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Pong AI, and some advice on the code I've managed to cobble together

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Started by skulldrudgery May 23, 2005 04:11 AM

2 comments, last by skulldrudgery 18 years, 11 months ago

skulldrudgery

253

Author

May 23, 2005 04:11 AM

I started working on this thing a couple of days ago. Not much planning on my part has led to a bunch of code that feels "improvised." Ugliness and redundancy are my biggest worries. I could use some advice on cleaning up the code. Plus, I need to add some AI. Right now I just got a "dumb" paddle going up and down randomly (at least 5 lines in a row). I'm almost afraid to post the code. But here it is:

#include <iostream>

using std::cout;
using std::cin;
using std::endl;

#include <iomanip>

using std::setw;

#include <ctime>
#include <cmath>
#include <conio.h>
#include <windows.h>

const int SCREEN_HEIGHT = 25;
const int SCREEN_WIDTH  = 80;
const int GAME_OBJECT_STR_LENGTH = 4;
enum { pLEFT = 10, pRIGHT = 70, pMIDDLE = 39 };
enum { pTOP = 3, pBOTTOM = 22, pCENTER = 12 };
enum DIRECTION { d_LEFT = -1, d_NONE = 0, d_RIGHT = 1, d_UP = -1, d_DOWN = 1 };
enum { LOSE_LINE_LEFT = 8, LOSE_LINE_RIGHT = 72 };

// forward declarations/prototypes
void gotoxy( int, int );
void delay( int );
void print_interface();
void ai_move( int & );

int player1score = 0;
int player2score = 0;
int speedfactor = 100;
bool flag1 = false; // a flag because I'm lazy

// game object struct
struct game_object {
    char str_top[4];     // all game objects will consist of three (or less) char
    char str_middle[4];  // arrays of length 3 or less
    char str_bottom[4];
    int oldx, oldy;
    int tempx, tempy;
    int x, y;
};

// engine class
class pong {
    
    public:
        void draw_object( game_object & );
        void get_input( int & );
        void ball_move( game_object &, game_object &, game_object & );
        bool check_ball( game_object & );
        
} engine;

void pong::draw_object( game_object &object )
{
    // delete object at old location
    for ( int i = 0; i < GAME_OBJECT_STR_LENGTH - 1; i++ ) {
        if ( object.str_top )
            gotoxy( object.oldx + i, object.oldy ), cout &lt;&lt; <span class="cpp-literal">" "</span>;
    
        <span class="cpp-keyword">if</span> ( object.str_middle )
            gotoxy( object.oldx + i, object.oldy + <span class="cpp-number">1</span> ), cout &lt;&lt; <span class="cpp-literal">" "</span>;
        
        <span class="cpp-keyword">if</span> ( object.str_bottom )
            gotoxy( object.oldx + i, object.oldy + <span class="cpp-number">2</span>), cout &lt;&lt; <span class="cpp-literal">" "</span>;
    }
    
    <span class="cpp-comment">// draw object at new location</span>
    <span class="cpp-keyword">if</span> ( object.str_top )
        gotoxy( object.x, object.y ), cout &lt;&lt; object.str_top;
    
    <span class="cpp-keyword">if</span> ( object.str_middle )
        gotoxy( object.x, object.y + <span class="cpp-number">1</span> ), cout &lt;&lt; object.str_middle;
        
    <span class="cpp-keyword">if</span> ( object.str_bottom[ <span class="cpp-number">0</span> ] )
        gotoxy( object.x, object.y + <span class="cpp-number">2</span>), cout &lt;&lt; object.str_bottom;
}

<span class="cpp-keyword">void</span> pong::get_input( <span class="cpp-keyword">int</span> &amp;y )
{       
    <span class="cpp-keyword">if</span> ( GetAsyncKeyState( <span class="cpp-number">38</span> ) &amp;&amp; y != pTOP ) <span class="cpp-comment">// if the "up" key is pressed…</span>
        y–;
    
    <span class="cpp-keyword">if</span> ( GetAsyncKeyState( <span class="cpp-number">40</span> ) &amp;&amp; y != pBOTTOM - <span class="cpp-number">2</span> ) <span class="cpp-comment">// if the "down" key is pressed…</span>
        y++;
}

<span class="cpp-keyword">void</span> pong::ball_move( game_object &amp;ball, game_object &amp;p1, game_object &amp;p2 )
{
    <span class="cpp-keyword">static</span> DIRECTION Y_DIR = d_NONE;
    <span class="cpp-keyword">static</span> DIRECTION X_DIR = d_LEFT;
    
    <span class="cpp-keyword">if</span> ( flag1 == <span class="cpp-keyword">true</span> ) {
        Y_DIR = d_NONE;
        X_DIR = rand() % <span class="cpp-number">2</span> == <span class="cpp-number">0</span> ? d_LEFT : d_RIGHT;
        flag1 = <span class="cpp-keyword">false</span>;
    }
    
