Simple VGA window - Need help guys, Newbie.

This is a discussion on Simple VGA window - Need help guys, Newbie. within the A Brief History of Cprogramming.com forums, part of the Community Boards category; Code: #include<stdio.h> #define WHITE 0xF void set_mode(unsigned char mode) { _asm mov ah,00 _asm mov al,mode _asm int 10h } ...

  1. #1
    Registered User
    Join Date
    Sep 2003
    Posts
    1

    Simple VGA window - Need help guys, Newbie.

    Code:
    #include<stdio.h>
    
    #define WHITE 0xF
    
    void set_mode(unsigned char mode)
    {
    _asm mov ah,00
    _asm mov al,mode
    _asm int 10h
    }
    
    void pset(long x,long y,unsigned char color)
    {
    _asm mov ah,0ch
    _asm mov al,color
    _asm mov edx,x
    _asm mov edx,y
    _asm int 10h
    }
    
    
    void main(void)
    {
    set_mode(0x13);
    pset(10,10,WHITE);
    }
    I put this together after looking at the star field program, on the site, how do i get my window to stay put? a loop? i have visual c++ and borland c++ , so any help is helpful figures.

  2. #2
    Super Moderator VirtualAce's Avatar
    Join Date
    Aug 2001
    Posts
    9,590
    There is another starfield program on this site, I know because I wrote it and posted it somewhere. It is true 3D using a vector3D struct.

    Here is some help with your problem. Asm blocks can be placed within braces instead of placing _asm or asm in front of every line.
    Here is a small mode 13h VGA unit to get you started

    Code:
    //16 bit typedefs
    typedef unsigned char BYTE;
    typedef unsigned int WORD;
    typedef unsigned long DWORD;
    
    #define FALSE 0
    #define TRUE 1
    #define XYTOMEM(x,y) ((y<<8)+(y<<6)+x)
    
    struct tagVGA
    {
      BYTE far *Screen;
      BYTE far *Buffer;
      BYTE far *Surface;
      int BufferMode;
    }VGA;
    
    void SetMode(WORD mode);
    void Pset(WORD x,WORD y,BYTE color);
    void SetBufferMode(WORD newmode=TRUE);
    void Flip(void);
    void CLS(BYTE color);
    void Line(WORD x,WORD y,WORD x2,WORD y2,BYTE color);
    
    void SetMode(WORD mode)
    {
      asm {
        mov    ax,[mode]
        int      10h
      }
      VGA.BufferMode=FALSE;  
      VGA.Screen=(BYTE far*)MK_FP(0xa000,0);
      VGA.Buffer=new BYTE[64000L];
      VGA.Surface=VGA.Screen;
    }
    
    void Pset(WORD x,WORD y,BYTE color)
    {
      VGA.Surface[XYTOMEM(x,y)]=color;
    }
    
    
    void SetBufferMode(WORD newmode)
    {
      switch(newmode)
      {
         case TRUE:  VGA.Surface=VGA.Buffer;break;
         case FALSE: VGA.Surface=VGA.Screen;break;
         default: VGA.Surface=VGA.Screen;break; 
      }
    }
    
    void Flip(void)
    {
      //Does not check for screen refresh
      BYTE far *Screen=VGA.Surface;
      BYTE far *Buffer=VGA.Buffer;
      asm {
         push   si
         push   di
         push   ds
    
         les      di,[Screen]
         lds      si,[Buffer]
         mov    cx,07D00h
         rep     movsw
    
         pop    ds
         pop    di
         pop    si
       }
    }
    
    void CLS(BYTE color)
    {
      BYTE far *Surface=VGA.Surface;
      asm {
        les    di,[Surface]
        mov  al,[color]
        mov  ah,[color]
        mov  cx,07D00h
        rep   stosb
      }
    }
    
