---
title: velocity
framework: Compute Graph
role: symbol
role_heading: Instance Property
platforms: [iOS 27.0+, iPadOS 27.0+, Mac Catalyst 27.0+, macOS 27.0+, tvOS 27.0+, visionOS 27.0+]
path: computegraph/elementspawnparameters/velocity
---

# velocity

The initial velocity vector of the particle in world space units per second.

## Declaration

```swift
var velocity: SIMD3<Float> { get set }
```

## Discussion

Discussion This determines the particle’s initial direction and speed of movement. The magnitude of the vector represents the speed, while the direction represents the movement direction. A zero velocity means the particle starts stationary.