Complete fill with iterators.

@@ -74,7 +74,6 @@ where T: Add<Output = T> + Debug + Copy + From<i32> {
     type Item = Coordinate<T>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        println!("== LineIterator next: {:?}", self);
         match self.a {
             None    => None,
             Some(a) => {
@@ -273,14 +272,18 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
        + Debug + Copy + From<i32> {
 
     fn new(p :&'a Polygon<T>, direction :Direction) -> Self {
-        let mut v = VertexIterator { p:         p
-                                   , top:       p.vert_min()
-                                   , current:   Some(p.vert_min())
-                                   , edge:      None
-                                   , direction: direction };
-        v.next_edge();
-        println!("== new: {:?}", v);
-        v
+        let top  = p.vert_min();
+        let next = p.next_y(top, direction);
+        let edge = match next {
+            None       => None,
+            Some(next) => Some(p.vertex(top).edge_iter(&p.vertex(next))),
+        };
+
+        VertexIterator { p:         p
+                       , top:       top
+                       , current:   next
+                       , edge:      edge
+                       , direction: direction }
     }
 
     // if this yields "None" we are finished.
@@ -289,8 +292,6 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
         let next     = self.p.next_y(current, self.direction)?;
         let mut edge = self.p.vertex(current).edge_iter(&self.p.vertex(next));
 
-        println!("== next: {:?} {:?} {:?}", current, next, edge);
-
         match edge.next() {
             // It should be impossible that a new edge iterator has no values
             // at all… anyway, just in case I handle it here.
@@ -311,9 +312,7 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
 
     fn next(&mut self) -> Option<Self::Item> {
         // if for whatever reason edge is "None" finish this iterator.
-        let next = self.edge?.next();
-
-        println!("== next: {:?}", next);
+        let next = self.edge.as_mut()?.next();
 
         match next {
             Some(_) => next,
@@ -350,6 +349,10 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
         VertexIterator::new(self, Direction::Left)
     }
 
+    fn right_vertices(&self) -> VertexIterator<T> {
+        VertexIterator::new(self, Direction::Right)
+    }
+
     fn left(&self, v :usize) -> usize {
         let Polygon(Coordinates(cs)) = self;
 
@@ -438,57 +441,14 @@ impl<T> Fillable<T> for Polygon<T>
 where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
        + Debug + Clone + Copy + From<i32> {
     fn fill(&self) -> Coordinates<T> {
-        let Polygon(Coordinates(cs)) = self;
-
-        let vert_min = self.vert_min();
-
-        println!("== vert_min: [{}] {:?}", vert_min, cs[vert_min]);
-
-        let mut r = (vert_min, self.next_y(vert_min, Direction::Right));
-        let mut l = (vert_min, self.next_y(vert_min, Direction::Left));
-
-        let mut l_edge :Vec<Coordinate<T>> = Vec::new();
-        let mut r_edge :Vec<Coordinate<T>> = Vec::new();
-
-        let append_edge = | v :&mut Vec<Coordinate<T>>
-                          , e :(usize, Option<usize>)
-                          , f :Direction | {
-            match e {
-                (_, None)    => e,
-                (a, Some(b)) => {
-                    let mut edge = cs[a].edge(&cs[b]);
-                    v.append(&mut edge);
-                    (b, self.next_y(b, f))
-                },
-            }
-        };
-
-        let print_current = |s :&str, e :(usize, Option<usize>)| {
-            match e.1 {
-                None    => println!( "==        {}: [{:?}] - {:?}"
-                                   , s, e.1, "None"),
-                Some(e) => println!( "==        {}: [{:?}] - {:?}"
-                                   , s, e, cs[e]),
-            }
-        };
-
-        while l.1 != None || r.1 != None {
-            print_current("l", l);
-            l = append_edge(&mut l_edge, l, Direction::Left);
-            print_current("r", r);
-            r = append_edge(&mut r_edge, r, Direction::Right);
-        }
-
-        let l_edge2 :Vec<Coordinate<T>> = self.left_vertices().collect();
+        let scanlines = self.left_vertices().zip(self.right_vertices());
 
-        println!("== [{}] {:?}", l_edge.len(), l_edge);
-        println!("== [{}] {:?}", l_edge2.len(), l_edge2);
-        println!("== [{}] {:?}", r_edge.len(), r_edge);
+        // vertices is an iterator over all vertices making this polygon.
+        let vertices = scanlines.flat_map(|(l, r)| l.line_iter(&r));
 
-        // TODO we always miss the last scanline…
-        // TODO check what happend with at least 2 vertices with same y and
-        //      different x…
-        // loop though edges…
+        // for debug only…
+        //let vertices :Vec<(Coordinate<T>)> = vertices.collect();
+        //println!("== [{}] {:?}", vertices.len(), vertices);
 
         Coordinates(Vec::<Coordinate<T>>::new())
     }