title: Detecting touch on gameobject
body: <p>I want to detect a touch on a GameObject  without sucess. My code copied from some examples is:</p>
  
  <pre class="lang-cs prettyprint-override"><code>void Update()
  {
      if (Input.GetMouseButtonDown(0))
      {
          Debug.Log("Mouse Clicked!!");
          Vector3 worldPoint = Camera.main.ScreenToWorldPoint(Input.mousePosition);
          Vector2 worldPoint2D = new Vector2(worldPoint.x, worldPoint.y);
          RaycastHit2D hit = Physics2D.Raycast(worldPoint2D, Vector2.zero);
          Debug.Log(hit.collider);
  
      }
  }
  </code></pre>
  
  <p>The output is always null :(</p>
  
  <p>The game object is not moving and is a simple Cube with a box colider.</p>