Summary
Hi,
I’m testing Unreal Engine 5.8 and I noticed a potential issue with InstancedFoliageActor and ray tracing when using Evaluate World Position Offset.
In my case, enabling both Visible in Ray Tracing and Evaluate World Position Offset works correctly for a single foliage instance. However, after adding a second instance, the ray-traced shadows/reflections disappear.
If I disable Evaluate World Position Offset, ray tracing works correctly for multiple instances again.
This appears to be a bug. The same setup worked correctly in previous versions of Unreal Engine, where Evaluate World Position Offset and ray tracing could be used together on foliage instances without this issue.
Has anyone else encountered this behavior in Unreal Engine 5.8?
Thank you.
What Type of Bug are you experiencing?
Other
Steps to Reproduce
Create or place an Instanced Foliage Actor in the level.
Add a single animated foliage instance (for example, a tree using World Position Offset animation).
Enable:
Visible in Ray Tracing
Evaluate World Position Offset
Verify that ray-traced shadows/reflections work correctly.
Add a second instance of the same foliage asset.
Observe that ray tracing no longer works correctly for the foliage instances.
Expected Result
Ray tracing should continue to work correctly for all foliage instances while Evaluate World Position Offset is enabled.
Observed Result
Ray tracing works correctly for a single foliage instance, but disappears or stops updating correctly when a second instance is added.
Disabling Evaluate World Position Offset restores correct ray-tracing behavior for multiple instances.
Affects Versions
5.8
Platform(s)
Windows
