---
title: boneWeights
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnskinner/boneweights
---

# boneWeights

The geometry source that defines the influence of each bone on the positions the geometry’s vertices.

## Declaration

```swift
var boneWeights: SCNGeometrySource { get }
```

## Discussion

Discussion This geometry source’s semantic property must be boneWeights. Its data is an array of floating-point vectors, whose componentsPerVector count is the number of bones influencing each vertex. Each vector corresponds to a vertex in the geometry’s vertex geometry source, and each component in a vector specifies the influence of a bone on that vertex’s position. The boneIndices source determines which nodes in the bones array correspond to each component in the vector. A component value of 0.0 means that the bone has no influence on that vertex; positive or negative values scale the transformation of a bone node before SceneKit applies that transformation to the vertex. note: SceneKit performs skeletal animation on the GPU only if the componentsPerVector count in this geometry source is 4 or less. Larger vectors result in CPU-based animation and drastically reduced rendering performance.

## See Also

### Working with an Animation Skeleton

- [skeleton](scenekit/scnskinner/skeleton.md)
- [bones](scenekit/scnskinner/bones.md)
- [boneInverseBindTransforms](scenekit/scnskinner/boneinversebindtransforms.md)
- [boneIndices](scenekit/scnskinner/boneindices.md)