makes conveyors to use machine linking & refactors machine linking a bit (#2464)

* makes conveyors to use machine linking & refactors machine linking a bit

* nullable errors

* temp commit, starting work on construction

* working recipies & graphs

* fixes crash

* makes items gravitate towards the center when on a conveyor

* makes conveyors take bool signal too

* ignores components clientside

* default arm
entitymanager
maxtransmitters
unsubscribe methods

* twowayLEVER

* _

* componentreference
struct

* yaml run
leverDefinitelyNotCopiedFromGirderNoNoNo dies today :(

* nullable

* no divide by 0

* making sloth happy

* space gone - happy?

* final fix

* yes

* adds item to lathe

* conveyor item -> conveyor assembly

* technology

* reviews ADRESSED

* Update Content.Shared/GameObjects/Verbs/VerbUtility.cs

Co-authored-by: Paul <ritter.paul1+git@googlemail.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Client/GameObjects/Components/Conveyor/ConveyorVisualizer.cs

@@ -16,7 +16,6 @@ namespace Content.Client.GameObjects.Components.Conveyor
         private string _stateRunning;
         private string _stateStopped;
         private string _stateReversed;
-        private string _stateLoose;
 
         private void ChangeState(AppearanceComponent appearance)
         {
@@ -32,7 +31,6 @@ namespace Content.Client.GameObjects.Components.Conveyor
                 ConveyorState.Off => _stateStopped,
                 ConveyorState.Forward => _stateRunning,
                 ConveyorState.Reversed => _stateReversed,
-                ConveyorState.Loose => _stateLoose,
                 _ => throw new ArgumentOutOfRangeException()
             };
 
@@ -46,7 +44,6 @@ namespace Content.Client.GameObjects.Components.Conveyor
             _stateRunning = node.GetNode("state_running").AsString();
             _stateStopped = node.GetNode("state_stopped").AsString();
             _stateReversed = node.GetNode("state_reversed").AsString();
-            _stateLoose = node.GetNode("state_loose").AsString();
         }
 
         public override void InitializeEntity(IEntity entity)

Content.Client/GameObjects/Components/Conveyor/TwoWayLeverVisualizer.cs

@@ -1,5 +1,6 @@
 using System;
 using Content.Shared.GameObjects.Components.Conveyor;
+using Content.Shared.GameObjects.Components.MachineLinking;
 using JetBrains.Annotations;
 using Robust.Client.GameObjects;
 using Robust.Client.Interfaces.GameObjects.Components;
@@ -11,12 +12,11 @@ using YamlDotNet.RepresentationModel;
 namespace Content.Client.GameObjects.Components.Conveyor
 {
     [UsedImplicitly]
-    public class ConveyorSwitchVisualizer : AppearanceVisualizer
+    public class TwoWayLeverVisualizer : AppearanceVisualizer
     {
         private string _stateForward;
         private string _stateOff;
         private string _stateReversed;
-        private string _stateLoose;
 
         private void ChangeState(AppearanceComponent appearance)
         {
@@ -25,15 +25,14 @@ namespace Content.Client.GameObjects.Components.Conveyor
                 return;
             }
 
-            appearance.TryGetData(ConveyorVisuals.State, out ConveyorState state);
+            appearance.TryGetData(TwoWayLeverVisuals.State, out TwoWayLeverSignal state);
 
             var texture = state switch
             {
-                ConveyorState.Off => _stateOff,
+                TwoWayLeverSignal.Middle => _stateOff,
-                ConveyorState.Forward => _stateForward,
+                TwoWayLeverSignal.Right => _stateForward,
-                ConveyorState.Reversed => _stateReversed,
+                TwoWayLeverSignal.Left => _stateReversed,
-                ConveyorState.Loose => _stateLoose,
+                _ => _stateOff
-                _ => throw new ArgumentOutOfRangeException()
             };
 
             sprite.LayerSetState(0, texture);
@@ -46,7 +45,6 @@ namespace Content.Client.GameObjects.Components.Conveyor
             _stateForward = node.GetNode("state_forward").AsString();
             _stateOff = node.GetNode("state_off").AsString();
             _stateReversed = node.GetNode("state_reversed").AsString();
-            _stateLoose = node.GetNode("state_loose").AsString();
         }
 
         public override void InitializeEntity(IEntity entity)

