Manually register event handler for collisions

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();
 }