Introduction to Computing 2014 Assignment 4 (Preliminary Version) Simple Checkers Game

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1 Introduction to Computing 2014 Assignment 4 (Preliminary Version) Simple Checkers Game Assignment Value 10% of total mark for this paper. Date Due 5pm Friday 24 October Requirements 1. Design and implement a C++ program for the following specification. 2. Draw a structure diagram for your program using the program provided on the network. Submitting Your Assignment You must upload a copy of your C++ program source code (.cpp) file AND your structure diagram (.sdg) file to Turnitin by 5pm on Friday 24 October To make a submission to Turnitin: Log in to AUTonline and go to the page for this paper. Click on the "Assessment" button. Follow the TWO Turnitin links "View/Complete" for "Assignment 4". There is a separate link for each file you must submit. Assignment Requirements The aim of this assignment is to write a program, with a graphical user interface, that allows a game of Simple Checkers to be played on the computer. A minimal requirement (C) for a pass mark in this assignment is that your program draws the Checkers board on the computer display, and allows a user to click the mouse on a piece and move the piece to a vacant square (not necessarily a valid move). A good version (B) of the program will have the program move pieces according to the rules, including jumping. The on_screen buttons will also be operational. An excellent version (A) will know when a player has won or lost, and stop the game. [MORE DETAILS LATER] Introduction to Computing 2014 Assignment 4 Page 1

2 The Rules of Checkers Adapted from Wikipedia, the free encyclopedia, accessed 29 August Checkers or draughts is the name of several similar board games. In every kind of checkers, the other player's pieces can be taken by being "jumped" over. "Checkers" is the American name and draughts is the English name. The rules and championships are controlled by the World Draughts Federation. This assignment requires you to write a program that allows two players to play a simple version of Checkers. The rules given below are for this simple version. Rules for "Simple" Checkers Checkers is played on an 8x8 chess board as shown in the diagram. Only the dark squares are used (the light squares are never used). In a game of checkers, there are two players. The players are at opposite ends of the board. In the diagram, the two players would be at the top and bottom of the diagram. One player has dark pieces (usually red), and one player has light pieces (usually white). In your program you may use any colours, as long as it is clear which pieces and squares are light and dark. Do not use the same colours for pieces and squares. Pieces The pieces are flat and round. (In real Checkers there are also pieces known as "kings" but we will not be using king pieces.) Starting Position Each player starts with 12 pieces, placed on the dark squares of the three rows closest to their own side. For each player, the leftmost square of the row nearest the player is dark and the rightmost square is light. How to Move Players take turns moving their pieces. The darker colour moves first.there are two types of moves. In a step move, a piece is moved forward diagonally (towards the opponent), to a vacant adjacent dark square. A jump move may be made when an opponent s piece is on an adjacent square and the next diagonal square (in a straight line) is vacant. The moving piece jumps over the opponent s piece to the vacant square, and the opponent s piece is removed from the board. The jump must be made towards the opponent. In most variations of Checkers, multiple jumps are allowed. We do not allow this. In some variations of Checkers, if a jump is possible, it must be made. We will allow jumps to be optional, so a player may make a step move, even if a jump is possible. Winning and Losing the Game A player who has all their pieces jumped by the opponent will have no pieces left and loses the game. When it is their turn, a player must make either a step move or a jump move. If the player has no legal moves, they lose the game. Otherwise, the first player to get a piece to the opponent's side of board wins the game Introduction to Computing 2014 Assignment 4 Page 2

3 Program Specification The checkers board (drawn using Horstmann's graphics) is shown in the diagram below. The starting position Players can move a piece by clicking the mouse on one of their pieces and then clicking on the vacant (dark) square the piece is to move to. Players may also click on one of the two buttons at the bottom of the screen to start a new game or exit the program. When the program is waiting for a mouse click, it displays a prompt in the top left corner of the screen. When a piece is selected to move, this program highlights the square the piece is on (bright green) and returns to normal display after the piece is moved. A piece selection can be cancelled by clicking on the highlighted piece. Then the highlighting disappears, and the program waits for the same player to select another piece. A step move is shown below: A selected piece After a step move A fully operational program will not allow a player to make invalid moves. If a player selects a piece that has no valid moves, the player will need to cancel the selection and then select another piece Introduction to Computing 2014 Assignment 4 Page 3

