Game Design Foundations (Wordware Game and Graphics Library)

Our user interface (above) lets the player start a new game, choosing whether he would like to go first or second as either X or O, and lists the moves (spaces marked). The larger “big” board is where the current game is played and the player marks his desired space. The smaller board displays the computer thinking as calculated by the Min-Max with Alpha-Beta pruning search algorithm.

FORM1

Private Sub Form_Load() Dim i As Integer Form1.BorderStyle = 0 Text1.Text = " " + "Moves" + " " Frame1.Visible = False InitVariables playerMark = -1 End Sub Private Sub Option1_Click(index As Integer) Picture1.Enabled = True Picture1.PaintPicture BigBoard, 0, 0 Picture2.PaintPicture SmBoard, 0, 0 InitVariables showBigBoard showSmallBoard playerMark = (2 * (index Mod 2)) - 1 '-1 is "O", 1 is "X" playerDONE = 1 ' Computer goes first Option1(index).value = False ' reset Selected value Frame1.Visible = False Option2.Enabled = True Option2.value = False Option2.Visible = False If index < 2 Then ' Player’s turn Text5.Text = "Your turn, please mark a space" Picture1.Enabled = True ' Player goes first playerDONE = 0 Else ' Computer’s turn opening End If End Sub Private Sub Option2_Click() Frame1.Visible = True Text1.Text = " " + "Moves" + " " Option2.Enabled = False End Sub Private Sub Picture1_Click() Dim i As Integer Dim flag As Integer If playerDONE = 1 Then Exit Sub flag = -1 'check the area the player has selected to mark For i = 0 To 8 If PmouseX >= (15 * BigBoxXY(i, 0)) And PmouseX <= (15 * (BigBoxXY(i, 0) + 120)) Then If PmouseY >= (15 * BigBoxXY(i, 1)) And PmouseY <= (15 * (BigBoxXY(i, 1) + 95)) Then If ttt(0, i) = 0 Then ttt(0, i) = playerMark Text1.Text = Text1.Text + "You marked space " + Str(i + 1) + " " Text4.Text = "Marked " + Str(i + 1) showSmallBoard ' display current path scenario of board playerDONE = 1 showBigBoard opening Exit Sub End If End If End If Next i End Sub Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer,   X As Single, Y As Single) PmouseX = X PmouseY = Y End Sub Private Sub Picture1_Paint() showBigBoard End Sub Private Sub Picture2_Paint() showSmallBoard End Sub Public Sub showBigBoard() Dim i As Integer For i = 0 To 8 If ttt(0, i) = 1 Then Picture1.PaintPicture markX, 15 * BigBoxXY(i, 0), 15 * BigBoxXY(i, 1) End If If ttt(0, i) = -1 Then Picture1.PaintPicture markO, 15 * BigBoxXY(i, 0), 15 * BigBoxXY(i, 1) End If Next i Clevel = 0 showSmallBoard End Sub Public Sub showSmallBoard() Dim i As Integer For i = 0 To 8 If ttt(Clevel, i) = 1 Then Picture2.PaintPicture smarkX, 15 * SmBoxXY(i, 0), 15 * SmBoxXY(i, 1) End If If ttt(Clevel, i) = -1 Then Picture2.PaintPicture smarkO, 15 * SmBoxXY(i, 0), 15 * SmBoxXY(i, 1) End If Next i End Sub

