Gravity Simulation always pulls objects toward a single point

I am trying to simulate gravity for a game. I am testing my gravity system using a sphere like a planet and cubes, to test the gravity, but all of the cubes accumulate towards the horizontal centre of the sphere. Is there any way I can solve this as it makes it less realistic?

This is the code that I have attached to the sphere (planet):

Code (CSharp):

1. public float pullRadius;
2.     public float pullForce;
3.  
4.     public void FixedUpdate()
5.     {
6.         foreach (Collider coll in Physics.OverlapSphere(transform.position, pullRadius))
7.         {
8.             if (coll != this)
9.             {
10.                 Vector3 forceDirection = transform.position - coll.transform.position;
11.                 coll.transform.Translate(forceDirection.normalized * pullForce * Time.fixedDeltaTime);
12.             }
13.         }
14.     }

Thanks.

 

I'm not totally sure what you mean by this. The picture doesn't seem to show any accumulation, since there's only one cube in it. Could you elaborate a bit?

I did notice something odd, though:

Code (CSharp):

1. if (coll != this)

I'm pretty sure that this will always evaluate to true, since this isn't even a Collider. It looks like you're trying to avoid the attractive body applying gravity to itself, which could be done like this:

Code (CSharp):

1. thisCollider = GetComponent<Collider>();
2.  
3. //...
4.  
5. if (coll != thisCollider)
6. {
7.     //...
8. }

On the other hand, applying gravity to itself would always give a 0 vector, so it wouldn't have any effect. I'm not sure whether it's actually worth screening self-gravitation, because there might be more overhead when running GetComponent depending on how you use it.