programmatically initialized PolygonCollider2D resulting NullReferenceException upon accessing

First thing first, I don't know if this is a bug or not or Collider2Ds classes are not meant to be created programatically ( through initialization ).

So, I have some simple snippet script written like this

Code (CSharp):

1. var col = new PolygonCollider2D ();
2. col.CreatePrimitive (4, Vector2.one, Vector2.zero);
3. Debug.Log("Overlap :: " + Physics2D.OverlapCollider (col , new ContactFilter2D () { layerMask = this.ObstacleMask } , null));

and when I test the script, I got

Code (CSharp):

1. NullReferenceException

error referring to

Code (CSharp):

1. col.CreatePrimitive (...);

Is there any workaround or approach without need to add the component to the game object ?

 

You can't use "new" on anything that inherits from monobehaviour. You need to use AddComponent<PolygonCollider2D>() to create and add it to a GameObject. AddComponent also returns the component that you are adding, so you can still modify it easily from that return value.

 

You also cannot pass null to the portion expecting an array in the method call.
I believe you always have to set useLayerMask to true for your filter, for it to take the layers into consideration.

 

Ah, I see, I've too much doing some traditional way ( not Unity way ).
Although I'm doing that because I just need that

Collider

in that only moment / logic, but I guess I just need disable the component.

Yeah, I forgot about that

useLayerMask

, but is it really can't do

null

on Array result ? I just need the return value of the function, but if that's really unavoidable I understand.

 

Yes, it can't be null. In fact it has to be a size big enough for your needs, because the return value (from the docs) states that it's how many were overlapped and that could fit inside the array.
You can re-use the array, though.. so, it won't be costing you much memory.

 

Thanks for it, but now I'm confused, I always got "0" result from Physics2D.OverlapCollider(...), I want to know what causing this result of the OverlapCollider ? What I mean is, is the function returns 0 if no overlap collider, and if there overlapping it returns the count of the collider that overlap with ?


EDIT :
Nevermind, I've got it working now, I don't know what causing it but now it's working properly

 

Hmm.. It should return the count of overlapped colliders .. but also depends on the size of the supplied array.

If you pass in an array of size 0, you will always get zero.
If you pass in a size of 4 and there are 2, you should get two.
if you pass in a size of 2 and there are > 2, you will only get 2.

That's what I gathered from the docs

Is that what you did, and no matter what you always got zero?

 

Yeah something todo with the array size, I forgot to edit the value so I always got 0.