Content.Client/IgnoredComponents.cs

@@ -135,7 +135,6 @@
             "DisposalBend",
             "Recycler",
             "Conveyor",
-            "ConveyorSwitch",
             "Flippable",
             "Airtight",
             "MovedByPressure",
@@ -211,6 +210,8 @@
             "CrematoriumEntityStorage",
             "RandomArcade",
             "RandomSpriteState",
+            "ConveyorAssembly",
+            "TwoWayLever"
         };
     }
 }

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

@@ -1,13 +1,12 @@
 #nullable enable
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 using Content.Server.GameObjects.Components.Interactable;
 using Content.Server.GameObjects.Components.Items.Storage;
+using Content.Server.GameObjects.Components.MachineLinking;
 using Content.Server.GameObjects.Components.Power.ApcNetComponents;
-using Content.Server.GameObjects.EntitySystems;
 using Content.Shared.GameObjects.Components.Conveyor;
 using Content.Shared.GameObjects.Components.Interactable;
+using Content.Shared.GameObjects.Components.MachineLinking;
 using Content.Shared.Interfaces.GameObjects.Components;
 using Content.Shared.Physics;
 using Content.Shared.Utility;
@@ -17,7 +16,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.Map;
 using Robust.Shared.Interfaces.GameObjects;
-using Robust.Shared.Interfaces.Random;
 using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Serialization;
@@ -26,16 +24,14 @@ using Robust.Shared.ViewVariables;
 namespace Content.Server.GameObjects.Components.Conveyor
 {
     [RegisterComponent]
-    public class ConveyorComponent : Component, IInteractUsing
+    public class ConveyorComponent : Component, ISignalReceiver<TwoWayLeverSignal>, ISignalReceiver<bool>
     {
-        [Dependency] private readonly IEntityManager _entityManager = default!;
-
         public override string Name => "Conveyor";
 
         /// <summary>
         ///     The angle to move entities by in relation to the owner's rotation.
         /// </summary>
-        [ViewVariables]
+        [ViewVariables(VVAccess.ReadWrite)]
         private Angle _angle;
 
         /// <summary>
@@ -66,8 +62,6 @@ namespace Content.Server.GameObjects.Components.Conveyor
             }
         }
 
-        private ConveyorGroup? _group = new ConveyorGroup();
-
         /// <summary>
         ///     Calculates the angle in which entities on top of this conveyor
         ///     belt are pushed in
@@ -142,7 +136,7 @@ namespace Content.Server.GameObjects.Components.Conveyor
                 return;
             }
 
-            var intersecting = _entityManager.GetEntitiesIntersecting(Owner, true);
+            var intersecting = Owner.EntityManager.GetEntitiesIntersecting(Owner, true);
             var direction = GetAngle().ToVec();
 
             foreach (var entity in intersecting)
@@ -155,107 +149,33 @@ namespace Content.Server.GameObjects.Components.Conveyor
                 if (entity.TryGetComponent(out IPhysicsComponent? physics))
                 {
                     var controller = physics.EnsureController<ConveyedController>();
-                    controller.Move(direction, _speed);
+                    controller.Move(direction, _speed, entity.Transform.WorldPosition - Owner.Transform.WorldPosition);
                 }
             }
         }
 
-        private async Task<bool> ToolUsed(IEntity user, ToolComponent tool)
-        {
-            if (!Owner.HasComponent<ItemComponent>() &&
-                await tool.UseTool(user, Owner, 0.5f, ToolQuality.Prying))
-            {
-                State = ConveyorState.Loose;
-
-                Owner.AddComponent<ItemComponent>();
-                _group?.RemoveConveyor(this);
-                Owner.RandomOffset(0.2f);
-
-                return true;
-            }
-
-            return false;
-        }
-
-        public void Sync(ConveyorGroup group)
-        {
-            _group = group;
-
-            if (State == ConveyorState.Loose)
-            {
-                return;
-            }
-
-            State = group.State == ConveyorState.Loose
-                ? ConveyorState.Off
-                : group.State;
-        }
-
-        /// <summary>
-        ///     Disconnects this conveyor from any switch.
-        /// </summary>
-        private void Disconnect()
-        {
-            _group?.RemoveConveyor(this);
-            _group = null;
-            State = ConveyorState.Off;
-        }
-
         public override void ExposeData(ObjectSerializer serializer)
         {
             base.ExposeData(serializer);
 
