Unwanted event bubbling

Unity Engine
1

In my 2D game, I have a sword swing mechanic. It consists of the player object playing a sword swing animation, and a seperate object (childed to the player) that acts as the visual sword slash and hitbox for the swing.

My problem is, when I try to detect an enemy getting hit by the sword, it damages the player because it thinks that the sword is part the of the player. How can I prevent this?

Player collides with enemy (In player script):

    public void OnTriggerEnter2D(Collider2D collision) {
        if (gameObject.CompareTag("Player") && collision.CompareTag("Enemy")) {
            PlayerHurt();
        }
    }

Damage enemy when hit by sword (In enemy script):

    public void OnTriggerEnter2D(Collider2D collision) {
        if (collision.CompareTag("PlayerSword")) {
            Damage();
        }
    }
2

What is “it” in this case?

Is the sword damaging the player? Then make it so your own weapons don’t damage you.

Is the enemy damaging the player through the sword? Then make it so enemies only deal damage to players.

3

I believe ‘it’ is referring to the enemy, so the enemy is damaging the player because of the sword, because it’s counting the sword as part of the player. Enemies damage player when touching player, but sword is also counted as player, because it’s a child of it.

A simple solution would be to not make it a child of the player and simply have it instantiate at the players coordinates but as it’s own object - no longer a child.

4

It is the enemy damaging the player through the sword. And I have already made it so it should supposedly only deal damage to players. However, this isn’t the case.

if (gameObject.CompareTag("Player") && collision.CompareTag("Enemy"))
5

I want the sword to be at the player at all times because the sword would already flip with the players direction, and much more. There isn’t another way to do this?

6

Welcome to debugging!

You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is
  • you’re getting an error or warning and you haven’t noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: https://discussions.unity.com/t/700551 or this answer for Android: https://discussions.unity.com/t/699654

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://discussions.unity.com/t/839300/3

7

This is because the child is inheriting the tag from the parent. Even if you change the tag on the weapon to ‘weapon’, then Debug.Log(this.tag) it, it will say ‘Player’ when the enemy touches the sword.

8

Found this, give that a go :slight_smile: