# normalDirection

> Specifies how to calculate lighting for the billboard.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.6/script-reference/unityengine.md)
* **Assembly:** UnityEngine.ParticleSystemModule

```csharp
public float normalDirection { get; set; }
```

### Remarks

A value of 0 means Unity calculates lighting as though the billboard was a sphere. This results in the billboard looking more like a sphere. A value of 1 means Unity calculates lighting for the billboard as a flat quad.

### Examples

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

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

    private ParticleSystem ps;
    private ParticleSystemRenderer psr;
    public float normalDirection = 1.0f;

    void Start() {

        ps = GetComponent<ParticleSystem>();
        psr = GetComponent<ParticleSystemRenderer>();

        psr.material = new Material(Shader.Find("Sprites/Default"));
    }

    void Update() {

        psr.normalDirection = normalDirection;
    }

    void OnGUI() {

        normalDirection = GUI.HorizontalSlider(new Rect(25, 25, 100, 30), normalDirection, 0.0f, 1.0f);
    }
}
```