# BoundingSphereBox A combined bounding volume consisting of a bounding sphere and an optional axis-aligned bounding box. ``` @frozen struct BoundingSphereBox ``` ## Overview `BoundingSphereBox` represents the culling bounds of a [`LowLevelMeshInstance`](/documentation/RealityKit/LowLevelMeshInstance). When `halfExtents` is set, the renderer uses the tighter box bounds for culling; otherwise it falls back to the bounding sphere. ## Topics ### Creating a bounding volume [`init(center: SIMD3, radius: Float)`](/documentation/RealityKit/BoundingSphereBox/init(center:radius:)) Creates a bounding sphere with the given center and radius. [`init(center: SIMD3, halfExtents: SIMD3)`](/documentation/RealityKit/BoundingSphereBox/init(center:halfExtents:)) Creates a bounding box with the given center and half-extents, with a circumscribed sphere. [`init(center: SIMD3, fullExtents: SIMD3)`](/documentation/RealityKit/BoundingSphereBox/init(center:fullExtents:)) Creates a bounding box with the given center and full extents, with a circumscribed sphere. [`init(boxMin: SIMD3, boxMax: SIMD3)`](/documentation/RealityKit/BoundingSphereBox/init(boxMin:boxMax:)) Creates a bounding box from minimum and maximum corner positions, with a circumscribed sphere. ### Accessing the dimensions [`var center: SIMD3`](/documentation/RealityKit/BoundingSphereBox/center) The center of the bounding volume in model space. [`var halfExtents: SIMD3?`](/documentation/RealityKit/BoundingSphereBox/halfExtents) The half-extents of the optional axis-aligned bounding box. [`var fullExtents: SIMD3?`](/documentation/RealityKit/BoundingSphereBox/fullExtents) The full extents of the optional axis-aligned bounding box. ### Instance Properties [`var radius: Float`](/documentation/RealityKit/BoundingSphereBox/radius) The bounding sphere radius. ## Relationships ### Conforms To [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)