Playback visualization + started on timeline in editor

Assets/Scripts/LevelEditor/BeatGrid.cs

@@ -0,0 +1,56 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.UI;
+
+using TMPro;
+
+namespace RhythmHeavenMania.Editor
+{
+    public class BeatGrid : MonoBehaviour
+    {
+        private RectTransform rectTransform;
+
+        public float snap;
+        public float count;
+
+        private float lastPosX;
+
+        private List<GameObject> Lines = new List<GameObject>();
+
+        private void Start()
+        {
+            rectTransform = GetComponent<RectTransform>();
+
+            for (int i = 0; i < count; i++)
+            {
+                GameObject line = Instantiate(transform.GetChild(0).gameObject, transform);
+                line.transform.localPosition = new Vector3(i, line.transform.localPosition.y);
+                line.SetActive(true);
+
+                Lines.Add(line);
+            }
+        }
+
+        private void Update()
+        {
+            var pos = new Vector2(Mathf.RoundToInt(Mathf.Abs(transform.parent.localPosition.x) / 100) - 1, transform.localPosition.y);
+            transform.localPosition = pos;
+
+            if (pos.x != lastPosX)
+                UpdateGridNum();
+
+            lastPosX = transform.localPosition.x;
+        }
+
+        private void UpdateGridNum()
+        {
+            for (int i = 0; i < Lines.Count; i++)
+            {
+                var line = Lines[i];
+                float newNum = transform.localPosition.x + i;
+                line.transform.GetChild(0).GetComponent<TMP_Text>().text = newNum.ToString();
+            }
+        }
+    }
+}