Key Features

Fast and reliable precompute

The Enlighten precompute is now much faster and more reliable, which significantly improves the workflow when using Enlighten in very large and highly detailed worlds.

This release includes many optimisations that combine to reduce precompute time and memory footprint by at least 50% in a typical world. In a very large world with millions of instances and high triangle density we measured more than 90% reduction in precompute time and memory footprint.

For very large and highly detailed worlds, improved geometry processing algorithms now prevent cases where the precompute might take forever or run out of memory. When a mesh contains invalid data, instead of an error the precompute now reports a warning and continues.

You can now focus on configuring the lighting to balance visual quality with runtime cost, without worrying about the precompute.

Safe default configuration

The default Enlighten configuration for created levels is now tuned to ensure that the precompute completes quickly. It is no longer necessary to manually choose lighting mode and resolution before running the precompute.

In a newly created level:

• Static meshes use probe lighting.

• For all actors, Enlighten Quality is Medium and Enlighten Probe Resolution is 1/4.

• Landscape Export LOD Bias is 2.

• The number of Probe LOD Levels is automatically limited based on the Enlighten Bounce Distance.

• Sky Hidden Below Horizon is enabled.

In all levels:

• Meshes which have only materials with Is Sky checked are excluded from the radiosity computation.

• Excessively large meshes are automatically excluded from the radiosity computation.

In a level saved with an older version, the default configuration of newly added meshes is preserved.

Separate sky in probe lighting

This release adds the option to apply direct sky lighting separately from bounce lighting. With this, the probe lighting result in an outdoor area is more accurate when lit by sky lighting from above and sun bounce from below.

The images below show combined sky and bounce on the left, and separate sky and bounce on the right.

The cliff wall is mostly indirectly lit. There is strong sunlight bounce from below, and strong sky lighting from above. With combined sky and bounce the cliff appears lit from no specific direction. With separate sky and bounce the cliff appears brightly lit from below by yellow bounce from the sun, and also brightly lit from above by blue sky.

To apply sky lighting separately from bounce, set r.Enlighten.SeparateSky=1 in DefaultEngine.ini.

Landscape with probe lighting

This release adds the option to use probe lighting in combination with Landscape. To enable probe lighting, set the lighting mode of the Landscape actor to Contribute Probe.

Adaptive probe placement allows fine control over the lighting resolution and eliminates lightmap seams.

Nanite production ready

This release includes various improvements that enable production use of Nanite in combination with Enlighten.

• Enlighten view modes now work with Nanite meshes.

• When Nanite is enabled for a Landscape, use Contribute Probe lighting mode to enable Enlighten indirect lighting.

• The warnings are reported by the precompute when a Nanite mesh has Contribute Lightmap lighting mode are now more useful.

Lightweight sky capture

This release delivers an 8-10x reduction in the per frame rendering thread cost when Real Time Capture is enabled for a movable Sky Light actor.

The processing that previously ran on the CPU now runs in a compute shader on the GPU.

Important changes

Mesh auto-instancing is now usable with the mobile renderer in combination with Enlighten.

Packed Level Actor now correctly reflects Enlighten properties of actors within the level instance. Enlighten lighting is preserved when the packed level actor is rebuilt.

Reduced precompute time and memory usage when instanced foliage has Cast Shadows unchecked.

The Enlighten precompute no longer reports an error when the world contains two foliage types with the same display name.

The precompute now reports a warning when a Nanite foliage type uses Detail lighting mode.

The Enlighten precompute now reports a warning when a static mesh instance has an invalid Scale value, such as zero. The instance is now automatically excluded from the Enlighten radiosity computation.

The precompute now reports a more useful diagnostic when the Enlighten resolution is unusually high.

The Sky Lighting show flag now toggles Enlighten sky lighting.

Probes that see invalid surfaces are no longer shown in the Probes view mode.

The precompute no longer fails when a mesh Lightmap UV channel contains invalid values. The invalid values are now silently ignored.

The Enlighten precompute now produces the correct results for a world which contains a Water Body.

Fixed bugs

Fixed excesssively bright sky reflections when Sky Light Mobility is set to Dynamic.

Removed the unexpected External Types section in the Build menu.

Fixed missing indirect lighting for mesh that contains a material section with zero triangles.

Fixed incorrect albedo for a Hierarchical Instanced Static Mesh with Contribute Lightmap lighting mode.

Fixed missing indirect lighting for Nanite foliage with Detail lighting mode.

Fixed a crash when running the EnlightenStripEnlightenData commandlet for a level with World Partition enabled.

Fixed a crash when loading a level with Lightmass lighting when Hardware Ray Tracing is enabled.

The precompute process no longer fails with System.OutOfMemoryException when the available system memory is very low.

Fixed a stack overflow in the precompute CalculateSystemDependencies task with instances scaled very small.

Fixed precompute excessive memory usage and incorrect results in a scene with a very high triangle density.

Fixed a rare crash in the precompute CompressLightTransport task.

Fixed a rare crash in the precompute CreateOutputProbeSet task.

Fixed a rare crash in the precompute CreateProbeOctree task.

Known Issues

Runtime virtual texturing is not supported. Materials that sample from a Runtime Virtual Texture asset may have incorrect Enlighten albedo.

The Rect Light actor is not supported on mobile platforms.