Cell
- Base:
- UDataAsset
- Type:
- UNCell
- Header File:
- NexusWorldAssembly/Public/Cell/NCell.h
The basic structural and functional unit of all living organisms. It is the smallest unit of life classified as a living thing, acting as the fundamental building block of all tissues and organs
A cell represents a map's meta-data, allowing it to be placed in a World Assembly operation. It is meant to disconnect the actual UWorld (Map) from this data, allowing generation to occur without having to load any of the actual map data itself until it is actually used (FNSpawnCellProxiesTask).
This allows for an extremely efficient World Assembly operation, off of the Game Thread.
Cell-level instances spawned at runtime/author-time are locked out from editing. Open the source level directly when you need to make changes. See the Cell Editor as part of the Editor Mode.
Cell Actor​
The ANCellActor functions as the root of all evil, and also houses the level-side data for the UNCell.
| Setting | Description |
|---|---|
| Cell Junctions | Internal mapping of a ticket/identifier to a Junction. |
| Author Time Actors | A user-defined list of AActors that should be destroyed when a ANCellLevelInstance is loaded. Will not effect cell spatial calculations either. |
| Initialize Callback Actors | Reference list to all AActors that implement the INCellInitialized interface. Populated automatically during the save process to avoid finding at build time. |
| Sidecar | Soft-pointer to the associated side-car data (UNCell) for the level. |
| Cell Junction Next Identifier | Storage for the next internal ticket/identifier. |
Cell Root Component​
The UNCellRootComponent represents the data which is going to get mirrored into the UNCell when saved.
Bounds Settings​
| Setting | Type | Description | Default |
|---|---|---|---|
| Calculate On Save | bool | Should the bounds of the cell be calculated / updated on save. | true |
| Include Non Colliding | bool | Include non-colliding AActors in bounds calculations. | false |
| Include Editor Only | bool | Include AActors flagged as EditorOnly in bounds calculations. | false |
| Actor Ignore Tags | TArray<FName> | AActor's with these tags will be ignored during bounds calculations. | NCell_Ignore, NCell_BoundsIgnore |
Rotation Constraints​
The cell exposes a dual-interval FNRotationConstraints set. The matching interval constrains a candidate rotation's own pose; the difference interval constrains the delta between two rotations. Either interval can be enabled independently.
| Setting | Type | Description | Default |
|---|---|---|---|
| Enforce Matching? | bool | Enables the matching-interval test on the candidate rotation itself. | true |
| Minimum Matching Rotation | FRotator | Lower bound (inclusive) of the matching interval. | (0,0,-180.f) |
| Maximum Matching Rotation | FRotator | Upper bound (inclusive) of the matching interval. | (0,0,180.f) |
| Enforce Difference? | bool | Enables the difference-interval test on the delta between two rotations. | false |
| Minimum Difference Rotation | FRotator | Lower bound (inclusive) of the difference interval. | (0,0,-180.f) |
| Maximum Difference Rotation | FRotator | Upper bound (inclusive) of the difference interval. | (0,0,180.f) |
Hull Settings​
| Setting | Type | Description | Default |
|---|---|---|---|
| Calculate On Save | bool | Should the hull be calculated / updated on save. | true |
| Allow Non Convex | bool | Allow the hull to be non-convex; creating a complex collision mesh. There is a performance cost to using non-convex meshes inside of an assembly operation, choose wisely. | false |
| Include Non Colliding | bool | Include non-colliding AActors in hull calculations. | false |
| Include Editor Only | bool | Include AActors flagged as EditorOnly in hull calculations. | false |
| Build Method | ENullBuildMethod | This is the method/version used by Chaos to create the convex hull initially. It is currently locked out due to some of the newer versions of the system producing n-gons. | Original |
| Actor Ignore Tags | TArray<FName> | AActor's with these tags will be ignored during hull calculations. | NCell_Ignore, NCell_HullIgnore |
Proxy Color​
Voxel Settings​
| Setting | Type | Description | Default |
|---|---|---|---|
| Use Voxel Data | bool | Voxel data is currently ignored. Should a cell's voxel data be used in assembly operations. | false |
| Calculate On Save | bool | Should the voxel data of the cell be calculated / updated on save. | true |
| Include Non Colliding | bool | Include non-colliding AActors in voxel data calculations. | false |
| Include Editor Only | bool | Include AActors flagged as EditorOnly in voxel data calculations. | false |
| Actor Ignore Tags | TArray<FName> | AActor's with these tags will be ignored during voxel data calculations. | NCell_Ignore, NCell_VoxelIgnore |
| Collision Channel | ECollisionChannel | The collision channel used when tracing for collisions to determine occupancy. | WorldStatic |
Side-Car Data​
Each cell is stored as a side-car asset (<CellName>_NCell.uasset) that lives next to the source level. The side-car holds the cached bounds, hull, voxel data, junction set, and a thumbnail snapshot of the level — none of which require the level itself to be loaded for the assembly task graph to schedule work against the cell.
When a thumbnail is captured for the ANCellActor in the level editor (via the Capture Thumbnail menu option in Cell Editor), it propagates (with gizmos) to the side-car automatically so the cell shows similar preview in the content browser as the source level.
The side-car asset's content-browser context menu includes a Select Level action button that jumps to the source level in the content browser — handy when triaging a generation result and you need to open the source map for the cell that produced a particular proxy.