#!/usr/bin/perl -w

use lib ( '../Vector2D' );
use Vector2D;

my $POLYGONS_MAX_Y = 11;
my $A = new Vector2D(  2,  3 );
my $B = new Vector2D(  7,  1 );
my $C = new Vector2D( 13,  5 );
my $D = new Vector2D( 13, 11 );
my $E = new Vector2D(  7,  7 );
my $F = new Vector2D(  2,  9 );

my @AB = [ $A, $B ];
my @BC = [ $B, $C ];
my @CD = [ $C, $D ];
my @DE = [ $D, $E ];
my @EF = [ $E, $F ];
my @FA = [ $F, $A ];

my @polygon = ( @AB, @BC, @CD, @DE, @EF, @FA );

my @ET;  # global Edge Table
# each entry in the ET contains the Ymax coordinate of the edge,
# the x cooridnate of the bottom endpoint Xbot and the x increment 
# used in the stepping from one scan lime to the next 1/m
for my $edge (@polygon) {
        my $y    = ( @{$edge}->[0]->gety() <  @{$edge}->[1]->gety() ) ? @{$edge}->[0]->gety() : @{$edge}->[1]->gety() ;
        my $Ymax = ( @{$edge}->[0]->gety() >= @{$edge}->[1]->gety() ) ? @{$edge}->[0]->gety() : @{$edge}->[1]->gety() ;
        my $Xbot = ( @{$edge}->[0]->gety() <  @{$edge}->[1]->gety() ) ? @{$edge}->[0]->getx() : @{$edge}->[1]->getx() ;

        my $invSlope    = &calcOneOverSlope($edge);
        my $rec = {
                Ymax            => $Ymax,
                Xbot            => $Xbot,
                invSlope        => $invSlope
        };
        print "$y -> $Ymax | $Xbot | $invSlope\n";
        push( @{$ET[$y]}, $rec );
}

for my $i (1..$POLYGONS_MAX_Y) {
        if ( $ET[$i] ) {
                print "ET[$i] = ";
                for my $r ( ${ET[$i]} ) {
                        print "{" . $r->{Ymax} . "|" . $r->{Xbot} . "|" . $r->{invSlope} . "}" ;
                }
                print "\n";
        } else {
                print "ET[$i] = NULL\n";
        }
}

sub calcOneOverSlope {
        my $edge = shift;
        my $y = @{$edge}->[0]->gety()-@{$edge}->[1]->gety();
        my $x = @{$edge}->[0]->getx()-@{$edge}->[1]->getx();
        if ( $y == 0 ) { return undef; }
        return $x/$y;
}