# init(positions:triangleIndices:materials:) Creates a reverb mesh resource from a list of positions, triangle indices, and material indices. ``` convenience init(positions: [SIMD3], triangleIndices: [UInt32], materials: [UInt32]) throws ``` ## Parameters `positions` The vertex positions of the mesh. `triangleIndices` The triangle indices that reference positions in the `positions` array. `materials` An array of material indices, one per triangle, that map each face to a material in the [`Audio.Material`](/documentation/RealityKit/Audio/Material) array provided to [`simulated(mesh:materials:)`](/documentation/RealityKit/Reverb/simulated(mesh:materials:)). ## Discussion Use this initializer when you have precise control over the geometry: ```swift let mesh = try ReverbMeshResource( positions: myPositions, triangleIndices: myIndices, materials: perFaceMaterialIndices ) ``` --- 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)