All side drifting now done the good way.

README.md

@@ -42,7 +42,7 @@ Valid properties are: `alg`, `algdisplay`, `base`, `colored`, `colors`, `flags`,
 Define the animated algorithm like this: `alg=R F' x2 R D Lw'`. It handles standard cube notation and some more. If no alg is given, the playback buttons don't appear.
 
 #####Standard notation
-Roofpig supports (almost) all standard cube notation. Layer(s): **F, B, R, L, U, D. M, E, S. x, y, z. Fw, Bw, Rw, Lw, Uw, Dw, f, b, r, l, u, d**. Turns: **2, ', 2'**. You can also use **², Z, 1** and **3**.
+Roofpig supports (almost) all standard cube notation. Layer(s): **F, B, R, L, U, D. M, E, S. x, y, z. Fw, Bw, Rw, Lw, Uw, Dw, f, b, r, l, u, d**. Turns: **2, ', 2'**. You can also use **², Z, 1**, and **3**.
 
 
 #####Rotation notation

src/Alg.coffee

@@ -97,17 +97,17 @@ class Alg
         new Move(code, @world3d, @speed)
 
   unhand: ->
-    drift = {U: 'U', D: 'D', L: 'L', R: 'R', F: 'F', B: 'B'}
+    drift = {U: 'U', D: 'D', L: 'L', R: 'R', F: 'F', B: 'B'} # drift.U says what center is on U
     colors = new Colors(drift, "", "")
 
     result = []
     for move in @moves
-      drifted_move = this.fwd_drift(move.as_brdflu(), drift)
+      drifted_move = this.drift(move.as_brdflu(), drift)
       result.push(drifted_move)
-      move.track_fwd_drift(drift)
+      move.track_drift(drift)
     result.join(' ').replace(/[ ]+/g, ' ').replace(/^ +| +$/g, '')
 
-  fwd_drift: (code, side_drift) ->
+  drift: (code, side_drift) ->
     return code unless code
 
     inverted_drift = {}
@@ -123,10 +123,9 @@ class Alg
 
   _side_drift: ->
     drift = {U: 'U', D: 'D', L: 'L', R: 'R', F: 'F', B: 'B'}
-    @next =  @moves.length
-    until this.at_start()
-      this.prev_move().track_drift(drift)
-    drift     # How to think about this: The 'real' U side is now on drift.U
+    for move in @moves
+      move.track_drift(drift)
+    drift
 
   _update_dom: (time = 'later') ->
     if @dom && @moves.length > 0

src/Colors.coffee

@@ -41,12 +41,12 @@ class Colors
   _undrift: (code, side_drift) ->
     return code unless code
 
-    reverse_drift = {}
+    uncased_drift = {}
     for own key, value of side_drift
-      reverse_drift[value] = key
-      reverse_drift[value.toLowerCase()] = key.toLowerCase()
+      uncased_drift[key] = value
+      uncased_drift[key.toLowerCase()] = value.toLowerCase()
 
-    (reverse_drift[char] || char for char in code.split('')).join('')
+    (uncased_drift[char] || char for char in code.split('')).join('')
 
   DEFAULT_COLORS = {g:'#0d0', b:'#07f', r:'red', o:'orange', y:'yellow', w:'#eee'}
   @_set_colors: (overrides, side_drift) ->
@@ -58,6 +58,10 @@ class Colors
       type = {s:'solved', i:'ignored', c:'cube'}[type] || type
       result[type] = DEFAULT_COLORS[color] || color
 
-    [r, d] = [result, side_drift]
+    inverted_drift = {}
+    for own key, value of side_drift
+      inverted_drift[value] = key
+
+    [r, d] = [result, inverted_drift]
     [r.U, r.D, r.R, r.L, r.F, r.B] = [r[d.U], r[d.D], r[d.R], r[d.L], r[d.F], r[d.B]]
     result

src/CompositeMove.coffee

@@ -20,9 +20,6 @@ class CompositeMove
   track_drift: (side_drift) ->
     move.track_drift(side_drift) for move in @moves
 
-  track_fwd_drift: (side_drift) ->
-    move.track_fwd_drift(side_drift) for move in @moves
-
   count: (count_rotations) ->
     return 1 if @official_text
 

src/Move.coffee

@@ -34,13 +34,6 @@ class Move
       this.undo()
 
   track_drift: (side_drift) ->
-    for cycle in [@layer.cycle1, @layer.cycle2] when cycle[0].length == 1 # center cycle
-      for side, location of side_drift
-        for i in [0..3]
-          if location == cycle[i]
-            side_drift[side] = cycle[(i+@turns+4)% 4]
-
-  track_fwd_drift: (side_drift) ->
     for cycle in [@layer.cycle1, @layer.cycle2] when cycle[0].length == 1 # center cycle
       for side, location of side_drift
         for i in [0..3]

test/Alg_spec.coffee

@@ -136,13 +136,13 @@ describe "Alg", ->
   it "#_side_drift", ->
     world = null
     expect(new Alg("F", world, "")._side_drift()).to.deep.equal(U: 'U', D: 'D', L: 'L', R: 'R', F: 'F', B: 'B')
-    expect(new Alg("M", world, "")._side_drift()).to.deep.equal(U: 'B', D: 'F', L: 'L', R: 'R', F: 'U', B: 'D')
-    expect(new Alg("M z", world, "")._side_drift()).to.deep.equal(U: 'L', D: 'R', L: 'F', R: 'B', F: 'U', B: 'D')
+    expect(new Alg("M", world, "")._side_drift()).to.deep.equal(B: 'U', F: 'D', L: 'L', R: 'R', U: 'F', D: 'B')
+    expect(new Alg("M z", world, "")._side_drift()).to.deep.equal(L: 'U', R: 'D', F: 'L', B: 'R', U: 'F', D: 'B')
     expect(new Alg("MZ", world, "")._side_drift()).to.deep.equal(U: 'D', D: 'U', L: 'L', R: 'R', F: 'B', B: 'F')
 
   it "@side_drift", ->
     expect(Alg.side_drift("F")).to.deep.equal(U: 'U', D: 'D', L: 'L', R: 'R', F: 'F', B: 'B')
-    expect(Alg.side_drift("M")).to.deep.equal(U: 'B', D: 'F', L: 'L', R: 'R', F: 'U', B: 'D')
+    expect(Alg.side_drift("M")).to.deep.equal(B: 'U', F: 'D', L: 'L', R: 'R', U: 'F', D: 'B')
 
   it "unhand", ->
     expect(new Alg("F L2", null, "").unhand()).to.equal("F L2")

test/Colors_spec.coffee

@@ -76,7 +76,7 @@ describe "Colors", ->
         expect(colors.to_draw('D', Layer.D).color).to.equal(colors.of(Layer.R))
 
   describe "side drift adjustments", ->
-    z_drift = {U: 'L', D: 'R', R: 'U', L: 'D', F: 'F', B: 'B'}
+    z_drift = {L: 'U', R: 'D', U: 'R', D: 'L', F: 'F', B: 'B'}
 
     it "side colors", ->
       plain_colors = new Colors(nodrift, "", "", "")