### Cohen-Sutherland Line Clipping Algorithm - Graphics & Multimedia Lab - C++ Program

Cohen-Sutherland Line Clipping Algorithm (2)

C++ program - Graphics & Multimedia Lab
Sourcecode:
```/*
* File:   cohsuthlineclip.cpp
* Author: nn
*
* Created on 12 January, 2012, 11:30 AM
*
* Cohen–Sutherland clipping algorithm clips a line from
*P0 = (x0, y0) to P1 = (x1, y1) against a rectangle with
*diagonal from (xmin, ymin) to (xmax, ymax).
*/

#include <cstdlib>
#include <graphics.h>
#define xmax 350
#define ymax 350
#define xmin 100
#define ymin 100
using namespace std;

typedef int OutCode;

const int INSIDE = 0; // 0000
const int LEFT = 1;   // 0001
const int RIGHT = 2;  // 0010
const int BOTTOM = 4; // 0100
const int TOP = 8;    // 1000

OutCode ComputeOutCode(double x, double y)
{
OutCode code;

code = INSIDE;          // initialised as being inside of clip window

if (x < xmin)           // to the left of clip window
code |= LEFT;
else if (x > xmax)      // to the right of clip window
code |= RIGHT;
if (y < ymin)           // below the clip window
code |= BOTTOM;
else if (y > ymax)      // above the clip window
code |= TOP;

return code;
}
void CohenSutherlandLineClipAndDraw(double x0, double y0, double x1, double y1)
{
OutCode outcode0 = ComputeOutCode(x0, y0);
OutCode outcode1 = ComputeOutCode(x1, y1);
bool accept = false;

while (true) {
if (!(outcode0 | outcode1)) {//Bitwise OR is 0. Trivially accept and get out of loop
accept = true;
break;
} else if (outcode0 & outcode1) {//Bitwise AND is not 0. Trivially reject and get out of loop
break;
}
else {

double x, y;

OutCode outcodeOut = outcode0? outcode0 : outcode1;
if (outcodeOut&TOP){           // point is above the clip rectangle
x = x0 + (x1-x0)*(ymax-y0)/(y1-y0);
y = ymax;
} else if(outcodeOut & BOTTOM) { // point is below the clip rectangle
x = x0 + (x1 - x0) * (ymin - y0) / (y1 - y0);
y = ymin;
} else if (outcodeOut & RIGHT) {  // point is to the right of clip rectangle
y = y0 + (y1 - y0) * (xmax - x0) / (x1 - x0);
x = xmax;
} else if (outcodeOut & LEFT) {   // point is to the left of clip rectangle
y = y0 + (y1 - y0) * (xmin - x0) / (x1 - x0);
x = xmin;
}

if (outcodeOut == outcode0) {
x0 = x;
y0 = y;
outcode0 = ComputeOutCode(x0, y0);
} else {
x1 = x;
y1 = y;
outcode1 = ComputeOutCode(x1, y1);
}
}
rectangle(xmin, ymin, xmax, ymax);
line(x0, y0, x1, y1);
getch();
// cleardevice();
}

if(accept) {

rectangle(xmin, ymin, xmax, ymax);
line(x0, y0, x1, y1);
printf("\n\tpoints p0=(%d,%d) p1=(%d,%d)",(int)x0,(int)y0,(int)x1,(int)y1);
}
}

int main(int argc, char** argv)
{
int gd=DETECT,gm;
initgraph(&gd,&gm,NULL);
outtextxy(300,10,"BEFORE LINE CLIPPING");
rectangle(xmin,ymin,xmax,ymax);
line(10,200,350,300);
getch();
cleardevice();
outtextxy(300,10,"AFTER LINE CLIPPING");
CohenSutherlandLineClipAndDraw(10,200,350,300);
getch();
closegraph();
return 0;
}

```
Output:

```nn@linuxmint ~ \$ g++ cohsuthlineclip.cpp -lgraph
nn@linuxmint ~ \$ g++ cohsuthlineclip.cpp -lgraph
coh.cpp: In function ‘int main(int, char**)’:
coh.cpp:105: warning: deprecated conversion from string constant to ‘char*’
coh.cpp:110: warning: deprecated conversion from string constant to ‘char*’
nn@linuxmint ~ \$ ./a.out ```