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# inputBias

An offset to add to the input value of the controller’s animation.

```
var inputBias: CGFloat { get set }
```

## Discussion

Use this property and the [`inputScale`](/documentation/SceneKit/SCNParticlePropertyController/inputScale) property to pre-process input values to the controller’s animation. For example, if you use the [`SCNParticleInputMode.overDistance`](/documentation/SceneKit/SCNParticleInputMode/overDistance) option to animate a particle’s opacity as a function of its distance from a specified point, a bias specifies the minimum distance at which the animation’s <doc://com.apple.documentation/documentation/QuartzCore/CABasicAnimation/fromValue> property or first keyframe value takes effect.

The default value is `0.0`, leaving the input value to the animation unchanged. The range of possible values depends on the controller’s animation.

---

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