Unreal Engine Issues
Unreal Engine Issues
Non-Nanite meshes not being correctly cleared from all levels of VSMs on actor destruction when r.Shadow.Virtual.NonNanite.IncludeInCoarsePages=0
UE - Rendering - Features - Shadows - Jun 15, 2026When using the r.Shadow.Virtual.NonNanite.IncludeInCoarsePages=0 to optimize VSM performance there are errors in how the VSM is invalidated when actors are destroyed with non-Nanite meshes. The curr ...
VSM r.Shadow.Virtual.UseReceiverMaskDirectional Breaks Cache Behavior Overrides
UE - Rendering - Features - Shadows - May 19, 2026Since 5.7 this CVAR has been turned on by default and it ibreaks / prevents shadow cache behaviour to be set as we used to in 5.6 on meshes when r.Shadow.Virtual.UseReceiverMaskDirectional 1 Most o ...
CSM Cached Shadows missing when changing FOV
UE - Rendering - Features - Shadows - Mar 30, 2026When changing the camera FOV with r.Shadows.CSMCaching enabled, the cached shadows don't appear to be used and shadows are missing. This occurs because the r.Shadow.RadiusThreshold can be low enoug ...
Clustered Deferred Shading relies on r.Nanite.ProjectEnabled Cvar
UE - Rendering - Features - Shadows - Feb 25, 2026When Nanite is disabled at the project level with r.Nanite.ProjectEnabled=0, clustered deferred shading stops working. This happens because the FDeferredShadingSceneRenderer::RenderLights method doe ...
Inconsistent VSM page behavior around the Dynamic Shadow Distance range
UE - Rendering - Features - Shadows - Feb 17, 2026When a sufficiently large object casts shadows near the Directional Light's Dynamic Shadow Distance range, the VSM pages are inconsistent in their shadowing - some will choose to shadow per-pixel, w ...
Using VSM and Distance Field Shadows on the same scene results in missing shadows
UE - Rendering - Features - Shadows - Feb 9, 2026Nanite geometry does not cast Distance Field Shadows outside of the clipmap range for Virtual Shadow Maps. Non-Nanite geometry does cast these shadows. ...
Hard shadow edges appear when using Displacement Fade on a Nanite tessellated landscape
UE - Rendering - Features - Shadows - Feb 2, 2026A hard shadow edge occurs when displacement fade is enabled on a Nanite landscape with tessellation. This occurs on the edge between two clipmap levels of the VSM. The artefact can be somewhat red ...
World-Space widgets don't cast whadows when using VSM
UE - Rendering - Features - Shadows - Oct 29, 2025When using Virtual Shadow Maps (VSM), widgets placed in world space do not cast any shadows. The same widgets correctly cast shadows when the Shadow Method is set to Shadow Maps instead of VSM. ...
Crash in FShadowSceneRenderer::AddDirectionalLightShadow
UE - Rendering - Features - Shadows - Jun 2, 2025This is a race condition between the FShadowScene update & rendering, where sometimes the renderer tries to access a data array before it has been populated leading to the crash. It happens fairly r ...
Virtual Shadow Maps on Spot Lights cause a blocky presentation similar to an incorrect mip level
UE - Rendering - Features - Shadows - May 26, 2025Spot Lights may present with very blocky shadow artefacts when a long attentuation radius is provided with a small cone angle. In extreme cases, this causes the VSMs to invalidate every frame. Notab ...