C/C++ Program to draw a line by DDA approach

//Program to draw a line by DDA approach

Source code

#include <graphics.h>

#include <stdlib.h>

#include <stdio.h>

#include <conio.h>

#include<math.h>

#include<dos.h>

int round(float y)

{

int y1;

float diff;

y1=y;

diff=y-y1;

if(diff>0.5)

 return(y1+1);

else

 return(y1);

}

int main(void)

{

  /* request auto detection */

  int gdriver = DETECT, gmode, errorcode;

  int xmax, ymax;

  int x,y,i,a;

  float x1,x2,y1,y2,x3,y3,m,m1,dy,dx,t=1;

  printf("Enter the value of x1,x2,y1,y2");

  scanf("%f%f%f%f",&x1,&x2,&y1,&y2);

  printf("enter 1 for left to right and 2 for right to left");

  scanf("%d",&a);

  clrscr();

  /* initialize graphics and local variables */

  initgraph(&gdriver, &gmode, "c:\\tc\\bgi");

  /* read result of initialization */

  errorcode = graphresult();

  /* an error occurred */

  if (errorcode != grOk)

  {

     printf("Graphics error: %s\n", grapherrormsg(errorcode));

     printf("Press any key to halt:");

     getch();

     exit(1);

  }

  setcolor(getmaxcolor());

  xmax = getmaxx();

  ymax = getmaxy();

  dy=y2-y1;

  dx=x2-x1;

  m=dy/dx;

  x1=x1+xmax/2;

  x2=x2+xmax/2;

  y1=ymax/2-y1;

  y2=ymax/2-y2;

  for(i=0;i<ymax;i++)

   putpixel(xmax/2,i,15);

  for(i=0;i<xmax;i++)

   putpixel(i,ymax/2,15);

 if(a==1)

  {

   if((m<1&&m>-1))

    {

     y3=y1;

     for(x=x1;x<x2;x++)

      {

putpixel(x,round(y3),15);

delay(100);

y3=y3-m;

      }

    }

 else

  {

   x3=x1;

   m1=t/m;

   for(y=y1;y>y2;y--)

    {

     putpixel(round(x3),y,15);

     delay(100);

     x3=x3+m1;

    }

   }

 }

 else

   {

    if((m<1&&m>-1))

     {

      y3=y2;

      for(x=x2;x>x1;x--)

     {

    putpixel(x,round(y3),15);

    delay(100);

    y3=y3+m;

   }

  }

 else

  {

   x3=x2;

   m1=t/m;

   for(y=y2;y<y1;y++)

    {

     putpixel(round(x3),y,15);

     delay(100);

     x3=x3-m1;

    }

   }

 }

  /* clean up */

  getch();

  closegraph();

  return 0;

}