Thread: 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.

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.

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.