# voxelExists(atIndex:allowAnyX:allowAnyY:allowAnyZ:allowAnyShell:) Returns a Boolean value indicating whether the voxel array contains voxel data for the specified index. ``` func voxelExists(atIndex index: MDLVoxelIndex, allowAnyX: Bool, allowAnyY: Bool, allowAnyZ: Bool, allowAnyShell: Bool) -> Bool ``` ## Parameters `index` An index describing both the location of the voxel within the three-dimensional grid of the voxel array and its relationship to the volume of the object modeled by the voxel array. `allowAnyX` If , this method treats the x component of the index parameter as a wildcard. If , this method requires an exact match for the x component. `allowAnyY` If , this method treats the y component of the index parameter as a wildcard. If , this method requires an exact match for the y component. `allowAnyZ` If , this method treats the z component of the index parameter as a wildcard. If , this method requires an exact match for the z component. `allowAnyShell` If , this method treats the w (shell level) component of the index parameter as a wildcard. If , this method requires an exact match for the shell level component. ## Return Value if the voxel array contains at least one voxel index matching the specified parameters; otherwise . ## Discussion Use the `allowAnyX`, `allowAnyY`, `allowAnyZ`, and `allowAnyShell` parameters to perform wildcard searches. For example: ```swift // Does a voxel exist at exactly the specified X, Y, Z, and shell level? exists = voxelArray.voxelExists(atIndex: index, allowAnyX: false, allowAnyY: false, allowAnyZ: false, allowAnyShell: false) // Does a voxel exist at the specified X, Y, and Z, regardless of shell level? exists = voxelArray.voxelExists(atIndex: index, allowAnyX: false, allowAnyY: false, allowAnyZ: false, allowAnyShell: true) // Are there surface voxels anywhere on the XY plane at a specific Z index? index.w = 0 exists = voxelArray.voxelExists(atIndex: index, allowAnyX: true, allowAnyY: true, allowAnyZ: false, allowAnyShell: false) // Are there any voxels three layers deep inside the object modeled by the voxel array, regardless of location? index.w = -3 exists = voxelArray.voxelExists(atIndex: index, allowAnyX: true, allowAnyY: true, allowAnyZ: true, allowAnyShell: false) ``` --- 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)