4 The following diagrams show a jump move: A selected piece After a jump move Notice that the jumped white piece has been removed from the board. [MAY BE MORE DETAILS LATER] Introduction to Computing 2014 Assignment 4 Page 4

5 Program Design In a program this complicated, it is important to separate the major parts of the program as much as possible, so that each part can be written and tested (almost) separately. I suggest you use the following program structure. int ccc_win_main(void) // main function for graphics program // piece positions on the board int board[num_rows][num_cols]; // result of the game int result; } do Initialise(board); // initialise the board Draw(board); // draw the board result = PlayGame(board); // play a game // wait for new game or exit game button click while (result!= NEW_GAME && result!= EXIT_PROGRAM) // get a mouse click } } while (result == NEW_GAME); return 0; 1. Variables Do not use global variables, apart from constants. The board array stores the locations of the players' pieces. In the 8 x 8 array, each value represents the type of piece at the corresponding square on the board. The first index of a two dimansional is usually the row number (0 to 7) and the second index is the column number (also 0 to 7). Usually the bottom left corner is row 0, column 0. The piece types can be defined as constants, such as NO_PIECE, DARK_PIECE and LIGHT_PIECE. The Initialise function fills the board array with appropriate starting values. The result variable contains the current game situation. This is a good way of implementing the logic of a program like this, where the program needs to go through a repetitive sequence of operations (players moving pieces), but the sequence can vary (for example, if a player cancels a piece selection). It can also deal with the a player clicking one of the on-screen buttons at any time. The possible values of result can also be defined as constants such as DARK_WINS, LIGHT_WINS, NEW_GAME, or EXIT_PROGRAM. 2. User Input User input will consist only of mouse clicks. The players will mostly click on the board, but may occasionally click the on-screen buttons. Call the cwin.get_mouse() function to get the position (Point value) where the mouse is clicked. Then check if the position is inside the rectangular area of the board or any of the buttons. Suppose the button rectangle has opposite corners at (14, 8) and (18, 10). Then the code could be: Point p = cwin.get_mouse(); // get the mouse click // is the click in the rectangle? if (p.get_x() >= 14 && p.get_x() <= 18 && p.get_y() >= 8 && p.get_y() <= 10) If the mouse is clicked in the board rectangle, then the program calculates the location of the clicked board square, and takes appropiriate action (such as select or move a piece) Introduction to Computing 2014 Assignment 4 Page 5

6 3. Functions The Initialise function initialises the board array for the start of a new game. It is called once at the start of each game. Choose a coordinate system for your window that suits your window layout. The Draw function draws the complete graphic image on the screen. In this function, clear the window and completely redraw the display. Do not try to display directly from different parts of the program, because it is very difficult to get the display correct when doing that. The PlayGame function plays a game, getting button clicks and calling Draw whenever the window display needs to change. You will need to write other functions for the PlayGame function to call, so that the PlayGame function does not get too big. The PlayGame function could have its own state variable to control its logic. The possible values of state could be DARK_SELECT, DARK_MOVE, LIGHT_SELECT, LIGHT_MOVE, DARK_WINS nad LIGHT_WINS for the normal sequence of playing, as well as NEW_GAME and EXIT_PROGRAM to handle on-screen button clicks. Pseudocode for the PlayGame function could be: do get a mouse click if new game button is clicked state = NEW_GAME else if exit button is clicked state = EXIT_ PROGRAM else if board rectangle is clicked calculate board position r,c if state == DARK_SELECT and board[r][c] == DARK_PIECE r1 = r, c1 = c state = DARK_MOVE else if state == DARK_MOVE and MoveValid(r1, c1, r, c) Move(r1, c1, r, c) state = LIGHT_SELECT else if state == LIGHT_SELECT and board[r][c] == LIGHT_PIECE r1 = r, c1 = c state = DARK_MOVE else if state == LIGHT_MOVE and MoveValid(r1, c1, r, c) Move(r1, c1, r, c) state = DARK_SELECT winner = Winner() if winner = DARK_PLAYER state = DARK_WINS else if winner = LIGHT_PLAYER state = LIGHT_WINS } while (state!= NEW_GAME and state!= EXIT_PROGRAM and state!= DARK_WINS and state!= LIGHT_WINS); return state Notice that complicated operations such as calculating whether a move is valid or whether either player has won are put into separate functions (MoveValid and Winner)to be designed later. [MAY BE MORE DETAILS LATER] Introduction to Computing 2014 Assignment 4 Page 6