    <span class="cpp-keyword">if</span> ( ball.x == pLEFT + <span class="cpp-number">1</span> ) { <span class="cpp-comment">// if the ball hits the line…</span>
       
        <span class="cpp-keyword">if</span> ( ball.y == p1.y - <span class="cpp-number">1</span> ) { <span class="cpp-comment">// if it hits the top of the paddle, reflect</span>
            Y_DIR = d_UP;           <span class="cpp-comment">// along x+ and y+</span>
            X_DIR = d_RIGHT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
        
        <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.y == p1.y ) { <span class="cpp-comment">// if it hits the middle, reflect along</span>
            Y_DIR = d_NONE;          <span class="cpp-comment">// x+ only</span>
            X_DIR = d_RIGHT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
        
        <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.y == p1.y + <span class="cpp-number">1</span> ) {
            Y_DIR = d_DOWN;
            X_DIR = d_RIGHT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
    } <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.x == pRIGHT - <span class="cpp-number">1</span> ) { <span class="cpp-comment">// if the ball hits the line…</span>
       
        <span class="cpp-keyword">if</span> ( ball.y == p2.y - <span class="cpp-number">1</span>  ) { <span class="cpp-comment">// if it hits the top of the paddle, reflect</span>
            Y_DIR = d_UP;            <span class="cpp-comment">// along x+ and y+</span>
            X_DIR = d_LEFT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
        
        <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.y == p2.y ) { <span class="cpp-comment">// if it hits the middle, reflect along</span>
            Y_DIR = d_NONE;          <span class="cpp-comment">// x+ only</span>
            X_DIR = d_LEFT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
        
        <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.y == p2.y + <span class="cpp-number">1</span> ) {
            Y_DIR = d_DOWN;
            X_DIR = d_LEFT;
            <span class="cpp-keyword">if</span> ( speedfactor &gt;= <span class="cpp-number">25</span> )
                speedfactor -= <span class="cpp-number">5</span>;
        }
    }
    
    <span class="cpp-keyword">if</span> ( ball.y == pTOP )
        Y_DIR = d_DOWN;
    <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( ball.y == pBOTTOM - <span class="cpp-number">2</span> )
        Y_DIR = d_UP;
    
    ball.oldx = ball.x;
    ball.oldy = ball.y;
    
    ball.x += X_DIR;
    ball.y += Y_DIR;
}

<span class="cpp-keyword">bool</span> pong::check_ball( game_object &amp;ball )
{
    <span class="cpp-keyword">if</span> ( ball.x == LOSE_LINE_RIGHT ) {
        player1score++;
        <span class="cpp-keyword">if</span> ( speedfactor - <span class="cpp-number">1</span> &lt; <span class="cpp-number">100</span> )
            speedfactor += <span class="cpp-number">2</span>;
        flag1 = <span class="cpp-keyword">true</span>;
        <span class="cpp-keyword">return</span> <span class="cpp-keyword">true</span>;
    }
    
    <span class="cpp-keyword">if</span> ( ball.x == LOSE_LINE_LEFT ) {
        player2score++;
        <span class="cpp-keyword">if</span> ( speedfactor - <span class="cpp-number">1</span> &lt; <span class="cpp-number">100</span> )
            speedfactor += <span class="cpp-number">2</span>;
        flag1 = <span class="cpp-keyword">true</span>;
        <span class="cpp-keyword">return</span> <span class="cpp-keyword">true</span>;
    }
    
    <span class="cpp-keyword">return</span> <span class="cpp-keyword">false</span>;
}

<span class="cpp-keyword">int</span> main()
{
    game_object paddle1, paddle2, ball;
    
    <span class="cpp-comment">// paddle 1 initialization</span>
    paddle1.x = pLEFT, paddle1.y = pCENTER;
    paddle1.oldx = paddle1.x, paddle1.oldy = paddle1.y;
    
    paddle1.str_top[ <span class="cpp-number">0</span> ] = '|', paddle1.str_top[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle1.str_top[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    paddle1.str_middle[ <span class="cpp-number">0</span> ] = '|', paddle1.str_middle[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle1.str_middle[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    paddle1.str_bottom[ <span class="cpp-number">0</span> ] = '|', paddle1.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle1.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>';

    <span class="cpp-comment">// paddle 2 initialization</span>
    paddle2.x = pRIGHT, paddle2.y = pCENTER;
    paddle2.oldx = paddle2.x, paddle2.oldy = paddle2.y;
    
    paddle2.str_top[ <span class="cpp-number">0</span> ] = '|', paddle2.str_top[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle2.str_top[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    paddle2.str_middle[ <span class="cpp-number">0</span> ] = '|', paddle2.str_middle[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle2.str_middle[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    paddle2.str_bottom[ <span class="cpp-number">0</span> ] = '|', paddle2.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        paddle2.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>';
    
