Spectral Lightmapped Prefab

Add Spectral Lightmapped Prefab as a component on a Blueprint actor to store reusable baked surface lighting and optional probe fields.

For a guided setup and an explanation of how the two prefab components work together, start with Prefabs.

This is a Blueprint component, not a Place Actors entry. Place a copy of the Blueprint in the level, keep the source static, bake it, and use Capture on that placed copy. Save the Blueprint after a successful capture.

What the capture contains

The shared payload stores baked surface-lightmap bindings and enabled sibling Spectral Prefab Volume fields. Loaded and future copies of the Blueprint can use that same lighting.

It does not calculate a fresh lighting solution for every copy's surroundings. A captured room moved somewhere else still carries the lighting it was authored with.

Native Mobility

This component has no separate mobility switch. Use the owning actor's normal root Mobility.

Instance state	Behavior
Static captured copy	Uses captured surface lighting; skips its own lightmap allocation while still contributing baked shadows and bounced light to the level
Movable captured copy	Uses its stored lighting and is excluded from the static lighting build, so it does not leave a baked shadow at its old position

Keep a suitable static source for updates. Changing a copy to Movable does not convert the stored capture into live lighting.

Prefab Bake & Capture

Capture

Available on a placed editor instance, not the Blueprint template, during play, or while a lighting build is active.

Copies the source's current baked mesh lighting and enabled sibling prefab probe fields into the Blueprint's shared payload. Loaded instances are refreshed, and future instances inherit the capture.

Capture is not Bake Lighting. If the source's geometry or lighting changed, bake first. Review the status message after capture instead of assuming that clicking the button produced complete data.

Replaces shared lightingWarning

Capture replaces the Blueprint's shared payload. Other instances can change as a result, even if they were not selected. Keep a recoverable Blueprint version before replacing a capture used throughout a project.

Clear Capture

Removes the shared prefab capture, refreshes instances, and turns off automatic capture on the source. The custom Details button is labeled Clear Capture.

It does not delete the level's ordinary MapBuildData or unrelated shared lightmap texture assets. It clears the reusable prefab payload, not all lighting in the scene.

Auto Capture After Bake

Default: disabled. Placed-instance control.

Automatically replaces the shared capture after future successful lighting builds from the designated capture source. A successful manual Capture designates the placed source instance; clearing the capture disables the option.

Use it only on the intended source. It does not automatically change the actor's mobility, and it does not mean every copy independently becomes a source.

Apply Captured Lighting

Default: enabled.

Applies the stored capture when the instance registers. Disable it when you want the instance not to use that payload without deleting the shared capture.

This toggle does not remove data from the Blueprint. Re-enable it when the stored capture should be applied again.

Status and cost fields

Shared Capture

Shows Not captured or counts of captured surface bindings and probe fields. A surface binding can represent a mesh LOD, so it should not be read as a count of actors.

A nonzero count confirms stored entries, not that they match geometry changed after the capture.

Captured Data Cost

Shows captured texture count and estimated memory, probe count and payload, and their combined estimate. Embedded lightmap textures and serialized probe lighting contribute to this figure.

It excludes the Blueprint's general geometry and gameplay cost. Disk compression and runtime texture residency can differ from the displayed estimate.

Last Capture

Identifies the capture source, or shows no source when none is recorded. Use it to check which copy last replaced the shared data.

Capture message

Reports the most recent capture result or explains that a static source must be baked and captured. Read it for missing-data or failure conditions before saving over an intended good version.

Updating the prefab

Changes to mesh layout, UVs, or embedded probe definitions require a new suitable bake and capture. A construction-script change can also replace components that the old payload was associated with.

For the normal sequence, see Lightmapped prefab workflow. Do not follow older instructions requiring a separate Prepare step or a plugin-specific Movable Prefab switch; those are legacy compatibility paths, not the current panel.

Blueprint functions

Apply Lighting reapplies the stored payload after components are replaced or a construction script reruns. It returns whether application succeeded and is safe to call repeatedly.

Read-only functions expose Is Movable Instance, Get Captured Mesh LOD Count, Get Captured Probe Volume Count, Get Captured Lighting Bytes, Get Captured Probe Payload Bytes, Get Captured Texture Memory Bytes, Get Captured Texture Count, Get Captured Probe Count, and Get Last Capture Source. These report the same kinds of state and cost as the panel, without initiating a bake.