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Displaying  Source Code(s)  
 

 
Program to implement Polygon Clipping Algorithm.

--------------------------------------------------------------------------------



#include<iostream.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>
#include<dos.h>
#include<process.h>

int pixels[2][4];
float xn1,xn2,yn1,yn2,x3,y3,m;


void show_quadrant()
{
cleardevice();
rectangle(120,40,320,240);
rectangle(320,40,520,240);
rectangle(120,240,320,440);
rectangle(320,240,520,440);
for(int i=130;i<=510;i+=10)
{
if(i==320)
continue;
outtextxy(i,237,"+");
}
for(i=50;i<=430;i+=10)
{
if(i==240)
continue;
outtextxy(317,i,"-");
}
outtextxy(310,230,"O");
outtextxy(530,240,"X");
outtextxy(320,450,"-Y");
outtextxy(100,240,"-X");
outtextxy(320,30,"Y");
}


void midpt(int x1,int y1,int x2,int y2,int xmin,int ymin,int xmax,int ymax)
{
int fl=1;
int pixels[2][4],i,j;
for(i=0;i<2;i++)
for(j=0;j<4;j++)
pixels[i][j]=0;
if(y1>ymax)
pixels[0][0]=1;
if(y1<ymin)
pixels[0][1]=1;
if(x1>xmax)
pixels[0][2]=1;
if(x1<xmin)
pixels[0][3]=1;
if(y2>ymax)
pixels[1][0]=1;
if(y2<ymin)
pixels[1][1]=1;
if(x2>xmax)
pixels[1][2]=1;
if(x2<xmin)
pixels[1][3]=1;

for(j=0;j<4;j++)
{
if(pixels[0][j]==0&&pixels[1][j]==0)
continue;

if(pixels[0][j]==1&&pixels[1][j]==1)
{
fl=3;
break;
}
fl=2;
}
switch(fl)
{
case 1:
line(320+x1,240-y1,320+x2,240-y2);
break;

case 3:
cout<<"

a" Line Is Not Visible...:-(";
break;

case 2:
int ox1=x1,ox2=x2,oy1=y1,oy2=y2;
xn1=x1;
yn1=y1;
xn2=x2;
yn2=y2;
fl=0;
x3=x1;
y3=y1;
while(1)
{
if(!(y1>ymax || y1<ymin || x1>xmax || x1<xmin) && (x3 || y3)!=0.1)
break;
x3=(x1+x2)/2.0;
y3=(y1+y2)/2.0;

if(!(y3>ymax || y3<ymin || x3>xmax || x3<xmin))
fl=1;
else
fl=0;

if(fl)
{
x2=x3;
y2=y3;
}
else
{
x1=x3;
y1=y3;
}
}
xn1=x3;
yn1=y3;
fl=0;
x1=ox1;
x2=ox2;
y1=oy1;
y2=oy2;
x3=x2;
y3=y2;
while(1)
{
if(!(y2>ymax || y2<ymin || x2>xmax || x2<xmin) && (x3 || y3)!=0.1)
break;
x3=(x1+x2)/2.0;
y3=(y1+y2)/2.0;

if(!(y3>ymax || y3<ymin || x3>xmax || x3<xmin))
fl=1;
else
fl=0;

if(fl)
{
x1=x3;
y1=y3;
}
else
{
x2=x3;
y2=y3;
}
}
xn2=x3;
yn2=y3;
line(320+xn1,240-yn1,320+xn2,240-yn2);
break;
}
}

void show_message()
{
char *mess[]={"-","=","["," ","P","o","l","y","g","o","n"," ",
"C","l","i","p","p","i","n","g"," ","]","=","-"};
int xx=28,xxx=52,i,j;
_setcursortype(_NOCURSOR);
for(i=0,j=24;i<16,j>=12;i++,j--)
{
gotoxy(xx,1);
cout<<mess[i];
xx++;
gotoxy(xxx,1);
cout<<mess[j];
xxx--;
delay(50);
}
_setcursortype(_NORMALCURSOR);
}


void main()
{
clrscr();
int gd=DETECT,gm,i,j;
int xmin,ymin,xmax,ymax,x[10],y[10],ver;
int choice,ed[20],num;
show_message();
cout<<"

" Enter The Co-Ordinates Of The Clipping Window."";
cout<<"

" Enter X(min) & Y(min) ":=";
cin>>xmin>>ymin;
cout<<"
" Enter X(max) & Y(max) ":=";
cin>>xmax>>ymax;
cout<<"

" Enter The No Of Vertices Of Polygon ":=";
cin>>ver;
for(i=0;i<ver;i++)
{
cout<<"
" Vertex X["<<i+1<<"] Y["<<i+1<<"] ":=";
cin>>x[i]>>y[i];
}
x[ver]=x[0];
y[ver]=y[0];
clrscr();
initgraph(&gd,&gm,"..\bgi");
clearviewport();
show_quadrant();
line(320+xmin,240-ymin,320+xmin,240-ymax);
line(320+xmin,240-ymax,320+xmax,240-ymax);
line(320+xmax,240-ymax,320+xmax,240-ymin);
line(320+xmax,240-ymin,320+xmin,240-ymin);
for(i=0;i<ver;i++)
line(320+x[i],240-y[i],320+x[i+1],240-y[i+1]);
getch();
cleardevice();
show_quadrant();
line(320+xmin,240-ymin,320+xmin,240-ymax);
line(320+xmin,240-ymax,320+xmax,240-ymax);
line(320+xmax,240-ymax,320+xmax,240-ymin);
line(320+xmax,240-ymin,320+xmin,240-ymin);
for(i=0;i<ver;i++)
{
midpt(x[i],y[i],x[i+1],y[i+1],xmin,ymin,xmax,ymax);
}
getch();
closegraph();
}

 

 

 

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