---
title: emitterShape
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnparticlesystem/emittershape
---

# emitterShape

The shape of the region of space where the system spawns new particles.

## Declaration

```swift
var emitterShape: SCNGeometry? { get set }
```

## Discussion

Discussion To randomize the locations where new particles spawn, assign a geometry to this property. This geometry defines the shape of the space where new particles may spawn, and the birthLocation and birthDirection properties define locations within and directions relative to the shape. For example, assigning a sphere geometry causes particles to spawn at random locations along the surface of the sphere (or within the volume of the sphere, according to the birthLocation property). note: For best results, use an instance of one of the SceneKit basic geometry classes (SCNPlane, SCNBox, SCNSphere, SCNPyramid, SCNCone, SCNCylinder, SCNCapsule, SCNTube, and SCNTorus). These classes provide a more efficient simulation and more even appearance to the rendered particle system. The default value is nil, specifying that all new particles emit from a single point. For particle systems attached to a node, this point is the origin of the node’s coordinate system. For particle systems attached directly to a scene using the addParticleSystem(_:transform:) method, use that method’s transform parameter to specify the emission point.

## See Also

### Managing Particle Emission Locations

- [birthLocation](scenekit/scnparticlesystem/birthlocation.md)
- [SCNParticleBirthLocation](scenekit/scnparticlebirthlocation.md)
- [birthDirection](scenekit/scnparticlesystem/birthdirection.md)
- [SCNParticleBirthDirection](scenekit/scnparticlebirthdirection.md)
- [emittingDirection](scenekit/scnparticlesystem/emittingdirection.md)
- [spreadingAngle](scenekit/scnparticlesystem/spreadingangle.md)