Hi,
from what I can tell, there is a line in VirtualTexturing.h which sets the fallback color for texture layers which are not ready yet to black, but I don’t think this is causing the issue:
FLinearColor LayerFallbackColor[VIRTUALTEXTURE_SPACE_MAXLAYERS] = { FLinearColor::Black };
However, I checked the commit history looking for related changes based on your description of the issue and found a commit that was introduced with 5.6 which changes the default Virtual Texture behavior in cooked builds to not wait on the render thread for root pages to be mapped. Instead the engine reads from an average fallback color generated during texture compilation which should remove render thread hitches.
If this change is indeed the cause of your issue, you should be able to revert to the old VT behavior by setting “r.VT.SyncProduceLockedTiles” to 1. This should wait for the VT’s root page to be mapped.
There is a bit more info in the comment inside ShouldSyncProduceLockedTiles() in VirtualTextureSystem.cpp which reads:
"If we return false then we may render with a VT before the root pages are mapped. When that happens the shader switches to using the single color fallback value instead of sampling the VT. When the root page is finally mapped we will return to normal high quality VT sampling.
todo[VT]: Make root pages always resident so that we never need to load sync the root pages."
Hopefully this helps. Please let me know if this works.
Best,
Sam
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