Implement note spawner.

rhythm_game/note/visual/note_animator.gd

@@ -1,27 +0,0 @@
-class_name NoteAnimator extends NoteView
-
-@export var pool: NotePool
-
-## TODO WARNING: This is currently only implemented for beat updates
-## going forward in time.
-func update_current_beat(beat: float) -> void:
-	var old_begin: int = _begin
-	var old_end: int = _end
-	super.update_current_beat(beat) # Update _begin and _end.
-	_update_note_visuals(old_begin, _begin)
-	_update_note_visuals(old_end, _end)
-
-
-# ======== IMPLEMENTATION ======== #
-var _note_map: Dictionary[int, NoteVisual]
-
-func _update_note_visuals(index_begin: int, index_end: int) -> void:
-	for i: int in range(index_begin, index_end):
-		# TODO: Either get or return node from pool,
-		# depending on if index_begin > or < than index_end.
-		pass
-
-func _set_notes(p_notes: NoteArray) -> void:
-	
-	notes = p_notes
-	_reset_view()

rhythm_game/note/visual/note_pool.gd

@@ -15,9 +15,21 @@ class_name NotePool extends Node
 @export var hold_skin: StringName = "default"
 
 func get_note(type: NoteVisual.TYPE) -> NoteVisual:
-	var note: NoteVisual
-	# TODO: Implement.
-	return note
+	match type:
+		NoteVisual.TYPE.TAP:
+			return get_tap()
+		NoteVisual.TYPE.HOLD:
+			return get_hold()
+		_:
+			return null
+
+func return_note(note: NoteVisual) -> void:
+	if note is TapNote:
+		note.reset()
+		return_tap(note as TapNote)
+	elif note is HoldNote:
+		note.reset()
+		return_hold(note as HoldNote)
 
 ## Get a tap note. Instantiates one if no free nodes are available.
 func get_tap() -> TapNote:

rhythm_game/note/visual/note_spawner.gd

@@ -0,0 +1,91 @@
+class_name NoteSpawner extends NoteView
+
+signal notes_spawned(beat: float)
+
+@export var lanes: Dictionary[int, Lane]
+
+@export var pool: NotePool
+
+## Spawn all the notes that should exist on this beat.
+func update(beat: float) -> void:
+	var old_begin: int = _begin
+	var old_end: int = _end
+	_update_view_relative_to_notes(notes, beat) # Updates _begin and _end.
+	
+	if _previous_beat <= beat:
+		_set_note_visuals(old_end, _end)
+		_remove_note_visuals(old_begin, _begin)
+	else:
+		_remove_note_visuals(_end, old_end)
+		_set_note_visuals(_begin, old_begin)
+	
+	_previous_beat = beat
+	notes_spawned.emit(beat)
+
+# ======== IMPLEMENTATION ======== #
+var _note_visuals: Dictionary[int, NoteVisual] # [Note ID, Note Visual]
+
+var _last_lane_holds: Dictionary[int, HoldNote]
+
+func _set_notes(p_notes: NoteArray) -> void:
+	super._set_notes(p_notes)
+	for note in _note_visuals.values():
+		if note == null:
+			continue
+		pool.return_note(note)
+
+# TODO Finish implementation.
+# Spawn or delete nodes in the range.
+func _set_note_visuals(index_begin: int, index_end: int) -> void:
+	for note_id: int in range(index_begin, index_end):
+		match notes.type_at(note_id):
+			Note.TYPE.TAP:
+				_set_visual_for_tap_at(note_id)
+			Note.TYPE.HOLD_START:
+				_set_visual_for_hold_start_at(note_id)
+			Note.TYPE.HOLD_END:
+				_set_visual_for_hold_end_at(note_id)
+
+func _remove_note_visuals(index_begin: int, index_end: int) -> void:
+	for note_id: int in range(index_begin, index_end):
+		match notes.type_at(note_id):
+			Note.TYPE.TAP:
+				_remove_visual_for_tap_at(note_id)
+			Note.TYPE.HOLD_START:
+				_remove_visual_for_hold_start_at(note_id)
+			Note.TYPE.HOLD_END:
+				_remove_visual_for_hold_end_at(note_id)
+
+func _set_visual_for_tap_at(note_id: int) -> void:
+	var lane_id: int = notes.lane_at(note_id)
+	var lane: Lane = lanes[lane_id]
+	var note: TapNote = pool.get_tap()
+	lane.add_child(note)
+	_note_visuals[note_id] = note
+
+func _set_visual_for_hold_start_at(note_id: int) -> void:
+	var lane_id: int = notes.lane_at(note_id)
+	var lane: Lane = lanes[lane_id]
+	var note: HoldNote = pool.get_hold()
+	lane.add_child(note)
+	_note_visuals[note_id] = note
+	_last_lane_holds[lane_id] = note
+
+func _set_visual_for_hold_end_at(note_id: int) -> void:
+	var lane_id: int = notes.lane_at(note_id)
+	var lane: Lane = lanes[lane_id]
+	var note: HoldNote = _last_lane_holds[lane_id]
+	if note == null:
+		note = pool.get_hold()
+	lane.add_child(note)
+	_note_visuals[note_id] = note
+	_last_lane_holds[lane_id] = null
+
+func _remove_visual_for_tap_at(note_id: int) -> void:
+	pass
+
+func _remove_visual_for_hold_start_at(note_id: int) -> void:
+	pass
+
+func _remove_visual_for_hold_end_at(note_id: int) -> void:
+	pass