MODULE1

'since C++ start arrays at index Zero we will too 'Set the Global variables Public ttt(0 To 9, 0 To 8) As Integer Public wp(0 To 7, 0 To 2) As Integer Public BigBoxXY(0 To 8, 0 To 2) As Integer Public SmBoxXY(0 To 8, 0 To 2) As Integer Public playerMark As Integer Public Path As String Public playerDONE As Integer Public PmouseX As Integer Public PmouseY As Integer Public markX As Picture Public markO As Picture Public smarkX As Picture Public smarkO As Picture Public BigBoard As Picture Public SmBoard As Picture Public caption1 As String Public Clevel As Integer Public L1nextspace As Integer Public Level1Data(0 To 9) As Integer Sub InitVariables() Dim i As Integer Dim j As Integer ' Change the path according to your Directory Path = "C://Wordware//VBTicTacToe//" Set BigBoard = LoadPicture(Path + "TicTacToeBigBoard.bmp") Set SmBoard = LoadPicture(Path + "TicTacToeSmBoard.bmp") Set markX = LoadPicture(Path + "BigX.bmp") Set markO = LoadPicture(Path + "BigO.bmp") Set smarkX = LoadPicture(Path + "SmallX.bmp") Set smarkO = LoadPicture(Path + "SmallO.bmp") Clevel = 0 Form1.Picture1.Enabled = False 'Initialize the Tic-Tac-Toe boards (all levels) to Zeor For i = 0 To 9 For j = 0 To 8 ttt(i, j) = 0 Next j Next i 'We start the arrays at Zero to match our C-code ' Rows wp(0, 0) = 0: wp(0, 1) = 1: wp(0, 2) = 2 wp(1, 0) = 3: wp(1, 1) = 4: wp(1, 2) = 5 wp(2, 0) = 6: wp(2, 1) = 7: wp(2, 2) = 8 ' Columns wp(3, 0) = 0: wp(3, 1) = 3: wp(3, 2) = 6 wp(4, 0) = 1: wp(4, 1) = 4: wp(4, 2) = 7 wp(5, 0) = 2: wp(5, 1) = 5: wp(5, 2) = 8 ' Diagonals wp(6, 0) = 0: wp(6, 1) = 4: wp(6, 2) = 8 wp(7, 0) = 2: wp(7, 1) = 4: wp(7, 2) = 6 ' Define our two Tic-Tac-Toe boards BigBoxXY(0, 0) = 0: BigBoxXY(0, 1) = 0 BigBoxXY(1, 0) = 125: BigBoxXY(1, 1) = 0 BigBoxXY(2, 0) = 243: BigBoxXY(2, 1) = 0 BigBoxXY(3, 0) = 0: BigBoxXY(3, 1) = 101 BigBoxXY(4, 0) = 125: BigBoxXY(4, 1) = 101 BigBoxXY(5, 0) = 243: BigBoxXY(5, 1) = 101 BigBoxXY(6, 0) = 0: BigBoxXY(6, 1) = 196 BigBoxXY(7, 0) = 125: BigBoxXY(7, 1) = 196 BigBoxXY(8, 0) = 243: BigBoxXY(8, 1) = 196 SmBoxXY(0, 0) = 0: SmBoxXY(0, 1) = 0 SmBoxXY(1, 0) = 22: SmBoxXY(1, 1) = 0 SmBoxXY(2, 0) = 44: SmBoxXY(2, 1) = 0 SmBoxXY(3, 0) = 0: SmBoxXY(3, 1) = 22 SmBoxXY(4, 0) = 22: SmBoxXY(4, 1) = 22 SmBoxXY(5, 0) = 44: SmBoxXY(5, 1) = 22 SmBoxXY(6, 0) = 0: SmBoxXY(6, 1) = 44 SmBoxXY(7, 0) = 22: SmBoxXY(7, 1) = 44 SmBoxXY(8, 0) = 44: SmBoxXY(8, 1) = 44 Randomize (Timer) ' initialize the Random number function End Sub 'Copy a new Tic-Tac-Toe board starting with the previous board Sub Copy_ttt(level As Integer) Dim index As Integer If level < 1 Then Exit Sub If level > 8 Then Exit Sub Clevel = level ' for small tic-tac-toe board For index = 0 To 8 ttt(level, index) = ttt(level - 1, index) Next index Form1.showSmallBoard End Sub ' Let's verify if there's an empty space to fill Function SpaceEmpty(level As Integer) As Integer Dim index As Integer For index = 0 To 8 If ttt(level, index) = 0 Then SpaceEmpty = index + 1 Exit Function End If Next index SpaceEmpty = 0 'no empty space was found End Function ' A function to check if the current board position is a winning ' one for either player Function IsThereaWin(level As Integer, MySide As Integer) As Integer Dim ttWin As Integer Dim OppWin As Integer Dim MyWin As Integer Dim wpindex As Integer Dim i As Integer OppWin = -3 * MySide MyWin = 3 * MySide For wpindex = 0 To 7 ' for each win (3 rows, 3 columns and 2 diagonals) ttWin = 0 For i = 0 To 2 ' add the 3 spaces as per direction to check ttWin = ttWin + ttt(level, wp(wpindex, i)) Next i If ttWin = MyWin Then ' I have 3 connecting marks IsThereaWin = 100 'I win plus space to move to Exit Function End If If ttWin = OppWin Then ' Opponent can get 3 connecting marks IsThereaWin = -100 'Forced plus space to block Exit Function End If Next wpindex IsThereaWin = 0 End Function ' Let's check to see if there's a forced move to make ' A forced move is a winning space or a blocking space to stop a loss Function Forced_Move(level As Integer, MySide As Integer) As Integer Dim index As Integer Dim trys As Integer Dim ttWin As Integer Dim OppWin As Integer Dim MyWin As Integer Dim wpindex As Integer Dim i As Integer Dim FMove As Integer Dim sgn1 As Integer OppWin = -3 * MySide MyWin = 3 * MySide For trys = 0 To 1 For index = 0 To 8 If level > 0 Then Copy_ttt (level) If ttt(level, index) = 0 Then ' empty space If trys = 0 Then ' Can we win on this turn ttt(level, index) = MySide Else ' Can our opponent win if we don't block on this turn ttt(level, index) = -MySide 'opponent End If FMove = IsThereaWin(level, MySide) If FMove <> 0 Then sgn1 = 1 If FMove < 0 Then sgn1 = -1 Forced_Move = sgn1 * (Abs(FMove) + index + 1) If level > 0 Then Copy_ttt (level) Exit Function End If End If Next index Next trys If level > 0 Then Copy_ttt (level) Forced_Move = 0 'No forced move End Function

