Collisions not Detected

Unity Engine
1

Hello All,

I have been stuck on this for days. I’ve watched countless videos, tried several methods, wrote different scripts, but I never have success.

I have a cannon in my game that fires at oncoming enemies. When the fireball hits the enemy, I need that to be detected and subtract health from the enemy. Sounds SO simple right? I hope so.

I had it working before, but it destroyed itself when it hit the terrain, so I need a check to make sure that the Fireball is the only one that is detected.

Here’s my code:

ENEMY:
Box Collider - Not a trigger

using UnityEngine;
using System.Collections;

public class enemy1 : MonoBehaviour {

	public GameObject target;
	public float speed = 5.0f;
	public int health = 1;
	public int maxHealth = 1;
	public int minHealth = 0;

	// Use this for initialization

	void Awake(){
		health = maxHealth;
		}

	void Start () {
	

	}

	// Update is called once per frame
	void Update () {
		transform.position = Vector3.MoveTowards (transform.position, new Vector3 (1016, 6, 1000), speed * Time.deltaTime);
		//transform.position = Vector3.MoveTowards (transform.position, new Vector3(target.transform.position.x, target.transform.position.y, target.transform.position.z), speed * Time.deltaTime);

		//Health Management
		if (health > maxHealth) {
				health = maxHealth;
		}
		if (health < minHealth) {
				health = minHealth;
		}

		//Check for damage
		//receiveDamage ();

		//If damage is <= minHealth, destroy it.
		Death ();

	}

	void OnTriggerEnter(Collider other){
		Debug.Log ("[COLLISION]Collision Detected!");
		if(other.gameObject.transform.name == "Fireball 1")
		{
		Debug.Log ("[COLLISION]Enemy has been hit!");
		receiveDamage (1);
		}
	}


	void receiveDamage(int damage)
	{
		health -= damage;
	}

	void Death()
	{
		if(health <= minHealth)
		{
			Debug.Log ("[ENEMY]Unit has been destroyed.");
			Destroy(gameObject);
		}
	}

}

FIREBALL:
Box Collider - Is a trigger

2

Also, the fireball moves slowly, so raycasting is not an option.

3

Do you have a Rigidbody on either the enemy or the fireball ?

4

Did you attach a rigidbody to both of them?

Edit: Too slow :slight_smile:

5

Both have a Rigidbody. The fireball is kinematic.

6

You may consider to move the rigidbody using its methods instead of setting transform.position.

7

Oh yeah, I move my objects through the Rigidbody it has helped me to fix a lot of various issues I was having with my characters movement.

Also, I think you should move the OnTriggerenter to the fireball object. I’m not sure about this but it may be that since your enemy is not a trigger, it can’t receive an OnTriggerenter message. Your fireball should though. If that’s not option, you can try using OnCollisionEnter(Collision collision) and get the other collider with collision.collider.

8

Kk, I changed it.

I would prefer to not use triggers and just use OnCollisionEnter(), but it doesn’t work either:

void OnCollisionEnter(Collision collision){
        Debug.Log ("[COLLISION]Collision Detected!");
        if(collision.gameObject.transform.name == "Fireball 1")
        {
        Debug.Log ("[COLLISION]Enemy has been hit!");
        receiveDamage (1);
        }
    }

Both have rigidbodies, none are triggers, none are kinematic.

None of the Debug messages show.

9

I have tried setting the enemy as a trigger and nothing changed.

10

Do you use physic layers ? Maybe the objects are on mutually non-collidable layers ?

11

Both are on the Default layer. I don’t understand layers yet since I have never messed with them.

12

Move both by modifying the rigidbody properties instead of the transforms and make sure to perform the movement in FixedUpdate.

13

I think I may have discovered something useful. The fireball is a particle system. When I fire it, the object moves but the collider stays in the origin position. This doesn’t make much sense to me.

14

Oh, I’m starting to understand now… lol

15

I ran some tests and a trigger need to handle it’s own collisions. It won’t trigger OnCollisionEnter on the other collider. You need to move collision logic to OnTriiggerEnter on the fireball!

16

for collision both gm having rigidbody’s and one of them MUST having Collider!!!