title: Is it possible to subtract a Vector2
body: <p>I'm trying to slightly change the velocity of a ball as it collides with objects, depending on the direction it is already travelling in, in a 2D game in Unity.</p>
  
  <p>To find the direction in which the ball is travelling, I have been using</p>
  
  <pre><code>public Vector2 ballDirection;
  public Vector2 lastPosition; 
  
  void OnCollisionEnter2D(Collision2D boing)
  {
      ballDirection = transform.position - lastPosition;
      lastPosition = transform.position;
  }
  </code></pre>
  
  <p>This however throws up an error reading</p>
  
  <p><code>Error  CS0034  Operator '-' is ambiguous on operands of type 'Vector3' and 'Vector2'</code>  </p>
  
  <p>The collision between the ball and any object prints as UnityEngine.Vector3</p>
  
  <p>Is it indeed possible to subtract a Vector2 or would I be able to change the collision type to Vector2 somehow?</p>