Cohen Sutherland Line Clipping Algorithm in C Programming

#include < stdio.h>
#include < stdlib.h>
#include < graphics.h>
#define MAX 20
 
enum { TOP = 0x1, BOTTOM = 0x2, RIGHT = 0x4, LEFT = 0x8 };
 
enum { FALSE, TRUE };
typedef unsigned int outcode;
 
outcode compute_outcode(int x, int y,int xmin, int ymin, int xmax, int ymax)
{
    outcode oc = 0;

    if (y > ymax)
 oc |= TOP;
    else if (y < ymin)
 oc |= BOTTOM;


    if (x > xmax)
 oc |= RIGHT;
    else if (x < xmin)
 oc |= LEFT;

    return oc;
}

void cohen_sutherland (double x1, double y1, double x2, double y2,double xmin, double ymin, double xmax, double ymax)
{
    int accept;
    int done;
    outcode outcode1, outcode2;

    accept = FALSE;
    done = FALSE;

    outcode1 = compute_outcode (x1, y1, xmin, ymin, xmax, ymax);
    outcode2 = compute_outcode (x2, y2, xmin, ymin, xmax, ymax);
    do
    {
 if (outcode1 == 0 && outcode2 == 0)
 {
     accept = TRUE;
     done = TRUE;
 }
 else if (outcode1 & outcode2)
 {
     done = TRUE;
 }
 else
 {
     double x, y;
     int outcode_ex = outcode1 ? outcode1 : outcode2;
     if (outcode_ex & TOP)
     {
  x = x1 + (x2 - x1) * (ymax - y1) / (y2 - y1);
  y = ymax;
     }

     else if (outcode_ex & BOTTOM)
     {
  x = x1 + (x2 - x1) * (ymin - y1) / (y2 - y1);
  y = ymin;
     }
     else if (outcode_ex & RIGHT)
     {
  y = y1 + (y2 - y1) * (xmax - x1) / (x2 - x1);
  x = xmax;
     }
     else
     {
  y = y1 + (y2 - y1) * (xmin - x1) / (x2 - x1);
  x = xmin;
     }
     if (outcode_ex == outcode1)
     {
  x1 = x;
  y1 = y;
  outcode1 = compute_outcode (x1, y1, xmin, ymin, xmax, ymax);
     }
     else
     {
  x2 = x;
  y2 = y;
  outcode2 = compute_outcode (x2, y2, xmin, ymin, xmax, ymax);
     }
 }
    } while (done == FALSE);

    if (accept == TRUE)
 line (x1, y1, x2, y2);
}



void main()
{
    int n;
    int i, j;
    int ln[MAX][4];
    int clip[4];
    int gd = DETECT, gm;

    initgraph (&gd, &gm, "");
    setbkcolor(WHITE);
    setcolor(BLUE);

    printf ("Enter the number of lines to be clipped:");
    scanf ("%d", &n);

    printf ("Enter the x- and y-coordinates of the line-endpoints:\n");
    for (i=0; i < n; i++)
 for (j=0; j<4; j++)
     scanf ("%d", &ln[i][j]);

    printf ("Enter the x- and y-coordinates of the left-top and right-:");
    printf ("bottom corners\nof the clip window:\n");
    for (i=0; i<4; i++)
 scanf ("%d", &clip[i]);

 cleardevice();

    rectangle (clip[0], clip[1], clip[2], clip[3]);
    for (i=0; i < n; i++)
 line (ln[i][0], ln[i][1], ln[i][2], ln[i][3]);
    getch();
    cleardevice();
    rectangle (clip[0], clip[1], clip[2], clip[3]);
    for (i=0; i < n; i++)
    {
 cohen_sutherland (ln[i][0], ln[i][1], ln[i][2], ln[i][3],
     clip[0], clip[1], clip[2], clip[3]);
 getch();
    }
    closegraph();
}

OUTPUT