[solved] 3D child collider seemingly messing with parent C# collision detection

Unity Engine
1

Hello everybody,

unfortunately I am a bit confused about what really is happening, but I suppose a child object (sword) which also has a box collider sends it´s collision detection “up” to the parent (Player) so that when I hit the enemy with the sword both detect a hit and loose a life. It looks like collision detection is
Is there maybe a way to exclude the detection of children? Or at least detect which child object collides with which other object?

My setup

Player (Rigidbody, C#, Box Collider)
±- Sword (Box Collider)

Enemy (Rigidbody, Box Collider)

I found a similar post but it is about 2D which maybe a bit different to cope with?

2

Show us your code for your collision. You can check what you are being hit with or what you are hitting based on the parameter that is passed in.

3

I do check for collision from both sides.

Player → Enemy (a C# script on the player checks if player collides with enemy player loses life)

void OnTriggerEnter(Collider other) {
            if (other.gameObject.CompareTag("enemy")) {
             print("PLAYER HIT");
            }
        }

Enemy → sword (a C# script on the enemy checks if enemy collides with sword enemy loses life)

    void OnTriggerEnter(Collider other) {
        if (other.gameObject.CompareTag("sword")) {
           print("ENEMY HIT");
        }
    }

Now comes the problem:
The player registers a hit in both situations …

4

So your player has a box collider with a script to compare sword and then the player takes damage?

Or does the sword check for enemy and then the sword does damage?

5

Nope.
Player has a script and a collider box which check if it collides with enemy.
±- In / below the player there is a sword with a collider box.

The enemy has a script and a collider box and checks if it collides with the sword.

Problem is:
When the sword hits the enemy both the enemy and the player register a hit.

6

Ok, sorry I think I mistyped.

I understand now. The player can hit the enemy, thus losing a life. Or the sword hits the enemy, thus killing the enemy.

Try adding a kinematic rigidbody to your sword.

1 Like
7

HOLY SMOKES! Thanks Brathmann, all I needed to do was add the rigid body and now everything works as it should :smile:

I have read several times that collisions are passed upwards the hierachy to the top most rigid body, so I did not expect a rigid body on a child would stop that.