Dimensions Fragment

The Dimensions Fragment defines the 2D spatial footprint for items placed within containers that use a Spatial Layout.

It specifies the base width and height, and whether the item can be rotated.
Rotation is only considered valid when the item's width and height are not equal (i.e., non-square shapes).

Fragment Tags

This fragment does not contribute any gameplay tags.

Properties

Property	Description
`Width`	The base width of the item in grid cells.
`Height`	The base height of the item in grid cells.
`CanRotate`	Allows the item to be rotated. Rotation is only relevant when `Width != Height`.

Operations

Function	Description
`GetBaseDimensions`	Returns the original dimensions defined by the fragment, ignoring any current rotation.
`GetDimensions`	Returns the current item dimensions, accounting for its rotation state (if applicable).
`GetDimensionsFromDefaultMemory`	Returns the dimensions for a default item, accounting for its rotation state (if a memory is available).
`CanRotate`	Checks whether the item supports rotation, based on its shape and the `CanRotate` flag.
`CanRotateItemInPlace`	Checks if the fragment supports rotation and if the item can be rotated in the occupied space.
`IsRotated`	Returns whether the item is currently rotated.
`IsRotatedFromDefaultMemory`	Returns whether the default item is currently rotated, based on a memory.
`SetRotated`	Sets the item's rotation state. Requires authority and valid memory.

Memory

This fragment uses the FInventoryItemFragmentDimensionsMemory structure to track the rotation state of the item at runtime.

Occupancy Masks

Occupancy Masks let items use non-rectangular footprints (crosses, L-pieces, circles, Tetris-like shapes) when placed inside grid-based containers. The layout/placement logic treats only the true cells of the mask as occupied, enabling richer packing and equipment silhouettes.

A mask is a grid (Width x Height) stored as a TArray<bool> (row-major).
Setting a cell to true means the cell is occupied by the item; false means cell is empty and ignored for collisions.
If no mask is defined, the item occupies its full rectangle (Width x Height, all true).
Masks respect rotation: the framework evaluates collisions using the mask transformed into the item’s current orientation.
A mask requires at least one occupied cell. The asset validation will fail for empty masks.

Event Payloads

This fragment emits events using the FInventoryItemDimensionsPayload structure.

Event	Description
`Inventory.Event.Item.RotationChanged`	Emitted when the item's rotation state changes.

Last modified: 11 December 2025