---
title: halfExtents
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/boundingspherebox/halfextents
---

# halfExtents

The half-extents of the optional axis-aligned bounding box.

## Declaration

```swift
var halfExtents: SIMD3<Float>? { get set }
```

## Discussion

Discussion When non-nil, the renderer uses the box for culling. Setting this to a value expands radius to circumscribe the box.

## See Also

### Accessing the dimensions

- [center](realitykit/boundingspherebox/center.md)
- [fullExtents](realitykit/boundingspherebox/fullextents.md)