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# boundingBox

The minimum region entirely enclosing the mesh’s vertex positions, expressed in the model coordinate system of the mesh.

```
var boundingBox: MDLAxisAlignedBoundingBox { get }
```

## Discussion

This property’s value is valid only if the mesh contains vertex data for the [`MDLVertexAttributePosition`](/documentation/ModelIO/MDLVertexAttributePosition) attribute. If the mesh does not contain position information, this property’s value is a bounding box whose `maxBounds` coordinate is greater than its `minBounds` coordinate.

Reading this property for the first time processes the mesh’s vertex data to calculate and cache a bounding box. Reading this property thereafter returns the cached value.

---

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