Sync playback to the actual beat count rather than relying on BPM

MuzikaGromche/Plugin.cs

@@ -29,42 +29,42 @@ namespace MuzikaGromche
                 Name = "MuzikaGromche",
                 Language = Language.RUSSIAN,
                 WindUpTimer = 46.3f,
-                Bpm = 130f,
+                Bars = 8,
             },
             new Track
             {
                 Name = "VseVZale",
                 Language = Language.RUSSIAN,
                 WindUpTimer = 39f,
-                Bpm = 138f,
+                Bars = 8
             },
             new Track
             {
                 Name = "DeployDestroy",
                 Language = Language.RUSSIAN,
                 WindUpTimer = 40.7f,
-                Bpm = 130f,
+                Bars = 8,
             },
             new Track
             {
                 Name = "MoyaZhittya",
                 Language = Language.ENGLISH,
                 WindUpTimer = 34.5f,
-                Bpm = 120f,
+                Bars = 8,
             },
             new Track
             {
                 Name = "Gorgorod",
                 Language = Language.RUSSIAN,
                 WindUpTimer = 43.2f,
-                Bpm = 180f,
+                Bars = 6,
             },
             new Track
             {
                 Name = "Durochka",
                 Language = Language.RUSSIAN,
                 WindUpTimer = 37f,
-                Bpm = 130f,
+                Bars = 10,
             }
         ];
 
@@ -88,24 +88,8 @@ namespace MuzikaGromche
             return Tracks[trackId];
         }
 
-        public static Coroutine JesterLightSwitching;
         public static Track CurrentTrack;
 
-        public static void StartLightSwitching(MonoBehaviour __instance)
-        {
-            StopLightSwitching(__instance);
-            JesterLightSwitching = __instance.StartCoroutine(RotateColors());
-        }
-
-        public static void StopLightSwitching(MonoBehaviour __instance)
-        {
-            if (JesterLightSwitching != null)
-            {
-                __instance.StopCoroutine(JesterLightSwitching);
-                JesterLightSwitching = null;
-            }
-        }
-
         public static void SetLightColor(Color color)
         {
             foreach (var light in RoundManager.Instance.allPoweredLights)
@@ -119,30 +103,6 @@ namespace MuzikaGromche
             SetLightColor(Color.white);
         }
 
-        // TODO: Move to Track class to make them customizable per-song
-        static List<Color> colors = [Color.magenta, Color.cyan, Color.green, Color.yellow];
-
-        public static IEnumerator RotateColors()
-        {
-            Debug.Log("Starting color rotation");
-            var i = 0;
-            while (true)
-            {
-                var color = colors[i];
-                Debug.Log("Chose color " + color);
-                SetLightColor(color);
-                i = (i + 1) % colors.Count;
-                if (CurrentTrack != null)
-                {
-                    yield return new WaitForSeconds(60f / CurrentTrack.Bpm);
-                }
-                else
-                {
-                    yield break;
-                }
-            }
-        }
-
         private void Awake()
         {
             string text = Info.Location.TrimEnd((PluginInfo.PLUGIN_NAME + ".dll").ToCharArray());
@@ -192,9 +152,20 @@ namespace MuzikaGromche
         // from the looped part. This also means that the light show starts before
         // the looped track does, so we need to sync them up as soon as we enter the Loop.
         public float WindUpTimer;
-        // BPM for light switching in sync with the music. There is no offset,
+
-        // so the Loop track should start precisely on a beat.
+        // Estimated number of beats per minute. Not used for light show, but might come in handy.
-        public float Bpm;
+        public float Bpm => 60f / (LoadedLoop.length / Beats);
+
+        // How many beats the loop segment has. The default strategy is to switch color of lights on each beat.
+        // This should be an integer, but it is stored as float for convenience of calculations.
+        public float Beats;
+
+        // Shorthand for four beats
+        public float Bars
+        {
+            get => Beats / 4f;
+            set => Beats = value * 4f;
+        }
 
         // MPEG is basically mp3, and it can produce gaps at the start.
         // WAV is OK, but takes a lot of space. Try OGGVORBIS instead.
@@ -203,6 +174,9 @@ namespace MuzikaGromche
         public AudioClip LoadedStart;
         public AudioClip LoadedLoop;
 
