# init(name:indexBuffer:indexCount:indexType:geometryType:material:topology:) Initializes a named submesh with a specific topology. ``` init(name: String, indexBuffer: any MDLMeshBuffer, indexCount: Int, indexType: MDLIndexBitDepth, geometryType: MDLGeometryType, material: MDLMaterial?, topology: MDLSubmeshTopology?) ``` ## Parameters `name` A descriptive name for the submesh. This property is not used in rendering, but can be useful in debugging. `indexBuffer` An object that provides index data for the submesh. `indexCount` The number of indices in the index buffer. `indexType` The data type of each index in the index buffer. `geometryType` The type of geometric primitives described by the index buffer. `material` A description of the intended surface appearance for rendering the submesh. `topology` An object describing the arrangement of geometric primitives in the index buffer. ## Return Value A new submesh object. ## Discussion Typically, a submesh is imported from an asset file as a member of a [`MDLMesh`](/documentation/ModelIO/MDLMesh) object, but you can also use this method to create a submesh programmatically. Use this method when the index buffer from which you’re creating a submesh does not contain a uniform array of geometric primitives. Pass [`MDLGeometryType.variableTopology`](/documentation/ModelIO/MDLGeometryType/variableTopology) for the `geometryType` parameter, and provide an `MDLSubmeshTopology` object for the `topology` parameter to describe how the points in the index buffer combine to produce the submesh’s shape. Otherwise, this method is equivalent to the [`init(name:indexBuffer:indexCount:indexType:geometryType:material:)`](/documentation/ModelIO/MDLSubmesh/init(name:indexBuffer:indexCount:indexType:geometryType:material:)) method. --- 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)