Scan line poly fill

#include


#include

#include



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 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]; // polygon

a[n][1]=a[0][1];





detectgraph(&gd,&gm);

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





/*- draw polygon -*/



for(i=0;i

{

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

}



getch();





for(i=0;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)) /*- calculate inverse slope -*/

{

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

}

}



for(y=0;y< 480;y++) // find x intersections

{

k =0;

for(i=0;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

for(i=0;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

{

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

getch();

}



}

return 0;

}