program based on POLYGON CLIPPING

POLYGON CLIPPING
#include
#include
#include
int n,p,x,y,i,j;
int xwmin,ywmin,xwmax,ywmax;
int x1,y1,x2,y2,xmax,ymax;
float m;
char flag;
float dy,dx;
main()
{int gd,gm;
int a[10][10],b[10][10],c[10][10],d[10][10],e[10][10];
detectgraph(&gd,&gm);
initgraph(&gd,&gm,"d:\\tc\\bgi");
printf("\n\n\tEnter the no. of edges of polygon : ");
scanf("%d",&n);
printf("\n\n\tEnter the cordinates of polygon :\n\n\n ");
for(i=0;i {
printf("\tX%d Y%d : ",i,i);
scanf("%d %d",&a[i][0],&a[i][1]); }
a[n][0]=a[0][0];
a[n][1]=a[0][1];
printf("\n\tEnter the co_ordinates of window :\n ");
printf("\n\txwmin , ywmin : ");
scanf("%d %d",&xwmin,&ywmin);
printf("\n\txwmax , ywmax : ");
scanf("%d %d",&xwmax,&ywmax);
xmax = 640; ymax = 480;
cleardevice();
setcolor(35);
for(i=0;i line(a[i][0],ymax-a[i][1],a[i+1][0],ymax-a[i+1][1]);
rectangle(xwmin,ymax-ywmin,xwmax,ymax-ywmax);
getch();
setcolor(35);
clip_left(a,b);
clip_right(b,c);
clip_bottom(c,d);
clip_top(d,e);
cleardevice();
setcolor(63);
for(i=0;i { line(e[i][0],ymax-e[i][1],e[i+1][0],ymax-e[i+1][1]); }
getch();
}/*-main()-*/
clip_left(int a[10][10], int b[10][10])
{p=0;flag=0;m=0;
for(i=0;i { dy=a[i+1][1]-a[i][1];
dx=a[i+1][0]-a[i][0];
if((dx!=0)&&(dy!=0))
{m=(dy/dx);}
if((a[i][0]=xwmin) ) flag=0;
if((a[i][0]>=xwmin)&&(a[i+1][0]>=xwmin)) flag=1;
if((a[i][0]>=xwmin)&&(a[i+1][0] if((a[i][0] switch(flag)
{
case 0 :x=xwmin;
if(dy!=0)
y=(int)(a[i][1]+m*(x-a[i][0]));
else
y=a[i][1];

b[p][0]=x;
b[p][1]=y;
p++;

b[p][0]=a[i+1][0];
b[p][1]=a[i+1][1];
p++;
break;

case 1 : b[p][0]=a[i+1][0];
b[p][1]=a[i+1][1];
p++;
break;

