[ENHANCEMENT/BUGFIX] Bopper sync and bpm change events

source/funkin/Conductor.hx

@@ -75,6 +75,17 @@ class Conductor
    */
   public var onStepHit(default, null):FlxSignal = new FlxSignal();
 
+  /**
+   * Signal fired when the current Conductor instance changes BPM.
+   */
+  public static var bpmChange(default, null):FlxSignal = new FlxSignal();
+
+  /**
+   * Signal fired when THIS Conductor instance changes BPM.
+   * TODO: This naming sucks but we can't make a static and instance field with the same name!
+   */
+  public var onBpmChange(default, null):FlxSignal = new FlxSignal();
+
   /**
    * The list of time changes in the song.
    * There should be at least one time change (at the beginning of the song) to define the BPM.
@@ -328,13 +339,20 @@ class Conductor
     Conductor.stepHit.dispatch();
   }
 
+  static function dispatchBpmChange():Void
+  {
+    Conductor.bpmChange.dispatch();
+  }
+
   static function setupSingleton(input:Conductor):Void
   {
     input.onMeasureHit.add(dispatchMeasureHit);
 
     input.onBeatHit.add(dispatchBeatHit);
 
     input.onStepHit.add(dispatchStepHit);
+
+    input.onBpmChange.add(dispatchBpmChange);
   }
 
   static function clearSingleton(input:Conductor):Void
@@ -344,6 +362,8 @@ class Conductor
     input.onBeatHit.remove(dispatchBeatHit);
 
     input.onStepHit.remove(dispatchStepHit);
+
+    input.onBpmChange.remove(dispatchBpmChange);
   }
 
   static function get_instance():Conductor
@@ -418,6 +438,7 @@ class Conductor
     var oldMeasure:Float = this.currentMeasure;
     var oldBeat:Float = this.currentBeat;
     var oldStep:Float = this.currentStep;
+    var oldBpm:Float = this.bpm;
 
     // If the song is playing, limit the song position to the length of the song or beginning of the song.
     if (FlxG.sound.music != null && FlxG.sound.music.playing)
@@ -469,6 +490,11 @@ class Conductor
     }
 
     // FlxSignals are really cool.
+    if (bpm != oldBpm)
+    {
+      this.onBpmChange.dispatch();
+    }
+
     if (currentStep != oldStep)
     {
       this.onStepHit.dispatch();

source/funkin/modding/IScriptedClass.hx

@@ -78,6 +78,11 @@ interface INoteScriptedClass extends IScriptedClass
  */
 interface IBPMSyncedScriptedClass extends IScriptedClass
 {
+  /**
+   * Called when the BPM changes.
+   */
+  public function onBpmChange(event:SongTimeScriptEvent):Void;
+
   /**
    * Called once every step of the song.
    */

source/funkin/modding/events/ScriptEventDispatcher.hx

@@ -102,9 +102,11 @@ class ScriptEventDispatcher
         case SONG_BEAT_HIT:
           t.onBeatHit(cast event);
           return;
+        case SONG_BPM_CHANGE:
+          t.onBpmChange(cast event);
+          return;
         case SONG_STEP_HIT:
           t.onStepHit(cast event);
-          return;
         default: // Continue;
       }
     }

source/funkin/modding/events/ScriptEventType.hx

@@ -63,6 +63,13 @@ enum abstract ScriptEventType(String) from String to String
    */
   var SONG_STEP_HIT = 'STEP_HIT';
 
+  /**
+   * Called when the BPM changes.
+   *
+   * This event is not cancelable.
+   */
+  var SONG_BPM_CHANGE = 'BPM_CHANGE';
+
   /**
    * Called when a note comes on screen and starts approaching the strumline.
    *

source/funkin/modding/module/Module.hx

@@ -91,6 +91,8 @@ class Module implements IPlayStateScriptedClass implements IStateChangingScripte
 
   public function onNoteGhostMiss(event:GhostMissNoteScriptEvent) {}
 
+  public function onBpmChange(event:SongTimeScriptEvent) {}
+
   public function onStepHit(event:SongTimeScriptEvent) {}
 
   public function onBeatHit(event:SongTimeScriptEvent) {}

source/funkin/play/character/BaseCharacter.hx

@@ -429,6 +429,7 @@ class BaseCharacter extends Bopper
       // super.onBeatHit handles the regular `dance()` calls.
     }
     FlxG.watch.addQuick('holdTimer-${characterId}', holdTimer);
+    FlxG.watch.addQuick('_realDanceEvery-${characterId}', _realDanceEvery);
   }
 
   public function isSinging():Bool

source/funkin/play/song/Song.hx

@@ -655,6 +655,8 @@ class Song implements IPlayStateScriptedClass implements IRegistryEntry<SongMeta
 
   public function onSongEvent(event:SongEventScriptEvent):Void {};
 
