Move viewsubscriber to shared + handle eye targets

Need this stuff for AI.

Robust.Client/GameObjects/EntitySystems/ViewSubscriberSystem.cs

@@ -0,0 +1,8 @@
+using Robust.Shared.GameObjects;
+
+namespace Robust.Client.GameObjects;
+
+public sealed class ViewSubscriberSystem : SharedViewSubscriberSystem
+{
+
+}

Robust.Server/GameObjects/EntitySystems/ViewSubscriberSystem.cs

@@ -6,22 +6,15 @@ namespace Robust.Server.GameObjects
     /// <summary>
     ///     Entity System that handles subscribing and unsubscribing to PVS views.
     /// </summary>
-    public sealed class ViewSubscriberSystem : EntitySystem
+    public sealed class ViewSubscriberSystem : SharedViewSubscriberSystem
     {
-        public override void Initialize()
-        {
-            base.Initialize();
-
-            SubscribeLocalEvent<ViewSubscriberComponent, ComponentShutdown>(OnViewSubscriberShutdown);
-        }
-
         /// <summary>
         ///     Subscribes the session to get PVS updates from the point of view of the specified entity.
         /// </summary>
-        public void AddViewSubscriber(EntityUid uid, ICommonSession session)
+        public override void AddViewSubscriber(EntityUid uid, ICommonSession session)
         {
             // If the entity doesn't have the component, it will be added.
-            var viewSubscriber = EntityManager.EnsureComponent<ViewSubscriberComponent>(uid);
+            var viewSubscriber = EntityManager.EnsureComponent<Shared.GameObjects.ViewSubscriberComponent>(uid);
 
             if (viewSubscriber.SubscribedSessions.Contains(session))
                 return; // Already subscribed, do nothing else.
@@ -35,9 +28,9 @@ public void AddViewSubscriber(EntityUid uid, ICommonSession session)
         /// <summary>
         ///     Unsubscribes the session from getting PVS updates from the point of view of the specified entity.
         /// </summary>
-        public void RemoveViewSubscriber(EntityUid uid, ICommonSession session)
+        public override void RemoveViewSubscriber(EntityUid uid, ICommonSession session)
         {
-            if(!EntityManager.TryGetComponent(uid, out ViewSubscriberComponent? viewSubscriber))
+            if(!EntityManager.TryGetComponent(uid, out Shared.GameObjects.ViewSubscriberComponent? viewSubscriber))
                 return; // Entity didn't have any subscriptions, do nothing.
 
             if (!viewSubscriber.SubscribedSessions.Remove(session))
@@ -47,7 +40,7 @@ public void RemoveViewSubscriber(EntityUid uid, ICommonSession session)
             RaiseLocalEvent(uid, new ViewSubscriberRemovedEvent(uid, session), true);
         }
 
-        private void OnViewSubscriberShutdown(EntityUid uid, ViewSubscriberComponent component, ComponentShutdown _)
+        protected override void OnViewSubscriberShutdown(EntityUid uid, ViewSubscriberComponent component, ComponentShutdown _)
         {
             foreach (var session in component.SubscribedSessions)
             {

Robust.Shared/GameObjects/Components/Eye/ViewSubscriberComponent.cs

@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+using Robust.Shared.Player;
+
+namespace Robust.Shared.GameObjects;
+
+// Not networked because doesn't do anything on client.
+[RegisterComponent]
+public sealed partial class ViewSubscriberComponent : Component
+{
+    internal readonly HashSet<ICommonSession> SubscribedSessions = new();
+}

Robust.Shared/GameObjects/Systems/SharedEyeSystem.cs

@@ -2,11 +2,41 @@
 using System.Numerics;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
+using Robust.Shared.Player;
 
 namespace Robust.Shared.GameObjects;
 
 public abstract class SharedEyeSystem : EntitySystem
 {
+    [Dependency] private readonly SharedViewSubscriberSystem _views = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<EyeComponent, PlayerAttachedEvent>(OnEyePlayerAttached);
+        SubscribeLocalEvent<EyeComponent, PlayerDetachedEvent>(OnEyePlayerDetached);
+    }
+
+    private void OnEyePlayerAttached(Entity<EyeComponent> ent, ref PlayerAttachedEvent args)
+    {
+        var value = ent.Comp.Target;
+
+        if (value != null && TryComp(ent.Owner, out ActorComponent? actorComp))
+        {
+            _views.AddViewSubscriber(value.Value, actorComp.PlayerSession);
+        }
+    }
+
+    private void OnEyePlayerDetached(Entity<EyeComponent> ent, ref PlayerDetachedEvent args)
+    {
+        var value = ent.Comp.Target;
+
+        if (value == null && TryComp(ent.Owner, out ActorComponent? actorComp))
+        {
+            _views.RemoveViewSubscriber(ent.Comp.Target!.Value, actorComp.PlayerSession);
+        }
+    }
+
     /// <summary>
     /// Refreshes all values for IEye with the component.
     /// </summary>
@@ -74,6 +104,10 @@ public void SetRotation(EntityUid uid, Angle rotation, EyeComponent? eyeComponen
         eyeComponent.Eye.Rotation = rotation;
     }
 
+    /// <summary>
+    /// Sets the eye component as tracking another entity.
+    /// Will also add the target to view subscribers so they can leave range and still work with PVS.
+    /// </summary>
     public void SetTarget(EntityUid uid, EntityUid? value, EyeComponent? eyeComponent = null)
     {
         if (!Resolve(uid, ref eyeComponent))
@@ -82,6 +116,20 @@ public void SetTarget(EntityUid uid, EntityUid? value, EyeComponent? eyeComponen
         if (eyeComponent.Target.Equals(value))
             return;
 
+        // Automatically handle view subs.
+        if (TryComp(uid, out ActorComponent? actorComp))
+        {
+            if (value != null)
+            {
+                _views.AddViewSubscriber(value.Value, actorComp.PlayerSession);
+            }
+            else
+            {
+                // Should never be null here
+                _views.RemoveViewSubscriber(eyeComponent.Target!.Value, actorComp.PlayerSession);
+            }
+        }
+
         eyeComponent.Target = value;
         Dirty(uid, eyeComponent);
     }

Robust.Shared/GameObjects/Systems/SharedViewSubscriberSystem.cs

@@ -0,0 +1,26 @@
+using Robust.Shared.Player;
+
+namespace Robust.Shared.GameObjects;
+
+public abstract class SharedViewSubscriberSystem : EntitySystem
+{
+    // NOOP on client
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<ViewSubscriberComponent, ComponentShutdown>(OnViewSubscriberShutdown);
+    }
+
+    /// <summary>
+    ///     Subscribes the session to get PVS updates from the point of view of the specified entity.
+    /// </summary>
+    public virtual void AddViewSubscriber(EntityUid uid, ICommonSession session) {}
+
+    /// <summary>
+    ///     Unsubscribes the session from getting PVS updates from the point of view of the specified entity.
+    /// </summary>
+    public virtual void RemoveViewSubscriber(EntityUid uid, ICommonSession session) {}
+
+    protected virtual void OnViewSubscriberShutdown(EntityUid uid, ViewSubscriberComponent component, ComponentShutdown _) {}
+}