-            serializer.DataReadWriteFunction(
-                "switches",
-                new List<EntityUid>(),
-                ids =>
-                {
-                    if (ids == null)
-                    {
-                        return;
-                    }
-
-                    foreach (var id in ids)
-                    {
-                        if (!Owner.EntityManager.TryGetEntity(id, out var @switch))
-                        {
-                            continue;
-                        }
-
-                        if (!@switch.TryGetComponent(out ConveyorSwitchComponent? component))
-                        {
-                            continue;
-                        }
-
-                        component.Connect(this);
-                    }
-                },
-                () => _group?.Switches.Select(@switch => @switch.Owner.Uid).ToList());
-
             serializer.DataField(ref _angle, "angle", 0);
             serializer.DataField(ref _speed, "speed", 2);
         }
 
-        public override void OnRemove()
+        public void TriggerSignal(TwoWayLeverSignal signal)
         {
-            base.OnRemove();
+            State = signal switch
-            Disconnect();
+            {
+                TwoWayLeverSignal.Left => ConveyorState.Reversed,
+                TwoWayLeverSignal.Middle => ConveyorState.Off,
+                TwoWayLeverSignal.Right => ConveyorState.Forward,
+                _ => ConveyorState.Off
+            };
         }
 
-        async Task<bool> IInteractUsing.InteractUsing(InteractUsingEventArgs eventArgs)
+        public void TriggerSignal(bool signal)
         {
-            if (eventArgs.Using.TryGetComponent(out ConveyorSwitchComponent? conveyorSwitch))
+            State = signal ? ConveyorState.Forward : ConveyorState.Off;
-            {
-                conveyorSwitch.Connect(this, eventArgs.User);
-                return true;
-            }
-
-            if (eventArgs.Using.TryGetComponent(out ToolComponent? tool))
-            {
-                return await ToolUsed(eventArgs.User, tool);
-            }
-
-            return false;
         }
     }
 }

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

@@ -0,0 +1,13 @@
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Conveyor
+{
+    /// <summary>
+    /// Dummy component for construction graph
+    /// </summary>
+    [RegisterComponent]
+    public class ConveyorAssemblyComponent : Component
+    {
+        public override string Name => "ConveyorAssembly";
+    }
+}

