---
title: opacity
framework: scenekit
role: symbol
role_heading: Type Property
path: scenekit/scnparticlesystem/particleproperty/opacity
---

# opacity

The particle’s opacity (or alpha value).

## Declaration

```swift
static let opacity: SCNParticleSystem.ParticleProperty
```

## Discussion

Discussion This property’s value is a floating-point scalar (an NSNumber object for particle property controllers, or a single float value for particle event or modifier blocks). This property controls the same alpha value as the color property. Use this property when you want to modify particle opacity without modifying color, or when you want to use opacity as the input for a SCNParticlePropertyController object. The particle system’s particleColor and particleColorVariation properties determine the initial alpha value for each particle.

## See Also

### Type Properties

- [angle](scenekit/scnparticlesystem/particleproperty/angle.md)
- [angularVelocity](scenekit/scnparticlesystem/particleproperty/angularvelocity.md)
- [bounce](scenekit/scnparticlesystem/particleproperty/bounce.md)
- [charge](scenekit/scnparticlesystem/particleproperty/charge.md)
- [color](scenekit/scnparticlesystem/particleproperty/color.md)
- [contactNormal](scenekit/scnparticlesystem/particleproperty/contactnormal.md)
- [contactPoint](scenekit/scnparticlesystem/particleproperty/contactpoint.md)
- [frame](scenekit/scnparticlesystem/particleproperty/frame.md)
- [frameRate](scenekit/scnparticlesystem/particleproperty/framerate.md)
- [friction](scenekit/scnparticlesystem/particleproperty/friction.md)
- [life](scenekit/scnparticlesystem/particleproperty/life.md)
- [position](scenekit/scnparticlesystem/particleproperty/position.md)
- [rotationAxis](scenekit/scnparticlesystem/particleproperty/rotationaxis.md)
- [size](scenekit/scnparticlesystem/particleproperty/size.md)
- [velocity](scenekit/scnparticlesystem/particleproperty/velocity.md)