# newIcosahedron(withRadius:inwardNormals:allocator:) Generates a mesh in the shape of a regular 20-sided polyhedron with triangular faces. ``` class func newIcosahedron(withRadius radius: Float, inwardNormals: Bool, allocator: (any MDLMeshBufferAllocator)?) -> Self ``` ## Parameters `radius` The distance from the icosahedron’s center to any one of its vertices. `inwardNormals` to generate normal vectors pointing toward the center of the icosahedron; to generate normal vectors pointing outward. `allocator` An object responsible for allocating mesh vertex data. If `nil`, Model I/O uses an internal allocator object. ## Return Value A new mesh object. ## Discussion This method generates vertex data for an icosahedron centered at the origin of its local coordinate system. An icosahedron is a rough approximation of a sphere—to generate a more precise approximation, create an icosahedron and use the [`newSubdividedMesh(_:submeshIndex:subdivisionLevels:)`](/documentation/ModelIO/MDLMesh/newSubdividedMesh(_:submeshIndex:subdivisionLevels:)) method to turn it into a geodesic sphere. The `inwardNormals` parameter determines the direction of generated vertex normal vectors for the mesh. Specify if the mesh will be viewed from inside (for example, for use in a sky effect), or if the mesh will be viewed from outside. --- 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)