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

@@ -1,219 +0,0 @@
-#nullable enable
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using Content.Server.GameObjects.EntitySystems;
-using Content.Shared.GameObjects.Components.Conveyor;
-using Content.Shared.Interfaces;
-using Content.Shared.Interfaces.GameObjects.Components;
-using Robust.Server.GameObjects;
-using Robust.Shared.GameObjects;
-using Robust.Shared.Interfaces.GameObjects;
-using Robust.Shared.Localization;
-using Robust.Shared.Serialization;
-using Robust.Shared.ViewVariables;
-
-namespace Content.Server.GameObjects.Components.Conveyor
-{
-    [RegisterComponent]
-    public class ConveyorSwitchComponent : Component, IInteractHand, IInteractUsing, IActivate
-    {
-        public override string Name => "ConveyorSwitch";
-
-        private ConveyorState _state;
-
-        /// <summary>
-        ///     The current state of this switch
-        /// </summary>
-        [ViewVariables]
-        public ConveyorState State
-        {
-            get => _state;
-            private set
-            {
-                _state = value;
-
-                if (Owner.TryGetComponent(out AppearanceComponent? appearance))
-                {
-                    appearance.SetData(ConveyorVisuals.State, value);
-                }
-            }
-        }
-
-        private ConveyorGroup? _group;
-
-        public void Sync(ConveyorGroup group)
-        {
-            _group = group;
-
-            if (State == ConveyorState.Loose)
-            {
-                return;
-            }
-
-            State = group.State == ConveyorState.Loose
-                ? ConveyorState.Off
-                : group.State;
-        }
-
-        /// <summary>
-        ///     Disconnects this switch from any conveyors and other switches.
-        /// </summary>
-        private void Disconnect()
-        {
-            _group?.RemoveSwitch(this);
-            _group = null;
-            State = ConveyorState.Off;
-        }
-
-        /// <summary>
-        ///     Connects a conveyor to this switch.
-        /// </summary>
-        /// <param name="conveyor">The conveyor to be connected.</param>
-        /// <param name="user">The user doing the connecting, if any.</param>
-        public void Connect(ConveyorComponent conveyor, IEntity? user = null)
-        {
-            if (_group == null)
-            {
-                _group = new ConveyorGroup();
-                _group.AddSwitch(this);
-            }
-
-            _group.AddConveyor(conveyor);
-            user?.PopupMessage(Loc.GetString("Conveyor linked."));
-        }
-
-        /// <summary>
-        ///     Cycles this conveyor switch to its next valid state
-        /// </summary>
-        /// <returns>
-        ///     true if the switch can be operated and the state could be cycled,
-        ///     false otherwise
-        /// </returns>
-        private bool NextState()
-        {
-            State = State switch
-            {
-                ConveyorState.Off => ConveyorState.Forward,
-                ConveyorState.Forward => ConveyorState.Reversed,
-                ConveyorState.Reversed => ConveyorState.Off,
-                ConveyorState.Loose => ConveyorState.Off,
-                _ => throw new ArgumentOutOfRangeException()
-            };
-
-            _group?.SetState(this);
-
-            return true;
-        }
-
-        /// <summary>
-        ///     Moves this switch to the group of another.
-        /// </summary>
-        /// <param name="other">The conveyor switch to synchronize with.</param>
-        /// <param name="user">The user doing the syncing, if any.</param>
-        private void SyncWith(ConveyorSwitchComponent other, IEntity? user = null)
-        {
-            other._group?.AddSwitch(this);
-
-            if (user == null)
-            {
-                return;
-            }
-
-            Owner.PopupMessage(user, Loc.GetString("Switches synchronized."));
-        }
-
-        public override void ExposeData(ObjectSerializer serializer)
-        {
-            base.ExposeData(serializer);
-
-            serializer.DataReadWriteFunction(
-                "conveyors",
-                new List<EntityUid>(),
-                ids =>
-                {
-                    if (ids == null)
-                    {
-                        return;
-                    }
-
-                    foreach (var id in ids)
-                    {
-                        if (!Owner.EntityManager.TryGetEntity(id, out var conveyor))
-                        {
-                            continue;
-                        }
-
-                        if (!conveyor.TryGetComponent(out ConveyorComponent? component))
-                        {
-                            continue;
-                        }
-
-                        Connect(component);
-                    }
-                },
-                () => _group?.Conveyors.Select(conveyor => conveyor.Owner.Uid).ToList());
-
-            serializer.DataReadWriteFunction(
-                "switches",
-                new List<EntityUid>(),
-                ids =>
-                {
-                    if (ids == null)
-                    {
-                        return;
-                    }
-
-                    foreach (var id in ids)
-                    {
-                        if (!Owner.EntityManager.TryGetEntity(id, out var @switch))
-                        {
-                            continue;
-                        }
-
-                        if (!@switch.TryGetComponent(out ConveyorSwitchComponent? component))
-                        {
-                            continue;
-                        }
-
-                        component.SyncWith(this);
-                    }
-                },
-                () => _group?.Switches.Select(@switch => @switch.Owner.Uid).ToList());
-        }
-
-        public override void OnRemove()
-        {
-            base.OnRemove();
-            Disconnect();
-        }
-
-        bool IInteractHand.InteractHand(InteractHandEventArgs eventArgs)
-        {
-            return NextState();
-        }
-
-        async Task<bool> IInteractUsing.InteractUsing(InteractUsingEventArgs eventArgs)
-        {
-            if (eventArgs.Using.TryGetComponent(out ConveyorComponent? conveyor))
-            {
-                Connect(conveyor, eventArgs.User);
-                return true;
-            }
-
-            if (eventArgs.Using.TryGetComponent(out ConveyorSwitchComponent? otherSwitch))
-            {
-                SyncWith(otherSwitch, eventArgs.User);
-                return true;
-            }
-
-            return true;
-        }
-
-        void IActivate.Activate(ActivateEventArgs eventArgs)
-        {
-            NextState();
-        }
-    }
-}