+  public function onBpmChange(event:SongTimeScriptEvent):Void {};
+
   public function onStepHit(event:SongTimeScriptEvent):Void {};
 
   public function onBeatHit(event:SongTimeScriptEvent):Void {};

source/funkin/play/stage/Bopper.hx

@@ -2,6 +2,7 @@ package funkin.play.stage;
 
 import flixel.FlxSprite;
 import flixel.FlxCamera;
+import flixel.math.FlxMath;
 import flixel.math.FlxPoint;
 import flixel.util.FlxTimer;
 import funkin.modding.IScriptedClass.IPlayStateScriptedClass;
@@ -23,7 +24,16 @@ class Bopper extends StageProp implements IPlayStateScriptedClass
    * Supports up to 0.25 precision.
    * @default 0.0 on props, 1.0 on characters
    */
-  public var danceEvery:Float = 0.0;
+  public var danceEvery(default, set):Float = 1;
+
+  var _realDanceEvery:Float = 1;
+
+  function set_danceEvery(value:Float):Float
+  {
+    this.danceEvery = value;
+    this.update_danceEvery();
+    return value;
+  }
 
   /**
    * Whether the bopper should dance left and right.
@@ -45,6 +55,13 @@ class Bopper extends StageProp implements IPlayStateScriptedClass
    */
   public var idleSuffix(default, set):String = '';
 
+  function set_idleSuffix(value:String):String
+  {
+    this.idleSuffix = value;
+    this.dance();
+    return value;
+  }
+
   /**
    * If this bopper is rendered with pixel art, disable anti-aliasing.
    * @default `false`
@@ -63,13 +80,6 @@ class Bopper extends StageProp implements IPlayStateScriptedClass
    */
   public var shouldBop:Bool = true;
 
-  function set_idleSuffix(value:String):String
-  {
-    this.idleSuffix = value;
-    this.dance();
-    return value;
-  }
-
   /**
    * The offset of the character relative to the position specified by the stage.
    */
@@ -159,19 +169,58 @@ class Bopper extends StageProp implements IPlayStateScriptedClass
     this.shouldAlternate = hasAnimation('danceLeft');
   }
 
+  /**
+   * Called when the BPM of the song changes.
+   */
+  public function onBpmChange(event:SongTimeScriptEvent)
+  {
+    update_danceEvery();
+  }
+
   /**
    * Called once every step of the song.
    */
   public function onStepHit(event:SongTimeScriptEvent)
   {
-    if (danceEvery > 0 && (event.step % (danceEvery * Constants.STEPS_PER_BEAT)) == 0)
+    if (_realDanceEvery > 0 && (event.step % (_realDanceEvery * Constants.STEPS_PER_BEAT)) == 0)
     {
       dance(shouldBop);
     }
   }
 
   public function onBeatHit(event:SongTimeScriptEvent):Void {}
 
+  function update_danceEvery():Void
+  {
+    if (danceEvery == 0 || shouldAlternate || this.animation.getByName('idle$idleSuffix') == null || shouldBop)
+    {
+      // for forced bopping, alternating dance and non-existing animation, it just works the same as before
+      _realDanceEvery = danceEvery;
+      return;
+    }
+
+    var daIdle = this.animation.getByName('idle$idleSuffix');
+    var numeratorTweak:Int = (Conductor.instance.timeSignatureNumerator % 2 == 0) ? 2 : Conductor.instance.timeSignatureNumerator; // hopefully we get only prime numbers...
+    if (FlxMath.getDecimals(danceEvery) == 0) // for int danceEvery
+    {
+      var idlePerBeat:Float = (daIdle.numFrames / daIdle.frameRate) / (Conductor.instance.beatLengthMs / 1000);
+      var danceEveryNumBeats:Int = Math.ceil(idlePerBeat);
+      if (danceEveryNumBeats > numeratorTweak)
+      {
+        while (danceEveryNumBeats % numeratorTweak != 0)
+          danceEveryNumBeats++;
+      }
+      _realDanceEvery = Math.max(danceEvery, danceEveryNumBeats);
+    }
+    else // for decymal danceEvery (X.25, X.50 and X.75)
+    {
+      // maybe to rework, for the moment it tries to have the same patern every sections
+      _realDanceEvery = danceEvery;
+      while ((4 * _realDanceEvery * Conductor.instance.stepLengthMs) < (daIdle.numFrames / daIdle.frameRate))
+        _realDanceEvery *= numeratorTweak;
+    }
+  }
+
   /**
    * Called every `danceEvery` beats of the song.
    */

source/funkin/play/stage/Stage.hx

@@ -771,6 +771,11 @@ class Stage extends FlxSpriteGroup implements IPlayStateScriptedClass implements
     }
   }
 
+  /**
+   * A function that gets called when the BPM of the song changes.
+   */
+  public function onBpmChange(event:SongTimeScriptEvent):Void {}
+
   /**
    * A function that gets called once per step in the song.
    * @param curStep The current step number.

source/funkin/ui/MusicBeatState.hx

@@ -65,13 +65,15 @@ class MusicBeatState extends FlxTransitionableState implements IEventHandler
 
