IContactCallback

Description

An interface that when implemented, can be called as a target by PhysicsWorld.SendContactCallbacks.

Unity calls OnContactBegin2D and OnContactEnd2D on the main thread after the simulation finishes.

Additional resources: PhysicsWorld.SendContactCallbacks, ITriggerCallback

 using UnityEngine;
 using Unity.U2D.Physics;

 // Add the PhysicsCallbacks.IContactCallback interface.
 public class DetectCollisions : MonoBehaviour, PhysicsCallbacks.IContactCallback
 {
     void Start()
     {
         PhysicsWorld world = PhysicsWorld.defaultWorld;

         // Create a small falling circle.
         PhysicsBody object1 = world.CreateBody(new PhysicsBodyDefinition
         {
             position = new Vector2(0.5f, 8f),
             type = PhysicsBody.BodyType.Dynamic
         });
         PhysicsShape objectShape1 = object1.CreateShape(CircleGeometry.defaultGeometry);

         // Create a larger static circle below.
         PhysicsBody object2 = world.CreateBody(new PhysicsBodyDefinition
         {
             position = new Vector2(0f, 0f),
             type = PhysicsBody.BodyType.Static
         });
         object2.CreateShape(new CircleGeometry { radius = 3f });

         // Set object 1 to activate collisions.
         objectShape1.contactEvents = true;
         objectShape1.callbackTarget = this;
     }

     // Log when the small circle collides.
     public void OnContactBegin2D(PhysicsEvents.ContactBeginEvent eventData)
     {
         var contact = eventData.contactId.contact;
         Debug.Log("Collision started between shapes: " + contact.shapeA + " and " + contact.shapeB);
     }

     // Log when the small circle stops colliding.
     public void OnContactEnd2D(PhysicsEvents.ContactEndEvent eventData)
     {
         var contact = eventData.contactId.contact;
         Debug.Log("Collision ended between shapes: " + contact.shapeA + " and " + contact.shapeB);
     }
 }

Public Methods