// GameHUD: Platformer Tutorial Master GUI script.
  
  // This script handles the in-game HUD, showing the lives, number of fuel cells remaining, etc.
  
  var guiSkin: GUISkin;
  var nativeVerticalResolution = 1200.0;
  
  // main decoration textures:
  var healthImage: Texture2D;
  var healthImageOffset = Vector2(0, 0);
  
  // the health 'pie chart' assets consist of six textures with alpha channels. Only one is ever shown:
  var healthPieImages : Texture2D[];
  var healthPieImageOffset = Vector2(10, 147);
  
  // the lives count is displayed in the health image as a text counter
  var livesCountOffset = Vector2(425, 160);
  
  // The fuel cell decoration image on the right side
  var fuelCellsImage: Texture2D;
  var fuelCellOffset = Vector2(0, 0);
  
  // The counter text inside the fuel cell image
  var fuelCellCountOffset = Vector2(391, 161);
  
  private var playerInfo : ThirdPersonStatus;
  
  // Cache link to player's state management script for later use.
  function Awake()
  {
          playerInfo = FindObjectOfType(ThirdPersonStatus);
  
          if (!playerInfo)
                  Debug.Log("No link to player's state manager.");
  }
  
  function OnGUI ()
  {
  
          var itemsLeft = playerInfo.GetRemainingItems();        // fetch items remaining -- the fuel cans. This can be a negative number!
  
          // Similarly, health needs to be clamped to the number of pie segments we can show.
          // We also need to check it's not negative, so we'll use the Mathf Clamp() function:
          var healthPieIndex = Mathf.Clamp(playerInfo.health, 0, healthPieImages.length);
  
          // Displays fuel cans remaining as a number.        
          // As we don't want to display negative numbers, we clamp the value to zero if it drops below this:
          if (itemsLeft < 0)
                  itemsLeft = 0;
  
          // Set up gui skin
          GUI.skin = guiSkin;
  
          // Our GUI is laid out for a 1920 x 1200 pixel display (16:10 aspect). The next line makes sure it rescales nicely to other resolutions.
          GUI.matrix = Matrix4x4.TRS (Vector3(0, 0, 0), Quaternion.identity, Vector3 (Screen.height / nativeVerticalResolution, Screen.height / nativeVerticalResolution, 1)); 
  
          // Health & lives info.
          DrawImageBottomAligned( healthImageOffset, healthImage); // main image.
  
          // now for the pie chart. This is where a decent graphics package comes in handy to check relative sizes and offsets.
          var pieImage = healthPieImages[healthPieIndex-1];
          DrawImageBottomAligned( healthPieImageOffset, pieImage );
          
          // Displays lives left as a number.        
          DrawLabelBottomAligned( livesCountOffset, playerInfo.lives.ToString() );        
          
          // Now it's the fuel cans' turn. We want this aligned to the lower-right corner of the screen:
          DrawImageBottomRightAligned( fuelCellOffset, fuelCellsImage);
  
          DrawLabelBottomRightAligned( fuelCellCountOffset, itemsLeft.ToString() );
  }
  
  function DrawImageBottomAligned (pos : Vector2, image : Texture2D)
  {
          GUI.Label(Rect (pos.x, nativeVerticalResolution - image.height - pos.y, image.width, image.height), image);
  }
  
  function DrawLabelBottomAligned (pos : Vector2, text : String)
  {
          GUI.Label(Rect (pos.x, nativeVerticalResolution - pos.y, 100, 100), text);
  }
  
  function DrawImageBottomRightAligned (pos : Vector2, image : Texture2D)
  {
          var scaledResolutionWidth = nativeVerticalResolution / Screen.height * Screen.width;
          GUI.Label(Rect (scaledResolutionWidth - pos.x - image.width, nativeVerticalResolution - image.height - pos.y, image.width, image.height), image);
  }
  
  function DrawLabelBottomRightAligned (pos : Vector2, text : String)
  {
          var scaledResolutionWidth = nativeVerticalResolution / Screen.height * Screen.width;
          GUI.Label(Rect (scaledResolutionWidth - pos.x, nativeVerticalResolution - pos.y, 100, 100), text);
  }