stick-the-quick/autoload/FX/AudioFader.gd

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GDScript3
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class_name AudioFader extends Node
const DEFAULT_FADE = 0.25
const MUTE_VOLUME: float = -20.0
func _ready() -> void:
process_mode = PROCESS_MODE_ALWAYS
func fade_in(
audio: AudioStreamPlayer,
duration: float = DEFAULT_FADE,
target: float = 0.0
) -> void:
audio.play()
audio.volume_db = MUTE_VOLUME
var dbps: float = (-MUTE_VOLUME - target)/duration
while audio.volume_db < target:
audio.volume_db += dbps*(await Wait.tick())
audio.volume_db = target
func fade_out(
audio: AudioStreamPlayer,
duration: float = DEFAULT_FADE
) -> void:
var dbps: float = (audio.volume_db - MUTE_VOLUME)/duration
while audio.volume_db > MUTE_VOLUME:
audio.volume_db -= dbps*(await Wait.tick())
audio.stop()
audio.volume_db = 0.0
func cross_fade(
stop: AudioStreamPlayer,
start: AudioStreamPlayer,
duration: float = DEFAULT_FADE,
target: float = 0.0
) -> void:
var dbps_out: float = (stop.volume_db + 20.0)/duration
var dbps_in: float = (-MUTE_VOLUME - target)/duration
start.play()
start.volume_db = MUTE_VOLUME
while stop.volume_db > MUTE_VOLUME or start.volume_db < target:
var delta: float = await Wait.tick()
if stop.volume_db > MUTE_VOLUME:
stop.volume_db -= delta*dbps_out
else:
stop.stop()
if start.volume_db < target:
start.volume_db += delta*dbps_in
stop.volume_db = 0.0
start.volume_db = target