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MonoBehaviour.OnTriggerEnter2D(Collider2D)

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Parameters

other The other Collider2D involved in this collision.

Description

Sent when another object enters a trigger collider attached to this object (2D physics only).

Further information about the other collider is reported in the Collider2D parameter passed during the call.

Note: Trigger events will be sent to disabled MonoBehaviours, to allow enabling Behaviours in response to collisions.

See Also: Collider2D class, OnTriggerExit2D, OnTriggerStay2D.

The folllowing two script examples create an OnTriggerEnter2D demo. Example1 generates a Unity logo sprite, GameObject1. This sprite is collided with by the Example2 sprite, GameObject2. The Example1 script creates the Rigidbody2D. The kinematic mode is used on this script. Example2 supports the OnCollisionEnter2D, OnCollisionStay2D and OnCollisionExit2D methods. These are called when GameObject2 collides with GameObject1. The script code for GameObject2 controls the time it takes to collide with GameObject1. GameObject2 is animated left-to-right repeatedly. When on the left side of the screen GameObject2 moves right towards GameObject1. When these have collided GameObject2 returns back to the left. The left side of the screen is the starting point for GameObject2. The right side of the screen is the constant position of GameObject1. The Example2 script code makes GameObject2 collide with GameObject1. GameObject2 stays collided for a short length of time.

#pragma strict
public class Example1 extends MonoBehaviour {
	private var bc: BoxCollider2D;
	private var rb: Rigidbody2D;
	function Awake() {
		var sprRend: SpriteRenderer = gameObject.AddComponent.<SpriteRenderer>() as SpriteRenderer;
		sprRend.color = new Color(0.9f, 0.9f, 0.9f, 1.0f);
		bc = gameObject.AddComponent.<BoxCollider2D>() as BoxCollider2D;
		bc.size = new Vector2(1.3f, 1.3f);
		bc.isTrigger = true;
		rb = gameObject.AddComponent.<Rigidbody2D>() as Rigidbody2D;
		rb.bodyType = RigidbodyType2D.Kinematic;
	}
	function Start() {
		gameObject.GetComponent.<SpriteRenderer>().sprite = Resources.Load.<Sprite>("logo");
		gameObject.transform.Translate(4.0f, 0.0f, 0.0f);
		gameObject.transform.localScale = new Vector2(2.0f, 2.0f);
	}
}
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Example1 : MonoBehaviour { private BoxCollider2D bc; private Rigidbody2D rb;

void Awake() { SpriteRenderer sprRend = gameObject.AddComponent<SpriteRenderer>() as SpriteRenderer; sprRend.color = new Color(0.9f, 0.9f, 0.9f, 1.0f);

bc = gameObject.AddComponent<BoxCollider2D>() as BoxCollider2D; bc.size = new Vector2(1.3f, 1.3f); bc.isTrigger = true;

rb = gameObject.AddComponent<Rigidbody2D>() as Rigidbody2D; rb.bodyType = RigidbodyType2D.Kinematic; }

void Start() { gameObject.GetComponent<SpriteRenderer>().sprite = Resources.Load<Sprite>("logo"); gameObject.transform.Translate(4.0f, 0.0f, 0.0f); gameObject.transform.localScale = new Vector2(2.0f, 2.0f); } }

Example2. This is the sprite that moves forwards and backwards and triggers with Example1.

#pragma strict
public class Example2 extends MonoBehaviour {
	private var other: GameObject;
	private var spriteMove: float;
	private var stayCount: float;
	function Awake() {
		var sprRend: SpriteRenderer;
		sprRend = gameObject.AddComponent.<SpriteRenderer>() as SpriteRenderer;
		sprRend.color = new Color(0.9f, 0.9f, 0.9f, 1.0f);
		var bc: BoxCollider2D;
		bc = gameObject.AddComponent.<BoxCollider2D>() as BoxCollider2D;
		bc.size = new Vector2(1.3f, 1.3f);
		bc.isTrigger = true;
		other = GameObject.Find("GameObject1");
	}
	function Start() {
		gameObject.GetComponent.<SpriteRenderer>().sprite = Resources.Load.<Sprite>("circle");
		gameObject.transform.Translate(-4.0f, 0.0f, 0.0f);
		spriteMove = 0.1f;
	}
	function FixedUpdate() {
		gameObject.transform.Translate(spriteMove, 0.0f, 0.0f);
		if (gameObject.transform.position.x < -4.0f) {
			// move GameObject2 to the right
			spriteMove = 0.1f;
		}
	}
	function OnTriggerEnter2D() {
		if (other.tag == "GameObject1") {
			// Stops GameObject2 moving
			stayCount = 0;
			Debug.Log("OnTriggerEnter2D");
		}
	}
	function OnTriggerStay2D() {
		Debug.Log("OnTriggerStay2D");
		stayCount = stayCount + 1;
		if (stayCount > 5) {
			// Starts GameObject2 return to the left
			spriteMove = -0.1f;
		}
	}
	function OnTriggerExit2D() {
		Debug.Log("OnTriggerExit2D");
	}
}
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Example2 : MonoBehaviour { private GameObject other; private float spriteMove; private float stayCount;

void Awake() { SpriteRenderer sprRend; sprRend = gameObject.AddComponent<SpriteRenderer>() as SpriteRenderer; sprRend.color = new Color(0.9f, 0.9f, 0.9f, 1.0f);

BoxCollider2D bc; bc = gameObject.AddComponent<BoxCollider2D>() as BoxCollider2D; bc.size = new Vector2(1.3f, 1.3f); bc.isTrigger = true;

other = GameObject.Find("GameObject1"); }

void Start() { gameObject.GetComponent<SpriteRenderer>().sprite = Resources.Load<Sprite>("circle"); gameObject.transform.Translate(-4.0f, 0.0f, 0.0f); spriteMove = 0.1f; }

void FixedUpdate() { gameObject.transform.Translate(spriteMove, 0.0f, 0.0f);

if (gameObject.transform.position.x < -4.0f) { // move GameObject2 to the right spriteMove = 0.1f; } }

void OnTriggerEnter2D() { if (other.tag == "GameObject1") { // Stops GameObject2 moving stayCount = 0; Debug.Log("OnTriggerEnter2D"); } }

void OnTriggerStay2D() { Debug.Log("OnTriggerStay2D"); stayCount = stayCount + 1;

if (stayCount > 5) { // Starts GameObject2 return to the left spriteMove = -0.1f; } }

void OnTriggerExit2D() { Debug.Log("OnTriggerExit2D"); } }

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