# id

> An optional identifier for the ray tracing geometry.

## Definition

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

```csharp
public int id { readonly get; set; }
```

### Remarks

You can use a non-zero value for id to uniquely identify the geometry used for ray tracing, no matter the location of the geometry data inside a vertex and index buffer. This can be used in scenarios where the geometry can be streamed in and out in different locations into a vertex and index buffer pool in GPU-driven rendering pipelines. If the value is 0 then Unity uses all the fields in [RayTracingSubGeometryDesc](/engine/6000.6/script-reference/unityengine/rendering/raytracingsubgeometrydesc.md) to generate a geometry identifier.