This question was created in reference to: [Hardware Raytraced Shadow of Nanite meshes do not react to WPO [Content removed]
I tried the 5.6 version to test if the issues described in the initial post where solved, which was the case for the Static Mesh part.
As for the ISMs, even though we configured them identicaly to the static meshes and enabled r.RayTracing.Geometry.InstancedStaticMeshes.EvaluateWPO=1, we end up without shadows cast by our instances.
Same behavior for HISMs.
Are we missing something ?
If not, and if support is in fact not available yet, can we still expect it to be included in 5.6 considering the preview is already out ?
I’ve been assigned to investigate this issue. Thanks a lot for including the repro scene. I can confirm that instanced static meshes do not cast shadows when “Evaluate World Position Offset in Ray Tracing” is checked or when r.RayTracing.Geometry.NaniteProxies.WPO is set to 1 (they do cast non-moving shadows when either of those two is disabled and r.RayTracing.Geometry.StaticMeshes.WPO is set 1).
I will assign this case back to Epic so someone with knowledge of this can take a look.
The combination of Nanite + ISM + WPO is not yet supported in ray tracing. Using that should print a warning “Nanite instanced static mesh using World Position Offset not supported in ray tracing yet”. Due to extreme memory and performance demand of that combination we don’t have immediate plans to support it. If you are targeting an offline use case I suggest not using Nanite for this mesh.