We’ve recently updated our project to 5.7 (from 5.5.4), we’re seeing bad composition of our volumetric cloud over the screen:
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I’ve been able to track down the issue to the new permutations of the volumetric cloud shaders “CLOUD_MIN_AND_MAX_DEPTH”.
Disabling compute to fallback to only having the Max depth solves our composition issues.
Substituting our cloud material for the cloud material in empty map also exhibits this issue.
Our cloud material does not exhibit this behavior in small sandbox maps (still built with world partition)
when debugging the pixels during “VolumetricComposeCloudOverScene” i can see that it takes the the front sample(bSampleFront) in “ComposeVolumetricRTOverScenePS” around line 1200. This is all fed from the volumetric cloud material, which writes to VolumetricTexture, VolumetricSecondaryTexture, and VolumetricDepthTexure with the min max depths.
I was wondering if Epic has seen this issue or can advise us as to why it’s happening?
Were you able to isolate this issue into a small repro project? We have seen a similar issue in our titles, but we have not been able to isolate this problem either. I am also escalating this ticket to a senior developer who will help you further. Please let us know if you have any further info.
Yes I am definitely interested in a repro because I have never seen that myself locally. It happens in one of our games sometimes, but I have never been able to reproduce and debug.
I don’t know if i can isolate the issue, this is present in our largest streaming map, but not in our smaller maps. I can get you a pix capture with full shader debug symbols (global and material shaders) which you can use to step through or make edits on the fly.
Looking at your capture, the sky dome mesh is writting depth. And that is confusing the upsampling shader assuming infinite depth for sky pixel. I have been able to reproduce on a small project now so I will try to improve/fix that.
In the meantime, you should have your artist set the sky dome mesh material use IsSky = true. That should make it not write depth and should fix the edges. Unless there is another bug causing it to write depth… Please tell me how it goes.