feat(ambience): underwater shaders + audio manager + main menu + CC0 assets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/ambience/AudioManager.gd

@@ -0,0 +1,124 @@
+extends Node
+
+var music_player: AudioStreamPlayer
+var ambient_loop: AudioStreamPlayer
+var whale_player: AudioStreamPlayer
+
+var _whale_timer: Timer
+var _music_tween: Tween
+
+const MUSIC_PATH := "res://audio/music/"
+const SFX_PATH := "res://audio/sfx/"
+
+func _ready() -> void:
+	music_player = AudioStreamPlayer.new()
+	music_player.bus = "Music"
+	music_player.volume_db = -10.0
+	add_child(music_player)
+
+	ambient_loop = AudioStreamPlayer.new()
+	ambient_loop.bus = "SFX"
+	ambient_loop.volume_db = -12.0
+	add_child(ambient_loop)
+
+	whale_player = AudioStreamPlayer.new()
+	whale_player.bus = "SFX"
+	whale_player.volume_db = -15.0
+	add_child(whale_player)
+
+	_whale_timer = Timer.new()
+	_whale_timer.one_shot = true
+	_whale_timer.timeout.connect(_on_whale_timer)
+	add_child(_whale_timer)
+	_schedule_next_whale()
+
+
+func play_music(track_name: String) -> void:
+	var path := MUSIC_PATH + track_name
+	if not ResourceLoader.exists(path):
+		return
+
+	var stream: AudioStream = load(path)
+	if stream == null:
+		return
+
+	music_player.stream = stream
+	music_player.stream.loop = true
+	music_player.volume_db = -40.0
+	music_player.play()
+
+	if _music_tween:
+		_music_tween.kill()
+	_music_tween = create_tween()
+	_music_tween.tween_property(music_player, "volume_db", -10.0, 3.0).set_trans(Tween.TRANS_SINE)
+
+
+func play_ambient_loop(loop_name: String) -> void:
+	var path := SFX_PATH + loop_name
+	if not ResourceLoader.exists(path):
+		return
+
+	var stream: AudioStream = load(path)
+	if stream == null:
+		return
+
+	ambient_loop.stream = stream
+	ambient_loop.stream.loop = true
+	ambient_loop.play()
+
+
+func play_whale_call_random() -> void:
+	var path := SFX_PATH + "whale_call.ogg"
+	if not ResourceLoader.exists(path):
+		return
+	if whale_player.playing:
+		return
+
+	var stream: AudioStream = load(path)
+	if stream == null:
+		return
+
+	whale_player.stream = stream
+	whale_player.play()
+
+
+func play_bubble_sfx(position: Vector3) -> void:
+	var path := SFX_PATH + "bubbles.ogg"
+	if not ResourceLoader.exists(path):
+		return
+
+	var player := AudioStreamPlayer3D.new()
+	player.bus = "SFX"
+	player.volume_db = -8.0
+	player.max_distance = 20.0
+	player.attenuation_model = AudioStreamPlayer3D.ATTENUATION_INVERSE_SQUARE_DISTANCE
+	add_child(player)
+	player.global_position = position
+
+	var stream: AudioStream = load(path)
+	if stream == null:
+		player.queue_free()
+		return
+
+	player.stream = stream
+	player.play()
+	player.finished.connect(player.queue_free)
+
+
+func set_music_volume(db: float) -> void:
+	music_player.volume_db = db
+
+
+func set_sfx_volume(db: float) -> void:
+	ambient_loop.volume_db = db
+	whale_player.volume_db = db - 3.0
+
+
+func _on_whale_timer() -> void:
+	play_whale_call_random()
+	_schedule_next_whale()
+
+
+func _schedule_next_whale() -> void:
+	_whale_timer.wait_time = randf_range(30.0, 90.0)
+	_whale_timer.start()

scripts/ambience/MainMenu.gd

@@ -0,0 +1,29 @@
+extends Control
+
+@onready var _options_popup: Window = $OptionsPopup
+@onready var _music_slider: HSlider = $OptionsPopup/VBox/MusicSlider
+@onready var _sfx_slider: HSlider = $OptionsPopup/VBox/SFXSlider
+
+func _ready() -> void:
+	AudioManager.play_music("underwater_theme.mp3")
+	AudioManager.play_ambient_loop("underwater_ambient.ogg")
+
+
+func _on_dive_pressed() -> void:
+	get_tree().change_scene_to_file("res://scenes/Main.tscn")
+
+
+func _on_options_pressed() -> void:
+	_options_popup.popup_centered()
+
+
+func _on_quit_pressed() -> void:
+	get_tree().quit()
+
+
+func _on_music_slider_value_changed(value: float) -> void:
+	AudioManager.set_music_volume(linear_to_db(value))
+
+
+func _on_sfx_slider_value_changed(value: float) -> void:
+	AudioManager.set_sfx_volume(linear_to_db(value))