    <span class="cpp-comment">// ball initialization</span>
    ball.x = pMIDDLE, ball.y = pCENTER;
    ball.oldx = ball.x, ball.oldy = ball.y;
    
    ball.str_top[ <span class="cpp-number">0</span> ] = '\<span class="cpp-number">0</span>', ball.str_top[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        ball.str_top[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    ball.str_middle[ <span class="cpp-number">0</span> ] = <span class="cpp-number">219</span>, ball.str_middle[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        ball.str_middle[ <span class="cpp-number">2</span> ] = '\<span class="cpp-number">0</span>';
    
    ball.str_bottom[ <span class="cpp-number">0</span> ] = '\<span class="cpp-number">0</span>', ball.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>',
        ball.str_bottom[ <span class="cpp-number">1</span> ] = '\<span class="cpp-number">0</span>';
        
    <span class="cpp-keyword">while</span>( <span class="cpp-number">1</span> ) {
        delay( speedfactor );
        print_interface();
        engine.draw_object( paddle1 );
        engine.draw_object( paddle2 );
        engine.draw_object( ball );
        
        <span class="cpp-keyword">if</span> ( kbhit() ) {
            paddle1.oldy = paddle1.y;
            paddle2.oldy = paddle2.y;
            engine.get_input( paddle1.y );
        }
        
        ai_move( paddle2.y );
        
        engine.ball_move( ball, paddle1, paddle2 );
        
        <span class="cpp-keyword">if</span> ( engine.check_ball( ball ) ) {
            paddle1.x = pLEFT, paddle1.y = pCENTER;
            paddle1.oldx = paddle1.x, paddle1.oldy = paddle1.y;
            
            paddle2.x = pRIGHT, paddle2.y = pCENTER;
            paddle2.oldx = paddle2.x, paddle2.oldy = paddle2.y;
            
            ball.x = pMIDDLE, ball.y = pCENTER;
            ball.oldx = ball.x, ball.oldy = ball.y;
            
            gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER - <span class="cpp-number">1</span> );
            cout &lt;&lt; <span class="cpp-literal">"                                     "</span>;
            
            gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER );
            cout &lt;&lt; <span class="cpp-literal">"Oops! Score is "</span> &lt;&lt; player1score &lt;&lt; <span class="cpp-literal">" - "</span> &lt;&lt; player2score &lt;&lt; endl;
            
            gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER + <span class="cpp-number">1</span> );
            cout &lt;&lt; <span class="cpp-literal">"                                     "</span>;
            
            delay( <span class="cpp-number">3000</span> );
            system( <span class="cpp-literal">"cls"</span> );
        } 
    }
}

<span class="cpp-comment">// a couple of functions for utility purposes</span>
<span class="cpp-keyword">void</span> gotoxy( <span class="cpp-keyword">int</span> x, <span class="cpp-keyword">int</span> y )
{
    COORD pos;
    HANDLE screen = GetStdHandle( STD_OUTPUT_HANDLE );

    pos.X = x;
    pos.Y = y;

    SetConsoleCursorPosition( screen, pos );
}

<span class="cpp-keyword">void</span> delay( <span class="cpp-keyword">int</span> milliseconds )
{
    time_t now = clock();
    time_t end = now + milliseconds;
    
    <span class="cpp-keyword">while</span>( now = clock() &lt; end );
}

<span class="cpp-keyword">void</span> print_interface()
{
    gotoxy( <span class="cpp-number">0</span>, <span class="cpp-number">0</span> );
    cout &lt;&lt; <span class="cpp-literal">"Player 1: "</span> &lt;&lt; player1score &lt;&lt; <span class="cpp-literal">"\tPlayer 2: "</span> &lt;&lt; player2score
            &lt;&lt; <span class="cpp-literal">"\t\tGamespeed is currently: "</span>
               &lt;&lt; setw( <span class="cpp-number">2</span> ) &lt;&lt; abs( speedfactor - <span class="cpp-number">100</span> ) &lt;&lt; <span class="cpp-literal">"/80\n\n"</span>
         &lt;&lt; <span class="cpp-literal">"        _________________________________________________________________\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span>
         &lt;&lt; <span class="cpp-literal">"       |________________________________|________________________________|\n"</span>;
}

<span class="cpp-keyword">void</span> ai_move( <span class="cpp-keyword">int</span> &amp;y )
{   
    <span class="cpp-keyword">static</span> DIRECTION dir = d_UP;
    <span class="cpp-keyword">static</span> <span class="cpp-keyword">int</span> dcounter = <span class="cpp-number">0</span>;
    
    <span class="cpp-keyword">if</span> ( y == pTOP )
        dir = d_DOWN;
    <span class="cpp-keyword">else</span>
        <span class="cpp-keyword">if</span> ( y == pBOTTOM - <span class="cpp-number">2</span> )
            dir = d_UP;
        <span class="cpp-keyword">else</span>
            <span class="cpp-keyword">if</span> ( dcounter &gt; <span class="cpp-number">5</span> )
                dir = rand() % <span class="cpp-number">2</span> == <span class="cpp-number">0</span> ? d_UP : d_DOWN;
    y += dir;
    dcounter++;
    <span class="cpp-keyword">if</span> ( dcounter &gt; <span class="cpp-number">6</span> )
        dcounter = <span class="cpp-number">0</span>;
}




</pre></div><!–ENDSCRIPT–>
Please excuse any n00bish-ness. I started off ok. I had an engine class, but after some time it just devolved into a collection of public functions, pointless to have as a class. I can make this hideous beast work, but I want to make it work right. Hints, tips, AI ideas, anything will be appreciated. Thanks in advance. The main thing is AI, though.

