A PROGRAM FOR POLYGON FILLING USING SCANFILL ALGORITHM

#include<stdio.h>

#include<conio.h>

#include<graphics.h>

 void main()

   {

int n,i,j,k,gd,gm,dy,dx;

int x,y,temp;

int a[20][2],xi[20];

float slope[20];

clrscr();

printf("\n\n\tEnter the no. of degrees of polygon:");

scanf("%d",&n);

printf("\n\n\tEnter the coordinates of polygon :\n\n\n");

for(i=0;i<n;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];

detectgraph(&gd,&gm);

initgraph(&gd,&gm,"c:\\tc\\bgi");

for(i=0;i<n;i++)   {

line(a[i][0],a[i][1],a[i+1][0],a[i+1][1]);

}

getch();

for(i=0;i<n;i++)

{

dy=a[i+1][1]-a[i][1];

dx=a[i+1][0]-a[i][0];

if(dy==0) slope[i]=1.0;

if(dx==0) slope[i]=0.0;

if((dy!=0)&&(dx!=0)){

slope[i]=(float)dx/dy;

}

 }

for(y=0;y<480;y++)

 {

k=0;

for(i=0;i<n;i++)

 {

if (((a[i][1]<=y)&&(a[i+1][1]>y))||

((a[i][1]>y)&&(a[i+1][1]<=y)))

{

xi[k]=(int)(a[i][0]=slope[i]*(y-a[i][1]));

k++;

}

    }

for(j=0;j<k-1;j++)

for(i=0;i<k-1;i++) 

   {

if(xi[i]>xi[i+1])

{

temp=xi[i];

xi[i]=xi[i+1];

xi[i+1]=temp;

}    

 }

setcolor(35);

for(i=0;i<k;i+=2)    {

line(xi[i],y,xi[i+1]+1,y);

getch();

                       }
                    } 
                 }


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