Combine LowLevelPhysics2D API shapes

To combine physics shapes into a compound shape, create a composer using a PhysicsComposer object.

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참고

This documentation is about writing C# scripts using the

LowLevelPhysics2D

API. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to 2D physics instead.

To combine physics shapes into a compound shape, create a composer using a

PhysicsComposer

object. For example, create a car shape by combining a car body and two wheels.

Follow these steps:

At the top of your script, import the
```
Unity.Collections
```
library that contains the allocator APIs the composer uses:
```
using Unity.Collections;
```
Create the
```
Geometry
```
shapes you want to combine. For more information, refer to Create a physics object.
Create a new
```
PhysicsComposer
```
object. Pass in an allocator, which creates temporary memory for building up the combined object. For example:
```
PhysicsComposer physicsComposer = PhysicsComposer.Create(Allocator.Temp);
```
For more information about allocators, refer to Allocator.
Add each object to the composer as a layer, specifying its geometry, its position, and how to combine the shape with the existing layers. For example:
```
physicsComposer.AddLayer(circleGeometry, PhysicsTransform.identity, PhysicsComposer.Operation.OR);
```
For more information about
```
Operation
```
, refer to the Layer operations section.
Create the combined shape using
```
CreatePolygonGeometry
```
. Pass in a scale, and an allocator that creates the memory to store the combined shape. For example:
```
using NativeArray<PolygonGeometry> combinedShape = composer.CreatePolygonGeometry(new Vector2(1f, 1f), Allocator.Temp);
```
참고
using
automatically disposes of the memory allocated for the
NativeArray
when it goes out of scope. For more information, refer to Destroy LowLevelPhysics2D API objects and manage memory.

Create a body with the combined shape using the

CreateShapeBatch

method. For example:


body.CreateShapeBatch(combinedShape, PhysicsShapeDefinition.defaultDefinition);

The

PhysicsComposer

API combines

CircleGeometry

CapsuleGeometry

PolygonGeometry

PhysicsShape

, or any closed region defined by a set of

Vector2

points.

Layer operations

The following

PhysicsComposer.Operation

operations are available:

```
OR
```
: Adds the shape.
```
AND
```
: Keeps only the overlapping areas between the new shape and the existing shape.
```
NOT
```
: Subtracts the new shape from the existing shapes.
```
XOR
```
: Removes overlapping areas, but keeps non-overlapping areas.

Example

The following example combines a circle and a capsule shape. Attach this script to a GameObject in a scene, then enter Play mode to check the combined shape.


using UnityEngine;using UnityEngine.LowLevelPhysics2D;using Unity.Collections;public class CombineShapes : MonoBehaviour{    // Create the definition for a circle object    public CircleGeometry MyCircleGeometry = CircleGeometry.defaultGeometry;    public PhysicsTransform CircleTransform = new Vector2(0f, 0f);    // Create the definition for a capsule object    public CapsuleGeometry MyCapsuleGeometry = CapsuleGeometry.defaultGeometry;    public PhysicsTransform CapsuleTransform = new Vector2(0.75f, 0f);    private void Awake()    {        PhysicsWorld m_PhysicsWorld = PhysicsWorld.defaultWorld;                // Create a composer to combine shapes        PhysicsComposer composer = PhysicsComposer.Create(Allocator.Temp);                // Add both shapes to the composer        composer.AddLayer(MyCircleGeometry, CircleTransform);        composer.AddLayer(MyCapsuleGeometry, CapsuleTransform, PhysicsComposer.Operation.OR);        // Combine the shapes        using NativeArray<PolygonGeometry> combinedShape = composer.CreatePolygonGeometry(new Vector2(1f, 1f), Allocator.Temp);                // Create a body with the combined shapes        PhysicsBody body = m_PhysicsWorld.CreateBody();               body.CreateShapeBatch(combinedShape, PhysicsShapeDefinition.defaultDefinition);        // Destroy the composer to also destroy the temporary allocator.        composer.Destroy();    }   }

Additional resources

Connect LowLevelPhysics2D API objects with joints
PhysicsCore2D repository on GitHub.

Unity Engine

User Manual

Script Reference

Unity Engine

Combine LowLevelPhysics2D API shapes

Layer operations

Example

Additional resources