appear to affect the issue

This flickering issue doesn’t appear to be the same issue as the kind of flickering that can occur with meshes that intersect the edge of the TLV.

Additional Notes

r.OneFrameThreadLag 0 will kill it. And the render frame has to struggle (lag) for it to occur.
r.rdg.asyncCompute 0 might stop it, but only because the lag shifts a bit. You will still be able to get it with asyncCompute 0, but it just might be harder to reproduce.

1. Open the attached project and look at the translucent material in the distance

Expected

No flickering occurs

Actual

Sometimes, at high framerates, the translucent material flickers