feat: add ArraySound class as ArrayView dependency

This simple implementation plays a constant sound that is only
implemented on bubble sort as the arithmetic average of the two values
being compared.

Author: danielzting

levels/bubble_sort.gd

@@ -48,3 +48,6 @@ func get_effect(i):
     if i >= _end:
         return EFFECTS.DIMMED
     return EFFECTS.NONE
+
+func get_frac():
+    return (array.frac(_index) + array.frac(_index + 1)) / 2.0

project.godot

@@ -14,6 +14,11 @@ _global_script_classes=[ {
 "language": "GDScript",
 "path": "res://models/array_model.gd"
 }, {
+"base": "Node",
+"class": "ArraySound",
+"language": "GDScript",
+"path": "res://views/array_sound.gd"
+}, {
 "base": "HBoxContainer",
 "class": "ArrayView",
 "language": "GDScript",
@@ -86,6 +91,7 @@ _global_script_classes=[ {
 } ]
 _global_script_class_icons={
 "ArrayModel": "",
+"ArraySound": "",
 "ArrayView": "",
 "BinaryTreeModel": "",
 "BogoSort": "",

views/array_sound.gd

@@ -0,0 +1,28 @@
+class_name ArraySound
+extends Node
+
+const SAMPLE_HZ = 44100
+const MIN_HZ = 110
+const MAX_HZ = 440
+
+var frac: float
+var player = AudioStreamPlayer.new()
+var _phase = 0.0
+var _playback: AudioStreamGeneratorPlayback
+
+func _fill_buffer(pulse_hz):
+    var increment = pulse_hz / SAMPLE_HZ
+    for i in range(_playback.get_frames_available()):
+        _playback.push_frame(Vector2.ONE * sin(_phase * TAU))
+        _phase = fmod(_phase + increment, 1.0)
+
+func _process(delta):
+    _fill_buffer(MIN_HZ + (MAX_HZ - MIN_HZ) * frac)
+
+func _init():
+    add_child(player)
+    player.stream = AudioStreamGenerator.new()
+    player.stream.buffer_length = 0.05
+    player.stream.mix_rate = SAMPLE_HZ
+    _playback = player.get_stream_playback()
+    player.play()

views/array_view.gd

@@ -16,13 +16,15 @@ var _rects = []
 var _positions = []
 var _pointer = Polygon2D.new()
 var _pointer_size: int
+var _sound = ArraySound.new()
 onready var _separation = 128 / _level.array.size
 
 func _init(level):
     _level = level
     add_child(_level) # NOTE: This is necessary for it to read input
     add_child(_tween) # NOTE: This is necessary for it to animate
     add_child(_pointer)
+    add_child(_sound)
     _pointer.hide()
 
 func _ready():
@@ -65,6 +67,7 @@ func _ready():
         _pointer.show()
 
 func _process(delta):
+    _sound.frac = _level.get_frac()
     if _pointer.visible:
         var pointed = _level.get_pointer()
         var height = rect_size.y - _pointer_size * 2
@@ -76,6 +79,7 @@ func _process(delta):
 
 func _on_ComparisonSort_done():
     set_process(false)
+    _sound.player.stop()
     _pointer.hide()
     for i in range(_rects.size()):
         _rects[i].color = ComparisonSort.EFFECTS.NONE