Travelling pointing arrows, brains can no longer point (#24864)

* Decoupled from gravity, constant animation time, manual networking, cubic interpolation

* Reduced overshoot

* Implemented PointAttemptEvent, reacts with mobstate & sleeping

* Brains can no longer point, PBs must be inside a chassis

* Removed chassis check, made callback more obvious

Content.Shared/Pointing/SharedPointingSystem.cs

@@ -1,17 +1,36 @@
 using Robust.Shared.Serialization;
+using System.Numerics;
 
 namespace Content.Shared.Pointing;
 
 public abstract class SharedPointingSystem : EntitySystem
 {
-    [Serializable, NetSerializable]
-    protected sealed class PointingArrowComponentState : ComponentState
-    {
-        public TimeSpan EndTime;
+    protected readonly TimeSpan PointDuration = TimeSpan.FromSeconds(4);
+    protected readonly float PointKeyTimeMove = 0.1f;
+    protected readonly float PointKeyTimeHover = 0.5f;
 
-        public PointingArrowComponentState(TimeSpan endTime)
-        {
-            EndTime = endTime;
-        }
+    [Serializable, NetSerializable]
+    public sealed class SharedPointingArrowComponentState : ComponentState
+    {
+        public Vector2 StartPosition { get; init; }
+        public TimeSpan EndTime { get; init; }
+    }
+
+    public bool CanPoint(EntityUid uid)
+    {
+        var ev = new PointAttemptEvent(uid);
+        RaiseLocalEvent(uid, ev, true);
+
+        return !ev.Cancelled;
     }
 }
+
+public sealed class PointAttemptEvent : CancellableEntityEventArgs
+{
+    public PointAttemptEvent(EntityUid uid)
+    {
+        Uid = uid;
+    }
+
+    public EntityUid Uid { get; }
+}