Edit: Oh yeah, and it's an ASCII pong, but you already knew that [looksaround]

skulldrudgery--A tricky bit of toil

superpig

1,826

May 23, 2005 05:03 AM

Putting everything into a class is not necessarily a good thing - it doesn't make your code more 'object oriented.' Some functions are naturally suited to being public globals. So don't worry about that.

My issues with your code would be:

Personally, I tend to group all my includes together and put them in alphabetical order (when dependencies are not a problem).
Those enums need commenting.
'flag1' is a terrible variable name. You could change it, or you could fix up the comment to tell us something useful.
You say that game objects will require arrays of length 3 or less, yet your arrays are of length 4. I think you want to change the comment to say 'strings of three characters or less, not including the null terminator.'
What's 'tempx' and 'tempy'?
Using commas like that is a fairly nasty idea, because you're doing two things with one statement. It looks like an attempt to avoid using curly braces after the if - that's a really bad habit to get into, because at first glance there is only one thing being done by that line of code, a misleading way to leave things. Add curly braces and split the gotoxy/cout into seperate statements.
It's often a good idea to bracket out seperate clauses in an if statement to avoid any potential problems with operator precedence (the get_input function's ifs are what I'm looking at).
Don't you want to be copying paddle2.y to paddle2.oldy regardless of whether the user has hit a key, because your AI is going to be moving the paddle?
gotoxy, delay, and ai_move need commenting.

Other than that, it's a fairly nice system you've got there.

Richard "Superpig" Fine - saving pigs from untimely fates - Microsoft DirectX MVP 2006/2007/2008/2009
"Shaders are not meant to do everything. Of course you can try to use it for everything, but it's like playing football using cabbage." - MickeyMouse

Anonymous

May 23, 2005 05:19 AM

I agree with superpig's comments. I also wrote a pong clone as my first game, if you want the source code it's here:

http://www.freewebs.com/crazyballsgame/

It uses directdraw, but the AI could be used in a text-game. Basically, check whether the ball is higher or lower than the AI paddle, and move the paddle a set number of spaces up or down accordingly.

If you scroll down the page ^ there's english underneath.

skulldrudgery

253

Author

May 24, 2005 07:43 AM

Thanks for the tips, superpig. Using your suggestions, and some from PMs and other forums (and of course, looking at other people's code), I think I have managed to clean it up and make it much prettier and easier to understand. As far as the AI, I can't believe how simple it was. I should have been able to figure it out on my own. To the AP, I took a look at your game. It was nice. I like the AI, even if it was a bit easy. Thanks for the good example.

Without further ado:

// ASCII Pong// Programmed by Muhammad al-Haider// pong.cpp#include <conio.h>#include <cmath>#include <ctime>#include <iomanip>#include <iostream>#include <windows.h>using namespace std;/*** global variables ***/const int str_length = 4; // length for game object stringsint p1score = 0;int p2score = 0;int speed = 100; // gamespeed (length of delay for the main game loop)bool randomize = true; // flag to randomize the direction the ball is moving/*** enumerations ***/enum { pLEFT = 10, pRIGHT = 70, pMIDDLE = 39 };    // horizontal(x) positions enum  { pTOP = 3, pBOTTOM = 22, pCENTER = 12 };    // vertical(y) positions   enum { LOSE_LINE_LEFT = 8, LOSE_LINE_RIGHT = 72 }; // the ball is out if it crosses                                                   // one of these lines enum DIRECTION { d_LEFT = -1, d_FLAT = 0, d_RIGHT = 1, // Direction an object is                 d_UP = -1, d_DOWN = 1 };              // travelling/*** structs ***/struct game_object {    char    szTop[ str_length ];  // all game objects will consist of three (or less)    char szMiddle[ str_length ];  // char strings of length 3 or less    char szBottom[ str_length ];    COORD old;    COORD current; };/*** prototypes/forward declarations ***/void print_title();void draw_object( game_object & );void draw_interface();void print_point_message();void ball_move( game_object &, COORD, COORD );void get_input( short & );void ai_move( short &, game_object &, short );bool check_ball( game_object & );void gotoxy( int, int );void delay( int );/******************************************************************************** Main                                                                         ********************************************************************************/int main(){    srand( time( NULL ) ); // seed random number generator        /*** initialize game_objects ***/        game_object paddle1, paddle2, ball;    short dir; // direction the ball is traveling    /**********    | paddle1 |    **********/    paddle1.old.X = paddle1.current.X = pLEFT;    paddle1.old.Y = paddle1.current.Y = pCENTER;        // top string    paddle1.szTop[ 0 ] = '|';    paddle1.szTop[ 1 ] = 0;    paddle1.szTop[ 2 ] = 0;        // middle string    paddle1.szMiddle[ 0 ] = '|';    paddle1.szMiddle[ 1 ] = 0;    paddle1.szMiddle[ 2 ] = 0;        // bottom string    paddle1.szBottom[ 0 ] = '|';    paddle1.szBottom[ 1 ] = 0;    paddle1.szBottom[ 2 ] = 0;        /**********    | paddle2 |    **********/    paddle2.old.X = paddle2.current.X = pRIGHT;    paddle2.old.Y = paddle2.current.Y = pCENTER;        // top string    paddle2.szTop[ 0 ] = '|';    paddle2.szTop[ 1 ] = 0;    paddle2.szTop[ 2 ] = 0;        // middle string    paddle2.szMiddle[ 0 ] = '|';    paddle2.szMiddle[ 1 ] = 0;    paddle2.szMiddle[ 2 ] = 0;        // bottom string    paddle2.szBottom[ 0 ] = '|';    paddle2.szBottom[ 1 ] = 0;    paddle2.szBottom[ 2 ] = 0;        /*******    | ball |    *******/    ball.old.X = ball.current.X = pMIDDLE;    ball.old.Y = ball.current.Y = pCENTER;        // top string    ball.szTop[ 0 ] = 0;    ball.szTop[ 1 ] = 0;    ball.szTop[ 2 ] = 0;        // middle string    ball.szMiddle[ 0 ] = 219;    ball.szMiddle[ 1 ] = 0;    ball.szMiddle[ 2 ] = 0;        // bottom string    ball.szBottom[ 0 ] = 0;    ball.szBottom[ 1 ] = 0;    ball.szBottom[ 2 ] = 0;        print_title();    while( 1 ) {        delay( speed );        draw_interface();        draw_object( paddle1 );        draw_object( paddle2 );        draw_object( ball );                paddle1.old.Y = paddle1.current.Y;        paddle2.old.Y = paddle2.current.Y;                // determine whether ball is moving left or right        if ( ball.old.X < ball.current.X )            dir = d_RIGHT;        if ( ball.old.X > ball.current.X )            dir = d_LEFT;                // move the game objects        if ( kbhit() ) get_input( paddle1.current.Y );        ai_move( paddle2.current.Y, ball, dir );        ball_move( ball, paddle1.current, paddle2.current );                if ( check_ball( ball ) ) { // if one of the players misses the ball                        // reset the game objects            paddle1.old.X = paddle1.current.X = pLEFT;            paddle1.old.Y = paddle1.current.Y = pCENTER;            paddle2.old.X = paddle2.current.X = pRIGHT;            paddle2.old.Y = paddle2.current.Y = pCENTER;            ball.old.X = ball.current.X = pMIDDLE;            ball.old.Y = ball.current.Y = pCENTER;            randomize = true; // randomize horizontal direction of the ball                        print_point_message(); // print a message that the score has changed            delay( 3000 ); // wait three seconds            system( "cls" ); // clear the board and continue        }    }}/******************************************************************************** "Drawing" Functions                                                          ********************************************************************************//*** prints the title and some short information ***/void print_title(){    cout << "\n\n\n\n\n\n\n\n\n\t\t\tASCII Pong version 1.0\n\t\t\tby Muhammad al-Haider"         << "\n\t\t\tskulldrudgery@hotmail.com";    delay( 4000 );    system( "cls" );}/*** prints an object to the screen and clears the object's former position ***/void draw_object( game_object &object ){    // delete object at old location    for ( int i = 0; i < str_length - 1; i++ ) {        