Content.Server/GameObjects/Components/MachineLinking/SignalButtonComponent.cs

@@ -30,11 +30,15 @@ namespace Content.Server.GameObjects.Components.MachineLinking
                 return;
             }
 
-            if (transmitter.TransmitSignal(user, new ToggleSignal()))
+            if (transmitter.TransmitSignal(new ToggleSignal()))
             {
                 // Since the button doesn't have an animation, I'm going to use a popup message
                 Owner.PopupMessage(user, Loc.GetString("Click."));
             }
+            else
+            {
+                Owner.PopupMessage(user, Loc.GetString("No receivers connected."));
+            }
         }
 
     }

Content.Server/GameObjects/Components/MachineLinking/SignalReceiverComponent.cs

@@ -7,8 +7,11 @@ using Content.Shared.Interfaces.GameObjects.Components;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Interfaces.Map;
+using Robust.Shared.Interfaces.Serialization;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
+using Robust.Shared.Serialization;
+using Robust.Shared.Utility;
 
 namespace Content.Server.GameObjects.Components.MachineLinking
 {
@@ -19,6 +22,8 @@ namespace Content.Server.GameObjects.Components.MachineLinking
 
         private List<SignalTransmitterComponent> _transmitters;
 
+        private int? _maxTransmitters = default;
+
         public override void Initialize()
         {
             base.Initialize();
@@ -26,6 +31,11 @@ namespace Content.Server.GameObjects.Components.MachineLinking
             _transmitters = new List<SignalTransmitterComponent>();
         }
 
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            serializer.DataField(this, x=> x._maxTransmitters, "maxTransmitters", null);
+        }
+
         public void DistributeSignal<T>(T state)
         {
             foreach (var comp in Owner.GetAllComponents<ISignalReceiver<T>>())
@@ -34,15 +44,18 @@ namespace Content.Server.GameObjects.Components.MachineLinking
             }
         }
 
-        public void Subscribe(SignalTransmitterComponent transmitter)
+        public bool Subscribe(SignalTransmitterComponent transmitter)
         {
             if (_transmitters.Contains(transmitter))
             {
-                return;
+                return true;
             }
 
+            if (_transmitters.Count >= _maxTransmitters) return false;
+
             transmitter.Subscribe(this);
             _transmitters.Add(transmitter);
+            return true;
         }
 
         public void Unsubscribe(SignalTransmitterComponent transmitter)
@@ -51,6 +64,20 @@ namespace Content.Server.GameObjects.Components.MachineLinking
             _transmitters.Remove(transmitter);
         }
 
+        public void UnsubscribeAll()
+        {
+            for (var i = _transmitters.Count-1; i >= 0; i--)
+            {
+                var transmitter = _transmitters[i];
+                if (transmitter.Deleted)
+                {
+                    continue;
+                }
+
+                transmitter.Unsubscribe(this);
+            }
+        }
+
         /// <summary>
         /// Subscribes/Unsubscribes a transmitter to this component. Returns whether it was successful.
         /// </summary>
@@ -78,7 +105,11 @@ namespace Content.Server.GameObjects.Components.MachineLinking
                 return false;
             }
 
-            Subscribe(transmitter);
+            if (!Subscribe(transmitter))
+            {
+                Owner.PopupMessage(user, Loc.GetString("Max Transmitters reached!"));
+                return false;
+            }
             Owner.PopupMessage(user, Loc.GetString("Linked!"));
             return true;
         }
@@ -101,15 +132,8 @@ namespace Content.Server.GameObjects.Components.MachineLinking
         {
             base.Shutdown();
 
-            foreach (var transmitter in _transmitters)
+            UnsubscribeAll();
-            {
-                if (transmitter.Deleted)
-                {
-                    continue;
-                }
 
-                transmitter.Unsubscribe(this);
-            }
             _transmitters.Clear();
         }
     }

