Merlin Simulator Part 3 by Erick Tejkowsi
01-24-02

Back in the late 1970's, Parker Brothers introduced a great handheld electronic game machine called Merlin. This week we continue with Part 3 of our Merlin Simulator project and continue adding functionality to the simulator.

Interface

If you'd like to start where we left off last week, download the project. Then, launch REALbasic and open Window1. Drag a Timer control from the toolbar and add it to your Window1 interface. It doesn't matter where you drag it to in the interface, since it will be invisible when the application executes. Change the properties of the Timer to match the following image:

Add the Code

Next, double click Window1 to open its Code Editor and make sure you have all of the following properties

Then, add a new method to Window1 as follows:

Method Name:PlayGameEcho
Parameters:indx as integer

To this new method, add this code:

dim i,n,index as integer
 index = indx
 
 //*******************************
 // Play Game: Echo
 //*******************************
 if NOT(gameover) then
   if gamestarted then
     if index = NoteArray(currentmove) then
       //******************************
       //user pressed correct next number 
       //******************************
       MusicMachinePlayNote(NoteArray(currentmove),TRUE)
       currentmove=currentmove+1
       if currentmove>ubound(NoteArray) then
         //***************
         //game is over
         //***************
         gameover=TRUE
         if errorcount=0 then
           noteplayer1.instrument=127//applause
           MusicMachinePlayNote(60,FALSE)
           noteplayer1.instrument=1//piano
           MsgBox "You win. No errors!"
         else//errorcount>0
           MsgBox "Game over! Press OK to see error count."
           for i=1 to len(str(errorcount))
             n = val(mid(str(errorcount),i,1))
             MusicMachinePlayNote(n,TRUE)
           next
         end if//error
       else
         //***************
         //game still playing 
         //***************
       end if//if currentmove>ubound(NoteArray) then
     else//if index = NoteArray(currentmove)
       //user didn't press correct next number
       noteplayer1.instrument=59//tuba
       MusicMachinePlayNote(50,FALSE)
       noteplayer1.instrument=1//piano
       errorcount = errorcount+1
     end if//if index = NoteArray(currentmove)
   else//if gamestarted 
     //for game # 3
     //only buttons between 
     //1-9 are valid choices
     
     if index>0 and index < 10 then redim NoteArray(index) gamestarted=TRUE //fill array with a random pattern for i=1 to index //find a random number between 1-9 inclusive //and store it in the array NoteArray(i)=rnd*(9)+1 MusicMachinePlayNote(NoteArray(i),TRUE) next currentmove=1 errorcount=0 end if//if index>
								0 and index
								< 10 end if//if gamestarted end if//if NOT(gameover)

This method takes of the game play for the next game we are implementing for Merlin. This week's game is game number 3: Echo. In this game, Merlin plays you a certain number of sounds, which you must replay to him. At the end of the game, Merlin tells you how many errors you entered before repeating the exact sequence.

Now, you need to "wire" the game into the interface. This is accomplished with the MouseUp events of the NumButton and UtilButton control arrays. Expand the NumButton control array in the Code Editor and add this code to it:

dim i,n as integer
 
 
 //**************************
 //
 //    START GAME
 //
 //**************************
 if newgame then
   //which game?
   select case index
     
   case 2
     //***********************
     //  start game: music machine
     //***********************
     newgame=FALSE
     gamenumber=2
     redim NoteArray(0)
     MsgBox "Music Machine game starting."
     
   case 3
     //***************
     //  start game: echo 
     //***************
     newgame=FALSE
     gamenumber=3
     //flash 0 and 10 to show game starting 
     numButton(0).ButtonOn
     numButton(10).ButtonOn
     //start timer to turn these lights off
     GameThreeTimer.mode=1
     gamestarted=FALSE
     gameover=FALSE
   else
   end select
   
 else
   
   //**************************
   //
   //   CONTINUE GAME 
   //
   //**************************
   select case gamenumber
   case 2
     //**********************
     //  play game: Music Machine 
     //**********************
     NoteArray.append index
     //no lights on here, because we have 
     //already lighted the button using the 
     //control's mousedown/up mechanism
     MusicMachinePlayNote(index,FALSE)
   case 3
     //**********************
     //  play game: echo 
     //**********************
     PlayGameEcho(index)
     
   end select//case gamenumber
 end if//if newgame

Next, expand the UtilButton control array in the Code Editor and add this code:

Finally, add these two lines of code to the GameThreeTimer:

numButton(0).ButtonOff
numButton(10).ButtonOff

As you probably can guess, this code turns off numButton(0) and numButton(10). Why do this? Well, Merlin momentarily lights these two lights at the start of the game to show which keys are not allowed for a game level choice. Since they get turned on at game startup, we use the Timer to turn them off a certain amount of time later.

Conclusion

Well, that's it for this week. Select Debug-Run to test your work. If you encounter any difficulties with the code or don't feel like entering it all, you can download the completed project. See you next week!

Merlin Simulator Part 3 by Erick Tejkowsi 01-24-02

Merlin Simulator Part 3 by Erick Tejkowsi
01-24-02