# vertexStartIndex

> The start index for the geometry of this shape within the PhysicsShapeGroup2D.

## Definition

* **Type:** Property
* **Namespace:** [UnityEngine](/engine/6000.0/script-reference/unityengine.md)
* **Assembly:** UnityEngine.Physics2DModule

```csharp
public int vertexStartIndex { get; set; }
```

### Remarks

Multiple [PhysicsShape2D](/engine/6000.0/script-reference/unityengine/physicsshape2d.md) in a [PhysicsShapeGroup2D](/engine/6000.0/script-reference/unityengine/physicsshapegroup2d.md) are represented as a single list of vertices. This index is the start of this shape within that list.

Additional Resources: [GetShapeVertex](/engine/6000.0/script-reference/unityengine/physicsshapegroup2d/getshapevertex.md), [GetShapeVertices](/engine/6000.0/script-reference/unityengine/physicsshapegroup2d/getshapevertices.md).

### Examples

```csharp
using UnityEngine;
using UnityEngine.Assertions;

public class Example : MonoBehaviour
{
    void Start()
    {
        // Create a shape group.
        var shapeGroup = new PhysicsShapeGroup2D();

        // Add a Capsule to the shape group.
        var capsuleShapeIndex = shapeGroup.AddCapsule
            (
                vertex0: Vector2.down,
                vertex1: Vector2.up,
                radius: 0.5f
            );

        // Add a Circle to the shape group.
        var circleShapeIndex = shapeGroup.AddCircle
            (
                center: new Vector2(-2f, 3f),
                radius: 1f
            );

        // Fetch the shapes.
        var capsuleShape = shapeGroup.GetShape(capsuleShapeIndex);
        var circleShape = shapeGroup.GetShape(circleShapeIndex);

        // Validate the shape vertex count.
        Assert.AreEqual(2, capsuleShape.vertexCount);
        Assert.AreEqual(1, circleShape.vertexCount);

        // Validate the Capsule vertex start index.
        // NOTE: The Capsule is the first shape so its index is 0.
        //  It has 2 vertices at indices 0 and 1.
        Assert.AreEqual(0, capsuleShape.vertexStartIndex);

        // Validate the Circle vertex start index.
        // NOTE: The Circle is the second shape so its index is 0.
        // It comes after the Capsule which has 2 vertices at indices 0 and 1 so
        // the Circle start index is 2.
        Assert.AreEqual(2, circleShape.vertexStartIndex);
    }
}
```