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# preliminary:planeAnchoring:alignment

An option that specifies the orientation of a plane.

## Discussion

This property is active only for the `preliminary:anchoring:type` value `plane`. The runtime recognizes real-word surfaces such as floors, tables, ceilings as horizontal planes. Vertical planes include walls, doors, and windows.

### Declaration

```other
uniform token preliminary:planeAnchoring:alignment (
        allowedTokens = ["horizontal", "vertical", "any"]
)
```

### Plane anchor types

- `horizontal`: Requests that the runtime anchor the prim on a floor, table, ceiling, or other flat surface.
- `vertical`: Requests that the runtime anchor the prim on a wall, door, window, or other vertical surface.
- `any`: Requests that the runtime anchor the prim on the first horizontal or vertical surface detected.

### Anchor a prim to a horizontal plane

The following asset definition requests that the runtime anchor this prim to the first surface the runtime detects that occupies a horizontal orientation in relation to the camera.

```swift
def Cube "PlaneAnchoredCube" (
    prepend apiSchemas = [ "Preliminary_AnchoringAPI" ]
)
{
    uniform token preliminary:anchoring:type = "plane"
    uniform token preliminary:planeAnchoring:alignment = "horizontal"
    ...
}
```

---

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