Start fixing vertex order

fractional/src/easel.rs

@@ -275,7 +275,7 @@ 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 top  = p.vert_min();
+        let top  = p.vert_min(direction);
         let next = p.next_y(top, direction);
         let edge = match next {
             None       => None,
@@ -330,7 +330,7 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
 impl<T> Polygon<T>
 where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
        + Copy + Debug + From<i32> {
-    fn vert_min<'a>(&'a self) -> usize {
+    fn vert_min<'a>(&'a self, d :Direction) -> usize {
         let Polygon(Coordinates(cs)) = self;
 
         type ICoord<'a,T> = (usize, &'a Coordinate<T>);
@@ -341,7 +341,12 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
                 Some(a) => {
                     let Coordinate(_, ay, _) = a.1;
                     let Coordinate(_, xy, _) = x.1;
-                    if xy < ay {Some(x)} else {Some(a)}
+                    match d {
+                        Direction::Left =>
+                            if xy < ay {Some(x)} else {Some(a)},
+                        Direction::Right =>
+                            if xy <= ay {Some(x)} else {Some(a)},
+                    }
                 },
             };
 
@@ -401,6 +406,16 @@ where T: Add<Output = T> + Sub<Output = T> + Div<Output = T>
                     cmp::Ordering::Less    => None,
                     // TODO On equal we need to find out which one of both to
                     //      keep in the list… (the outermost)
+                    //      But how can we find the outermost...
+                    //      I think it depends on the previous and next one
+                    //      which means this might not be best suited for
+                    //      a recursive approach...we could keep both...
+                    //      Anyway, it looks like this is only a problem
+                    //      for the first vertex so maybe it is enough
+                    //      to choose the correct one when starting which
+                    //      would be in the vert_min method.
+                    //      Well, after adding some logic to vert_min it
+                    //      seems it is also relevant for the last one.
                     cmp::Ordering::Equal   => inner(p, c, p.step(n, d), d),
                     cmp::Ordering::Greater => Some(n),
                 }

fractional/src/main.rs

@@ -342,8 +342,9 @@ fn _democanvas<T>( xcb         :&XcbEasel
             let rot1 = TMatrix::combine(vec!(rz, rx, t));
             let rot2 = TMatrix::combine(vec!(rz, ry, t));
 
-            let objects = vec!( (tetrahedron.transform(&rot1), 0xFFFF00)
-                              , (       cube.transform(&rot2), 0x0000FF) );
+            let objects = vec!( (tetrahedron.transform(&rot1), 0xFFFF00) );
+            //let objects = vec!( (tetrahedron.transform(&rot1), 0xFFFF00)
+            //                  , (       cube.transform(&rot2), 0x0000FF) );
             //let objects = vec!( (triangle.transform(&rot1), 0xFFFF00) );
 
             <XcbCanvas as Canvas<T>>::clear(&mut canvas);