sea-battle-vr/Assets/Scripts/Menu/MenuAnimation.cs

using Cysharp.Threading.Tasks;
using System;
using System.Threading;
using Unity.Mathematics.Geometry;
using UnityEngine;
using UnityEngine.SceneManagement;

public class MenuAnimation : MonoBehaviour
{
    [Header("Группы")]
    [SerializeField] private CanvasGroup beforePaymentGroup;
    [SerializeField] private CanvasGroup afterPaymentGroup;

    [Header("Инструкция")]
    [SerializeField] private CanvasGroup startInstruction;
    [SerializeField] private CanvasGroup periscopeInstruction;
    [SerializeField] private float switchSpeed = 4;
    [SerializeField] private float stayDelay = 2;

    [Header("Градиент")]
    [SerializeField] private RectTransform gradient;
    [SerializeField] private float normalHeight = 440;
    [SerializeField] private float payedHeight = 1080;
    [SerializeField] private float gradientTransitionSpeed = 2;

    private CancellationTokenSource cts;

    bool payed = false;

    public void Init(bool alreadyPayed)
    {
        beforePaymentGroup.alpha = alreadyPayed ? 0f : 1f;
        afterPaymentGroup.alpha = alreadyPayed ? 1 : 0f;
        float gradientHeight = alreadyPayed ? payedHeight : normalHeight;
        gradient.sizeDelta = new Vector2(gradient.sizeDelta.x, gradientHeight);

        startInstruction.alpha = 0;
        periscopeInstruction.alpha = 1;


        if (alreadyPayed)
        {
            payed = true;
            StartInstructionAnimation();
        }
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.R))
        {
            WalletManager.ResetBalance();
        }
    }

    private void OnDestroy()
    {
        cts?.Cancel();
        cts?.Dispose();
    }

    private void StopAnimation()
    {
        cts?.Cancel();
        cts?.Dispose();
        cts = null;
    }

    public void PerformTransition()
    {
        if(payed) return;

        StopAnimation();
        cts = new CancellationTokenSource();
        Transition(cts.Token).Forget();
    }

    private async UniTask Transition(CancellationToken ct)
    {
        GradientUp(ct).Forget();
        await TransitionToInstruction(ct);
        if (!ct.IsCancellationRequested)
        {
            await InstructionAnimation(ct);
        }
    }

    public void StartInstructionAnimation()
    {
        StopAnimation();
        cts = new CancellationTokenSource();
        InstructionAnimation(cts.Token).Forget();
    }

    private async UniTask TransitionToInstruction(CancellationToken ct)
    {
        float t;
        //тушим
        t = 0;
        while (t < 1 && !ct.IsCancellationRequested)
        {
            t += Time.deltaTime * switchSpeed;
            t = Mathf.Min(t, 1);

            beforePaymentGroup.alpha = 1 - t;
            await UniTask.Yield(ct);
        }

        //Зажигаем
        t = 0;
        while (t < 1 && !ct.IsCancellationRequested)
        {
            t += Time.deltaTime * switchSpeed;
            t = Mathf.Min(t, 1);

            afterPaymentGroup.alpha = t;
            await UniTask.Yield(ct);
        }
    }

    private async UniTask GradientUp(CancellationToken ct)
    {
        float t = 0;
        while(t < 1 && !ct.IsCancellationRequested)
        {
            t += Time.deltaTime * gradientTransitionSpeed;
            t = Mathf.Min(t, 1);

            float height = Mathf.Lerp(normalHeight, payedHeight, t);
            gradient.sizeDelta = new Vector2(gradient.sizeDelta.x, height);

            await UniTask.Yield(ct);
        }
        gradient.sizeDelta = new Vector2(gradient.sizeDelta.x, payedHeight);
    }

    private async UniTask InstructionAnimation(CancellationToken ct)
    {
        var ascendingGroup = startInstruction;
        var descendingGroup = periscopeInstruction;

        float t;

        while (!ct.IsCancellationRequested)
        {
            await UniTask.Delay(TimeSpan.FromSeconds(stayDelay), cancellationToken: ct);

            //тушим
            t = 0;
            while (t < 1 && !ct.IsCancellationRequested)
            {
                t += Time.deltaTime * switchSpeed;
                t = Mathf.Min(t, 1);

                descendingGroup.alpha = 1 - t;
                await UniTask.Yield(ct);
            }

            //Зажигаем
            t = 0;
            while (t < 1 && !ct.IsCancellationRequested)
            {
                t += Time.deltaTime * switchSpeed;
                t = Mathf.Min(t, 1);

                ascendingGroup.alpha = t;
                await UniTask.Yield(ct);
            }

            (ascendingGroup, descendingGroup) = (descendingGroup, ascendingGroup);
        }
    }
}