fix: implement variable separation to fill display

Block sizes remain constant but separation can be one more pixel so the
ArrayView fills its entire parent without looking blurry. This is just a
quick fix; a thorough implementation later should vary block sizes while
keeping separation constant so that large simulations with zero
separation between blocks look acceptable. This would involve smarter
and more complex positioning code.

Author: danielzting

scripts/levels.gd

@@ -7,7 +7,7 @@ const LEVELS = [
     MergeSort,
 ]
 const MIN_SIZE = 8
-const MAX_SIZE = 256
+const MAX_SIZE = 128
 
 var _level = LEVELS[0].new(ArrayModel.new())
 

views/array_view.gd

@@ -10,6 +10,7 @@ const SWAP_DURATION = 0.1
 var _tween = Tween.new()
 var _level: ComparisonSort
 var _rects = []
+var _positions = []
 var _unit_width: int
 var _unit_height: int
 onready var _separation = 128 / _level.array.size
@@ -23,16 +24,26 @@ func _ready():
     yield(get_tree(), "idle_frame")
     _unit_width = rect_size.x / _level.array.size
     _unit_height = rect_size.y / _level.array.size
+    # Keep track of accumulated pixel error from integer division
+    var error = float(rect_size.x) / _level.array.size - _unit_width
+    var accumulated = 0
+    var x = 0
     _level.connect("mistake", get_parent(), "flash")
     for i in range(_level.array.size):
         var rect = Polygon2D.new()
+        if accumulated >= 1:
+            x += 1
+            accumulated -= 1
         rect.polygon = [
             Vector2(0, 0),
             Vector2(0, rect_size.y),
             Vector2(_unit_width - _separation, rect_size.y),
             Vector2(_unit_width - _separation, 0),
         ]
-        rect.position = Vector2(i * _unit_width, rect_size.y)
+        accumulated += error
+        rect.position = Vector2(x, rect_size.y)
+        _positions.append(x)
+        x += _unit_width
         _rects.append(rect)
         add_child(rect)
     _level.array.connect("swapped", self, "_on_ArrayModel_swapped")
@@ -45,9 +56,9 @@ func _process(delta):
 func _on_ArrayModel_swapped(i, j):
     var time = SWAP_DURATION * (1 + float(j - i) / _level.array.size)
     _tween.interpolate_property(
-        _rects[i], "position:x", null, j * _unit_width, time)
+        _rects[i], "position:x", null, _positions[j], time)
     _tween.interpolate_property(
-        _rects[j], "position:x", null, i * _unit_width, time)
+        _rects[j], "position:x", null, _positions[i], time)
     var temp = _rects[i]
     _rects[i] = _rects[j]
     _rects[j] = temp