# PhysicsChainDefinition

> A PhysicsChain definition used to specify the chain of vertices that will produce multiple ChainSegmentGeometry shape types. Additionally, non-geometric properties can be specified here.

## Definition

* **Type:** Struct
* **Namespace:** [Unity.U2D.Physics](/engine/6000.5/script-reference/unity/u2d/physics.md)
* **Assembly:** UnityEngine.PhysicsCore2DModule

```csharp
public struct PhysicsChainDefinition
```

## Constructors

| Constructor                                                                                                                                               | Description                                                                                                    |
| --------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| [PhysicsChainDefinition()](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/ctor.md#physicschaindefinition\(\))                   | Create a default [PhysicsChain](/engine/6000.5/script-reference/unity/u2d/physics/physicschain.md) definition. |
| [PhysicsChainDefinition(System.Boolean)](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/ctor.md#physicschaindefinition\(bool\)) | Create a default [PhysicsChain](/engine/6000.5/script-reference/unity/u2d/physics/physicschain.md) definition. |

## Properties

| Property                                                                                                       | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| -------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| [contactFilter](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/contactfilter.md)     | The contact filter used to control which contacts this shape can participate in.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| [isLoop](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/isloop.md)                   | Indicates a closed chain formed by connecting the first and last vertices specified. When enabled, no ghost vertices should be defined in the [\_vertices](/engine/6000.5/script-reference/unity/u2d/physics/chaingeometry/vertices.md) with all being used to define [ChainSegmentGeometry](/engine/6000.5/script-reference/unity/u2d/physics/chainsegmentgeometry.md) with the ghost vertices being calculated automatically to force a closed loop. When disabled, the [\_vertices](/engine/6000.5/script-reference/unity/u2d/physics/chaingeometry/vertices.md) should define [\_ghost1](/engine/6000.5/script-reference/unity/u2d/physics/chainsegmentgeometry/ghost1.md) as the first vertex followed by at least two vertices or more defining the subsequent edges and finally a [\_ghost2](/engine/6000.5/script-reference/unity/u2d/physics/chainsegmentgeometry/ghost2.md) vertex, therefore there must be at least 4 vertices. |
| [surfaceMaterial](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/surfacematerial.md) | The surface material for the shape comprising of many properties such as friction, bounciness, rolling resistance etc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| [triggerEvents](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/triggerevents.md)     | Controls whether this chain produces trigger events which can be retrieved after the simulation has completed. This applies to triggers and non-triggers alike.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

## Static Properties

| Property                                                                                                           | Description                                                                                                 |
| ------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------- |
| [defaultDefinition](/engine/6000.5/script-reference/unity/u2d/physics/physicschaindefinition/defaultdefinition.md) | Get a default [PhysicsChain](/engine/6000.5/script-reference/unity/u2d/physics/physicschain.md) definition. |