Unreal Engine Issues

Niagara Mesh Renderer registers NumParticles x NumMeshVariants TLAS instances

When using the Niagara Mesh Renderer with multiple mesh variants selected via MeshIndex, the number of TLAS instances allocated is NumParticles × NumMeshVariants and enabling the Path Tracer can ca ...

FNiagaraRendererMeshes::GetDynamicRayTracingInstances(...) corrupting GPUScene when rendering multiple views

When rendering a game in splitscreen using Lumen HWRT, Nanite and a large number of Niagara Mesh Particles 1mil+, various meshes and actors will stop rendering. Setting r.RayTracing.Geometry.Niagar ...

Disabled Skeletal Mesh Sections cause Shadow Ray Tracing Flicker

If a skeletal mesh has a section disabled the ray traced shadow will flicker when the camera or itself moves. Previously in 5.6.0 no raytraced shadow would appear if a section was disabled. This wa ...

GetStaticRayTracingGeometries doesn't check if mesh has ray tracing disabled

An ensure is hit for static raytracing geometry because skeletal mesh assets that had ray tracing disabled were not handled in: FSkeletalMeshSceneProxy::GetStaticRayTracingGeometries The concurrent ...

5.6 Skeletal Meshes with Disabled Sections Flicker in Ray Tracing Scene

Skeletal meshes with disabled mesh sections will flicker in the Hardware Ray Tracing Scene. Also tested on //UE/Release-5.6, CL:45232827 ...

Uploading of the SBT via copy queue is not guaranteed to be synced with async compute queue but only direct queue in d3d12

When HitLighting is enabled, SBT commit is running on the Graphic Queue, and the pass "LumenSceneLighting->offscreenshadows->LumenDirectLightingHardwareRayTracingRGS" that uses SBT could run on the ...

If a mesh contains more than 32 material slots, it can cause a hash collision when computing the Raytracing CachedMeshCommandHash

Ray tracing scene doesn't reflect WPO with instance custom data

When custom instance data is used to calculate WPO in a Material and applied to an ISM the WPO value in the Lumen scene (ray tracing scene) is different than the visible scene resulting in incorrect ...

RayTracing - Nanite Foliage assets do not display shadows properly when painted with Foliage Tool

Crash when a Deferred Decal (Translucent) base material has a Nanite Override (Masked Surface) Material and the mesh has Nanite + Ray Tracing enabled.

A crash occurs when Nanite override material instance is used in a project with Ray tracing enabled where: 1 The Material assigned to the static mesh uses Deferred Decal / Translucent and the Nani ...