scripts/ambience/PlanktonParticles.gd

@@ -0,0 +1,57 @@
+extends GPUParticles3D
+
+func _ready() -> void:
+	amount = 500
+	lifetime = 10.0
+	one_shot = false
+	explosiveness = 0.0
+	randomness = 1.0
+	visibility_aabb = AABB(Vector3(-50, -30, -50), Vector3(100, 60, 100))
+
+	var process_mat := ParticleProcessMaterial.new()
+	process_mat.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
+	process_mat.emission_box_extents = Vector3(50.0, 30.0, 50.0)
+
+	process_mat.direction = Vector3(0.0, 0.0, 0.0)
+	process_mat.spread = 180.0
+	process_mat.initial_velocity_min = 0.0
+	process_mat.initial_velocity_max = 0.1
+
+	process_mat.linear_accel_min = -0.05
+	process_mat.linear_accel_max = 0.05
+	process_mat.radial_accel_min = -0.02
+	process_mat.radial_accel_max = 0.02
+
+	process_mat.damping_min = 0.5
+	process_mat.damping_max = 1.0
+
+	process_mat.scale_min = 0.02
+	process_mat.scale_max = 0.08
+
+	process_mat.color = Color(0.85, 0.92, 1.0, 0.8)
+
+	var grad := Gradient.new()
+	grad.set_color(0, Color(0.85, 0.92, 1.0, 0.0))
+	grad.set_color(1, Color(0.85, 0.92, 1.0, 0.0))
+	grad.add_point(0.1, Color(0.85, 0.92, 1.0, 0.8))
+	grad.add_point(0.9, Color(0.85, 0.92, 1.0, 0.8))
+	var grad_tex := GradientTexture1D.new()
+	grad_tex.gradient = grad
+	process_mat.color_ramp = grad_tex
+
+	process_material = process_mat
+
+	var quad := QuadMesh.new()
+	quad.size = Vector2(0.05, 0.05)
+
+	var mat := StandardMaterial3D.new()
+	mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
+	mat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
+	mat.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
+	mat.emission_enabled = true
+	mat.emission = Color(0.8, 0.9, 1.0)
+	mat.emission_energy_multiplier = 1.5
+	mat.albedo_color = Color(0.85, 0.92, 1.0, 0.8)
+
+	quad.surface_set_material(0, mat)
+	draw_pass_1 = quad

scripts/ambience/UnderwaterEnvironment.gd

@@ -0,0 +1,44 @@
+extends WorldEnvironment
+
+func _ready() -> void:
+	var env := Environment.new()
+
+	env.background_mode = Environment.BG_COLOR
+	env.background_color = Color(0.03, 0.12, 0.22)
+
+	env.ambient_light_source = Environment.AMBIENT_SOURCE_COLOR
+	env.ambient_light_color = Color(0.2, 0.4, 0.6)
+	env.ambient_light_energy = 0.4
+
+	env.fog_enabled = true
+	env.fog_light_color = Color(0.1, 0.3, 0.5)
+	env.fog_density = 0.02
+	env.fog_aerial_perspective = 0.3
+
+	env.volumetric_fog_enabled = true
+	env.volumetric_fog_density = 0.04
+	env.volumetric_fog_albedo = Color(0.2, 0.5, 0.7)
+	env.volumetric_fog_emission = Color(0.02, 0.06, 0.1)
+	env.volumetric_fog_emission_energy = 0.1
+	env.volumetric_fog_length = 64.0
+	env.volumetric_fog_detail_spread = 2.0
+
+	env.glow_enabled = true
+	env.glow_intensity = 0.5
+	env.glow_bloom = 0.1
+	env.glow_blend_mode = Environment.GLOW_BLEND_MODE_SOFTLIGHT
+
+	env.ssao_enabled = true
+	env.ssao_radius = 1.0
+	env.ssao_intensity = 1.0
+	env.ssao_power = 1.5
+	env.ssao_detail = 0.5
+
+	env.tone_mapper = Environment.TONE_MAPPER_FILMIC
+	env.exposure = 1.0
+
+	env.adjustment_enabled = true
+	env.adjustment_saturation = 1.1
+	env.adjustment_color_correction = null
+
+	environment = env