use MONKEY_TYPING;
augment class Pixel { method Str { "$.R $.G $.B" } }
augment class Bitmap {
    method P3 {
        join "\n", «P3 "$.width $.height" 255»,
        do for ^$.height { join ' ', @.data[]»[$_] }
    }
    method raster-circle ( $x0, $y0, $r, Pixel $value ) {
        my $f = 1 - $r;
        my $ddF_x = 0;
        my $ddF_y = -2 * $r;
        my ($x, $y) = 0, $r;
        self.set-pixel($x0, $y0 + $r, $value);
        self.set-pixel($x0, $y0 - $r, $value);
        self.set-pixel($x0 + $r, $y0, $value);
        self.set-pixel($x0 - $r, $y0, $value);
        while $x < $y {
            if $f >= 0 {
                $y--;
                $ddF_y += 2;
                $f += $ddF_y;
            }
            $x++;
            $ddF_x += 2;
            $f += $ddF_x + 1;
            self.set-pixel($x0 + $x, $y0 + $y, $value);
            self.set-pixel($x0 - $x, $y0 + $y, $value);
            self.set-pixel($x0 + $x, $y0 - $y, $value);
            self.set-pixel($x0 - $x, $y0 - $y, $value);
            self.set-pixel($x0 + $y, $y0 + $x, $value);
            self.set-pixel($x0 - $y, $y0 + $x, $value);
            self.set-pixel($x0 + $y, $y0 - $x, $value);
            self.set-pixel($x0 - $y, $y0 - $x, $value);
        }
    }
}