if ( object.szTop )<br>            gotoxy( object.old.X + i, object.old.Y ), cout &lt;&lt; <span class="cpp-literal">" "</span>;<br>    <br>        <span class="cpp-keyword">if</span> ( object.szMiddle )<br>            gotoxy( object.old.X + i, object.old.Y + <span class="cpp-number">1</span> ), cout &lt;&lt; <span class="cpp-literal">" "</span>;<br>        <br>        <span class="cpp-keyword">if</span> ( object.szBottom )<br>            gotoxy( object.old.X + i, object.old.Y + <span class="cpp-number">2</span>), cout &lt;&lt; <span class="cpp-literal">" "</span>;<br>    }<br>    <br>    <span class="cpp-comment">// draw object at new location</span><br>    <span class="cpp-keyword">if</span> ( object.szTop[ <span class="cpp-number">0</span> ] )<br>        gotoxy( object.current.X, object.current.Y ), cout &lt;&lt; object.szTop;<br>    <br>    <span class="cpp-keyword">if</span> ( object.szMiddle[ <span class="cpp-number">0</span> ] )<br>        gotoxy( object.current.X, object.current.Y + <span class="cpp-number">1</span> ), cout &lt;&lt; object.szMiddle;<br>        <br>    <span class="cpp-keyword">if</span> ( object.szBottom[ <span class="cpp-number">0</span> ] )<br>        gotoxy( object.current.X, object.current.Y + <span class="cpp-number">2</span>), cout &lt;&lt; object.szBottom;<br>}<br><br><span class="cpp-comment">/*** prints the "interface" of the game: the board, score and gamespeed ***/</span><br><span class="cpp-keyword">void</span> draw_interface()<br>{<br>    gotoxy( <span class="cpp-number">0</span>, <span class="cpp-number">0</span> ); <span class="cpp-comment">// reset the cursor, to begin printing from upper-left corner</span><br>    <br>    cout &lt;&lt; <span class="cpp-literal">"        Player 1: "</span> &lt;&lt; setw( <span class="cpp-number">2</span> ) &lt;&lt; p1score &lt;&lt; <span class="cpp-literal">"  Player 2: "</span> &lt;&lt; setw( <span class="cpp-number">2</span> )<br>         &lt;&lt; p2score &lt;&lt; <span class="cpp-literal">"\t    Gamespeed is currently: "</span> &lt;&lt; setw( <span class="cpp-number">2</span> ) &lt;&lt; abs( speed - <span class="cpp-number">100</span> )<br>         &lt;&lt; <span class="cpp-literal">"/80\n\n"</span>;<br>         <br>    cout &lt;&lt; <span class="cpp-literal">"        _________________________________________________________________\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   A   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   S   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   C   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   I   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   I   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   P   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   O   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   N   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"   G   |                                |                                |\n"</span><br>         &lt;&lt; <span class="cpp-literal">"       |________________________________|________________________________|\n"</span>;<br>}<br><br><span class="cpp-comment">/*** prints a message that the score has changed ***/</span><br><span class="cpp-keyword">void</span> print_point_message()<br>{<br>    gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER - <span class="cpp-number">1</span> );<br>    cout &lt;&lt; <span class="cpp-literal">"                         "</span>;<br>    <br>    gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER + <span class="cpp-number">1</span> );<br>    cout &lt;&lt; <span class="cpp-literal">"                         "</span>;<br>    <br>    gotoxy( pMIDDLE - <span class="cpp-number">10</span>, pCENTER );<br>    cout &lt;&lt; <span class="cpp-literal">"Oops! Score is "</span> &lt;&lt; p1score &lt;&lt; <span class="cpp-literal">" - "</span> &lt;&lt; p2score;<br>}<br>    <br><br><span class="cpp-comment">/*******************************************************************************<br>* "Moving" Functions                                                           *<br>*******************************************************************************/</span><br><br><span class="cpp-comment">/*** moves the ball and reflects it off the surfaces (paddles and borders) ***/</span><br><span class="cpp-keyword">void</span> ball_move( game_object &amp;ball, COORD p1, COORD p2 )<br>{<br>    <span class="cpp-keyword">static</span> DIRECTION Y_DIR = d_FLAT; <span class="cpp-comment">// y direction of the ball</span><br>    <span class="cpp-keyword">static</span> DIRECTION X_DIR = d_LEFT; <span class="cpp-comment">// x direction of the ball</span><br>    <br>    <span class="cpp-comment">// if the randomize flag is set, randomly choose directions and reset flag</span><br>    <span class="cpp-keyword">if</span> ( randomize ) {<br>        X_DIR = rand() % <span class="cpp-number">100</span> &lt; <span class="cpp-number">50</span> ? d_LEFT : d_RIGHT;<br>        Y_DIR = rand() % <span class="cpp-number">100</span> &lt; <span class="cpp-number">50</span> ? d_UP : d_DOWN;<br>        randomize = <span class="cpp-keyword">false</span>;<br>    }<br>    <br>    <span class="cpp-comment">// if the ball reaches the x coordinates (+1) of the left paddle…</span><br>    <span class="cpp-keyword">if</span> ( ball.current.X == pLEFT + <span class="cpp-number">1</span> ) {<br><br>        <span class="cpp-comment">// …check if any