Content.Server/GameObjects/Components/MachineLinking/SignalSwitchComponent.cs

@@ -1,5 +1,6 @@
 using Content.Shared.GameObjects.EntitySystems;
 using Content.Shared.GameObjects.Verbs;
+using Content.Shared.Interfaces;
 using Content.Shared.Interfaces.GameObjects.Components;
 using Robust.Server.GameObjects;
 using Robust.Shared.GameObjects;
@@ -52,7 +53,10 @@ namespace Content.Server.GameObjects.Components.MachineLinking
                 return;
             }
 
-            transmitter.TransmitSignal(user, _on);
+            if (!transmitter.TransmitSignal(_on))
+            {
+                Owner.PopupMessage(user, Loc.GetString("No receivers connected."));
+            }
         }
 
         private void UpdateSprite()

Content.Server/GameObjects/Components/MachineLinking/SignalTransmitterComponent.cs

@@ -10,6 +10,7 @@ using Robust.Shared.Interfaces.Map;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Serialization;
+using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
 
 namespace Content.Server.GameObjects.Components.MachineLinking
@@ -87,11 +88,10 @@ namespace Content.Server.GameObjects.Components.MachineLinking
             }
         }
 
-        public bool TransmitSignal<T>(IEntity user, T signal)
+        public bool TransmitSignal<T>(T signal)
         {
             if (_receivers.Count == 0)
             {
-                Owner.PopupMessage(user, Loc.GetString("No receivers connected."));
                 return false;
             }
 
@@ -150,8 +150,9 @@ namespace Content.Server.GameObjects.Components.MachineLinking
         {
             base.Shutdown();
 
-            foreach (var receiver in _receivers)
+            for (var i = _receivers.Count-1; i >= 0; i++)
             {
+                var receiver = _receivers[i];
                 if (receiver.Deleted)
                 {
                     continue;
@@ -159,6 +160,7 @@ namespace Content.Server.GameObjects.Components.MachineLinking
 
                 receiver.Unsubscribe(this);
             }
+
             _receivers.Clear();
         }
     }

Content.Server/GameObjects/Components/MachineLinking/SignalTwoWayLeverComponent.cs

@@ -0,0 +1,68 @@
+#nullable enable
+using System;
+using Content.Server.GameObjects.Components.MachineLinking.Signals;
+using Content.Shared.GameObjects.Components.Conveyor;
+using Content.Shared.GameObjects.Components.MachineLinking;
+using Content.Shared.Interfaces;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Server.GameObjects;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Localization;
+
+namespace Content.Server.GameObjects.Components.MachineLinking
+{
+    [RegisterComponent]
+    [ComponentReference(typeof(IActivate))]
+    public class SignalTwoWayLeverComponent : SignalTransmitterComponent, IInteractHand, IActivate
+    {
+        public override string Name => "TwoWayLever";
+
+        private TwoWayLeverSignal _state = TwoWayLeverSignal.Middle;
+
+        private bool _nextForward = true;
+
+        public TwoWayLeverSignal State
+        {
+            get => _state;
+            private set
+            {
+                _state = value;
+
+                if (Owner.TryGetComponent(out AppearanceComponent? appearance))
+                {
+                    appearance.SetData(TwoWayLeverVisuals.State, value);
+                }
+            }
+        }
+
+        private void NextState(IEntity user)
+        {
+            State = State switch
+            {
+                TwoWayLeverSignal.Left => TwoWayLeverSignal.Middle,
+                TwoWayLeverSignal.Middle => _nextForward ? TwoWayLeverSignal.Right : TwoWayLeverSignal.Left,
+                TwoWayLeverSignal.Right => TwoWayLeverSignal.Middle,
+                _ => TwoWayLeverSignal.Middle
+            };
+
+            if (State == TwoWayLeverSignal.Left || State == TwoWayLeverSignal.Right) _nextForward = !_nextForward;
+
+            if (!TransmitSignal(State))
+            {
+                Owner.PopupMessage(user, Loc.GetString("No receivers connected."));
+            }
+        }
+
+        bool IInteractHand.InteractHand(InteractHandEventArgs eventArgs)
+        {
+            NextState(eventArgs.User);
+            return true;
+        }
+
+        void IActivate.Activate(ActivateEventArgs eventArgs)
+        {
+            NextState(eventArgs.User);
+        }
+    }
+}

