# 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:** [UnityEngine.LowLevelPhysics2D](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d.md)
* **Assembly:** UnityEngine.Physics2DModule

```csharp
public struct PhysicsChainDefinition
```

## Constructors

| Constructor                                                                                                                                                           | Description                                                                                                                |
| --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------- |
| [PhysicsChainDefinition()](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschaindefinition/ctor.md#physicschaindefinition\(\))                   | Create a default [PhysicsChain](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschain.md) definition. |
| [PhysicsChainDefinition(System.Boolean)](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschaindefinition/ctor.md#physicschaindefinition\(bool\)) | Create a default [PhysicsChain](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschain.md) definition. |

## Properties

| Property                                                                                                                   | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| -------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [contactFilter](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschaindefinition/contactfilter.md)     | The contact filter used to control which contacts this shape can participate in.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| [isLoop](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/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 [ChainGeometry.vertices](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/chaingeometry/vertices.md) with all being used to define [ChainSegmentGeometry](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/chainsegmentgeometry.md) with the ghost vertices being calculated automatically to force a closed loop. When disabled, the [ChainGeometry.vertices](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/chaingeometry/vertices.md) should define [ChainSegmentGeometry.ghost1](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/chainsegmentgeometry/ghost1.md) as the first vertex followed by at least two vertices or more defining the subsequent edges and finally a [ChainSegmentGeometry.ghost2](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/chainsegmentgeometry/ghost2.md) vertex, therefore there must be at least 4 vertices. |
| [surfaceMaterial](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschaindefinition/surfacematerial.md) | The surface material for the shape comprising of many properties such as friction, bounciness, rolling resistance etc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| [triggerEvents](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/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/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschaindefinition/defaultdefinition.md) | Get a default [PhysicsChain](/engine/6000.3/script-reference/unityengine/lowlevelphysics2d/physicschain.md) definition. |