Key Features

Probe lighting leak reduction

This release automatically reduces the impact of light leaking through thin walls for meshes with Probe or Contribute Probe lighting mode. In areas where this type of light leak would previously occur, the Enlighten probe resolution is now automatically increased, with only a minor increase in runtime cost.

Landscape automatic probe placement

It is no longer necessary to manually place probe volumes to light actors above Landscape. Instead, you can now choose to automatically generate probes above a Landscape actor.

Probes are placed only when the Create Enlighten Probe Volume property of the Landscape actor is checked. Control the resolution with the Enlighten Adaptive Probe Resolution property of the Landscape actor. When World Settings > Use Landscape Water Level is checked, Enlighten probes are not placed for Landscape below World Settings > Landscape Water Level.

Precompute on Intel 12th generation CPU

The Enlighten precompute now supports Intel 12th gen Alder Lake CPU models. Multithreaded tasks now make good use of both P and E cores.

Enlighten data moved to BuiltData asset

Enlighten data is now stored in the BuiltData asset.

The BuiltData asset is created after running the precompute, only for levels that have Enlighten enabled. When you delete the BuiltData asset associated with a level, the Enlighten lighting for the level is deleted. We recommend to unload the level first so that you can safely delete the BuiltData asset.

We recommend to delete any existing EnlightenData asset after you save the level package with Enlighten UE4 4.01.

Mobile deferred renderer

Enlighten lighting is now available for the ES3.1 Mobile Preview, only when using the Mobile Deferred Renderer. The Mobile Forward Renderer is not supported.

The following Enlighten features are not supported:

Landscape LOD
Per mesh probe lighting
Real time sky capture
Enlighten Texture Environment

With or without Enlighten, Reflection Environment lighting appears slightly darker in ES3.1 than SM5

iOS Metal and Android Vulkan mobile deferred renderer

Enlighten lighting is now available for Android Vulkan and iOS Metal with the Mobile Deferred Renderer. The Mobile Forward Renderer is not supported.

The current implementation has some limitations:

iOS Metal: indirect lighting and reflections may not match the mobile preview exactly.
Android Vulkan: lightmaps are limited to a maximum intensity of 16. This may cause unexpectedly dark indirect lighting when using realistic sun light intensity.

Control ray traced sun shadow cost

Use the new Dynamic Enlighten Shadow Distance property in World Settings to limit the distance at which ray traced Enlighten shadows are enabled for the Directional Light actor. Distant systems fall back to cheaper precomputed shadowing.

Fast export of world before precompute

There is no longer a long wait to export levels before the precompute starts, so you can continue working in the editor without interruption.

Strip Enlighten properties for all levels

To convert an entire project to vanilla UE4, use the new flag -StripAll with the EnlightenStripEnlightenData commandlet to remove Enlighten properties from all levels and the assets they refer to. Add the -AllAsset flag to include unreferenced assets.

Warn when precompute might take longer than expected

A warning is now reported when a single level receives light bounces from more than 50 other levels. To limit the distance at which a level receives light bounces, specify Enlighten Bounce Distance. To silence the warning, increase the Level Dependency Threshold in project settings.

Important changes

Added script to rebuild iOS Enlighten libraries and tools from source.
When using the ES3.1 mobile preview, updates to Enlighten Static Albedo are now deferred until you switch back to SM5.
Enabled use of unsupported experimental D3D11 RHI Thread in combination with Enlighten: use at your own risk!

Fixed bugs

Fixed missing probe lighting until level reload after changing Adaptive Probe Grid Spacing
Fixed incorrect editor preview after undo/redo of changes to Enlighten World Settings.
Fixed probe sample method sometimes changing to Per Pixel for components generated by a Blueprint asset saved with older versions of Enlighten UE4.
Fixed failure to save Lightmass shadow map data in a level that contains only shadow maps.
Fixed SkyLight Light Color and Indirect Intensity producing incorrect result for Enlighten indirect lighting.
Fixed rare crash during the precompute for scene that contains complex Contribute Probe instances.
Fixed crash or extremely bright lighting when a light intensity or the indirect intensity are less than zero.
(P2) Fixed some cases of probe lighting leaking through walls.
(P2) Fixed link error with Enlighten libraries when BuildConfiguration.bEnableEnlightenDevelopment=true.
(P2) Fixed endless loop of automatic Enlighten static albedo update after Contribute Probe actor is deleted.
(P2) Fixed behavior of Reflection Environment Lightmap Mixing which could cause unexpected brightening or darkening of reflections on glossy materials under certain lighting conditions.
(P2) Fixed a source control error when running the EnlightenPrecompute commandlet for a newly created level with -AutoCheckOutPackages flag.
(P2) Fixed crash when the same level is loaded by more than one concurrent PIE game instance.

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