Unreal Engine Issues

GPU ISM LOD uses bounds length instead of radius

When calculating LOD for instances on GPU in NaniteCullingCommon.ush we use:float RadiusSq = length2(LocalBoxExtent); This doesn't exactly match the CPU logic for static mesh component LOD select ...

Windowed Fullscreen does not support multiple resolutions

LevelEditor: "Replace Actor" marks level as dirty even when using external actors

When using external actors, adding/removing/replacing/editing an actor instance inside a level does not cause any modification to the Level package, which helps reduce contention for the map file on ...

UE5.4 Regression - crash when disabling shader optimization while raytracing is enabled on D3D12

Certain interactions between a Rect Light with a Light Function and a Post-Process volume lead to a check() when compiling a Ray Tracing PSO for tracing lights. This check() only happens when shader ...

Niagara compiler error, branch in custom hlsl doesn't work properly

Sandbox Visitors can fail on empty directories on non-Windows platforms

When a Sandbox Visitor checks a directory and it doesn't exist, it returns true on Windows and false on other platforms. The code that uses the result of this check, IterateDirectory, doesn't conti ...

'Max World Position Offset Displacement' causes culling issue on HISMC/foliage in 5.4

Foliage/hierarchical instanced static mesh components have issues with culling when their material's "Max World Position Offset Displacement" value is a higher amount, e.g. 100.0. ...

Incorrect behavior after attaching an actor to a non-root component of another actor in the Editor

UE allows actors to be attached to other actors. More precisely, it allows the root component of an actor (child) to be attached to any component of another actor (parent). From now on, "parent" and ...

GPU Lightmass does not support bounce lighting from landscapes

GPU Lightmass does not support bounce lighting from landscapes, but CPU Lightmass does. ...

The light in the Blueprint Editor's Preview Scene does not respond to any lighting channel but 0.

In the Blueprint Editor, Primitive Components can be configured to respond to Lighting Channels 0, 1, and/or 2. However, if channel 0 is disabled (even with another one enabled), the Preview Actor's ...