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    my $post_fix = $t /= $d;
    return $c * ($post_fix) * $t * (($s + 1) * $t - $s) + $b;
}

sub ease_out  {
    my $self = shift;
    my ($t,$b,$c,$d) = (shift,shift,shift,shift);

    return $b if ($t < EPSILON);
    return $c if ($d < EPSILON);

    my $s = 1.70158;
    return $c * (($t = $t / $d - 1) * $t * (($s + 1) * $t + $s) + 1) + $b;
}

sub ease_both  {
    my $self = shift;
    my ($t,$b,$c,$d) = (shift,shift,shift,shift);

    return $b if ($t < EPSILON);
    return $c if ($d < EPSILON);

    my $s = 1.70158;
    if (($t /= $d / 2) < 1) {
        return $c / 2 * ($t * $t * ((($s *= (1.525)) + 1 )* $t - $s)) + $b;
    }
    my $post_fix = $t-= 2;
    return $c / 2 * (($post_fix) * $t * ((($s *= (1.525)) + 1) * $t + $s) + 2) + $b;
}

1;

__END__

# MAN3 POD

=head1 NAME

Algorithm::Easing::Backdraft - Calculate eased translations between two positive whole integer values over time

=cut

=head1 SYNOPSIS

        use Algorithm::Easing;
        use Algorithm::Easing::Backdraft;

        # this example produces traditional 'backdraft' output;

        my $translation = Algorithm::Easing::Backdraft->new;

        # total time for eased translation as a real positive integer value
        my $d = 2.5;

        # begin
        my $b = 0;

        # change
        my $c = 240;

        # time passed in seconds as a real positive integer between each frame
        my $frame_time = 0.0625;

        my @p = [319,0];

        for(my $t = 0; $t < 2.5; $t += 0.0625) {
            $p[1] = $translation->ease_out($t,$b,$c,$d)

            # plot
            ...;
        }

=cut

=head1 METHODS

=cut

=head2 ease_none
    usage :
    
        Parameters : 
            Let t be time,
            Let b be begin,
            Let c be change,
            Let d be duration,
        Results :
            Let p be position,
            
        my $p = $obj->ease_none($t,$b,$c,$d);

This method is used for a linear translation between two positive real whole integers using a positive real integer as the parameter for time.

=cut

=head2 ease_in
    usage :
    
        Parameters : 
            Let t be time,
            Let b be begin,
            Let c be change,
            Let d be duration,
        Results :
            Let p be position,
            
        my $p = $obj->ease_in($t,$b,$c,$d);

This method is used to ease in between two positive real whole integers using a positive real integer as the parameter for time in the fashion of a backdraft.

=cut

=head2 ease_out
    usage :
    
        Parameters : 
            Let be time,
            Let b be begin,
            Let c be change,
            Let d be duration,
        Results :