algorithm to make the charter faster

source/funkin/backend/utils/SortedArrayUtil.hx

@@ -0,0 +1,49 @@
+package funkin.backend.utils;
+
+/**
+ * All types of utils only usable in a sorted array.
+ */
+ class SortedArrayUtil {
+	/**
+	 * Gets the index of a possible new element of an Array of T using an efficient algorithm.
+	 * @param array Array of T to check in
+	 * @param getVal Function that returns the position value of T
+	 * @return Index
+	 */
+	public static inline function binarySearch<T>(array:Array<T>, val:Float, getVal:T->Float):Int {
+		if (array.length <= 0) return 0; // if the array is empty, it should be equal to zero (the beginning)
+		if (getVal(array[0]) > val) return 0; // in case its the minimum
+		if (getVal(array[array.length-1]) < val) return array.length; // in case its the maximum
+
+        // binary search
+		var iMin:Int = 0;
+		var iMax:Int = array.length-1;
+
+		var i:Int = 0;
+		var mid:Float;
+		while(iMin <= iMax) {
+			i = Math.floor((iMin + iMax) / 2);
+			mid = getVal(array[i]);
+			if (mid < val)
+                iMin = i+1
+			else if (mid > val)
+				iMax = i-1;
+			else {
+                iMin = i;
+                break;
+            }
+		}
+		return iMin;
+	}
+
+    /**
+     * Adds to a sorted array, using binary search.
+     * @param array Array to add to
+     * @param val Value to add
+     * @param getVal Function that returns the value that needs to be sorted
+     */
+    public static inline function addSorted<T>(array:Array<T>, val:T, getVal:T->Float) {
+		if (val != null)
+        	array.insert(binarySearch(array, getVal(val), getVal), val);
+    }
+}

source/funkin/editors/charter/Charter.hx

@@ -399,6 +399,7 @@ class Charter extends UIState {
 		vocals = FlxG.sound.load(Paths.voices(__song, __diff));
 		vocals.group = FlxG.sound.defaultMusicGroup;
 
+		trace("generating notes...");
 		for(strID=>strL in PlayState.SONG.strumLines) {
 			for(note in strL.notes) {
 				var n = new CharterNote();
@@ -409,6 +410,12 @@ class Charter extends UIState {
 
 			strumLines.add(new CharterStrumline(strL));
 		}
+		trace("sorting notes...");
+		notesGroup.sort(function(i, n1, n2) {
+			if (n1.step == n2.step)
+				return FlxSort.byValues(FlxSort.ASCENDING, n1.id, n2.id);
+			return FlxSort.byValues(FlxSort.ASCENDING, n1.step, n2.step);
+		});
 
 		refreshBPMSensitive();
 	}
@@ -522,6 +529,8 @@ class Charter extends UIState {
 							deletes.push(s);
 						} else {
 							s.updatePos(newStep, newID, s.susLength, s.type);
+							notesGroup.remove(s);
+							notesGroup.add(s);
 
 							drags.push({
 								note: s,
@@ -785,8 +794,11 @@ class Charter extends UIState {
 				for(n in changes)
 					n.note.updatePos(n.note.step, n.note.id, n.before, n.note.type);
 			case CNoteDrag(notes, deletes):
-				for(n in notes)
+				for(n in notes) {
 					n.note.updatePos(n.oldStep, n.oldID, n.note.susLength, n.note.type);
+					notesGroup.remove(n.note);
+					notesGroup.add(n.note);
+				}
 				for(d in deletes) {
 					notesGroup.add(d);
 					d.revive();
@@ -832,8 +844,11 @@ class Charter extends UIState {
 				for(n in changes)
 					n.note.updatePos(n.note.step, n.note.id, n.after, n.note.type);
 			case CNoteDrag(notes, deletes):
-				for(n in notes)
+				for(n in notes) {
 					n.note.updatePos(n.newStep, n.newID, n.note.susLength, n.note.type);
+					notesGroup.remove(n.note);
+					notesGroup.add(n.note);
+				}
 				deleteNotes(deletes, false);
 				selection = [for(n in notes) n.note];
 		}

source/funkin/editors/charter/CharterNoteGroup.hx

@@ -9,7 +9,6 @@ class CharterNoteGroup extends FlxTypedGroup<CharterNote> {
 	var __currentlyLooping:Bool = false;
 
 	public override function forEach(noteFunc:CharterNote->Void, recursive:Bool = false) {
-		i = 0;
 		__loopSprite = null;
 
 		max = FlxG.height / 70 / camera.zoom;
@@ -21,19 +20,34 @@ class CharterNoteGroup extends FlxTypedGroup<CharterNote> {
 		if (FlxG.state is Charter && !FlxG.sound.music.playing)
 			curStep = cast(FlxG.state, Charter).conductorFollowerSpr.y / 40;
 
-		while(i < length) {
+		var begin = SortedArrayUtil.binarySearch(members, curStep - max, getVarForEach);
+		var end = SortedArrayUtil.binarySearch(members, curStep + max, getVarForEach);
+
+		for(i in begin...end) {
 			__loopSprite = members[i];
-			if (__loopSprite == null || !__loopSprite.exists) {
-				i++;
-				continue;
-			}
-			if (Math.abs(__loopSprite.step - curStep) - __loopSprite.susLength < max)
+			if (!cast(FlxG.state, Charter).selection.contains(__loopSprite))
 				noteFunc(__loopSprite);
-			i++;
 		}
+		for(c in cast(FlxG.state, Charter).selection)
+			noteFunc(c);
+
 		__currentlyLooping = oldCur;
 	}
 
+	public override function add(v:CharterNote):CharterNote {
+		SortedArrayUtil.addSorted(members, v, getVar);
+		return v;
+	}
+
+	public override function remove(v:CharterNote, force:Bool = true):CharterNote
+		return super.remove(v, true);
+
+	private static function getVar(n:CharterNote)
+		return n.step;
+
+	private static function getVarForEach(n:CharterNote)
+		return n.step + n.susLength;
+
 	public override function draw() {
 		@:privateAccess var oldDefaultCameras = FlxCamera._defaultCameras;
 		@:privateAccess if (cameras != null) FlxCamera._defaultCameras = cameras;