+        // This does not account for the timestamp when Jester has actually popped
+        public float FixedLoopDelay => LoadedStart.length - WindUpTimer;
+
         // How often this track should be chosen, relative to the sum of weights of all tracks.
         public SyncedEntry<int> Weight;
 
@@ -215,6 +189,41 @@ namespace MuzikaGromche
             AudioType.OGGVORBIS => "ogg",
             _ => "",
         };
+
+        public float CalculateBeat(AudioSource start, AudioSource loop)
+        {
+            // If popped, calculate which beat the music is currently at.
+            // In order to do that we should choose one of two strategies:
+            //
+            // 1. If Start source is still playing, use its position since WindUpTimer
+            // 2. Otherwise use Loop source, adding the delay after WindUpTimer,
+            //    which is the remaining of the Start, i.e. (LoadedStart.length - WindUpTimer).
+            //
+            // NOTE: PlayDelayed also counts as isPlaying, so loop.isPlaying is always true.
+
+            var elapsed = start.isPlaying
+                // [1] Start source is still playing
+                ? start.time - WindUpTimer
+                // [2] Start source has finished
+                : loop.time + FixedLoopDelay;
+
+            var normilized = elapsed / LoadedLoop.length % 1f;
+
+            var beat = normilized * Beats;
+#if DEBUG
+            Debug.LogFormat("MuzikaGromche beat {0,10:N4} {1,10:N4} {2,10:N4}", Time.realtimeSinceStartup, normilized, beat);
+#endif
+            return beat;
+        }
+
+        static readonly List<Color> Colors = [Color.magenta, Color.cyan, Color.green, Color.yellow];
+
+        public Color ColorForBeat(float beat)
+        {
+            int beatIndex = (int)(Math.Floor(beat) % Beats);
+
+            return Colors[beatIndex % Colors.Count];
+        }
     }
 
     public readonly struct RandomWeightedIndex
@@ -370,6 +379,10 @@ namespace MuzikaGromche
 
         public static CanModifyResult CanModifyWeightsNow()
         {
+#if DEBUG
+            // In debug mode let us modify weights any time without restarting the level
+            return CanModifyResult.True();
+#else
             var startOfRound = StartOfRound.Instance;
             if (!startOfRound)
             {
@@ -384,6 +397,7 @@ namespace MuzikaGromche
                 return CanModifyResult.False("Only while orbiting");
             }
             return CanModifyResult.True();
+#endif
         }
     }
 
@@ -435,7 +449,7 @@ namespace MuzikaGromche
 
                 //  ...and start modded music
                 Plugin.CurrentTrack = Plugin.ChooseTrack();
-                // Set up custom 
+                // Set up custom popup timer, which is shorter than Start audio
                 __instance.popUpTimer = Plugin.CurrentTrack.WindUpTimer;
 
                 // Override popGoesTheWeaselTheme with Start audio
@@ -449,7 +463,6 @@ namespace MuzikaGromche
 
             if (__instance.previousState != 2 && __state.previousState == 2)
             {
-                Plugin.StopLightSwitching(__instance);
                 Plugin.ResetLightColor();
             }
 
@@ -469,8 +482,14 @@ namespace MuzikaGromche
 
                 Debug.Log($"Start length: {Plugin.CurrentTrack.LoadedStart.length}; played time: {time}");
                 Debug.Log($"Playing loop music: maxDistance: {__instance.creatureVoice.maxDistance}, minDistance: {__instance.creatureVoice.minDistance}, volume: {__instance.creatureVoice.volume}, spread: {__instance.creatureVoice.spread}, in seconds: {delay}");
+            }
 
-                Plugin.StartLightSwitching(__instance);
+            // Manage the timeline: switch color of the lights according to the current playback/beat position.
+            if (__instance.previousState == 2)
+            {
+                var beat = Plugin.CurrentTrack.CalculateBeat(start: __instance.farAudio, loop: __instance.creatureVoice);
+                var color = Plugin.CurrentTrack.ColorForBeat(beat);
+                Plugin.SetLightColor(color);
             }
         }
     }