---
title: inputOrigin
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnparticlepropertycontroller/inputorigin
---

# inputOrigin

A node whose distance to each particle provides input values for the controller’s animation.

## Declaration

```swift
weak var inputOrigin: SCNNode? { get set }
```

## Discussion

Discussion This property applies only when the controller’s inputMode value is SCNParticleInputMode.overDistance. When you select that input mode, this property’s value must be a node in the scene containing the particle system; otherwise, SceneKit ignores this property. The default value is nil. SceneKit calculates the distance between this node’s position vector (converted to the scene’s world coordinate space) and each particle and then uses the resulting value as the input to the controller’s animation. For example, if you use this option to animate particle opacity from 1.0 to 0.0, all particles beyond a certain distance from the inputOrigin node are fully transparent—regardless of any random velocity or direction variations in reaching that distance. To refine the relationship between a range of distances and a range of input values for the controller’s animation, use the inputBias and inputScale properties.

## See Also

### Managing the Controller’s Animation

- [animation](scenekit/scnparticlepropertycontroller/animation.md)
- [inputMode](scenekit/scnparticlepropertycontroller/inputmode.md)
- [inputBias](scenekit/scnparticlepropertycontroller/inputbias.md)
- [inputScale](scenekit/scnparticlepropertycontroller/inputscale.md)
- [inputProperty](scenekit/scnparticlepropertycontroller/inputproperty.md)