Update() {
    player = GameObject.FindGameObjectWithTag ("Player");
    //Debug.Log (player.transform.position + " " + transform.position);

    Vector3 direction = (player.transform.position - transform.position).normalized;
    Debug.Log (direction);
    Ray ray = new Ray (transform.position, direction);
    RaycastHit hit;

    Debug.DrawRay (transform.position, direction, Color.red);

    if(Physics.Raycast(ray, out hit, 3f)) {
        gameObject.renderer.material.color = Color.blue;
        //Debug.Log("OK");
    }
    else {
        gameObject.renderer.material.color = Color.white;
    }
}