# ParticleSystemEmitterVelocityMode

> Control how a Particle System calculates its velocity.

## Definition

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

```csharp
public enum ParticleSystemEmitterVelocityMode
```

## Fields

| Value                                                                                                   | Description                                                                                                                                                                                              |
| ------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [Custom](/engine/6000.7/script-reference/unityengine/particlesystememittervelocitymode/custom.md)       | When the Particle System calculates its velocity, it instead uses the custom value set in [\_emitterVelocity](/engine/6000.7/script-reference/unityengine/particlesystem/mainmodule/emittervelocity.md). |
| [Rigidbody](/engine/6000.7/script-reference/unityengine/particlesystememittervelocitymode/rigidbody.md) | Calculate the Particle System velocity by using a Rigidbody or Rigidbody2D component, if one exists on the GameObject.                                                                                   |
| [Transform](/engine/6000.7/script-reference/unityengine/particlesystememittervelocitymode/transform.md) | Calculate the Particle System velocity by using the Transform component.                                                                                                                                 |