Manually register event handler for collisions

Hi, wanted to know if anyone knew of a way to manually register with collision calls, like collision enter and exit. I’ve tried peeking around in the unity classes but can’t even find where they start.

The ultimate goal is to register a method for collisions from another game object.

Edit: I don’t think you can directly call the physics events, but there are some workarounds

I think what you want is to be able to call OnCollisionEnter (for example) from somewhere that you choose? But in this case you want to call the function when another object collides with your original object?

You could put whatever happens in OnCollisionEnter in some function, and call that function from OnCollisionEnter.

You could thencall that same function from anywhere you want.

public class MyGameObject : MonoBehaviour
{
    protected void OnCollisionEnter(Collider c)
    {
         SomeFunction();
    }
    
    
    public void SomeFunction()
    {
         // I'm doing stuff
    }
}


// then somewhere else
protected void OnCollisionEnter(Collider c)
{
	MyGameObject myGameObject = c.GetComponent<MyGameObject>; 
	if(myGameObject != null)
		myGameObject.SomeFunction();
}

But that’s not flexible, because I assume that you’ll be doing all sorts of different things on all types of objects. You could do something with delegates like this (my syntax could be wrong)

public class CustomCollisionScript : MonoBehaviour
{
	public delegate void CollisionFunction(Collider c);
	public CollisionFunction customFunction;    
}


public class MyGameObject : MonoBehaviour
{
	protected void Awake()
	{
		this.GetComponent<CustomCollisionScript>().customFunction = OnCollisionEnter;
	}

	protected void OnCollisionEnter(Collider c)
	{
		// do stuff
	}
}

// somewhere else
protected void OnCollisionEnter(Collider c)
{
	CustomCollisionScript customCollisionScript = c.GetComponent<CustomCollisionScript>; 
	if(customCollisionScript != null)
		customCollisionScript.customFunction();
}

I came back all the way from 2023 to say that not being able to do this adds to the horrible design of Unity, and forces users to also implement horrible designs.

I don’t know what was the big deal with making the event public, Mr. Unity.