Sub Tic_Tac_Toe() Dim X As Integer Dim MySide As Integer Dim spaceon As Integer Dim FMove As Integer Dim i As Integer Dim value As Integer X = 0: MySide = -playerMark If SpaceEmpty(0) Then 'Game still on ' A forced move to win or to block a win is the best mark move X = Forced_Move(1, MySide) spaceon = Abs(X) Mod 100 If X <> 0 Then ' A forced move has been calculated ttt(0, spaceon - 1) = MySide ' either a '1' or a '-1' Form1.Text1.Text = Form1.Text1.Text + " I marked space " + Str(spaceon) + " " End If 'find a space that's not forced If X = 0 Then ' Initialize the level 1 available mark spaces to an extremely low value For i = 0 To 9 Level1Data(i) = -999 Next i ' Call the Min-Max Function where Alpha is very low and Beta is very high X = MinMaxValue(1, MySide, -999, 999) ' find the best move ' find the best space to mark from the level 1 list of valid spaces to mark spaceon = SpaceEmpty(0) - 1 X = -999 For i = 1 To 9 if Level1Data(i) > X Then spaceon = i X= Level1Data(i) End If Next i ttt(0, spaceon - 1) = MySide ' Mark the best space Form1.Text1.Text = Form1.Text1.Text + " I marked space " + Str(spaceon) + " " End If Form1.Text4.Text = "Marked " + Str(spaceon) Form1.showSmallBoard ' display current path scenario of board End If Form1.showBigBoard playerDONE = 0 FMove = IsThereaWin(0, playerMark) If FMove <= -100 Then ' Be prepared to see this message often Form1.Text1.Text = Form1.Text1.Text + " " + "HURRAY! I WON!" + " " Form1.Text1.Text = Form1.Text1.Text + " Play me again?" Form1.Text5.Text = "Would you like to play me again?" playerDONE = 100 Form1.Option2.Visible = True Exit Sub End If If FMove >= 100 Then ' You may never see this message Form1.Text1.Text = Form1.Text1.Text + " " + "WOW! YOU'VE WON!" + " " Form1.Text1.Text = Form1.Text1.Text + " Play me again?" Form1.Text5.Text = "Would you like to play me again?" playerDONE = 100 Form1.Option2.Visible = True Exit Sub End If If FMove = 0 Then ' No win found and all spaces marked playerDONE = 0 Form1.Text5.Text = "Your turn, please mark a space" If SpaceEmpty(0) = 0 Then ' no more empty spaces to mark Form1.Text1.Text = Form1.Text1.Text + " " + "DRAW!" + " " Form1.Text1.Text = Form1.Text1.Text + " Play me again?" Form1.Text5.Text = "Would you like to play me again?" Form1.Option2.Visible = True Exit Sub End If End If End Sub ' Just like a chess opening database, here are standard ' Tic-Tac-Toe opening marks Sub opening() Dim i As Integer Dim j As Integer Dim k As Integer Form1.Text5.Text = "" ' clear message ' Check to see if we go first and second j = 0 For i = 0 To 8 If ttt(0, i) <> 0 Then j = j + 1 k = i End If Next i If j > 1 Then Form1.Text5.Text = "" Tic_Tac_Toe ' find a space to mark Exit Sub End If If j = 0 Then ' we go first i = Int(Rnd * 5) ' valid first marks are spaces 1,3,5,7 and 9 i = i * 2 ' we have a random number 0 through 4 so we double it ttt(0, i) = -playerMark Form1.Text4.Text = "Marked " + Str(i + 1) Form1.Text1.Text = Form1.Text1.Text + " I marked space " + Str(i + 1) + " " playerDONE = 0 Form1.showBigBoard Form1.Text5.Text = "Your turn, please mark a space" Form1.Picture1.Enabled = True ' Player goes Exit Sub End If If j = 1 Then ' we go second ' valid moves are center and the opposite corner if the opponent ' marked a corner space i = -1 ' a flag If k = 4 And i = -1 Then ' center space marked AAA: i = Int(Rnd * 4) ' valid first marks are spaces 1,3,7 and 9 If i = 4 Then GoTo AAA ' can't mark the center space i = i * 2 ' we have a random number 0 through 4 so we double it End If If i = -1 Then ' center space was not marked i = 4 ' mark center space (space 5) End If ttt(0, i) = -playerMark Form1.Text4.Text = "Marked " + Str(i + 1) Form1.Text1.Text = Form1.Text1.Text + " I marked space " + ' Str(i + 1) + " " playerDONE = 0 Form1.showBigBoard Form1.Text5.Text = "Your turn, please mark a space" Form1.Picture1.Enabled = True ' Player goes Exit Sub End If End Sub

