VR performance significantly (50% reduction) affected by shadows flat or higher.

[ThomasMay]

I spent hours trying to figure out why my fps performance was really bad on Enigma's Cold War server multiplayer. Turned out it was one setting that was the culprit. Shadows, any quality.

I noticed enormous performance reduction when looking at the front line 30-50+ miles away. In some cases my fps was steady at 60-70 with shadows flat then upon turning head in VR towards the front, my fps went down to 35-40. Shadows flat -> high I saw basically no further performance decrease.

I figured out a good way to repro this issue on ECW server. I jump into a Su-25 facing away from the front. Then just by looking behind I immediately see this performance problem. Attached are the requested VR perf issue files. I have also attached a screenshot of example settings where I have shadows off and my performance is great at close to 90 fps in the same test environment.


 

SHADOWS_FLAT_45FPS_cold-war-northern-eye-production-v151-20221116-134836.trk dcs.log DxDiag.txt

[BIGNEWY]

@ThomasMay

welcome to our forum and thank you for posting here after our discord chat. 

We will take a look 

thank you

[ThomasMay]

Hi!

Thanks for your patience on discord and hope this helps!

 

[fagulha]

Same here but already knew that the problem was from the Flat Shadows because it occured after the 2.8 update and other users here in the forum shared same issue and found the culprit. Nevertheless when i have some time to dig in (life is punching me right now) i will post here my report with the needed files attached.

I´m sure ED is already working on this and when possible this issue is no more, i will wait as always (eager to see this fixed of course).

Keep up.

F.

[desolunatic]

Yes appears to be shadows related - on Tempest Blueflash server same spawnpoint in VR,
30 fps vs 45fps, in both cases Terrain Object Shadows set to off, for 30fps Shadows - medium, 45fps - Shadows off

 

Edited November 17, 2022 by desolunatic

[festr]

I have exactly the same but it changes dramatically when there are no clouds. Seems like presence of any clouds + shadows enabled causes this (in 2.7 clouds did not cast shadows?) 

[ThomasMay]

 

58 minutes ago, AirMeister said:

Honestly i don't think it's a "bug". 

It's just how it is now. It's normal for any game that performance takes a hit when the picture gets prettier. (added or enhanced graphic options)

But in DCS the performance hit is usually quite extreme especially when put next to the gain in graphics. 

We've seen it with the new clouds. That was also a 30% hit. 
Now they enhanced the lighting/shadows , another 30% hit. 

Cloud hit is just forgotten about and never 'fixed'. (i don't think it can be)
Same goes for these shadows/lighting 

They keep trying to enhance graphics but the game engine just isn't suited for these enhancements. 
I'm honestly not trying to be whiny but , for god's sake stop trying to enhance the graphics until there is a more decent and modern game engine 

 

 

Your post got me thinking (always a good thing) Initially I assumed, yeah, of course it’s the shadows because enabling them causes it. But it also could be just normal if you really think about it.

1. Fps is fine when you look away from a front line that’s filled by objects that are already tens of miles away. 

2. fps plummets when you turn your head towards the object filled front line and in no way could be able to see them even with direct line of sight as they are so far.

clearly it’s just shadows, right? Wrong! Could be something else 

There are couple of reasons that come to mind initially.

Possible cause #1: sub-standard shadow culling for distant vehicles/buildings/other GameObjects could be one reason.

Possible cause #2: shadow culling is fine, but as player looks towards the front there has to be added calculations for the numerous objects and players located near the front line and this pushes basically any cpu over the edge. Apparently causing a ”shadow issue”.

I’m interested if this is something that happens in any way on a flat screen 4k usage or is this only in VR. If it’s only in VR, I would be more likely to think it might be something like possible cause #1

In any case, objects that the player absolutely cannot see causes this in both cases #1 and #2. Maybe there’s something that could be optimized?

When multicore? Right?

Edited November 17, 2022 by ThomasMay
Mistake in quoting :)

[durp]

Would be interesting to hear if the 'flat' shadows are now supposed to be smoothed (feature) or if this is something that is not supposed to be (bug). 

With DCS 2.7 "Flat" shadows referred to a basic shadow outline without smoothing. In 2.8 the Shadow:Flat option seems broken* and TerrainObjectShadows:Flat appears to look more like TerrainObjectShadows:Default (smoothed) with a similar (if not the same) performance impact.

 

* It used to draw the aircraft shadow, unsmoothed. Now it doesn't do anything unless TerrainObjectShadows is set to either flat or default (and in either option the aircraft shadow is also drawn smoothed)

Edited November 18, 2022 by durp
terrible typo hotfix

[Nealius]

Shadows have always been a performance killer in VR since DCS 2.5. 