     Conductor.beatHit.add(this.beatHit);
     Conductor.stepHit.add(this.stepHit);
+    Conductor.bpmChange.add(this.bpmChange);
   }
 
   public override function destroy():Void
   {
     super.destroy();
     Conductor.beatHit.remove(this.beatHit);
     Conductor.stepHit.remove(this.stepHit);
+    Conductor.bpmChange.remove(this.bpmChange);
   }
 
   function handleFunctionControls():Void
@@ -119,6 +121,15 @@ class MusicBeatState extends FlxTransitionableState implements IEventHandler
     FlxG.resetState();
   }
 
+  public function bpmChange():Bool
+  {
+    var event = new SongTimeScriptEvent(SONG_BPM_CHANGE, conductorInUse.currentBeat, conductorInUse.currentStep);
+
+    dispatchEvent(event);
+
+    return true;
+  }
+
   public function stepHit():Bool
   {
     var event = new SongTimeScriptEvent(SONG_STEP_HIT, conductorInUse.currentBeat, conductorInUse.currentStep);

source/funkin/ui/MusicBeatSubState.hx

@@ -64,6 +64,7 @@ class MusicBeatSubState extends FlxSubState implements IEventHandler
 
     Conductor.beatHit.add(this.beatHit);
     Conductor.stepHit.add(this.stepHit);
+    Conductor.bpmChange.add(this.bpmChange);
 
     initConsoleHelpers();
   }
@@ -108,6 +109,15 @@ class MusicBeatSubState extends FlxSubState implements IEventHandler
     sort(SortUtil.byZIndex, FlxSort.ASCENDING);
   }
 
+  public function bpmChange():Bool
+  {
+    var event = new SongTimeScriptEvent(SONG_BPM_CHANGE, conductorInUse.currentBeat, conductorInUse.currentStep);
+
+    dispatchEvent(event);
+
+    return true;
+  }
+
   /**
    * Called when a step is hit in the current song.
    * Continues outside of PlayState, for things like animations in menus.

source/funkin/ui/charSelect/CharSelectGF.hx

@@ -73,6 +73,8 @@ class CharSelectGF extends FlxAtlasSprite implements IBPMSyncedScriptedClass
     #end
   }
 
+  public function onBpmChange(event:SongTimeScriptEvent):Void {}
+
   public function onStepHit(event:SongTimeScriptEvent):Void {}
 
   var danceEvery:Int = 2;

source/funkin/ui/charSelect/CharSelectPlayer.hx

@@ -35,6 +35,8 @@ class CharSelectPlayer extends FlxAtlasSprite implements IBPMSyncedScriptedClass
     });
   }
 
+  public function onBpmChange(event:SongTimeScriptEvent):Void {}
+
   public function onStepHit(event:SongTimeScriptEvent):Void {}
 
   public function onBeatHit(event:SongTimeScriptEvent):Void

source/funkin/ui/debug/charting/ChartEditorState.hx

@@ -2167,6 +2167,8 @@ class ChartEditorState extends UIState // UIState derives from MusicBeatState
           currentPlayerCharacterPlayer.onBeatHit(cast event);
         case SONG_STEP_HIT:
           currentPlayerCharacterPlayer.onStepHit(cast event);
+        case SONG_BPM_CHANGE:
+          currentPlayerCharacterPlayer.onBpmChange(cast event);
         case NOTE_HIT:
           currentPlayerCharacterPlayer.onNoteHit(cast event);
         default: // Continue
@@ -2183,6 +2185,8 @@ class ChartEditorState extends UIState // UIState derives from MusicBeatState
           currentOpponentCharacterPlayer.onBeatHit(cast event);
         case SONG_STEP_HIT:
           currentOpponentCharacterPlayer.onStepHit(cast event);
+        case SONG_BPM_CHANGE:
+          currentPlayerCharacterPlayer.onBpmChange(cast event);
         case NOTE_HIT:
           currentOpponentCharacterPlayer.onNoteHit(cast event);
         default: // Continue
@@ -5654,7 +5658,8 @@ class ChartEditorState extends UIState // UIState derives from MusicBeatState
   function handleHelpKeybinds():Void
   {
     // F1 = Open Help
-    if (FlxG.keys.justPressed.F1 && !isHaxeUIDialogOpen) {
+    if (FlxG.keys.justPressed.F1 && !isHaxeUIDialogOpen)
+    {
       this.openUserGuideDialog();
     }
   }

source/funkin/ui/haxeui/components/CharacterPlayer.hx

@@ -197,6 +197,16 @@ class CharacterPlayer extends Box
     if (character != null) character.onUpdate(event);
   }
 
+  /**
+   * Called when the BPM changes in the song
+   * Used to play character animations.
+   * @param event The event.
+   */
+  public function onBpmChange(event:SongTimeScriptEvent):Void
+  {
+    if (character != null) character.onBpmChange(event);
+  }
+
   /**
    * Called when an beat is hit in the song
    * Used to play character animations.