HoHCI-BikeSteering/Assets/Scripts/Display/CountdownDisplay.cs

using System;
using TMPro;
using UnityEngine;
using Debug = System.Diagnostics.Debug;

namespace Display
{
    public class CountdownDisplay : MonoBehaviour
    {
        public int countdown = 3;
        public TextMeshProUGUI countdownText;
        public float distance;
        
        private Camera cam;
        private Transform camTransform;
        private Transform canvasTransform;

        public delegate string CountdownDoneCallback();

        public CountdownDoneCallback OnCountdownDone { get; set; }

        private float lastTime;

        private void Start()
        {
            cam = Camera.main;
            Debug.Assert(cam != null, nameof(cam) + " != null");
            camTransform = cam.transform;
            lastTime = Time.time;
            canvasTransform = GetComponentInChildren<Canvas>().transform;
        }

        private void Update()
        {
            var t = Time.time;
            if (t - lastTime >= 1)
            {
                lastTime = t;
                countdown--;
                countdownText.text = $"{countdown}";
                if (countdown == 0)
                {
                    countdownText.text = OnCountdownDone?.Invoke();
                    Destroy(gameObject, 0.5f);
                }
            }
            

            canvasTransform.SetPositionAndRotation(camTransform.position + camTransform.forward * distance,
                camTransform.rotation);
        }
    }
}