Have an invisible sensor object created for each enemy (this can be done in the constructor of the enemy class with an instance field in the class to hold the sensor) that it can use to detect obstacles in the line of sight. Have the enemy add the sensor object anywhere into the world in the 'addedToWorld' method. In act method, if player is in world, then do the following for checking line of sight: * place sensor halfway between player and enemy; * size width of sensor image to distance between player and enemy (height of sensor image should be two); * rotate the sensor to the angle between the player and enemy; * call a method in Sensor class that return a boolean value indicating any intersecting objects besides player and enemy;