Unity - OnTriggerEnter not registering collision

Question

I'm trying to do collision for a 2D character and a collider object. I have defined the OnTriggerEnter function to display a message in the debugger when a trigger is entered. The character is the "CharacterRobotBoy" asset from the Unity standard assets package (contains a BoxCollider2D) and I want it to collide with another object with attached BoxCollider2D, set as a trigger. I have trigger ticked on the second object.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PickUpCheck : MonoBehaviour {


    private int pickUpCount;

    // Use this for initialization
    void Start () {
        pickUpCount = 0;
    }


    void OnTriggerEnter(Collider collider)
    {
       // if (collider.gameObject.name == "RobotBoy")
       //     pickUpCount++;
        Debug.Log("PickUp " + pickUpCount);
    }

    // Update is called once per frame

    void Update () {

    }
}

I've tried attaching the script to both the character and the other object but can't seem to register collisions with the trigger.

/edit - I've read there is or was an OnTriggerEnter2D. I've tried calling this but it's not recognized in Visual Studio. Not sure if it still exists or I'm doing something wrong?

/edit - Switched code to -

void OnTriggerEnter2D(Collider2D collider)
{
   // if (collider.gameObject.name == "RobotBoy")
   //     pickUpCount++;
    Debug.Log("PickUp " + pickUpCount);
}

But still no luck...

Pick up object

/edit - @Eddge Have set a common layer for both the character and pickup object, though I think collisions should still occur with no layers set?

Collision Matrix

This answer was informative, but I made sure I have the described components in my set up already - colliders on both objects, rigidbody present on one of the objects and one set as trigger.

/edit Solved! - Ok, so I cleaned up the debug (thanks to @Eddge for the suggestion). I moved the script to the character and noticed that collisions were occurring but not with the pickup object.

I switched the code in the OnTriggerEnter2D to output the name of the collided objects and this helped me get a clearer idea of what was going on:

void OnTriggerEnter2D(Collider2D collider)
{
    Debug.Log(collider.gameObject.name);
}

Turns out the problem was with the BoxCollider2D in the prefab I modified to be the pickup. I rebuilt the game object and this solved the problem.

Look at Carlos's answer and then see these answers: stackoverflow.com/questions/49178539/… stackoverflow.com/questions/48304293/… In regards to the second one OnTriggerEnter2D only works with 2d colliders and OnTriggerEnter only work with 3d colliders. — AresCaelum
Thanks, new info for me in both of those links. But still not getting a response from the script on collision. To clarify, the character object has both a Box Collider 2D and a Rigidbody 2D. The pickup object only had a Box Collider 2D, but I've since added and tried the script with a Rigidbody2D also. Still no response... — G.G.

Carlos Eduardo Pérez Carlos Eduardo Pérez · Accepted Answer · 2018-03-12T22:35:35

If you're working on a 2D game, you must use OnTriggerEnter2D(Collider2D other). Currently, you're using OnTriggerEnter which will only register 3D collisions. Also, make sure you're passing a Collider2D as the function's parameter.

So change your code to this:

 void OnTriggerEnter2D(Collider2D collider)
{
   // if (collider.gameObject.name == "RobotBoy")
   //     pickUpCount++;
    Debug.Log("PickUp " + pickUpCount);
}

Check out the Unity API docs

Unity - OnTriggerEnter not registering collision

2 Answers