---
title: boneIndices
framework: scenekit
role: symbol
role_heading: Type Property
path: scenekit/scngeometrysource/semantic-swift.struct/boneindices
---

# boneIndices

The semantic for bone index data, used for skeletal animation of skinned surfaces.

## Declaration

```swift
static let boneIndices: SCNGeometrySource.Semantic
```

## Discussion

Discussion For a geometry source, this semantic identifies data containing skeletal animation data for each vertex in the geometry. SceneKit uses this information to determine which bone nodes in the skeleton affect the behavior of each vertex. For a custom shader program, you use this semantic to bind SceneKit’s bone index data to an input attribute of the shader. For details on skeletal animation, see SCNSkinner.

## See Also

### Skeletal Animation Semantics

- [boneWeights](scenekit/scngeometrysource/semantic-swift.struct/boneweights.md)