Implementation of Cohen Sutherland line clipping algorithm

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<math.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 &gt; ymax)
    oc |= TOP;
    else if (y &lt; ymin)
    oc |= BOTTOM;
    if (x &gt; xmax)
    oc |= RIGHT;
    else if (x &lt; 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 &amp;&amp; outcode2 == 0)
        {
            accept = TRUE;
            done = TRUE;
        }
        else if (outcode1 &amp; outcode2)
        {
            done = TRUE;
        }
        else
        {
            double x, y;
            int outcode_ex = outcode1 ? outcode1 : outcode2;
            if (outcode_ex &amp; TOP)
            {
                x = x1 + (x2 - x1) * (ymax - y1) / (y2 - y1);
                y = ymax;
            }
            else if (outcode_ex &amp; BOTTOM)
            {
                x = x1 + (x2 - x1) * (ymin - y1) / (y2 - y1);
                y = ymin;
            }
            else if (outcode_ex &amp; 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", &amp;n);
    printf ("Enter the x- and y-coordinates of the line-endpoints:\n");
    for (i=0; i&lt;n; i++)
    for (j=0; j&lt;4; j++)
    scanf ("%d", &amp;ln[i][j]);
    clip[0]=100;
    clip[1]=100;
    clip[2]=300;
    clip[3]=300;
    initgraph (&amp;gd, &amp;gm, "..//bgi");
    rectangle (clip[0], clip[1], clip[2], clip[3]);
    for (i=0; i&lt;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&lt;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();
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

#include<stdio.h>

#include<conio.h>

#include<graphics.h>

#include<math.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);

{

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]);

clip[0]=100;

clip[1]=100;

clip[2]=300;

clip[3]=300;

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();

}

Leave a Comment