# cullMeshInstances(_:indices:outIndices:configuration:) Culls mesh instances against a frustum, writing surviving indices to an output span. ``` static func cullMeshInstances(_ meshInstances: LowLevelMeshInstanceArray, indices: Span, outIndices: inout OutputSpan, configuration: LowLevelRenderer.CullConfiguration) ``` ## Parameters `meshInstances` The mesh instance array to test. `indices` The candidate indices to test. `outIndices` The span that receives surviving indices. Must have free capacity of at least `indices.count`. `configuration` The cull configuration supplying the frustum planes. ## Discussion Tests each instance’s bounds against the planes in `configuration.frustum`, using `meshInstance.bounds` when set and falling back to the mesh part’s bounds otherwise. Instances whose bounds lie entirely outside any single plane are discarded; the rest are appended to `outIndices` in the same order as `indices`. `nil` slots in `meshInstances` are skipped. --- 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)