bouncing circle off another circle

Do you mean circle or sphere?

Can't you just use the rigidbody component? Calculations will probably be way much more optimize than anything you will come up with.

This should make you feel like using the rigidbody component, http://en.wikipedia.org/wiki/Elastic_collision

Hi, I meant circles, but ended up using sphereColliders.

This is what i have so far. I am calculating the angles between the static sphere and the shooting sphere on collision to get the normal angle between them, calculating the angle between shooting direction angle and normal angle, multiplicating it by two to get the right exit angle and then trying to change the direction. And it changes, but wrong:

 function OnCollisionEnter(collision : Collision) {
   
         var dynCircle = this.transform.position;
         var statCircle = collision.transform.position;
         
         var collisionNormal = dynCircle - statCircle;
         var oppositeDir = -dynCircle;
         
         var normalAngle = Vector3.Angle(Vector3.back, collisionNormal);
         var shootingAngle = Vector3.Angle(Vector3.back, oppositeDir);
 
         var angle = (normalAngle - shootingAngle) *2;
 
         this.transform.rotation = Quaternion.AngleAxis(angle, Vector3.up);
             
 }

Is the game 2D? or 3D?

I make the same question as fafase. Why not use a rigidbody? It does that out of the box.