Simul Support ExchangeCategory: VRVR Water Rendering issues?
Skoots asked 2 years ago

Team and I are developing a VTOL Sim and found some major issues with TrueSky Water in VR.

1) Water culls in shallows based on various camera angles (looks like its receding)
2) Rendering is drastically different in each eye for both it’s draw and reflections (left eye might show water correctly while right shows it receding. This bug flips eyes as you turn your head to look at it)

This was tested on a flight sim we were developing in UE4 on a Oculus Rift CV1. For reference, “instanced stereo” was enabled in UE4’s project settings. And “share buffers for VR” was also checked in the “TrueSkySequenceActor”. Tried a combination of the settings. Excuse the poor performance, for some reason TrueSky has been running really poorly on his 970 system while its been fine my 1070 although this was listed as a known bug on some cards in a post from 6 days ago.
Here is a video demonstrating the bug –

We’re thinking of purchasing TrueSky for our project but at the moment will need to figure out a solution for water. In addition, our existing water refuses to render clouds over it due to translucency and changing the translcency sort priority has 0 affect with Truesky’s clouds.

If anyone has some insight on this or has a suggestion for another water package we should look into, please let us know!
– Scott

Michael Szuplewski Staff replied 2 years ago

Hello Scott, we’ve been aware of this issue for a while, however due to the current situation I’ve not got access to a VR headset where this problem is present to debug it. If it at all possible, are you able to test with other headsets, since it isn’t present on the DK2.

Elias Lallos replied 2 years ago

Hello Michael,
I’m a member of the same team with Scott. To answer your question, we currently only have an Oculus Rift (first generation commercial) for testing and development. So this bug isn’t actually present on the DK2, how curious – do you know if it appears on any other commercial headsets like say the Vive series, or the Rift S?

Also we’ve been trying to get various translucent materials to play nice with the trueSky clouds, and we found some information indicating that we should be making use of a trueSky Material Function called “trueSKYTransparencyModifier”. However upon examination of the function it would appear nothing inside is it really hooked up to do anything.

-Basecolor goes to a multiply node, multiplied by 1, and then goes to Output.
-Emissive never makes it to Output at all
-Opacity gets clamped from 0 to 1, gets multiplied by 1, and then goes to Output

So the function currently doesn’t affect any change to the material wired into it, and even breaks emissiveness completely. Even trying to hook it up into a material causes an error since the Emissive portion is disconnected. Are there plans to finish this function? Without using that, what else should we be doing to ensure trueSky translucency works with other materials? Changing Sort Priority on other translucent objects doesn’t seem to have any affect – for example, trueSky clouds always render behind our ocean material.

Thank you for taking the time to help us out, it’s very much appreciated!

Kind Regards,

Elias Lallos replied 2 years ago

Also I forgot to mention, we did have a look through the documentation at:

Though all the way at the the bottom of the page, the section for Transparent materials is unfinished and lacking any information. So yes any help or direction you could provide to us will be extremely wonderful, thank you!


Michael Szuplewski Staff replied 2 years ago

Hello Elias
The Water bug has also been obsevred on the Valve Index, with our testing we thought this may have been an Index only issue but with your experience it seems to be more universal.

I haven’t personally looked much into the transparency modifier function, however it should be functionaing correctly so either I or someone else will take a look into the issue, it may be that an old or broken version has accidentally be packaged into the version of the build you have.

Skoots replied 2 years ago

Hi Michael, has anyone had a chance to look into these issues yet? Its been a couple months since the initial post and the latest 4.25 build’s transparency modifier is still the same (nodes not linked, unable to compile and official documentation saying to use it). In addition the water bug in VR still exists making it unusable in VR.

If anyone could point us in the right direction on how to allow materials with transparency to work correctly with TrueSky clouds, it would be much appreciated.

– Scott

trespassvr replied 10 months ago

Hi, I’m experiencing this with the water, with a HP Reverb G1 using either the Steam or Mixed Reality UE4 plugins. Seems like only having a DK2 is not enough to support VR. I’m happy to pay for a headset to get you guys to fix this. I’ve checked 4.3.142173e9f in both 4.25 and 4.26 and both exhibit the same problem. Would like to be able to release an experience that supports VR with great looking sky and water, but this currently is too limiting to not have VR support for water. Unreal water in 4.26 works in VR, but you have to disable “Separate translucency” in the project settings. Meanwhile Unreal clouds don’t work in VR. would like to go fully with a TrueSky/Water solution as your plugin looks and interacts with the landscape I’m making much better.

Skoots replied 10 months ago

Hey Trespassvr, we gave TrueSky a year to get this resolved and despite multiple requests never got a solution. Simul seemed uninterested in improving their product with full VR support despite advertising as such, and so our studio swapped over to a much less expensive and (and arguably better) alternative called Ultra Dynamic Sky. It’s available on the unreal marketplace, clouds are blueprint based (meaning you have full control over them unlike TS which locked most of it out behind the plugin itself), and built on UE4’s volumetric which at some point should be VR ready. But more importantly, the author of the plugin resolved the water over clouds in less than 24 hours of contacting them. The solution was to apply “cloud fogging” on both his cloud material and our water’s material. In addition, UDS’s clouds allowed us to use a less expensive water solution (Aquatic Surface, also on marketplace), that has working transparency in VR. Our studio tested, and confirmed working on a CV1, Quest 2 and Rift S.

Im sorry it may not be the solution you may have been looking for, but it was the alternative our studio decided to go with after not seeing any movement from simul.

– Scott