# allowRoll

> Allow billboard particles to roll around their z-axis.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.7/script-reference/unityengine.md)
* **Assembly:** UnityEngine.ParticleSystemModule

```csharp
public bool allowRoll { get; set; }
```

### Remarks

Allows billboards to roll with the Camera. It is often useful to disable this option when using VR, to give particles a more believable grounding in the world.

### Examples

```csharp
using UnityEngine;
using System.Collections;

[RequireComponent(typeof(ParticleSystem))]
public class ExampleClass : MonoBehaviour
{

    private ParticleSystemRenderer psr;
    public bool allowRoll = true;

    void Start()
    {
        psr = GetComponent<ParticleSystemRenderer>();
        psr.material = new Material(Shader.Find("Sprites/Default"));
    }

    void Update()
    {
        var psr = GetComponent<ParticleSystemRenderer>();
        psr.allowRoll = allowRoll;

        Camera.main.transform.rotation = Quaternion.Euler(0.0f, 0.0f, Mathf.Sin(Time.time * 0.2f) * 90.0f);
    }

    void OnGUI()
    {
        allowRoll = GUI.Toggle(new Rect(25, 45, 200, 30), allowRoll, "Allow Roll");
    }
}
```