# SetPosition(int, Vector3)

> Set the position of a vertex in the trail.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
public void SetPosition(int index, Vector3 position)
```

### Parameters

**** (\[int]\(https\://learn.microsoft.com/dotnet/api/system.int32)): Which position to set.**** (\[Vector3]\(/engine/6000.0/script-reference/unityengine/vector3)): The new position.

### Remarks

You can only use this method to modify existing positions in the Trail. You cannot use it to add new positions.

When setting multiple positions, consider using [TrailRenderer.SetPositions](/engine/6000.0/script-reference/unityengine/trailrenderer/setpositions.md) instead because it is much faster than making individual function calls for each position.

Additional Resources: [TrailRenderer.positionCount](/engine/6000.0/script-reference/unityengine/trailrenderer/positioncount.md) property.