Basic audio manager setup.

src/audio_manager.odin

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+package game
+
+import rl "vendor:raylib"
+
+Fade_State :: enum {
+    None,
+    In,
+    Out,
+}
+
+// setup sound IDs so gameplay code never 
+// touches raw Raylib sound handles
+Sound_ID :: enum {
+    Ball_Collision,
+    Score_Goal,
+    UI_Select,
+    UI_Confirm,
+}
+
+Audio_Manager :: struct {
+    sounds:            map[Sound_ID]rl.Sound,
+    music:             rl.Music,
+    music_loaded:      bool,
+    
+    sfx_vol:           f32, // User SFX volume setting
+    user_music_vol:    f32, // User Music volume setting
+    current_music_vol: f32, // Live interpolated output volume
+    
+    // Runtime Fade State
+    fade_state:        Fade_State,
+    fade_elapsed_sec:  f32,
+    fade_duration_sec: f32,
+}
+// ------------------------------------------------------------------------------
+// Lifecycle procs
+// ------------------------------------------------------------------------------
+audio_init :: proc(audio: ^Audio_Manager) {
+	rl.InitAudioDevice()
+	audio.sounds = make(map[Sound_ID]rl.Sound)
+
+	// Load SFX
+    audio.sfx_vol = 0.5
+	audio.sounds[.UI_Select] = rl.LoadSound("assets/audio/ui/select.ogg")
+	audio.sounds[.Ball_Collision]  = rl.LoadSound("assets/audio/gameplay/ballhit.ogg")
+
+	// Load Music Stream
+    audio.user_music_vol = 0.1
+    audio.current_music_vol = 0.0
+    audio.fade_state = .None
+    audio.music = rl.LoadMusicStream("assets/audio/gameplay/music/track_1.wav")
+    audio.music_loaded = true
+    rl.SetMusicVolume(audio.music, audio.current_music_vol)
+}
+
+audio_update :: proc(audio: ^Audio_Manager, dt: f32) {
+	if !audio.music_loaded do return
+
+	// Process Fade if the audio state machine requires
+	if audio.fade_state != .None {
+	    audio.fade_elapsed_sec += dt
+	    // convert elapsed seconds over target seconds into a 0.0 -> 1.0 percentage
+	    progress_pct := clamp(audio.fade_elapsed_sec / audio.fade_duration_sec, 0.0, 1.0)
+
+	    #partial switch audio.fade_state {
+	    case .In:
+	    	audio.current_music_vol = rl.Lerp(0.0, audio.user_music_vol, progress_pct)
+	        // progress is 100% or more stop fading in music
+	        if progress_pct >= 1.0 do audio.fade_state = .None
+
+	    case .Out:
+	    	audio.current_music_vol = rl.Lerp(audio.user_music_vol, 0.0, progress_pct)
+	        // progress is 100% or more stop fading out music and stop the stream
+	        if progress_pct >= 1.0 {
+	            audio.fade_state = .None
+	            rl.StopMusicStream(audio.music)
+	        }
+	    }
+	} else {
+		// not fading, output matches the user setting directly
+        audio.current_music_vol = audio.user_music_vol
+    }
+
+    rl.SetMusicVolume(audio.music, audio.current_music_vol)
+
+    // keep audio stream buffer fed
+    if rl.IsMusicStreamPlaying(audio.music) {
+        rl.UpdateMusicStream(audio.music)
+    }
+}
+
+audio_manager_quit :: proc(audio: ^Audio_Manager) {
+	for _, sound in audio.sounds {
+		rl.UnloadSound(sound)	
+	}
+	delete(audio.sounds)
+	rl.UnloadMusicStream(audio.music)
+	rl.CloseAudioDevice()
+}
+
+// ------------------------------------------------------------------------------
+// Utilities
+// ------------------------------------------------------------------------------
+audio_play_music :: proc(audio: ^Audio_Manager) {
+    if audio.music_loaded {
+        // Only trigger start if it isn't playing already
+        if !rl.IsMusicStreamPlaying(audio.music) {
+            rl.PlayMusicStream(audio.music)
+        }
+    }
+}
+
+audio_stop_music :: proc(audio: ^Audio_Manager) {
+    if audio.music_loaded && rl.IsMusicStreamPlaying(audio.music) {
+        rl.StopMusicStream(audio.music)
+    }
+}
+
+audio_play_sfx :: proc(audio: ^Audio_Manager, id: Sound_ID) {
+	if sound, ok :=	audio.sounds[id]; ok {
+		rl.SetSoundVolume(sound, audio.sfx_vol)
+		rl.PlaySound(sound)	
+	}
+}
+
+// ------------------------------------------------------------------------------
+// Audio Fading
+// ------------------------------------------------------------------------------
+audio_fade_in :: proc(audio: ^Audio_Manager, duration: f32 = 1.0) {
+    if !audio.music_loaded do return
+
+    if !rl.IsMusicStreamPlaying(audio.music) {
+        rl.PlayMusicStream(audio.music)
+    }
+
+    audio.fade_state = .In
+    audio.fade_duration_sec = max(0.001, duration)
+    audio.fade_elapsed_sec = 0.0
+    audio.current_music_vol = 0.0
+    rl.SetMusicVolume(audio.music, 0.0)
+}
+
+audio_fade_out :: proc(audio: ^Audio_Manager, duration: f32 = 1.0) {
+    if !audio.music_loaded || !rl.IsMusicStreamPlaying(audio.music) do return
+
+    audio.fade_state = .Out
+    audio.fade_duration_sec = max(0.001, duration)
+    audio.fade_elapsed_sec = 0.0
+}