Data Layer
The data layer is a new feature in UE5 that can replace sub-levels, allowing the same location to change under different conditions (controlled by blueprints, such as when a player has a certain task or activates a specific gameplay mode), transforming the entire scene.
Generally, only items that change during gameplay will be placed in the data layer; purely model scenes do not need to be placed in the data layer.
Terrain cannot use the data layer.
Data layers can be organized in a nested manner.
An Actor can be placed in multiple data layers.
One file per Actor
A new feature in UE5, no longer placing all content in a level into a single level, but instead storing each Actor in the level as a separate file (file naming and management are handled automatically by Unreal).
This solves the issue of a large map where changing a parameter of one Actor requires submitting the entire map, making it very suitable for collaborative map editing and optimizing the daily development update process.
Actors in World Partition
These screenshots are taken from the detail panel of the Actors.
Data Layer
The detail panel of each Actor can configure which data layer the Actor belongs to, and can also be easily added through the data layer Outliner.
RuntimeGrid
In the world partition section of each Actor's detail panel, you can specify which 'runtime grid' the Actor belongs to during runtime. If None is filled in, the default will be used (which will be discussed later).
IsPartiallyLoaded
This checkbox determines the loading mechanism for the Actor when placed in a map with enabled world partition. Generally, it is checked.
Checked:
If the Actor is not in any data layer, it will load based on the player's distance.
If it is in a data layer, it will load once any of the associated data layers are enabled.
However, the reality is that even if the data layer is enabled, once checked, it will still adhere to the distance loading principle.
Unchecked:
If the Actor is not in any data layer, it will load (meaning permanently loaded, which should be avoided as much as possible).
If the Actor is in a data layer, it will be loaded once any of the associated data layers are enabled.
In simple terms, data layers have a higher priority.
Runtime Grid Definition
Previously, we discussed how Actors are assigned to different runtime grids; here we will discuss how to define a runtime grid.
The world partition panel in the editor can load blocks to be edited and viewed in fixed units of 512m x 512m.
However, during gameplay, a different set of runtime grids is used to handle unit loading, and this different set is called 'RuntimeGrid'.
RuntimeGrid is defined in the WorldSettings section of each world partition map.
As shown in the above image, there is a default MainGrid with a size of 256m and a loading range of 768m. If an Actor is not assigned to any data layer, it will use this MainGrid.
However, I have also added another grid: the Gameplay grid, which has a size of 10 meters, a loading range of 20 meters, and a color of cyan.
As shown in the above image, I placed a cube in the Gameplay grid; if the player's camera is more than 20 meters away from the grid where the cube is located, the cube will be unloaded.
Deprecated Items
Level Blueprint
The Level Blueprint is no longer recommended for use; any Actor referenced by the Level Blueprint willbe permanently loaded!
Alternative:
If you must reference, it is recommended to use one Actor (exposed variable) and then manually select the reference in the detail panel. Such mutually referenced Actors will be packaged together in the same level during packaging!
LevelBounds
Level Bounds is a box that was automatically generated for each level based on the placement of Actors within the level, enclosing all Actors in the level. It is now deprecated. Smart objects rely on Level Bounds to query interactive objects within the level, and Level Blueprint game locations depend on Level Bounds to determine whether an Actor is within the level.
Level Blueprint Game Location
Incompatible Items
Actors built with brushes will not be automatically managed and streamed by the world partition; they must be converted to StaticMesh.