Conveyor Belt appearance when power is off (#2762)

* Conveyor Belt appearance when power is off

If the conveyor belt is running and the power turns off the belt stops pushing things but the animation continues. This changes it so the animation stops if there is no power and resumes when it returns.

* Change from using Initialize, to OnAdd and OnRemove

Content.Server/GameObjects/Components/Conveyor/ConveyorComponent.cs

@@ -1,4 +1,4 @@
-#nullable enable
+#nullable enable
 using System.Threading.Tasks;
 using Content.Server.GameObjects.Components.Interactable;
 using Content.Server.GameObjects.Components.Items.Storage;
@@ -28,6 +28,8 @@ namespace Content.Server.GameObjects.Components.Conveyor
     {
         public override string Name => "Conveyor";
 
+        [ViewVariables] private bool Powered => !Owner.TryGetComponent(out PowerReceiverComponent? receiver) || receiver.Powered;
+
         /// <summary>
         ///     The angle to move entities by in relation to the owner's rotation.
         /// </summary>
@@ -41,7 +43,6 @@ namespace Content.Server.GameObjects.Components.Conveyor
         private float _speed;
 
         private ConveyorState _state;
-
         /// <summary>
         ///     The current state of this conveyor
         /// </summary>
@@ -52,13 +53,45 @@ namespace Content.Server.GameObjects.Components.Conveyor
             set
             {
                 _state = value;
+                UpdateAppearance();
+            }
+        }
 
-                if (!Owner.TryGetComponent(out AppearanceComponent? appearance))
+        public override void OnAdd()
+        {
+            base.OnAdd();
+            if (Owner.TryGetComponent(out PowerReceiverComponent? receiver))
+            {
+                receiver.OnPowerStateChanged += OnPowerChanged;
+            }
+        }
+
+        public override void OnRemove()
+        {
+            base.OnRemove();
+            if (Owner.TryGetComponent(out PowerReceiverComponent? receiver))
+            {
+                receiver.OnPowerStateChanged -= OnPowerChanged;
+            }
+        }
+
+        private void OnPowerChanged(object? sender, PowerStateEventArgs e)
+        {
+            UpdateAppearance();
+        }
+
+        private void UpdateAppearance()
+        {
+            if (Owner.TryGetComponent<AppearanceComponent>(out var appearance))
+            {
+                if (Powered)
                 {
-                    return;
+                    appearance.SetData(ConveyorVisuals.State, _state);
+                }
+                else
+                {
+                    appearance.SetData(ConveyorVisuals.State, ConveyorState.Off);
                 }
-
-                appearance.SetData(ConveyorVisuals.State, value);
             }
         }
 

Resources/Prototypes/Entities/Constructible/Specific/Conveyor/conveyor.yml

@@ -27,6 +27,7 @@
     drawdepth: FloorObjects
   - type: SignalReceiver
     maxTransmitters: 1
+  - type: PowerReceiver
   - type: Conveyor
   - type: Appearance
     visuals:
@@ -34,7 +35,6 @@
       state_running: conveyor_started_cw
       state_stopped: conveyor_stopped_cw
       state_reversed: conveyor_started_cw_r
-  - type: PowerReceiver
   - type: Construction
     graph: ConveyorGraph
     node: entity