# vertexStart

> The index of the first vertex from a vertex buffer that defines a ray tracing geometry.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine.Rendering](/engine/6000.5/script-reference/unityengine/rendering.md)
* **Assembly:** UnityEngine.CoreModule

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

### Remarks

Together with [RayTracingSubGeometryDesc.vertexCount](/engine/6000.5/script-reference/unityengine/rendering/raytracingsubgeometrydesc/vertexcount.md) it defines the range of vertices that are referenced by the indices from an index buffer.