---
title: motionStartTime
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtl4primitiveaccelerationstructuredescriptor/motionstarttime
---

# motionStartTime

Configures the motion start time for this geometry.

## Declaration

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

## Discussion

Discussion The default value of this property is 0.0f.