---
title: radius
framework: gameplaykit
role: symbol
role_heading: Instance Property
path: gameplaykit/gkagent/radius
---

# radius

The agent’s radius.

## Declaration

```swift
var radius: Float { get set }
```

## Discussion

Discussion Goals that involve an agent’s position relative to other agents make use of this property. For example, a goal created with the goalToAvoidAgents:timeBeforeCollisionToAvoid: method will attempt to move an agent such that its radius does not overlap with those of the other specified agents. note: The units of radius are arbitrary; you choose how to map agent positions and sizes into your game scene. It often makes sense to use the same coordinate system as your game engine—for example, when using agents in a SpriteKit-based game, you’d typically express radius in screen points.

## See Also

### Constraining an Agent’s Movement

- [mass](gameplaykit/gkagent/mass.md)
- [maxAcceleration](gameplaykit/gkagent/maxacceleration.md)
- [maxSpeed](gameplaykit/gkagent/maxspeed.md)