---
title: SkeletonResource.BlendMask
framework: realitykit
role: symbol
role_heading: Structure
path: realitykit/skeletonresource/blendmask
---

# SkeletonResource.BlendMask

Describes a single blend mask for selective animation control.

## Declaration

```swift
struct BlendMask
```

## Overview

Overview Blend masks enable selective application of animations by defining per-joint weights. They allow fine-grained control over which parts of a skeleton are affected by specific animations, enabling layered animation systems and partial poses. typealias BlendMask = SkeletonResource.BlendMask // Create blend masks for different body regions // Joints not listed default to weight 1.0 (full animation effect) let armOnlyMask = BlendMask(     name: "armOnly",     jointWeights: ["shoulder": 0.0] // Only affect upperArm, forearm, hand )

let handOnlyMask = BlendMask(     name: "handOnly",     jointWeights: ["shoulder": 0.0, "upperArm": 0.0, "forearm": 0.0] // Only affect hand )

## Topics

### Creating a blend mask

- [init(name:jointWeights:)](realitykit/skeletonresource/blendmask/init(name:jointweights:).md)

### Accessing mask values

- [jointWeights](realitykit/skeletonresource/blendmask/jointweights.md)
- [id](realitykit/skeletonresource/blendmask/id.md)

### Instance Properties

- [name](realitykit/skeletonresource/blendmask/name.md)

## Relationships

### Conforms To

- [Identifiable](swift/identifiable.md)

## See Also

### Configuring animation evaluation

- [animationEvaluation](realitykit/skeletonresource/animationevaluation-swift.property.md)
- [SkeletonResource.AnimationEvaluation](realitykit/skeletonresource/animationevaluation-swift.struct.md)