AddComponent returns null

Tag: Untagged
Layer: Default

Code (CSharp):

1.  
2. namespace x
3. {
4.     public class testCube : MonoBehaviour
5.     {
6.  
7.         void Awake()
8.         {
9.             var cl = gameObject.AddComponent<Collider>();
10.             if (cl == null)
11.             {
12.                 Debug.Log("Is null");
13.             }
14.             else
15.             {
16.                 cl.isTrigger = true;
17.                 cl.contactOffset = 100.0f;
18.             }
19.         }
20.    
21.         void OnTriggerEnter(Collider _collider)
22.         {
23.             Debug.Log($"CollEnter");
24.         }
25.  
26.         void OnTriggerExit(Collider _collider)
27.         {
28.             Debug.Log($"CollExit");
29.         }
30.  
31.     }
32. }

Created a default cube, then attached the script above.
After pressing play I got: "Is null". Why? How? What can I do about it?

Time.scaleTime is 1. Even if I remove standard collider it still isn't there. Moving it to Start() doesn't change it either.

 

I don't think you're supposed to add a "Collider" to objects; it's a base class that is inherited by various specific kinds of Collider, like BoxCollider, SphereCollider, etc. Try adding a specific kind of collider instead?

 

Always check your console! If you try

AddComponent<Collider>()

, you'll get following message in there, explaining why you get null back:

That's also why you want to always keep your console free of warnings and errors, even if they don't break things, otherwise it's easy to miss important messages like this.

 

var cl = gameObject.AddComponent<SphereCollider>();

works and is not null anymore, but the Colliders still don't react. Neither

void OnTriggerEnter(Collider other)

nor

void OnTriggerEnter(SphereCollider other)

Those are two GameObjects with the same script which are placed in seperate location, then I moved one cube into another cube and nothing happened.

 

Remember, a trigger cannot collide with another trigger. Since you are placing the same script on both objects and the script sets the collider to be a trigger in Awake(), I believe this is your problem.

 

@howaboutno000

For Physics collisions to work, you'll also have to have a Rigidbody in one of the colliding objects.

So if you have a collider or collider set as a trigger in a prop object, then your player should have a collider and a Rigidbody, otherwise OnTriggerEnter / OnCollisionEnter won't register anything.

 

This ^ ^ ^

 

That did it, why won't Unity throw an error if there's a collider without rigidbodies, are there any other usages to the colliders?

Anyways, thank you.

 

The terrain.

The floor.

The ceiling.

The walls.

etc.

Not everything moves in a Physics game.