// Script that puts a window on-screen where the player can toggle who he controls
  // It works by sending SetControllable messages to turn the different characters on and off.
  // It also changes who the CameraScrolling scripts looks at.
  
  // An internal reference to the attached CameraScrolling script
  private var cameraScrolling : CameraScrolling;
  
  // Who is the player controlling
  private var selected = 0;
  
  // List of objects to control
  var targets : Transform[];
  
  // What to display on the buttons in the window
  var targetButtonNames : String[];
  
  // On start up, we send the SetControllable () message to turn the different players on and off.
  function Awake () {
  
          // Get the reference to our CameraScrolling script attached to this camera;
          cameraScrolling = GetComponent (CameraScrolling);
          
          // Set the scrolling camera's target to be our character at the start.
          cameraScrolling.SetTarget (targets[0], true);
          
          // tell all targets (except the first one) to switch off.
          for (var i=0; i < targets.Length; i++) 
                  targets[i].gameObject.SendMessage ("SetControllable", (i == 0), SendMessageOptions.DontRequireReceiver);
  }
  
  private var windowRect = Rect (20, 20, 250, 50);
  // Make the onscreen GUI to let the player switch control between Lerpz and the spaceship.
  function OnGUI () {
          // Make a popup window
          windowRect = GUILayout.Window (0, windowRect, DoControlsWindow, "Controls");
          
          // The window can be dragged around by the users - make sure that it doesn't go offscreen.
          windowRect.x = Mathf.Clamp (windowRect.x, 0.0, Screen.width - windowRect.width);
          windowRect.y = Mathf.Clamp (windowRect.y, 0.0, Screen.height - windowRect.height);
  }
  
  // Make the contents of the window
  function DoControlsWindow (windowID : int) {
          // Make the window be draggable in the top 20 pixels.
          GUI.DragWindow (Rect (0,0, System.Decimal.MaxValue, 20));
          
          GUILayout.Label ("Select a character...");
  
          // Let the player select the character
          selected = GUILayout.Toolbar (selected, targetButtonNames);
  
          // If the user has selected a new character, we'll send new SetControllable messages to turn on the other character. 
          // Then we'll change who the CameraScrolling script is tracking.
          if (GUI.changed && targets[selected] != cameraScrolling.GetTarget ()) {
                  targets[selected].gameObject.SendMessage ("SetControllable", true, SendMessageOptions.DontRequireReceiver);
                  cameraScrolling.GetTarget ().gameObject.SendMessage ("SetControllable", false, SendMessageOptions.DontRequireReceiver);
                  cameraScrolling.SetTarget (targets[selected]);
          }
          
          // Show a different instruction label depending on what was selected above.
          switch (selected) {
                  case 0:
                          GUILayout.Label ("Instructions:\nUse the left and right arrow keys to move and space bar to jump.  To run, hold down the control key.");
                  break;
                  case 1:
                          GUILayout.Label ("Instructions:\nUse the left and right arrow keys to rotate and the up arrow to thrust.");
                  break;
          }
  }
  
  // Ensure there is a CameraScrolling script attached to the same GameObject, as this script
  // relies on it.
  @script RequireComponent (CameraScrolling)