Mobile UE5 - Odd black flickering on Instanced Static Meshes (Foliage)

Hey Everyone,

So i am working on a small vr title in my own time and when using Instanced Foliage for optimisation reasons you can see there is lots of black flickering all over the meshes, the meshes are solid so there is no need for double sided materials and disabling the one Directional Light in the level doesnt change anything just makes the level darker.

I have included a image for reference:

This only happens with instanced Foliage and not Static Meshes which makes it super odd and must be a setting in the engine just not sure where or what

Kind Regards
James

It seems an issue something like shadow are double sided like:

r.RayTracing.Shadows.EnableTwoSidedGeometry 0

but I guess you are not using ray-tracing because VR, isn’t it? I need to know because there is more cvars can cause it!

try also:
foliage.ForceLOD 0

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Yer running it in a VR default project so there shouldnt be any ray-tracing ill give that a shot also fingers crossed those work pretty sure i tried the forceLod 0 one tho

If you deactivate post process and skylight it happens? Try to find the source of the problem…

this video is old, but perhaps helps you

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tried those CVars and it didnt change anything and the skylight didnt do anything or post process if i stick screen percentage up to 200 then it becomes a smooth black blob but that just because of effectively just throwing more pixels.
Could just be a bug with the current versions lumen instanced foliage and will get fixed in the next version

I saw in many places something like:
“Create a Blueprint actor > put your tree mesh into it and uncheck evaluate world position offset > Create a Foliage Actor and select your Blueprint actor in it”

LUMEN FOLIAGE

I have the same problem also in Open World and its only on foliage assets, not the static assets. Also wanted to support VR, so these black flickers appear as soon as I switched from Deferred renderer to the Forward renderer. Going back to Deferred gets rid of them. So I dunno, I guess maybe its an actual bug where foliage assets just don’t work with the forward renderer atm.

*edit I figured out the setting that fixes it. You have to disable “Vertex Fogging For Opaque” which is enabled by default and only applies to the Forward Renderer. It seems this option basically just breaks foliage rendering.

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this worked perfectly THANKYOU! my days I cant express in text just how good it feels to see foliage working again!

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THANK YOU found this thread after quite a bit of searching and it’s exactly what I needed. Very much appreciated!

hi guys! I am having the same issue in a vr project that i am making. Weird black pixels flickering…


Do you know what to do ?