first commit

NitroxPatcher/Patches/Dynamic/LargeWorldEntity_UpdateCell_Patch.cs

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+using System.Collections.Generic;
+using System.Reflection;
+using System.Reflection.Emit;
+using HarmonyLib;
+using NitroxClient.MonoBehaviours;
+using NitroxModel.DataStructures;
+using NitroxModel.Helper;
+using UnityEngine;
+
+namespace NitroxPatcher.Patches.Dynamic;
+
+public sealed partial class LargeWorldEntity_UpdateCell_Patch : NitroxPatch, IDynamicPatch
+{
+    private static readonly MethodInfo TARGET_METHOD = Reflect.Method((LargeWorldEntity t) => t.UpdateCell(default));
+
+    /*
+     * MODIFIED LINE:
+     * streamer.cellManager.RegisterEntity(this);
+     * 
+     * BECOMES:
+     * LargeWorldEntity_UpdateCell_Patch.EntityUpdated(streamer.cellManager.RegisterEntity(this), this);
+     * 
+     * For this we only need to take the result of RegisterEntity (which is already on the stack) and instead of removing it (pop instruction)
+     * we feed it to our method
+     */
+    public static IEnumerable<CodeInstruction> Transpiler(IEnumerable<CodeInstruction> instructions)
+    {
+        return new CodeMatcher(instructions).MatchEndForward([
+                                                new CodeMatch(OpCodes.Ldarg_1),
+                                                new CodeMatch(OpCodes.Ldfld),
+                                                new CodeMatch(OpCodes.Ldarg_0),
+                                                new CodeMatch(OpCodes.Callvirt),
+                                                new CodeMatch(OpCodes.Pop),
+                                            ])
+                                            .RemoveInstruction() // Remove Pop instruction
+                                            .InsertAndAdvance([
+                                                new CodeInstruction(OpCodes.Ldarg_0), // this
+                                                new CodeInstruction(OpCodes.Call, Reflect.Method(() => EntityUpdated(default, default)))
+                                            ]).InstructionEnumeration();
+    }
+
+    private static void EntityUpdated(bool success, LargeWorldEntity largeWorldEntity)
+    {
+        // Successfully moving from one cell to another isn't interesting to us
+        if (success)
+        {
+            return;
+        }
+        
+        // The entity has left the regular loaded zone
+        // NB: Very important to check for selfActive because it's false when the entity is unloaded by EntityCell.AddEntity
+
+        if (largeWorldEntity.gameObject.activeSelf)
+        {
+            if (largeWorldEntity.TryGetNitroxId(out NitroxId nitroxId))
+            {
+                largeWorldEntity.gameObject.EnsureComponent<OutOfCellEntity>().Init(nitroxId);
+            }
+        }
+        // Entity was added to a sleeping cell so it'll be just like it's 
+        else if (largeWorldEntity.TryGetComponent(out OutOfCellEntity outOfCellEntity))
+        {
+            Object.Destroy(outOfCellEntity);
+        }
+    }
+}