    void Line(WORD x,WORD y,WORD x2,WORD y2,BYTE color)
    {
      int eterm=0;
      int diffx=x2-x;
      int diffy=y2-y;
      int yunit=320;
      int xunit=1;
      WORD offset=XYTOMEM(x,y);
      int length=0;
    
      if (diffx<0)
      {
        xunit=-xunit;
        diffx=-diffx;
      }
      if (diffy<0)
      {
        yunit=-yunit;
        diffy=-diffy;
       }
    
       if (diffx>diffy)
       {
          length=diffx+1;
          for (int i=0;i<length;i++)
          {      
             VGA.Surface[offset]=color;
             offset+=xunit;
             eterm+=diffx;
             if (eterm>diffy)
             {
                eterm-=diffy;
                offset+=yunit;
             }
          }
       }
       else
       {
          length=diffy+1;
          for (i=0;i<length;i++)
          {
             VGA.Surface[offset]=color;
             offset+=yunit;
             eterm+=diffy;
             if (eterm>0)
             {
                eterm-=diffx;
                offset+=xunit;
             }
          }
        }
    }
    If the line drawing algo does not work right then PM me - I coded this from memory and I always mess the line algo up.

    Test the lines like this:

    //Blue line from top left to center
    Line(0,0,160,100,1);

    //Red line from top right to center
    Line(319,0,160,100,4);

    //Green line from bottom left to center
    Line(0,199,160,100,2);

    //Yellow line from bottom right to center
    Line(319,199,160,100,14);

    If these lines are not right then the algo is messed up either on the x axis or the y.

    Again, PM me if you have any probs.

  3. #3
    Super Moderator VirtualAce's Avatar
    Join Date
    Aug 2001
    Posts
    9,590
    Create a library out of the VGA module and then add this for the starfield. Do not add this to the VGA module because you want to be able to re-use the VGA module for other programs.


    Code:
    #include <stdlib.h>
    
    struct point3D
    {
       double x;
       double y;
       double z;
    };
    
    #define NUMSTARS 200
    #define MAXZ 50
    #define VIEWDIST 320
    
    
    point3D Stars[NUMSTARS];
    
    void CreateStars(void);
    void MoveStars(double speed);
    void DisplayStars(void);
    
    void CreateStars(void)
    {
      for (int i=0;i<NUMSTARS;i++)
      {
         Stars[i].x=-random(320)+random(640);
         Stars[i].y=-random(200)+random(400);
         Stars[i].z=random(MAXZ);
       }
    }
    
    void MoveStars(double speed)
    {
      for (int i=0;i<NUMSTARS;i++)
      {
        double x=Stars[i].x;
        double y=Stars[i].y;
        double z=Stars[i].z;
        z+=speed;
        if (z<0 || z>MAXZ)
        {
           x=-random(320)+random(640);
           y=-random(200)+random(400);
           z=random(MAXZ); 
        }
        Stars[i].x=x;
        Stars[i].y=y;
        Stars[i].z=z;
       }
    }
    
    void DisplayStars(void)
    {
      for (int i=0;i<NUMSTARS;i++)
      {
         double x=Stars[i].x;
         double y=Stars[i].y;
         double z=Stars[i].z;
         if (z==0.0) z=1.0;
         int screenx=(x*VIEWDIST)/z;
         int screeny=(y*VIEWDIST)/z;
         if (screenx<0 || screenx>319 || screen y<0 || screeny>199)
         {
             Stars[i].x=-random(320)+random(640);
             Stars[i].y=-random(200)+random(400);
             Stars[i].z=random(MAXZ); 
         }
         else VGA.Surface[XYTOMEM(screenx,screeny)]=15;
      }
    }
    
    int main(void)
    {
      double shipspeed=2;
      SetMode(0x13);
      SetBufferMode();
      CreateStars();
      while (!kbhit())
      {
         CLS(0);
         MoveStars(shipspeed);
         DisplayStars();
      }
      return(0);
    }

    Again, if you have probs with the code or understanding what it does - PM me or post here.

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