investigating VR 512 per-frame FPS loss

[ThatPieMan]

When using the 512 per-frame on cockpit display res, if you enable a VID view, ie, TADS, or enable the PNVS I've found FPS to drop by around 5~ish frames.

Not using per-frame results in what seems to be frame judder on the VID and PNVS view, as if its being rendered at ~15 fps, relative to 45 which I can read off the counter. This is obviously also an issue, especially in the case of PNVS flying.

Running in VR this is quite a large amount of FPS to lose. Running on a reverb G2, 3080. Track file (hopefully the right one) included. 

Might just be something to add to the optimization pile, but figured it was worth recording.
 

VIDPNVSFPSBug.trk

[BIGNEWY]

Hi, 

I have taken a look and for me it was ok, can you let me know your system specification. 

I will have another tester check also. 

thanks

[JSpidey]

I'm getting judder too when turning on the TADS either in the front seat or the VID page in the back.

[ThatPieMan]

On 4/25/2022 at 9:23 PM, BIGNEWY said:

Hi, 

I have taken a look and for me it was ok, can you let me know your system specification. 

I will have another tester check also. 

thanks

No worries. I'm running OXR @110%, MR auto, with a 3080, 5900x, 32gb @3200mhz, 1TB SSD, HP reverb G2. Settings screenshot included. Should probably throw that all in the sig tbh. 

[BIGNEWY]

I run my reverb G2 at 60% in steamVR and 1.0 PD in DCS, I target higher FPS with my settings. 

 

[ThatPieMan]

2 hours ago, BIGNEWY said:

I run my reverb G2 at 60% in steamVR and 1.0 PD in DCS, I target higher FPS with my settings. 

 

Gotcha. Might need to tweak some settings. A flight member also came up with a theory due to this, as they had the same issue with judders in the IHADSS/PNVS and on the vid underlay for the MFD's. 

Quote

when the cockpit display option is not set to "every frame", it only sends a draw call every second frame.  But when IHDDS rendering is set to render in just one eye, that eyepiece of the VR headset is already interleaved with the refresh rate in the other eye, so it's rendering effectively at quarter overall frame rate.

Are you able to confirm? It would make sense why frames would drop, and overall visual clarity and smoothness increases on the MFD underlay/PNVS/IHADSS. 

Edited April 27, 2022 by ThatPieMan

[BIGNEWY]

3 minutes ago, ThatPieMan said:

Are you able to confirm? It would make sense why frames would drop, and overall visual clarity and smoothness increases. 

rendering every frame will be more demanding, personally never use it.