[fagulha]

Just now, AirMeister said:

So.... nothing in the last two patches ?

 

Nope.

[Steel Jaw]

So shadows should be off in VR?

[fagulha]

26 minutes ago, Steel Jaw said:

So shadows should be off in VR?

For the first time i set Shadows to OFF and i get the exact same performance in VR in previous 2.7 with Shadows to Flat Only. With 2.8 if i set to Flat only, as usual, i lost a noticeable performance. Instead of 30 FPS (in high density of statics, etc) i get 15/20 FPS. Flying in VR without Shadows even in Flat it´s not the same experience. Although, i must say, after last update i get better FPS but majority of the performance is lower. Going to test tomorrow (holiday here in Portugal). If there´s anything worth mention i will post it here.

By the way, i´m using latest Nvidia drivers (526.98).

So, my advice is to try both options to get a better feel of the perfomance loss, or not. If so leave feedback please.

Meanwhile check this drivers version in this post, might help. In my case i didn´t get better performance so i updated to the latest drivers:

 

[hazzer]

On 11/30/2022 at 9:46 PM, fagulha said:

For the first time i set Shadows to OFF and i get the exact same performance in VR in previous 2.7 with Shadows to Flat Only. With 2.8 if i set to Flat only, as usual, i lost a noticeable performance. Instead of 30 FPS (in high density of statics, etc) i get 15/20 FPS. Flying in VR without Shadows even in Flat it´s not the same experience. Although, i must say, after last update i get better FPS but majority of the performance is lower. Going to test tomorrow (holiday here in Portugal). If there´s anything worth mention i will post it here.

By the way, i´m using latest Nvidia drivers (526.98).

So, my advice is to try both options to get a better feel of the perfomance loss, or not. If so leave feedback please.

Meanwhile check this drivers version in this post, might help. In my case i didn´t get better performance so i updated to the latest drivers:

 

In the past I could run shadows with my setup. Now they have to be off otherwise I lose about 10-20 fps. Game looks horrible without those shadows as well. 

[durp]

Yah, flying at low altitudes or with rotary I find shadows are required.

Would be also nice to get feedback on my above post. 

Would be interesting to hear if the 'flat' shadows are now supposed to be smoothed (feature) or if this is something that is not supposed to be (bug). 

So one could figure out what to expect... not to mention that with flat shadows also aircraft shadows were drawn in <= 2.7. With 2.8 those are not drawn anymore with shadows:flat and the other flat setting (terrain object shadows) does smoothed rendering, which tanks the performance. But the other thread about those shadow artifacts was tagged as 'fixed'.

 

[MattCri]

today patch lowed framerate even more for me

[Marklar]

1 hour ago, MattCri said:

today patch lowed framerate even more for me

Disappointed but not surprised.

[Default774]

No performance changes for me.
5800x3d, rtx 2080, 32gb ram, rift s

Edited December 16, 2022 by Default774

[WipeUout]

No change here either in my test track (F-18 Caucasus).

Sorry that this bug is taking so much time and effort! 

[zildac]

Not noticed a performance decrease with todays patch, but very quick trial flight earlier. However I still have a circa 20fps decrease from 2.7 with terrain shadows set to flat, sooo still set to off at the moment. Somewhat disappointed tbh.

[MattCri]

53 minutes ago, WipeUout said:

No change here either in my test track (F-18 Caucasus).

Sorry that this bug is taking so much time and effort! 

i have no changes in caucasus bug a very noticeable drop in persian gulf

[Gryzor]

1 hour ago, MattCri said:

i have no changes in caucasus bug a very noticeable drop in persian gulf

In PG I have slower framerates too (0.4 ms more), maybe related to night-lightning improvement.

[Gripen 4-1]

wrong thread - moved

Edited December 21, 2022 by Gripen 4-1

[Mr_sukebe]

Sounds more like an "opportunity" as part of VR tweaking, i.e. turn them off to enhance your frame rate.

[Gripen 4-1]

1 hour ago, Mr_sukebe said:

Sounds more like an "opportunity" as part of VR tweaking, i.e. turn them off to enhance your frame rate.

Turn what off?

I would turn it of, if i would know what causes an 4 ms loss between 2.7 and 2.8.1

You can not switch dynamic weather off

Edited December 21, 2022 by Gripen 4-1

[Mr_sukebe]

1 hour ago, Gripen 4-1 said:

Turn what off?

I would turn it of, if i would know what causes an 4 ms loss between 2.7 and 2.8.1

You can not switch dynamic weather off

 

I thought that this thread was discussing the impacting of enabling (or not) shadows?