Cookbook: UDK cascading HUD messages

Many games have some messaging system on their HUDs (player picked up some power-up, have taken some damage, timer is ticking away, etc.). Using just the simple extension of HUD class, you can achieve similar results.

We'll use a simple structure to represent our message:

   1:  //message struct define

   2:  struct HUDMessage

   3:  {

   4:      var string sMessage;

   5:      var float fMessageTimer;

   6:  };

Simple method to display string on HUD (based on great vectorlab tutorial):

   1:  //========================================================================

   2:   function DrawString(string text, int X, int Y, int R, int G, int B, int A)

   3:   {

   4:      Canvas.SetPos(X, Y);

   5:      Canvas.SetDrawColor(R, G, B, A);

   6:      Canvas.Font = class'Engine'.static.GetMediumFont();    

   7:      Canvas.DrawText(text);

   8:   }

All messages are stored in a simple dynamic array and updated/displayed/removed each frame:

   1:  var array<HUDMessage> aMessages;

   2:   

   3:  //public method to be called from anywhere in game (your actors, etc.)

   4:  //========================================================================

   5:  function StringToHUD(string message, float timer = 0)

   6:  {

   7:      local HUDMessage newMessage;

   8:   

   9:      newMessage.sMessage = message;

  10:      newMessage.fMessageTimer = -timer; //make it appear longer, optional

  11:      

  12:      aMessages.InsertItem(0,newMessage); //insert at the beginning!

  13:  }

  14:   

  15:  //========================================================================

  16:  simulated event Tick(float DeltaTime)

  17:  {

  18:      local int i;

  19:   

  20:      //update message array

  21:      for (i = 0; i < aMessages.length; ++i)

  22:      {

  23:          aMessages[i].fMessageTimer += DeltaTime;

  24:      }

  25:  }

  26:   

  27:  //draw routine to display cascaded messages

  28:  //========================================================================

  29:  function DrawCustomMessage()

  30:  {

  31:      local HUDMessage message;

  32:      local offsetY = 200;

  33:          

  34:      foreach aMessages(message) //display all messages

  35:      {

  36:                  //message is still to be displayed

  37:          if (message.fMessageTimer < 2.0f)

  38:          {                                    

  39:              DrawString(message.sMessage,0,offsetY,255,255,255,255,true);

  40:              offsetY += 20; //update next message position

  41:          }

  42:          else //expired, remove

  43:          {

  44:              aMessages.RemoveItem(message);

  45:          }

  46:     }

  47:

  48:  }

  49:   

  50:  //========================================================================

  51:  function DrawHUD()

  52:  {

  53:      super.DrawHUD(); //don't forget to call parent method!

  54:      

  55:      DrawCustomMessage(); //our messaging routine

  56:   }

And here is an example screenshot directly from game: