Last reviewed 30 Apr 2026
Applies to
UdonSharp VRChat Worlds SDK World UI
Difficulty Beginner

Synced Countdown Timer

A simple network-synced countdown timer you can start from an interact button.

Category: Networking Systems

UdonSharp Script

using UdonSharp;
using UnityEngine;
using TMPro;
using VRC.SDKBase;
using VRC.Udon;

public class SyncedCountdownTimer : UdonSharpBehaviour
{
    public TextMeshProUGUI timerText;
    public float durationSeconds = 30f;

    [UdonSynced] private float endTime;
    [UdonSynced] private bool isRunning;

    public override void Interact()
    {
        VRCPlayerApi localPlayer = Networking.LocalPlayer;
        if (localPlayer == null) return;

        Networking.SetOwner(localPlayer, gameObject);
        endTime = Time.time + durationSeconds;
        isRunning = true;
        RequestSerialization();
        UpdateDisplay();
    }

    public override void OnDeserialization()
    {
        UpdateDisplay();
    }

    private void Update()
    {
        if (!isRunning) return;

        float remaining = endTime - Time.time;
        if (remaining <= 0f)
        {
            isRunning = false;
            remaining = 0f;
        }

        if (timerText != null)
        {
            timerText.text = "Timer: " + Mathf.CeilToInt(remaining).ToString();
        }
    }

    private void UpdateDisplay()
    {
        if (timerText == null) return;
        if (!isRunning)
        {
            timerText.text = "Timer: 0";
            return;
        }

        float remaining = Mathf.Max(0f, endTime - Time.time);
        timerText.text = "Timer: " + Mathf.CeilToInt(remaining).ToString();
    }
}

License:

Setup

  1. Add script to a button object with VRC_Interactable.
  2. Create a TextMeshProUGUI label and assign it to timerText.
  3. Set durationSeconds.

Extra Tips and Troubleshooting

Tips and Tricks

  • Use short, readable timer durations for social activities.
  • Pair timer completion with audio cue for clarity.

Troubleshooting

  • If timer text does not update, verify TextMeshPro reference assignment.

Related Content

Prefab Setup Notes

Import the prefab or script into a throwaway test scene before adding it to a live world. Confirm inspector references, ownership behavior, sync, triggers, UI hooks, and audio or object links before moving it into the production scene.

Testing Checklist

  • Test once as a local player and again with a second client or late joiner if the behavior can affect more than one player.
  • Confirm ownership, sync, trigger zones, UI references, and audio or object references are assigned intentionally.
  • Check desktop and VR interaction distance so players can actually use the feature in context.
  • Keep a backup of the scene before changing prefabs, UdonBehaviours, or serialized references.

Related Pages

Official References