Masked TwoSided material causing lumen direct lighting to leak through walls

UE - Graphics Features - Lumen - Apr 23, 2024

It appears that LumenScene's Hardware Ray Tracing is causing light leaking into a sealed room (which should be perfectly black). This bug does not appear to happen on AMD GPUs. ...

Custom node not working with material attributes

UE - Rendering Architecture - Materials - Jul 15, 2024

Using Material Attributes as an input to a Custom Expression causes the HLSL Translator to create multiple CustomExpression# functions, for each used member of the Material Attributes, rather than u ...

High Virtual Texture Sample/Lookup Cost when using a Virtual Texture in a Material Layer Blend

UE - Rendering Architecture - Materials - Mar 14, 2025

Some Material Attribute blends in Material Layer Blends can cause Virtual Texture samples to be duplicated in HLSL. This can be avoided by sampling the Virtual Texture in the Parent Material, and pa ...

Packed level actors and Level instances are sometimes not included in HLOD build on a World Partition Level

UE - World Creation - Worldbuilding Tools - HLOD - Mar 14, 2025

Context World Partition - Hierarchical Level of Detail (HLOD) system uses custom HLOD Layers to organize large amounts of Static Mesh Actors and generate a single proxy mesh and Material. Problem T ...

Building Lighting will Generate Additional Lightmaps after Rotating Lightsource

UE - Graphics Features - Jul 7, 2015

Lightmap sizes seem inconsistent after rotating a light source and rebuilding the lighting. This causes concern about file sizes when packaging the project that is using baked static lighting. The ...

Creating an exposed variable does not always update correctly to the bp's Details panel

UE - Gameplay - Blueprint - Feb 20, 2015

Creating an exposed variable does not always update correctly to the bp's Details panel. They will show as having multiple values until the bp is clicked off and back onto. ...

The Add node does not update in the Construction Script

UE - Gameplay - Blueprint - Feb 28, 2015

The Add node does not update in the Construction Script. Reproduced in 4.7.1 binary and Main (//depot/UE4/Promotable-CL-2455917) ...

PhysX generates extra "sleep" event when moving Kinematic actors away from Simulated actors with Teleport option.

UE - Simulation - Physics - Aug 4, 2016

Issue seems to be related to NpRigidDynamic::setKinematicTarget. When called by itself (like in the case of Kinematic bodies moved without teleportation), the simulated actor is woken and is put ba ...

Orthographic Camera view doesn't work with movable directional light shadows and partly with stationary shadows

UE - Graphics Features - Feb 26, 2015

See attached video for clear examples. When using the orthographic camera perspective with default light settings to stationary for directional light source. Other light sources work as intended. T ...

Illegal Else Without Matching If

UE - Simulation - Physics - Feb 3, 2017

Looks like there's a missing if/else pair in BodyInstance.cpp ...