Combine Physics Core 2D API shapes

Unity.U2D.Physics

PhysicsComposer

1. At the top of your script, import the

   Unity.Collections

   library that contains the allocator APIs the composer uses:

   using Unity.Collections;

2. Create the

   Geometry

   shapes you want to combine. For more information, refer to Create a physics object.
3. 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.
4. 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.
5. 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);

   Note

   using

   automatically disposes of the memory allocated for the

   NativeArray

   when it goes out of scope. For more information, refer to Destroy Physics Core 2D API objects and manage memory.
6. Create a body with the combined shape using the

   CreateShapeBatch

   method. For example:

   body.CreateShapeBatch(combinedShape, PhysicsShapeDefinition.defaultDefinition);

PhysicsComposer

CircleGeometry

CapsuleGeometry

PolygonGeometry

PhysicsShape

Vector2

Layer operations

PhysicsComposer.Operation

• 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

using UnityEngine;using Unity.U2D.Physics;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 Physics Core 2D API objects with joints
• PhysicsCore2D repository on GitHub.