Unity 5 collision still occuring - c#-4.0

Question

I'm working on a 2D plane dodging game and I'm having issues in Unity 5, I'm trying to stop the collision between two incoming planes, I've tried many different solutions but those don't work. I can't put them in different layers because they still need to collide with the player. This is the code I have for the first plane. Enemy and Bullets are both tags. Thanks
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class BulletPlane : MonoBehaviour {
public float speed = 6f;
public float reloadTime = 1f;
public GameObject bulletPrefab;
public GameObject explosion;
public GameObject smoke;
public GameObject warning;
public GameObject self;
public float reloadSecond = .10f;
private float elapsedTime = 0;
public float timeElapsed = 0;
private Rigidbody2D rigidBody;
void Start()
{
rigidBody = GetComponent<Rigidbody2D> ();
rigidBody.velocity = new Vector2 (0, speed);
Vector3 warningPos = transform.position;
warningPos += new Vector3 (0, -10.5f, 0);
Instantiate (warning, warningPos, Quaternion.identity);
}
void Update() {
elapsedTime++;
Vector3 spawnPos = transform.position;
Vector3 secondPos = transform.position;
elapsedTime = 0f;
spawnPos += new Vector3 (0, -1.2f, 0);
secondPos += new Vector3 (-1, -0.9f, 0);
Instantiate (bulletPrefab, spawnPos, Quaternion.identity);
Instantiate (smoke, secondPos, Quaternion.identity);
if (elapsedTime > reloadSecond) {
spawnPos += new Vector3 (0, -1.2f, 0);
secondPos += new Vector3 (-1, -0.9f, 0);
Instantiate (bulletPrefab, spawnPos, Quaternion.identity);
Instantiate (smoke, secondPos, Quaternion.identity);
elapsedTime = 0f;
timeElapsed++;
}
}
void OnTriggerEnter2D(Collider2D other) {
if (other.gameObject.CompareTag ("Player")) {
Destroy (other.gameObject);
} else if (other.gameObject.CompareTag ("Enemy")) {
Physics2D.IgnoreCollision (other.GetComponent<Collider2D> (), gameObject.GetComponent<Collider2D> (), true);
} else if (other.gameObject.CompareTag ("Bullets")) {
Physics2D.IgnoreCollision (other.GetComponent<Collider2D> (), gameObject.GetComponent<Collider2D> (), true);
}
}
}
This is the code for the other enemy plane
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class EnemyPlane : MonoBehaviour {
public float speed = -6f;
public float reloadTime = 1f;
public GameObject bulletPrefab;
public GameObject explosion;
private float elapsedTime = 0;
private Rigidbody2D rigidBody;
void Start()
{
rigidBody = GetComponent<Rigidbody2D> ();
rigidBody.velocity = new Vector2 (0, speed);
}
void OnTriggerEnter2D(Collider2D other) {
if (other.gameObject.CompareTag ("Ally")) {
} else if (other.gameObject.CompareTag ("Enemy")) {
Physics2D.IgnoreCollision (other.GetComponent<Collider2D> (), gameObject.GetComponent<Collider2D> (), true);
} else if (other.gameObject.CompareTag ("BulletPlane")) {
Physics2D.IgnoreCollision (other.GetComponent<Collider2D> (), gameObject.GetComponent<Collider2D> (), true);
}
}
}

Answer 1

You still be able to set the layer, while your player can still be able to interact with.
Suppose you have 3 different objects
Plane A
Plane B
Player
and you want Plane A to don't collide with Plane B, but still collide with Player.
You can set the collision matrix on
Edit -> Project Settings -> Physics2D
How to setup?
Set Plane A to Layer 'CollideOnlyWithPlayer'
Set Player to layer 'Player'
Then in the collision matrix, you can unchek all for layer CollideOnlyWithPlayer
But check for CollideWithPlayer to Player layer
The collision matrix define how object interact within the other object in layer.
It's defined by two indices, the vertical one and the horizontal one.
When you check for example, Vertical 'Player' to Horizontal 'Player'
this means, that your player can interact with player
And when you check for example, Vertical 'Player' to Horizontal 'CollideWithPlayer'
this means that your player physic can interact with object layered to CollideWithPlayer.
Pleas see the full documentation here
https://docs.unity3d.com/Manual/LayerBasedCollision.html