Polygon Clipping Algorithm by sutherland and hodgeman > C Program
Computer Graphics
Polygon Clipping Algorithm by sutherland and hodgeman > C Program
#include<stdio.h>
#include<conio.h>
#define round(a) ((int)(a+0.5))
int k;
float xmin,ymin,xmax,ymax,arr[20],m;
void clipl(float x1,float y1,float x2,float y2)
{
if(x2-x1)
m=(y2-y1)/(x2-x1);
else
m=100000;
if(x1 >= xmin && x2 >= xmin)
{
arr[k]=x2;
arr[k+1]=y2;
k+=2;
}
if(x1 < xmin && x2 >= xmin)
{
arr[k]=xmin;
arr[k+1]=y1+m*(xmin-x1);
arr[k+2]=x2;
arr[k+3]=y2;
k+=4;
}
if(x1 >= xmin && x2 < xmin)
{
arr[k]=xmin;
arr[k+1]=y1+m*(xmin-x1);
k+=2;
}
}
void clipt(float x1,float y1,float x2,float y2)
{
if(y2-y1)
m=(x2-x1)/(y2-y1);
else
m=100000;
if(y1 <= ymax && y2 <= ymax)
{
arr[k]=x2;
arr[k+1]=y2;
k+=2;
}
if(y1 > ymax && y2 <= ymax)
{
arr[k]=x1+m*(ymax-y1);
arr[k+1]=ymax;
arr[k+2]=x2;
arr[k+3]=y2;
k+=4;
}
if(y1 <= ymax && y2 > ymax)
{
arr[k]=x1+m*(ymax-y1);
arr[k+1]=ymax;
k+=2;
}
}
void clipr(float x1,float y1,float x2,float y2)
{
if(x2-x1)
m=(y2-y1)/(x2-x1);
else
m=100000;
if(x1 <= xmax && x2 <= xmax)
{
arr[k]=x2;
arr[k+1]=y2;
k+=2;
}
if(x1 > xmax && x2 <= xmax)
{
arr[k]=xmax;
arr[k+1]=y1+m*(xmax-x1);
arr[k+2]=x2;
arr[k+3]=y2;
k+=4;
}
if(x1 <= xmax && x2 > xmax)
{
arr[k]=xmax;
arr[k+1]=y1+m*(xmax-x1);
k+=2;
}
}
void clipb(float x1,float y1,float x2,float y2)
{
if(y2-y1)
m=(x2-x1)/(y2-y1);
else
m=100000;
if(y1 >= ymin && y2 >= ymin)
{
arr[k]=x2;
arr[k+1]=y2;
k+=2;
}
if(y1 < ymin && y2 >= ymin)
{
arr[k]=x1+m*(ymin-y1);
arr[k+1]=ymin;
arr[k+2]=x2;
arr[k+3]=y2;
k+=4;
}
if(y1 >= ymin && y2 < ymin)
{
arr[k]=x1+m*(ymin-y1);
arr[k+1]=ymin;
k+=2;
}
}
void main()
{
int gd=DETECT,gm,n,poly[20],i;
float xi,yi,xf,yf,polyy[20];
clrscr();
printf("Coordinates of rectangular clip window :\n");
scanf("%f%f%f%f",&xmin,&ymin,&xmax,&ymax);
printf("\n\nPolygon to be clipped :\nNumber of sides :");
scanf("%d",&n);
printf("Enter the coordinates :");
for(i=0;i<2*n;i++)
scanf("%f",&polyy[i]);
polyy[i]=polyy[0];
polyy[i+1]=polyy[1];
for(i=0;i < 2*n+2;i++)
poly[i]=round(polyy[i]);
initgraph(&gd,&gm,"C:\\TC\\BGI");
setcolor(RED);
rectangle(xmin,ymax,xmax,ymin);
printf("\t\tUNCLIPPED POLYGON");
setcolor(WHITE);
fillpoly(n,poly);
getch();
cleardevice();
k=0;
for(i=0;i < 2*n;i+=2)
clipl(polyy[i],polyy[i+1],polyy[i+2],polyy[i+3]);
n=k/2;
for(i=0;i < k;i++)
polyy[i]=arr[i];
polyy[i]=polyy[0];
polyy[i+1]=polyy[1];
k=0;
for(i=0;i < 2*n;i+=2)
clipt(polyy[i],polyy[i+1],polyy[i+2],polyy[i+3]);
n=k/2;
for(i=0;i < k;i++)
polyy[i]=arr[i];
polyy[i]=polyy[0];
polyy[i+1]=polyy[1];
k=0;
for(i=0;i < 2*n;i+=2)
clipr(polyy[i],polyy[i+1],polyy[i+2],polyy[i+3]);
n=k/2;
for(i=0;i < k;i++)
polyy[i]=arr[i];
polyy[i]=polyy[0];
polyy[i+1]=polyy[1];
k=0;
for(i=0;i < 2*n;i+=2)
clipb(polyy[i],polyy[i+1],polyy[i+2],polyy[i+3]);
for(i=0;i < k;i++)
poly[i]=round(arr[i]);
if(k)
fillpoly(k/2,poly);
setcolor(RED);
rectangle(xmin,ymax,xmax,ymin);
printf("\tCLIPPED POLYGON");
getch();
closegraph();
}
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