case 2: x=xwmin;
if(dy!=0)
y=(int)(a[i][1]+m*(x-a[i][0]));
else
y=a[i][1];
b[p][0]=x;
b[p][1]=y;
p++;
}}
b[p][0]=b[0][0];
b[p][1]=b[0][1];
cleardevice();
setcolor(35);
rectangle(xwmin,ymax-ywmin,xwmax,ymax-ywmax);
setcolor(63);
for(i=0;i {
line(b[i][0],ymax-b[i][1],b[i+1][0],ymax-b[i+1][1]);
getch();
}
getch();}
clip_right(int b[10][10],int c[10][10])
{
n=p; p=0; m=0;
for(i=0;i { dy=b[i+1][1]-b[i][1];
dx=b[i+1][0]-b[i][0];
if((dx!=0)&&(dy!=0))
{m=(dy/dx);}
if((b[i][0]>xwmax)&&(b[i+1][0]<=xwmax) ) flag=0;
if((b[i][0]<=xwmax)&&(b[i+1][0]<=xwmax) ) flag=1;
if((b[i][0]<=xwmax)&&(b[i+1][0]>xwmax) ) flag=2;
if((b[i][0]>xwmax)&&(b[i+1][0]>xwmax) ) flag=3;
switch(flag)
{
case 0 : x=xwmax;
if(dy!=0)
y=(int)(b[i][1]+m*(x-b[i][0]));
else
y=b[i][1];
c[p][0]=x;
c[p][1]=y;
p++;
c[p][0]=b[i+1][0];
c[p][1]=b[i+1][1];
p++;
break;
case 1 : c[p][0]=b[i+1][0];
c[p][1]=b[i+1][1];
p++;
break;
case 2 : x=xwmax;
if(dy!=0)
y=(int)(b[i][1]+m*(x-b[i][0]));
else
y=b[i][1];
c[p][0]=x;
c[p][1]=y;
p++;}}
c[p][0]=c[0][0];
c[p][1]=c[0][1];
cleardevice();setcolor(35);
rectangle(xwmin,ymax-ywmin,xwmax,ymax-ywmax);
setcolor(63);
for(i=0;i {
line(c[i][0],ymax-c[i][1],c[i+1][0],ymax-c[i+1][1]);
getch();
}
getch();}
clip_bottom(int c[10][10],int d[10][10])
{
n=p; p=0; m=0;
for(i=0;i {
dy=c[i+1][1]-c[i][1];
dx=c[i+1][0]-c[i][0];
if((dx!=0)&&(dy!=0))
{
m=(dy/dx);
}
if((c[i][1]=ywmin) ) flag=0;
if((c[i][1]>=ywmin)&&(c[i+1][1]>=ywmin) ) flag=1;
if((c[i][1]>=ywmin)&&(c[i+1][1] if((c[i][1] switch(flag)
{
case 0 : y=ywmin;
if(dx!=0)
x=abs((int)(c[i][0]+(1/m)*(y-c[i][1])));
else
x=c[i][0];
d[p][0]=x;
d[p][1]=y;
p++;
d[p][0]=c[i+1][0];
d[p][1]=c[i+1][1];
p++;
break;
case 1 : d[p][0]=c[i+1][0];
d[p][1]=c[i+1][1];
p++;
break;
case 2 : y=ywmin;
if(dx!=0)
x=abs((int)(c[i][0]+(1/m)*(y-c[i][1])));
else
x=c[i][0];
d[p][0]=x;
d[p][1]=y;
p++;
}}
d[p][0]=d[0][0];
d[p][1]=d[0][1];
cleardevice();
setcolor(35);
rectangle(xwmin,ymax-ywmin,xwmax,ymax-ywmax);
setcolor(63);
for(i=0;i {
line(d[i][0],ymax-d[i][1],d[i+1][0],ymax-d[i+1][1]);
getch();
}getch();}
clip_top(int d[10][10],int e[10][10])
{ n=p;
p=0;
for(i=0;i { dy=d[i+1][1]-d[i][1];
dx=d[i+1][0]-d[i][0];
if((dx!=0)&&(dy!=0))
{m=(dy/dx);}
if((d[i][1]>ywmax)&&(d[i+1][1]<=ywmax) ) flag=0;
if((d[i][1]<=ywmax)&&(d[i+1][1]<=ywmax) ) flag=1;
if((d[i][1]<=ywmax)&&(d[i+1][1]>ywmax) ) flag=2;
if((d[i][1]>ywmax)&&(d[i+1][1]>ywmax) ) flag=3;
switch(flag)
{ case 0 : y=ywmax;
if(dx!=0)
x=abs((int)(d[i][0]+(1/m)*(y-d[i][1])));
else
x=d[i][0];
e[p][0]=x;
e[p][1]=y;
p++;
e[p][0]=d[i+1][0];
e[p][1]=d[i+1][1];
p++;
break;
case 1 : e[p][0]=d[i+1][0];
e[p][1]=d[i+1][1];
p++;
break;
case 2 : y=ywmax;
if(dx!=0)
x=abs((int)(d[i][0]+(1/m)*(y-d[i][1])));
else
x=d[i][0];
e[p][0]=x;
e[p][1]=y;
p++;}}

e[p][0]=e[0][0];
e[p][1]=e[0][1];
cleardevice();
setcolor(35);
rectangle(xwmin,ymax-ywmin,xwmax,ymax-ywmax);
setcolor(63);
for(i=0;i {line(e[i][0],ymax-e[i][1],e[i+1][0],ymax-e[i+1][1]);
getch();}
getch(); getch();
}


/***************OUTPUT*****************/


Enter the co ordinate (left,top) of windows:50,50
Enter the co ordinate (right,bottom)of windows:25,25

Enter the no. of vertex of polgon:3

Enter the vertex of point1 :-30,15
Enter the vertex of point2 :-50,15
Enter the vertex of point3 :-35,65
*********************************************************************************
NOTE THAT O/P IS graphical representation please check it on turbo c++ s/w