Cohen-Sutherland algo.cpp

#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;

    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]);

    initgraph (&gd, &gm, "..//bgi");

    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();
}