---
title: "union(with:)"
framework: modelio
role: symbol
role_heading: Instance Method
path: "modelio/mdlvoxelarray/union(with:)"
---

# union(with:)

Extends the voxel array to also cover the volume of the specified voxel array.

## Declaration

```swift
func union(with voxels: MDLVoxelArray)
```

## Parameters

- `voxels`: The voxel array to combine with this voxel array.

## Discussion

Discussion After a union operation, the voxel array contains voxels that were present either in the original array or in the specified array. That is, a union operation creates a voxel array that combines two volumes. Performing a union, intersection, or difference operation clears out shell level information from all voxels in the array. (That is, the w component of every MDLVoxelIndex value in the voxel array is reset to 0.)

## See Also

### Performing Constructive Solid Geometry Operations

- [intersect(with:)](modelio/mdlvoxelarray/intersect(with:).md)
- [difference(with:)](modelio/mdlvoxelarray/difference(with:).md)