<!--
{
  "availability" : [
    "iOS: 8.0.0 - 26.0.0",
    "iPadOS: 8.0.0 - 26.0.0",
    "macCatalyst: 13.1.0 - 26.0.0",
    "macOS: 10.8.0 - 26.0.0",
    "tvOS: 9.0.0 - 26.0.0",
    "visionOS: 1.0.0 - 26.0.0",
    "watchOS: 3.0.0 - 26.0.0"
  ],
  "documentType" : "symbol",
  "framework" : "SceneKit",
  "identifier" : "/documentation/SceneKit/SCNParticleSystem/isAffectedByPhysicsFields",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "SceneKit"
    ],
    "preciseIdentifier" : "c:objc(cs)SCNParticleSystem(py)affectedByPhysicsFields"
  },
  "title" : "isAffectedByPhysicsFields"
}
-->

# isAffectedByPhysicsFields

A Boolean value that determines whether physics fields in the scene affect the motion of particles.

```
var isAffectedByPhysicsFields: Bool { get set }
```

## Discussion

[`SCNPhysicsField`](/documentation/SceneKit/SCNPhysicsField) objects attached to nodes in the scene apply forces to bodies in their area of effect. For example, a radial gravity field attracts bodies toward its center, and a vortex field applies forces that circulate around a specified axis. The forces applied by a physics field on each particle are proportional to its mass, as specified by the [`particleMass`](/documentation/SceneKit/SCNParticleSystem/particleMass) property.

The default value is <doc://com.apple.documentation/documentation/Swift/false>, specifying that physics fields in the scene do not affect particles.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)