Mirror operation on Physics Asset produces wrong results for constraints, including flipped axes

UE - Runtime - Simulation - Feb 7, 2025

The Physics Asset Editor has a "mirror" feature that allows physics bodies and constraints to be mirrored from one side of a skeleton to the other. If this operation worked correctly, it could save ...

Deleting transient actor marks level dirty

UE - World Creation - Worldbuilding Tools - Feb 6, 2025

The licensee has noticed that the deletion of a transient actor still marks the scene as dirty and asks it to be saved. Checking the source it was noted that the transient flag is not verified on de ...

FLevelInstanceActorGuid::GetGuid issue in Multiplayer

UE - World Creation - Worldbuilding Tools - Level Instances - Feb 3, 2025

I am doing some runtime manipulation of data layers and I am running into a check failure due to a zero guid in FLevelInstanceActorGuid::GetGuid during multiplayer testing. When I debug FLevelInsta ...

Foot Placement: Division by 0

UE - Characters - Animation - Jan 31, 2025

static FVector PointDirectionPlaneIntersection(const FVector Point, const FVector Direction, const FPlane Plane) { return Point + Direction * ((Plane.W - (Point | Plane)) / (Direction | Plane)) ...

Lumen ignores Landscape Holes (Landscape Visibility) when Hardware Ray Tracing is enabled and Ray Lighting Mode is set to Surface Cache

UE - Rendering - Graphics Features - Ray Tracing - Jan 31, 2025

Context Lumen is the default global illumination and reflections system. Lumen renders diffuse interreflection with infinite bounces and indirect specular reflections in large, detailed environments ...

Foot Placement: Up vector is not configurable

UE - Characters - Animation - Jan 31, 2025

Up vector is not configurable so Foot Placement does support variable gravity cases. ...

SkinnedMeshComponent::BoneTransformUpdateMethodQueue is never reset in server builds

UE - Rendering - Architecture - Jan 27, 2025

We reset BoneTransformUpdateMethodQueue in USkinnedMeshComponent::CreateRenderState_Concurrent and USkinnedMeshComponent::SendRenderDynamicData_Concurrent but these code paths are never called in se ...

HLODs appear dark/near black when built for very large geometry with Virtual Textures enabled

UE - World Creation - Worldbuilding Tools - HLOD - Jan 27, 2025

Building HLODs for a very large landscape with Virtual Textures enabled results in the built HLODs being very dark for the most part. Building the same large landscape's HLODs with Virtual Textures ...

In -game in Editor, if streaming-in a LevelInstance and initialize its world partition, then leaving that cell and make it go outside the streaming grid, to re-enter it again, will trigger a check(!StreamingPolicy) if no GC has happened during that time.

UE - World Creation - Worldbuilding Tools - World Partition - Jan 27, 2025

This crash can be fixed by adding a couple of || IsRunningGame() like it is done here:    FGenerateStreamingContext Context = FGenerateStreamingContext()        .SetLevelPackagesToGenerate((bIsPIE ...