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# pipeRadius

The minor radius of the torus, defining the pipe that encircles the torus ring. Animatable.

```
var pipeRadius: CGFloat { get set }
```

## Discussion

In the definition of a torus as a surface of revolution, the pipe radius defines a circle that is rotated around an axis (the Y axis of the torus’ local coordinate space). Rotating the circle around this axis makes it follow a circular path (whose radius is defined by the [`ringRadius`](/documentation/SceneKit/SCNTorus/ringRadius) property) and creates the surface of the torus.

The default pipe radius is `0.25`. A pipe radius of zero or less creates an empty geometry.

You can animate changes to this property’s value. See [Animating SceneKit Content](/documentation/SceneKit/animating-scenekit-content).

---

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