About the ssgi_unroll_kernel_ option in scene viewer

[Calinou]

I noticed there's a ssgi_unroll_kernel_ option in the Render Options panel at the bottom of the scene viewer GUI:

This option is disabled by default, but enabling it improves performance on a GeForce RTX 4090:

SSGI type	1920x1080	3840x2160
Unroll disabled	596 FPS (1.68 mspf)1	175 FPS (5.71 mspf)
Unroll enabled	613 FPS (1.63 mspf)1	181 FPS (5.53 mspf)

Is there a reason it's not enabled by default? I can't spot any visual difference in quality, both in still scenes and when moving the camera.

Footnotes

1. Measured with V-Sync forcibly disabled in NVIDIA Control Panel, as the low GPU utilization causes the GPU to downclock (which makes the FPS estimation incorrect). Otherwise, I only get 300 FPS in 1080p on a 120 Hz display with V-Sync enabled. ↩ ↩²

[gboisse]

Thanks for reporting. We found this option to be slightly slower on our HW, but it does indeed calculate the same result.

[Calinou]

Thanks for reporting. We found this option to be slightly slower on our HW, but it does indeed calculate the same result.

I've tested this option on a Radeon RX 6900 XT and can confirm it makes no noticeable performance difference, so that makes sense.