feat: nerf bubble sort and add dimming effects

The player no longer has to go through the sorted end in bubble sort,
which is now dimmed. The sorted subarrays of insertion sort and
selection sort are dimmed too.

Author: danielzting

levels/bubble_sort.gd

@@ -15,6 +15,7 @@ them. Otherwise, hit RIGHT ARROW to continue.
 """
 
 var _index = 0
+var _end = array.size
 var _swapped = false
 
 func _init(array).(array):
@@ -31,13 +32,16 @@ func next():
         array.swap(_index, _index + 1)
         _swapped = true
     _index += 1
-    if _index == array.size - 1:
+    if _index + 1 == _end:
         if not _swapped:
             emit_signal("done")
         _index = 0
+        _end -= 1
         _swapped = false
 
 func get_effect(i):
+    if i >= _end:
+        return EFFECTS.DIMMED
     if i == _index or i == _index + 1:
         return EFFECTS.HIGHLIGHTED
     return EFFECTS.NONE

levels/insertion_sort.gd

@@ -39,6 +39,8 @@ func next():
 func get_effect(i):
     if i == _index or i == _index - 1:
         return EFFECTS.HIGHLIGHTED
+    if i < _end:
+        return EFFECTS.DIMMED
     return EFFECTS.NONE
 
 func _grow():

levels/selection_sort.gd

@@ -40,4 +40,6 @@ func next():
 func get_effect(i):
     if i == _index or i == _base:
         return EFFECTS.HIGHLIGHTED
+    if i <= _base:
+        return EFFECTS.DIMMED
     return EFFECTS.NONE