part of the paddle would "hit" it, if it hits the…</span><br>        <span class="cpp-keyword">if</span> ( ball.current.Y == p1.Y - <span class="cpp-number">1</span> ) { <span class="cpp-comment">// …top, reflect along y+ and x+</span><br>            Y_DIR = d_UP;<br>            X_DIR = d_RIGHT;<br>            <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>;<br>        } <span class="cpp-keyword">else</span><br>            <span class="cpp-keyword">if</span> ( ball.current.Y == p1.Y ) { <span class="cpp-comment">// …middle, reflect along x+ only</span><br>                Y_DIR = d_FLAT;<br>                X_DIR = d_RIGHT;<br>                <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>;<br>            } <span class="cpp-keyword">else</span><br>                <span class="cpp-keyword">if</span> ( ball.current.Y == p1.Y + <span class="cpp-number">1</span> ) { <span class="cpp-comment">// …bottom, reflect along y- and x+</span><br>                    Y_DIR = d_DOWN;<br>                    X_DIR = d_RIGHT;<br>                    <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>; <span class="cpp-comment">// speed increases each time the ball is hit</span><br>                }<br>    } <span class="cpp-comment">// end if ( ball.current.X == pLEFT + 1 )</span><br>    <br>    <span class="cpp-comment">// if the ball reaches the x coordinates (-1) of the right paddle…</span><br>    <span class="cpp-keyword">if</span> ( ball.current.X == pRIGHT - <span class="cpp-number">1</span> ) {<br>        <br>        <span class="cpp-comment">// …check if any part of the paddle would "hit" it, if it hits the…</span><br>        <span class="cpp-keyword">if</span> ( ball.current.Y == p2.Y - <span class="cpp-number">1</span> ) { <span class="cpp-comment">// …top, reflect along y+ and x-</span><br>            Y_DIR = d_UP;<br>            X_DIR = d_LEFT;<br>            <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>;<br>        } <span class="cpp-keyword">else</span><br>            <span class="cpp-keyword">if</span> ( ball.current.Y == p2.Y ) { <span class="cpp-comment">// …middle, reflect along x- only</span><br>                Y_DIR = d_FLAT;<br>                X_DIR = d_LEFT;<br>                <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>;<br>            } <span class="cpp-keyword">else</span><br>                <span class="cpp-keyword">if</span> ( ball.current.Y == p2.Y + <span class="cpp-number">1</span> ) { <span class="cpp-comment">// …bottom, reflect along y- and x-</span><br>                    Y_DIR = d_DOWN;<br>                    X_DIR = d_LEFT;<br>                    <span class="cpp-keyword">if</span> ( speed &gt;= <span class="cpp-number">25</span> ) speed -= <span class="cpp-number">3</span>;<br>                }<br>    } <span class="cpp-comment">// end if ( ball.current.Y == p2.current.Y - 1 )</span><br>    <br>    <span class="cpp-comment">// if the ball hits the top border…</span><br>    <span class="cpp-keyword">if</span> ( ball.current.Y == pTOP ) Y_DIR = d_DOWN; <span class="cpp-comment">// reflect along y-</span><br>    <br>    <span class="cpp-comment">// if the ball hits the bottom border…</span><br>    <span class="cpp-keyword">if</span> ( ball.current.Y == pBOTTOM - <span class="cpp-number">2</span> ) Y_DIR = d_UP; <span class="cpp-comment">// reflect along y+</span><br>    <br>    <span class="cpp-comment">// update the old coordinates to the current ones</span><br>    ball.old.X = ball.current.X;<br>    ball.old.Y = ball.current.Y;<br>    <br>    <span class="cpp-comment">// update the coordinates of the ball according to the directions the it's moving</span><br>    ball.current.X += X_DIR;<br>    ball.current.Y += Y_DIR;<br>}<br><br><span class="cpp-comment">/*** moves the computer paddle according to the ai routine ***/</span><br><span class="cpp-keyword">void</span> ai_move( <span class="cpp-keyword">short</span> &amp;y, game_object &amp;ball, <span class="cpp-keyword">short</span> h_direction )<br>{   <br>    <span class="cpp-keyword">static</span> DIRECTION dir = d_UP; <span class="cpp-comment">// vertical direction</span><br>    <span class="cpp-keyword">static</span> <span class="cpp-keyword">int</span> dcounter = <span class="cpp-number">0</span>; <span class="cpp-comment">// number of lines moved in one direction</span><br>    <br>    <span class="cpp-comment">// if the ball is close to the right paddle and is traveling that way…</span><br>    <span class="cpp-keyword">if</span> ( ball.current.X &gt; <span class="cpp-number">60</span> &amp;&amp; h_direction == d_RIGHT ) {<br>        dcounter = <span class="cpp-number">0</span>; <span class="cpp-comment">// reset counter</span><br>        <br>        <span class="cpp-keyword">if</span> ( y &gt; ball.current.Y ) <span class="cpp-comment">// if the paddle is lower than the ball, move up</span><br>            y–;<br>        <br>        <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( y &lt; ball.current.Y ) <span class="cpp-comment">// if higher, move down</span><br>            y++;<br>    } <span class="cpp-keyword">else</span> <span class="cpp-keyword">if</span> ( h_direction == d_RIGHT ) {<br>        <span class="cpp-comment">// if the ball is not close, the paddle moves randomly</span><br><br>    <br>        <span class="cpp-keyword">if</span> ( y == pTOP ) dir = d_DOWN;<br>        <span class="cpp-keyword">else</span><br>            <span