Help with a simple game

This is a discussion on Help with a simple game within the Game Programming forums, part of the General Programming Boards category; I'm trying to learn as I go. I found a simple game in a graphics book that I've been messing ...

  1. #1
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    Mar 2004
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    Help with a simple game

    I'm trying to learn as I go. I found a simple game in a graphics book that I've been messing with to learn about graphics. The game originally put a ship "<--*-->" (that's the ship) on the very top of a window and you could move it from left to right while stars would pass by making it look like it was moving through space.

    I want to move the ship down about 10 spaces to the middle of the console window just to know that I can do it.

    It's a console application. Here is the code.

    The line that makes the ship is:

    Draw_String(player_x,5,"<--*-->")

    Instead of 5, it used to be 0 which placed it at the top. The way I have it now does the job somewhat but there is still "residue" leftover and you can still see the ship behind it as it moves. I want to get rid of the leftover graphic from the ship.

    Code:
    // PROG2_1.CPP - A simple console based game to illustrate
    // a generic game loop
    
    // INCLUDES ///////////////////////////////////////////////
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <ctype.h> 
    #include <conio.h>
    #include <windows.h>
    #include <time.h>
    
    // DEFINES ////////////////////////////////////////////////
    
    #define MAX_X        77  // maximum x position for player
    #define SCROLL_POS   24  // the point that scrolling occurs
      
    // PROTOTYPES /////////////////////////////////////////////
    
    void Init_Graphics(void);
    inline void Set_Color(int fcolor, int bcolor);
    inline void Draw_String(int x,int y, char *string);
    
    // GLOBALS ////////////////////////////////////////////////
    
    CONSOLE_SCREEN_BUFFER_INFO con_info;   // holds screen info
    
    HANDLE hconsole;         // handle to console
    int    game_running = 1; // state of game, 0=done, 1=run
    
    // FUNCTIONS //////////////////////////////////////////////
    
    void Init_Graphics(void)
    {
    // this function initializes the console graphics engine
    
    COORD console_size = {80,25}; // size of console
    
    // seed the random number generator with time
    srand((unsigned)time(NULL));
    
    // open i/o channel to console screen
    hconsole=CreateFile("CONOUT$",GENERIC_WRITE | GENERIC_READ,
             FILE_SHARE_READ | FILE_SHARE_WRITE,
             0L, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0L);
    
    // make sure we are in 80x25
    SetConsoleScreenBufferSize(hconsole,console_size);
    
    // get details for console screen                       
    GetConsoleScreenBufferInfo(hconsole,&con_info);
    
    } // end Init_Graphics
    
    ///////////////////////////////////////////////////////////
    
    inline void Set_Color(int fcolor, int bcolor=0) 
    {
    // this function sets the color of the console output
    SetConsoleTextAttribute(hconsole,(WORD)((bcolor << 4) | 
                            fcolor));
    
    } // Set_Color
    
    ///////////////////////////////////////////////////////////
    
    inline void Draw_String(int x,int y, char *string)
    {
    // this function draws a string at the given x,y
    
    COORD cursor_pos; // used to pass coords
    
    // set printing position
    cursor_pos.X = x;
    cursor_pos.Y = y;
    SetConsoleCursorPosition(hconsole,cursor_pos);
    
    // print the string in current color
    printf("%s",string);
    
    } // end Draw_String
    
    ///////////////////////////////////////////////////////////
    
    inline void Clear_Screen(void)
    {
    // this function clears the screen
    
    // set color to white on black
    Set_Color(15,0);
    
    // clear the screen
    for (int index=0; index<=25; index++)
        Draw_String(0, SCROLL_POS,"\n");
    
    } // end Clear_Screen
    
    // MAIN GAME LOOP /////////////////////////////////////////
    
    void main(void)
    {
    char key;            // player input data
    int  player_x = 40;  // player's x position
    
    // SECTION: initialization
    
    // set up the console text graphics system
    Init_Graphics();
    
    // clear the screen
    
    
    // SECTION: main event loop, this is where all the action  
    // takes place, the general loop is erase-move-draw
    
    while(game_running)
         {
         // SECTION: erase all the objects or clear screen
    
    
         // nothing to erase in our case   
    
         // SECTION: get player input
         if (kbhit())
            {
            // get keyboard data, and filter it
            key = toupper(getch());
    
            // is player trying to exit, if so exit
            if (key=='Q' || key==27)
               game_running = 0; 
    
            // is player moving left        
            if (key=='A')
               player_x--;
               
            // is player moving right
            if (key=='S')
               player_x++;
    
            } // end if   
    
         // SECTION: game logic and further processing
         
         // make sure player stays on screen 
         if (++player_x > MAX_X)
            player_x=MAX_X;     
    
         if (--player_x < 0)
            player_x=0;     
    
         // SECTION: draw everything
    
         // draw next star at random position
         Set_Color(15,0);
         Draw_String(rand()%80, SCROLL_POS, ".\n");
         
         // draw player 
         Set_Color(2,0);
         
         Draw_String(player_x,5,"<--*-->");
         Set_Color(0,0);
    	 Draw_String(player_x,4,"<<<<<--*-->>>>>");
    
    	 
           
    
         // SECTION: synchronize to a constant frame rate
         Sleep(40);   
    Clear_Screen();
         } // end while
    
    // SECTION: shutdown and bail
    
    
    printf("\nG A M E  O V E R \n\n");
    
    } // end main

  2. #2
    ...
    ... is offline
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    everytime the ship moves, clear the space behind it (IE, draw a bunch of spaces or a tab at the position behind the ship).
    I came up with a cool phrase to put down here, but i forgot it...

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