---
title: fresnelExponent
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnparticlesystem/fresnelexponent
---

# fresnelExponent

The reflectivity exponent SceneKit uses when rendering the particle’s image as a cube map. Animatable.

## Declaration

```swift
var fresnelExponent: CGFloat { get set }
```

## Discussion

Discussion This property only takes effect when the particleImage property is an array of six images defining a cube map. In this case, SceneKit renders each particle as a reflective sphere. The fresnel exponent modulates the reflectivity of a surface from different view angles. At the default value of 1.0, reflections have the same intensity across the entire surface of the particle. At higher values, the edges of the particle are more reflective than the center. You can animate changes to this property’s value. See Animating SceneKit Content.

## See Also

### Specifying Particle Appearance

- [particleSize](scenekit/scnparticlesystem/particlesize.md)
- [particleSizeVariation](scenekit/scnparticlesystem/particlesizevariation.md)
- [particleColor](scenekit/scnparticlesystem/particlecolor.md)
- [particleColorVariation](scenekit/scnparticlesystem/particlecolorvariation.md)
- [particleImage](scenekit/scnparticlesystem/particleimage.md)
- [stretchFactor](scenekit/scnparticlesystem/stretchfactor.md)