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# trimStart

The optional time, in seconds, at which the animation plays.

```
var trimStart: TimeInterval? { get set }
```

## Discussion

This property is `nil` by default, which plays the animation from the
starting frame defined by [`start`](/documentation/RealityKit/SampledAnimation/start).

If you set a value for this property, the animation visually begins from
an additional seconds offset from the starting frame and decreases the
duration by that amount.

If you set a negative value for this property, the duration increases
and the additional animation data fills in based on the
[`fillMode`](/documentation/RealityKit/SampledAnimation/fillMode) you choose.

---

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