Function MinMaxValue(level As Integer, MySide As Integer, alpha As Integer, beta As Integer) As Integer Dim WIN As Integer Dim index As Integer Dim MTlist As Long Dim nextspace As Integer Dim X As Integer Dim succval As Integer ' reset current level board Copy_ttt (level) If SpaceEmpty(level) = 0 Then MinMaxValue = 0 Exit Function End If 'find a space that's not forced 'list all open spaces MTlist = 0 ' List all the open (unmarked) spaces on this level X = Forced_Move(level, MySide) ' Is there a forced move (a win or a ' block of a win) If X <> 0 Then ' a forced move has been flagged MTlist = Abs(X Mod 100) ' space is 1 to 9 Else For index = 0 To 8 If ttt(level, 8 - index) = 0 Then ' subtract from 8 for ascending order MTlist = MTlist * 10 + (9 - index) End If Next index End If While MTlist > 0 nextspace = MTlist Mod 10 ' next space to mark MTlist = (MTlist - nextspace) / 10 ' remainder of possible spaces ' to mark Copy_ttt (level) ttt(level, nextspace - 1) = MySide Form1.Text4.Text = "Marked " + Str(nextspace) Form1.showSmallBoard ' display current path scenario of board WIN = IsThereaWin(level, MySide) If WIN >= 100 Then succval = WIN Else succval = -MinMaxValue(level + 1, -MySide, -beta, -alpha) Endif If level = 1 Then ' Save this space's value Level1Data(nextspace) = succval If succval = 100 Then ' Winning line found MinMaxValue = succval Exit Function End If End If 'The Alpha-Beta pruning code If succval >= beta Then MinMaxValue = beta Exit Function End If If succval > alpha Then alpha = succval Wend MinMaxValue = alpha ' return a draw End Function

//since C++ start arrays at index Zero we will too int ttt[8][8]={ {0,0,0,0,0,0,0,0},{0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0},{0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0},{0,0,0,0,0,0,0,0}, {0,0,0,0,0,0,0,0},{0,0,0,0,0,0,0,0}}; int wp[8][3]={{0,1,2},{3,4,5},{6,7,8}, // Rows {0,3,6},{1,4,7},{2,5,8}, // Columns {0,4,8},{2,4,6}}; // Diagonals // Copy a new Tic-Tac-Toe board starting with the previous board void Copy_ttt(int level) { int index; if(level<1) return; // invalid parameter for(index=0; index<9; index++) ttt[level][index]= ttt[level-1][index] } // Let's verify if there's an empty space to fill int SpaceEmpty(int level) { int index; for(index=0; index<9; index++) if(ttt[level][index]==0)return(index+1); return 0; // no empty space was found } // Let's check to see if there's a forced move to make // A forced move is a winning space or a blocking space to stop // a loss int Forced_Move(int level, int MySide) { int index, trys, ttWin; int OppWin= -3 * MySide; int MyWin= 3 * MySide; for(index=0; index<9;index++) for(trys=0; trys<2; trys++){ if(level>0) Copy_ttt(level); if(ttt[level][index] == 0){ // empty space if(trys ==0)ttt[level][index]= MySide; else ttt[level][index]=-MySide; // opponent ttWin= ttt[level][wp[index][0] + ttt[level][wp[index][1] + ttt[level][wp[index][2]; if(ttWin == MyWin)return(100 + index); // I win plus space to move to else if(ttWin == OppWin)return(-(100 + index)); // Forced plus space to block } return 0; // No forced move } void Tic_Tac_Toe() { int x=0, MySide= 1, spaceon; while(SpaceEmpty(0) && x < 100){ // Game still on x= Forced_Move(1, MySide); spaceon= abs(x)%100; if(x != 0)ttt[0][spaceon]= x/100; // either a '1' or a '-1' else{ // find a space that's not forced BestMove(1); // find the best move } x= 0; // reset 'x' } }

(This code can be found on the book’s companion CD.)