143 lines
3.0 KiB
GDScript3
143 lines
3.0 KiB
GDScript3
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## Class for playing music and providing an interface to keep events in sync.
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class_name Conductor extends Node
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## If true, start immediately when ready.
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@export var autostart: bool = false
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## Music to play.
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@export var music: Music
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signal started
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signal ticked(beat_update: BeatUpdate)
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signal ticked_forward(new_beat: float)
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#signal ticked_backward(new_beat: float)
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signal finished
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func start() -> void:
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assert(music != null)
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assert(_audio_player != null)
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_stop_playback_and_initialize()
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_active = true
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started.emit()
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func is_active() -> bool:
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return _active
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func current_time() -> float:
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return(_audio_player.get_playback_position() +
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AudioServer.get_time_since_last_mix() +
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_music_offset - _remaining_silence)
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func previous_time() -> float:
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return _previous_time
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func current_beat() -> float:
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return _sync_track.to_beat(current_time())
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func previous_beat() -> float:
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return _previous_beat
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func current_bpm() -> float:
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return _sync_track.bpm_at_time(current_time())
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func add_time(seconds: float) -> void:
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if _audio_player == null:
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return
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_audio_player.seek(_audio_player.get_playback_position() + seconds)
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_previous_time = current_time()
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_previous_beat = current_beat()
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# ====== IMPLEMENTATION ====== #
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var _active: bool = false
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var _previous_time: float = -1.0
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var _previous_beat: float = -1.0
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var _audio_player: AudioStreamPlayer = null
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var _sync_track: SyncTrack = SyncTrack.new()
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var _music_offset: float
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var _music_playing: bool = false
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var _remaining_silence: float = 0.0
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func _ready() -> void:
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_audio_player = AudioStreamPlayer.new()
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add_child(_audio_player)
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_audio_player.finished.connect(_on_music_finished)
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if autostart:
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start()
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func _on_music_finished() -> void:
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_music_playing = false
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_active = false
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finished.emit()
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func _process(delta: float) -> void:
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if not _active:
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return
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if _music_playing:
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_beat_update()
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else:
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_update_silence(delta)
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func _update_silence(elapsed_time: float) -> void:
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_remaining_silence -= elapsed_time
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if _remaining_silence < 0:
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_play_music_from_offset(-_remaining_silence)
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_remaining_silence = 0.0
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func _beat_update() -> void:
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var _current_time = current_time()
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# _audio_player.get_playback_position() used in current_time()
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# is not perfect and may return a lesser value than last frame.
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# This makes sure the beat never updates backward.
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if _current_time <= _previous_time:
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return
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var _current_beat = _sync_track.to_beat(_current_time)
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ticked.emit(BeatUpdate.new(_current_beat, _previous_beat))
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ticked_forward.emit(_current_beat)
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_previous_beat = _current_beat
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_previous_time = _current_time
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func _stop_playback_and_initialize() -> void:
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if _audio_player.playing:
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_audio_player.stop()
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_active = false
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_music_playing = false
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_previous_time = -1.0
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_previous_beat = -1.0
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_music_offset = music.offset
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_remaining_silence = _music_offset
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_audio_player.stream = music.stream
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_sync_track.initialize(music.tempo)
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func _play_music_from_offset(offset: float) -> void:
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_audio_player.play(offset)
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_music_playing = true
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