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Check Physics Core 2D API intersections

To check whether 2D physics objects overlap or will collide, also known as intersections, use query methods.
Read time 2 minutesLast updated 14 days ago
Note
This documentation is about writing C# scripts using the 
Unity.U2D.Physics
API. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to 2D physics instead.
To check whether 2D physics objects overlap or will collide, also known as intersections, use Physics Core 2D API query methods.
Use one of the following methods:
  • The 
    PhysicsQuery
     API to check for overlaps. For example, 
    PhysicsQuery.CapsuleAndCircle
    to check whether a capsule overlaps with a circle.
  • The 
    Intersect
    method of a geometry object to check if it overlaps with another geometry object. For example, 
    CapsuleGeometry.Intersect
    .
The world object also has the following methods:
All methods are thread-safe. For more information, refer to Optimize the Physics Core 2D API with multithreading.
Important
These methods return 
NativeArray
types, which you must dispose of to free the memory they use. For more information, refer to Destroy objects and manage memory.

Example

To cast rays to check whether a shape will collide with other shapes, use the 
CastGeometry
API.
For example, the following script checks if a small falling circle will collide with objects underneath it. Attach the script to a GameObject and enter Play mode, then use the Big Circle checkbox to toggle an object underneath the falling circle.
using UnityEngine;using Unity.U2D.Physics;using Unity.Collections;public class CastGeometryExample : MonoBehaviour{    private PhysicsWorld world;    public bool BigCircle;    void Start()    {        world = PhysicsWorld.defaultWorld;        // Create a small falling circle        CircleGeometry object1Geometry = CircleGeometry.Create(0.5f, new Vector2(0.5f, 8f));        PhysicsBody object1 = world.CreateBody(new PhysicsBodyDefinition        {             position = object1Geometry.center,            type = PhysicsBody.BodyType.Dynamic        });        object1.CreateShape(object1Geometry);        if (BigCircle)        {            // Create a larger static circle below            CircleGeometry object2Geometry = CircleGeometry.Create(3f, new Vector2(0f, 0f));            PhysicsBody object2 = world.CreateBody(new PhysicsBodyDefinition            {                 position = object2Geometry.center,                type = PhysicsBody.BodyType.Static            });            object2.CreateShape(object2Geometry);        }        // Set translation and filter for the cast        Vector2 translation = new Vector2(0, -10f); // Move downwards        PhysicsQuery.QueryFilter filter = new PhysicsQuery.QueryFilter();        // Cast the circle geometry through the world        NativeArray<PhysicsQuery.WorldCastResult> results = world.CastGeometry(object1Geometry, translation, filter, PhysicsQuery.WorldCastMode.Closest, Allocator.Temp);        if (results.Length > 0)        {            Debug.Log("Collision will occur!");        }        // Dispose of the NativeArray to free memory        results.Dispose();    }}

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