PROGRAM TO IMPLEMENT SUTHERLAND-COHEN CLIPPING ALGORITHM

#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>
void draw_line(float,float,float,float);
int linecode(int,int,int,int,int,int);
main()
{
 int driver,mode;
 float x1,y1,x2,y2;
 int Xu,Yu,Xb,Yb;
 int code,code1,code2;
 float slope,x,y;
 clrscr();
 printf("Enter the two end-points of the line:");
 printf("\nx1 =");
 scanf("%f",&x1);
 printf("y1 =");
 scanf("%f",&y1);
 printf("x2 =");
 scanf("%f",&x2);
 printf("y2 =");
 scanf("%f",&y2);
 printf("\n\nEnter the upper-left and bottom-right vertices of the clip rectangle");
 printf("\nEnter the upper-left vertex of the rectangle\n");
 printf("Xu =");
 scanf("%d",&Xu);
 printf("Yu =");
 scanf("%d",&Yu);
 printf("\nEnter the bottom-right vertex of the rectangle\n");
 printf("Xb =");
 scanf("%d",&Xb);
 printf("Yb =");
 scanf("%d",&Yb);
 clrscr();
 driver = DETECT;
 initgraph(&driver,&mode,"\\turboc3\\bgi"); //The path may be different
 printf("Line....");
 draw_line(x1,y1,x2,y2);
 getch();
 clrscr();
 printf("Clipping area....");
 rectangle(Xu,Yu,Xb,Yb);
 getch();
 clrscr();
 printf("Clipped line....");
 rectangle(Xu,Yu,Xb,Yb);
code1 = linecode(x1,y1,Xu,Yu,Xb,Yb);
 code2 = linecode(x2,y2,Xu,Yu,Xb,Yb);
 while(1)
{
 if((code1|code2) == 0)// Accept
   {
    draw_line(x1,y1,x2,y2);
    break;
   }
 if(code1&code2)// Reject
break;
 if(code1 != 0)
code = code1;
 else
code = code2;
 slope = (y2-y1)/(x2-x1);
 if(code & 8)
   {
x = x1 + (1/slope) * (Yu - y1);
y = Yu;
   }
       if(code & 4)
   {
 x = x1 + (1/slope) * (Yb - y1);
 y = Yb;
   }
if(code & 2)
  {
 y = y1 + slope * (Xb - x1);
 x = Xb;
  }
if(code & 1)
  {
 y = y1 + slope * (Xu - x1);
 x = Xu;
  }
if(code == code1)
  {
 x1 = x;
 y1 = y;
 code1 = linecode(x1,y1,Xu,Yu,Xb,Yb);
  }
if(code == code2)
  {
 x2 = x;
 y2 = y;
 code2 = linecode(x2,y2,Xu,Yu,Xb,Yb);
  }
     }
 getch();
 closegraph();
}
//Use DDA algorithm to draw the line
void draw_line(float x1,float y1,float x2,float y2)
{
 float m,c;
 float x,y,x0,y0;
 float dy,dx;

 m = (y2 - y1)/(x2 - x1);

 if(fabs(m) <= 1)
 {
  if(x1 < x2) //line drawn left to right
    {
y0 = y1;
for(x=x1;x<=x2;x++)
   {
    y = y0 + m;
                putpixel(x,y,EGA_WHITE);
    y0 = y;
   }
}
   else //line drawn right to left
{
 y0 = y1;
 for(x=x1;x>=x2;x--)
    {
y = y0 - m;
putpixel(x,y,EGA_WHITE);
y0 = y;
    }
}
 }
 else //fabs(m)>1
 {
  if(y1 < y2) //Line drawn top to bottom
    {
x0 = x1;
for(y=y1;y<=y2;y++)
   {
    x = x0 + 1/m;
    putpixel(x,y,EGA_WHITE);
    x0 = x;
   }
   }
  else //line drawn bottom to top
   {
    x0 = x1;
    for(y=y1;y>=y2;y--)
 {
  x = x0 - 1/m;
  putpixel(x,y,EGA_WHITE);
  x0 = x;
 }
   }
 }
}

int linecode(int x,int y,int x1,int y1,int x2,int y2)
{
 int lncode = 0;
 if(y<y1)
    lncode |= 8;
 if(y>y2)
    lncode |= 4;
 if(x>x2)
    lncode |= 2;
 if(x<x1)
    lncode |= 1;
 return lncode;
}