test/Assets/PerfectWorld/Scripts/World/LitModelHolder.cs

using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using BrewMonster;
using BrewMonster.Scripts;
using Cysharp.Threading.Tasks;
using UnityEngine;

public class LitModelHolder : MonoSingleton<LitModelHolder>
{
    [SerializeField] private AddressableObject[] addressableObjects;
    private CECHostPlayer _hostPlayer;

    [Header("Distance Streaming")]
    [SerializeField] private float _loadImmediateDistance = 200f;
    [SerializeField] private float _paddingDistance = 400f;
    
    [Header("Performance")]
    [SerializeField] private float _checkIntervalSeconds = 0.25f;
    [SerializeField] private float _minHostMoveToUpdate = 2.0f;
    [SerializeField] private int _scanChunkSize = 64;
    [SerializeField] private int _maxLoadsPerTick = 4;
    [SerializeField] private int _maxUnloadsPerTick = 16;
    
    private int _scanIndex = 0;

    // this list is only available if we want to wait until all the objects are loaded.
    private List<AddressableObject> _objectsToLoad = new List<AddressableObject>(); 
    private List<AddressableObject> _objectsToUnload = new List<AddressableObject>();

    private Vector3 _lastHostPos;
    private bool _hasLastHostPos = false;
    private AddressableObject _currentObjectToCheck; // the object that we're currently checking for loading/unloading.

    private async void Awake()
    {
        CancellationToken destroyToken = this.GetCancellationTokenOnDestroy();
        
        // Wait until Addressables are initialized.
        while (!AddressableManager.Instance.IsInitialized())
        {
            await UniTask.DelayFrame(1, cancellationToken: destroyToken);
        }

        while (_hostPlayer == null)
        {
            _hostPlayer = GetHostPlayer();
            await UniTask.Delay(100);
            continue;
        }

        while (!_hostPlayer.IsAllResReady())
        {
            await UniTask.Delay(100);
            continue;
        }

        // run this once at the beginning of the game. So we can load all the objects that are close to the host player.
        await LoadObjectBaseOnDistance(destroyToken);

        // Start distance-based streaming loop. This will be running continuously in the background.
        StreamByDistanceLoop(destroyToken).Forget();
    }

    private async UniTask LoadObjectBaseOnDistance(CancellationToken destroyToken)
    {
        if (_paddingDistance < _loadImmediateDistance)
        {
            _paddingDistance = _loadImmediateDistance;
        }

        float immediateSqr = _loadImmediateDistance * _loadImmediateDistance;
        float paddingSqr = _paddingDistance * _paddingDistance;

        while (_hostPlayer == null)
        {
            _hostPlayer = GetHostPlayer();
            if (_hostPlayer != null) break; // we found the host player.
            await UniTask.Delay(10);
            continue;
        }

        await UniTask.DelayFrame(1); // wait for the host player to be initialized.

        await TickStreaming(_hostPlayer.transform.position, immediateSqr, paddingSqr, true, destroyToken);
    }

    private async UniTask StreamByDistanceLoop(CancellationToken destroyToken)
    {
        if (_paddingDistance < _loadImmediateDistance)
        {
            _paddingDistance = _loadImmediateDistance;
        }

        float immediateSqr = _loadImmediateDistance * _loadImmediateDistance;
        float paddingSqr = _paddingDistance * _paddingDistance;

        int intervalMs = Mathf.Max(10, Mathf.RoundToInt(_checkIntervalSeconds * 1000f));
        float minMoveSqr = _minHostMoveToUpdate * _minHostMoveToUpdate;

        while (!destroyToken.IsCancellationRequested)
        {
            if (_hostPlayer == null)
            {
                _hostPlayer = GetHostPlayer();
                if (_hostPlayer != null) break; // we found the host player.
                await UniTask.Delay(1000, cancellationToken: destroyToken);
                continue;
            }

            Vector3 hostPos = _hostPlayer.transform.position;
            if (_hasLastHostPos)
            {
                if ((hostPos - _lastHostPos).sqrMagnitude < minMoveSqr)
                {
                    await UniTask.Delay(intervalMs, cancellationToken: destroyToken);
                    continue;
                }
            }

            _hasLastHostPos = true;
            _lastHostPos = hostPos;

            await TickStreaming(hostPos, immediateSqr, paddingSqr, false, destroyToken);

            await UniTask.Delay(intervalMs, cancellationToken: destroyToken);
        }
    }
    
    private async UniTask TickStreaming(Vector3 hostPos, float immediateSqr, float paddingSqr, bool waitUntilFinished, CancellationToken destroyToken)
    {
        if (addressableObjects == null || addressableObjects.Length == 0)
        {
            return;
        }

        int count = addressableObjects.Length;
        int chunk = _scanChunkSize <= 0 ? count : Mathf.Min(_scanChunkSize, count);

        int loads = 0;
        int unloads = 0;

        for (int i = 0; i < chunk; i++)
        {
            if (_scanIndex >= count)
            {
                _scanIndex = 0;
            }