class="cpp-keyword">if</span> ( y == pBOTTOM - <span class="cpp-number">2</span> ) dir = d_UP;<br>            <span class="cpp-keyword">else</span> <span class="cpp-comment">// if the dcounter is more than five, change to a random direction </span><br>                <span class="cpp-keyword">if</span> ( dcounter == <span class="cpp-number">8</span> ) dir = rand() % <span class="cpp-number">2</span> == <span class="cpp-number">0</span> ? d_UP : d_DOWN;<br>    <br>        dcounter++;<br>        y += dir;<br>    <br>        <span class="cpp-comment">// reset the counter for the number of lines moved</span><br>        <span class="cpp-keyword">if</span> ( dcounter &gt; <span class="cpp-number">8</span> ) dcounter = <span class="cpp-number">0</span>;<br>    }<br>}<br><br><span class="cpp-comment">/*******************************************************************************<br>* Input Functions                                                              *<br>*******************************************************************************/</span><br><br><span class="cpp-comment">/*** get direction input from player, and change y coordinate appropriately ***/</span><br><span class="cpp-keyword">void</span> get_input( <span class="cpp-keyword">short</span> &amp;y )<br>{       <br>    <span class="cpp-keyword">if</span> ( GetAsyncKeyState( <span class="cpp-number">38</span> ) &amp;&amp; y != pTOP ) y–; <span class="cpp-comment">// "up" key, ignore if paddle is at top</span><br>    <span class="cpp-keyword">if</span> ( GetAsyncKeyState( <span class="cpp-number">40</span> ) &amp;&amp; y != pBOTTOM - <span class="cpp-number">2</span> ) y++; <span class="cpp-comment">// "down" key, ignore if paddle is</span><br>                                                           <span class="cpp-comment">// at bottom (- 2 to account for</span><br>                                                           <span class="cpp-comment">// paddle length)</span><br>}<br><br><span class="cpp-comment">/*******************************************************************************<br>* Winning Condition Functions                                                  *<br>*******************************************************************************/</span><br><br><span class="cpp-comment">/*** check if the ball has gone "out" ***/</span><br><span class="cpp-keyword">bool</span> check_ball( game_object &amp;ball )<br>{<br>    <span class="cpp-keyword">if</span> ( ball.current.X == LOSE_LINE_RIGHT ) { <span class="cpp-comment">// if player 2 misses the ball…</span><br>        p1score++; <span class="cpp-comment">// …player one scores</span><br>        <span class="cpp-keyword">if</span> ( speed - <span class="cpp-number">1</span> &lt; <span class="cpp-number">100</span> ) speed += <span class="cpp-number">2</span>; <span class="cpp-comment">// if the game speed is over 0, decrease by 2</span><br>        randomize = <span class="cpp-keyword">true</span>; <span class="cpp-comment">// choose a random direction for the ball ( left or right)</span><br>        <span class="cpp-keyword">return</span> <span class="cpp-keyword">true</span>; <span class="cpp-comment">// the ball was missed</span><br>    }<br>    <br>    <span class="cpp-keyword">if</span> ( ball.current.X == LOSE_LINE_LEFT ) { <span class="cpp-comment">// if player 1 misses the ball…</span><br>        p2score++; <span class="cpp-comment">// …player two scores</span><br>        <span class="cpp-keyword">if</span> ( speed - <span class="cpp-number">1</span> &lt; <span class="cpp-number">100</span> ) speed += <span class="cpp-number">2</span>; <span class="cpp-comment">// if the game speed is over 0, decrease by 2</span><br>        randomize = <span class="cpp-keyword">true</span>; <span class="cpp-comment">// choose a random direction for the ball ( left or right)</span><br>        <span class="cpp-keyword">return</span> <span class="cpp-keyword">true</span>; <span class="cpp-comment">// the ball was missed</span><br>    }<br>    <br>    <span class="cpp-keyword">return</span> <span class="cpp-keyword">false</span>; <span class="cpp-comment">// the ball was not missed</span><br>}<br><br><span class="cpp-comment">/*******************************************************************************<br>* Utility Functions                                                            *<br>*******************************************************************************/</span><br><br><span class="cpp-comment">// move the cursor to the given coordinates</span><br><span class="cpp-keyword">void</span> gotoxy( <span class="cpp-keyword">int</span> x, <span class="cpp-keyword">int</span> y )<br>{<br>    COORD pos;<br>    HANDLE screen = GetStdHandle( STD_OUTPUT_HANDLE );<br><br>    pos.X = x;<br>    pos.Y = y;<br><br>    SetConsoleCursorPosition( screen, pos );<br>}<br><br><span class="cpp-comment">// delay for a given number of milliseconds - busy waiting</span><br><span class="cpp-keyword">inline</span> <span class="cpp-keyword">void</span> delay( <span class="cpp-keyword">int</span> m )<br>{<br>    <span class="cpp-keyword">for</span> ( time_t end = clock() + m; clock() &lt; end; );<br>}<br><br><br><br></pre></div><!–ENDSCRIPT–><br><br>@ superpig feel the impotent force of my ratings++ &#111;n you

skulldrudgery--A tricky bit of toil

Pong AI, and some advice on the code I've managed to cobble together

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