World Partition - Data Layers
- Organize actors in editor and runtime; replaces older Layers. Requires World Partition.
- Data Layer Assets (project-level; Name, Type, Debug Color) and Data Layer Instances (world-specific).
- Types: Editor (organization; load/unload/visibility in editor) and Runtime (manipulated at runtime via Blueprint/C++; e.g. Valley of the Ancient Light/Dark World).
- Runtime states: Loaded (loaded but not visible), Activated (loaded and visible). Set Data Layer Instance Runtime State; C++ UDataLayerSubsystem::SetDataLayerInstanceRuntimeState; "In client/server only the server can activate a DataLayer" (HasAuthority).
- Performance: loading too many assets at once can cause issues; widely used assets assigned to too many Runtime Data Layer Instances can degrade streaming performance.
- Level Instances inherit Data Layer. WorldDataLayer file: assigning only affects actor file; renaming affects label only; deleting only affects WorldDataLayer file.
- Debug: wp.DumpDatalayers, wp.Runtime.SetDataLayerRuntimeState, ToggleDataLayerActivation, ToggleDrawDataLayers. DataLayerToAssetCommandlet for legacy.