            _currentObjectToCheck = addressableObjects[_scanIndex];
            _scanIndex++;

            if (_currentObjectToCheck == null)
            {
                continue;
            }

            float distSqr = (_currentObjectToCheck.transform.position - hostPos).sqrMagnitude;

            if (distSqr <= immediateSqr)
            {
                if (!_currentObjectToCheck.IsLoaded && !_currentObjectToCheck.IsLoading)
                {
                    _currentObjectToCheck.LoadAsset().Forget();
                    _objectsToLoad.Add(_currentObjectToCheck);
                }
            }
            else if (distSqr > paddingSqr)
            {
                if (_currentObjectToCheck.IsLoaded || _currentObjectToCheck.IsLoading)
                {
                    _objectsToUnload.Add(_currentObjectToCheck);
                }
            }
        }

        // unload the objects that are too far away.
        foreach (var obj in _objectsToUnload)
        {
            obj.UnloadAsset();
        }

        while (!IsFinishedLoadingObjects() && waitUntilFinished)
        {
            await UniTask.DelayFrame(1, cancellationToken: destroyToken);
        }
        _objectsToLoad.Clear();

        BMLogger.Log("[LitModelHolder] All objects are loaded.");
    }

    /// <summary>
    /// Get the Host Player instance. 
    /// </summary>
    /// <returns></returns>
    private CECHostPlayer GetHostPlayer()
    {
        return CECGameRun.Instance.GetHostPlayer();
    }

    /// <summary>
    /// Return True if all the objects that are needed to be loaded are loaded.
    /// </summary>
    /// <returns></returns>
    private bool IsFinishedLoadingObjects()
    {
        AddressableObject obj = null;
        for (int i = 0; i < _objectsToLoad.Count; i++)
        {
            obj = _objectsToLoad[i];
            if (obj == null)
            {
                continue;
            }

            if (!obj.IsLoaded && !obj.IsLoading)
            {
                return false;
            }
        }

        return true;
    }
    
    private void OnDestroy()
    {
        if (addressableObjects == null)
        {
            return;
        }

        for (int i = 0; i < addressableObjects.Length; i++)
        {
            AddressableObject obj = addressableObjects[i];
            if (obj == null)
            {
                continue;
            }

            if (obj.IsLoaded || obj.IsLoading)
            {
                obj.UnloadAsset();
            }
        }
    }

    // Keep this part of the code for the initial setup of the addressable objects.
    // We have to run this once on every scene.
    #if UNITY_EDITOR
    [SerializeField] private GameObject[] originalObjects;

    [ContextMenu("Setup Addressable Objects")]
    public void SetupAddressableObjects()
    {
        foreach (var originalObject in originalObjects)
        {
            var addressableObject = originalObject.GetComponent<AddressableObject>();
            if (addressableObject == null)
            {
                addressableObject = originalObject.AddComponent<AddressableObject>();
            }
            
            if (addressableObject != null)
            {
                addressableObject.GetAssetPath();
            }
        }
    }

    [ContextMenu("Validate Addressable Objects")]
    private void ValidateAddressableObjects()
    {
        if (addressableObjects == null || addressableObjects.Length == 0)
        {
            Debug.LogWarning("[LitModelHolder] addressableObjects is empty.");
            return;
        }

        int nullCount = 0;
        int emptyPathCount = 0;
        int multiChildCount = 0;

        var pathCounts = new System.Collections.Generic.Dictionary<string, int>();

        for (int i = 0; i < addressableObjects.Length; i++)
        {
            AddressableObject obj = addressableObjects[i];
            if (obj == null)
            {
                nullCount++;
                continue;
            }

            if (string.IsNullOrEmpty(obj.assetPath))
            {
                emptyPathCount++;
            }
            else
            {
                pathCounts.TryGetValue(obj.assetPath, out int c);
                pathCounts[obj.assetPath] = c + 1;
            }

            // If this is > 1 it often indicates duplicate instantiation under the anchor.
            if (obj.transform.childCount > 1)
            {
                multiChildCount++;
            }
        }

        int duplicatePathKeys = 0;
        foreach (var kvp in pathCounts)
        {
            if (kvp.Value > 1)
            {
                duplicatePathKeys++;
            }
        }

        Debug.Log($"[LitModelHolder] ValidateAddressableObjects:\n" +
                  $"- total={addressableObjects.Length}\n" +
                  $"- nullEntries={nullCount}\n" +
                  $"- emptyAssetPath={emptyPathCount}\n" +
                  $"- duplicateAssetPathKeys={duplicatePathKeys}\n" +
                  $"- anchorsWithMoreThanOneChild={multiChildCount}");
    }
    #endif
}