Hi Unrealers,
New here, I got a question bugging me for a while. Before I run and buy the new RTX 2080:
When using Unreal editor with RTX card/drivers install, can I enable Ray-tracing features in the VR view?
That’s it, if anyone knows at Epic team the answer then please let me know if this option and will be available or not… thx stewart
This may explain to you how expenisve RTX is… It may also answer you question if RTX is VR readey 
On top of this, the guy is using a 2080 Ti not only a 2080.
AJK, that does NOT answer my question please re read OP…
Unreal editor with RTX 2080 Ti card/drivers install, can I enable Ray-tracing features in the VR view?
The engine at release 4.21 still does not have Ray Tracing enabled… it will only occur in future releases, so you might just want to wait for the purchase hoping the prices will decrease. The expectations are that 4.23 will be the release where “some” features will be added.
Since when? I’ve only seen posts from Epic staff saying DXR features will start being released in 4.22, early 2019.
Not just me, but others are following each update in the rendering modules at 4.22 branch and really nothing significant there, just commented sections and empty code skeletons, it is just my feeling that this won’t happen, thats why I called “expectations” and not for a fact. I do wish I am wrong, lol
Hi,
I just installed my RTX 2080ti. I was so excited to walk through my VR maps with Ray tracing and see all the amazing reflections without any lags. YES, please.
First bummer: Steam VR is cranking up the Application Resolution to 200%. First level walk thought - laaag. wt… After I found out why I reduced the setting to 140% (were my 1080ti was) everything was nice and smooth now.
I activated “Compute skincache” restart compiled 5000 shader, than activated ray-tracing and again compiled 5000 shader - so much tension and…
NOTHING!
I tried 2 different maps with enough reflecting surfaces and enough lighting. There is no change whatsoever with or without ray tracing in VR.
Sooo disappointing. One the other hand also very early. I really hope they are not forgetting about VR.
(I’m using a Vive pro. Unreal Engine 4.22 preview 2)
Raytracing is not enabled for any other cards other than RTX cards. Also, it’s probably not going to work in VR
Just to clarify on this thread, since there are other thread discussing this already, ray tracing will be available at UE 4.22 as Early Access, for now we are on a Preview 2, which means 4.22 is not ready yet as they are still working on 4.22, but it is getting there. A feature being on Early Access means also that it might not yet be available for all platforms (if would ever be available) and there will be still some engine releases until the feature can lease the Early Access status.
As I don’t have VR gear to test, I would suggest @AronBaron to make sure your Windows version matches 1809 (it is the release from October last year where DXR was released). Also you need to start editor with -dx12 in the shortcut in the Target field, and make sure the Raytracing is enabled in the settings.
There is no technical reason ray tracing can’t work in VR at 90fps right now. Techniques like ray traced direct shadows and AO have low compute cost because they don’t perform any shading, only intersection testing. You could potentially take one AO ray sample per four pixel quad, blur and accumulate over multiple frames. It even has performance advantages over current techniques because the actual BVH traversal is performed out of core, completely in parallel with rendering. If you don’t use ray tracing, those parts of the silicon just sit idle.
For relatively simple scenes with simple lighting, ray traced reflections are probably feasible in VR as well, again maybe not at full resolution but still with much greater quality than screen space reflections. Even for more complex scenes, if you only have reflective materials covering a small portion of the screen, the number of rays needed is small.
The only things stopping us are simple engine bugs. The ray tracing effects are not respecting the stereo rendering pipeline when they composite into the frame.
Here are my test results:
Setup: i7-8700k, 16GB RAM, HTC Vive pro, RTX2080ti, UE 4.22 Preview2, DX12 active, Windows 10 64bit version 1809, Steam VR Application resolution manual set down to 100%, Level SciFiHallway, Nvidia driver 418.91
Step 0: (for comparison, Level in UE4.21, dx11, no ray-tracing) = 4.5ms
Step 1: (ray-tracing off, just the level in dx12) = 22ms (Goal would be less than 11ms. 22ms is already noticeable lag)
Step 2: (SkinCache activated) = 18ms (A few seconds after activation of SkinCache - Windows popup: video card driver crashed)
Step 3: (Ray-Tracing activated): 150ms and one eye black (After leaving the game - Windows popup: video card driver crashed)
Build lighting with ray tracing on always crashes Unreal Engine at the point where it tries to build reflection capture.
I tried two levels I build on my own. Both >100ms, only one level where one lens is black.
I can definitely see a difference now, but not for the better. Anyone an idea what or where to tweak or what to test next?
@NilsonLima thanks for dx12 hint.
Rig: i9 8 core, 64gig, 2080 TI 11gig
UE 4.24
I created a ray trace project. 120 fps in editor.
Toggling vr edit mode… ray tracing works but lots of dropped frames and stuttering
Play vr preview is similar. My guess is around 50 fps or worse. Adjusting the ray trace settings had no effect on the fps.
I also noticed some difference in each eye. There looks like there is a culling breakpoint. One eye ray traces whilst the the other just renders the material without light fx.
This can look odd in vr. A bit like billboards that face the player don’t work correctly in stereo.
Please try this thinks: download dev-branch and 4,26 gpu lightmass. I saw a video even reflection is bake. Try again bake dxr maybe working. I think working. Please try and write me because i will very expensive pc buy for vr rtx.
Because this thread was the firs thing that came up when i did a search of Unreal Engine VR RTX i’ll reply to clear a
few things up to help others.
RTX does run in VR but there is obviously a performance overhead to running RTX in it’s current state. Keep in mind that with VR headsets that use async re-projection if you drop below 90fps you actually drop down to 45fps which is why it’s recommended that all VR games run at a minimum of 90fps to distribute via Steam, etc.
To enable RTX in Unreal Engine (4.22 or later, must have an RTX supporting graphics card) go to **Edit **> Project Settings and search for RHI, change the dropdown to DX12. Then search for **Ray **and check the box for **Ray Tracing **- Restart the editor.
Performance with RTX will vary based on many factors such as complexity of scene, numbers of light sources, etc. but you can adjust RTX settings to improve performance - You can also run the game with resolution scaling (down sample). In VR especially this will help performance and due to the screen door effect it’s less noticeable than running scaled on a monitor.
Another issue with running RTX in VR is that you can only run it in the deferred renderer whereas the Forward renderer is roughly 30% more performant, produces a clearer image due to rendering order and recommended for VR.
What do you mean by “produces a clearer picture due to rendering order?” Im kinda curious as i can afford to switch to forward, im just hesitant to do it this early as it lacks a lot of features deferred has.
Deferred shading defers the light and material rendering to a separate rendering pass after object/material info is accumulated into a G-Buffer then resolves the lighting in screen space.
This inherently muddy’s up the final image slightly compared to Forward rendering which does lighting in the base pass.
Also for Deferred shading you are recommended to use TAA which has it’s own temporal blur that occurs over your final image whereas with forward it’s recommended to use MSAA which is a clearer AA method.
I recommend doing a test with two projects using the same assets, one in Deferred with TAA and one in Forward with MSAA so you can see the difference for yourself.
Thanks for the info. Also, TAA with catmull rom pattern does help un-blur the image a bit at no real quality loss