Content.Server/GameObjects/Components/Recycling/RecyclerComponent.cs

@@ -173,7 +173,7 @@ namespace Content.Server.GameObjects.Components.Recycling
                 if (entity.TryGetComponent(out IPhysicsComponent physics))
                 {
                     var controller = physics.EnsureController<ConveyedController>();
-                    controller.Move(direction, frameTime);
+                    controller.Move(direction, frameTime, entity.Transform.WorldPosition - Owner.Transform.WorldPosition);
                 }
             }
         }

Content.Server/GameObjects/EntitySystems/ConveyorSystem.cs

@@ -17,78 +17,4 @@ namespace Content.Server.GameObjects.EntitySystems
             }
         }
     }
-
-    public class ConveyorGroup
-    {
-        private readonly HashSet<ConveyorComponent> _conveyors;
-        private readonly HashSet<ConveyorSwitchComponent> _switches;
-
-        public ConveyorGroup()
-        {
-            _conveyors = new HashSet<ConveyorComponent>(0);
-            _switches = new HashSet<ConveyorSwitchComponent>(0);
-            State = ConveyorState.Off;
-        }
-
-        public IReadOnlyCollection<ConveyorComponent> Conveyors => _conveyors;
-
-        public IReadOnlyCollection<ConveyorSwitchComponent> Switches => _switches;
-
-        public ConveyorState State { get; private set; }
-
-        public void AddConveyor(ConveyorComponent conveyor)
-        {
-            _conveyors.Add(conveyor);
-            conveyor.Sync(this);
-        }
-
-        public void RemoveConveyor(ConveyorComponent conveyor)
-        {
-            _conveyors.Remove(conveyor);
-        }
-
-        public void AddSwitch(ConveyorSwitchComponent conveyorSwitch)
-        {
-            _switches.Add(conveyorSwitch);
-
-            if (_switches.Count == 1)
-            {
-                SetState(conveyorSwitch);
-            }
-
-            conveyorSwitch.Sync(this);
-        }
-
-        public void RemoveSwitch(ConveyorSwitchComponent conveyorSwitch)
-        {
-            _switches.Remove(conveyorSwitch);
-        }
-
-        public void SetState(ConveyorSwitchComponent conveyorSwitch)
-        {
-            var state = conveyorSwitch.State;
-
-            if (state == ConveyorState.Loose)
-            {
-                if (_switches.Count > 0)
-                {
-                    return;
-                }
-
-                state = ConveyorState.Off;
-            }
-
-            State = state;
-
-            foreach (var conveyor in Conveyors)
-            {
-                conveyor.Sync(this);
-            }
-
-            foreach (var connectedSwitch in _switches)
-            {
-                connectedSwitch.Sync(this);
-            }
-        }
-    }
 }

Content.Shared/GameObjects/Components/Conveyor/SharedConveyorComponent.cs

@@ -12,9 +12,8 @@ namespace Content.Shared.GameObjects.Components.Conveyor
     [Serializable, NetSerializable]
     public enum ConveyorState
     {
-        Off = 0,
+        Off,
         Forward,
-        Reversed,
+        Reversed
-        Loose
     }
 }

Content.Shared/GameObjects/Components/MachineLinking/TwoWayLeverSignal.cs

@@ -0,0 +1,19 @@
+using System;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.GameObjects.Components.MachineLinking
+{
+    [Serializable, NetSerializable]
+    public enum TwoWayLeverVisuals : byte
+    {
+        State
+    }
+
+    [Serializable, NetSerializable]
+    public enum TwoWayLeverSignal : byte
+    {
+        Middle,
+        Left,
+        Right
+    }
+}

Content.Shared/Physics/ConveyedController.cs

@@ -1,8 +1,11 @@
 #nullable enable
 using Content.Shared.GameObjects.Components.Movement;
 using Robust.Shared.GameObjects.Components;
+using Robust.Shared.Interfaces.Random;
+using Robust.Shared.IoC;
 using Robust.Shared.Maths;
 using Robust.Shared.Physics;
+using Robust.Shared.Random;
 
 namespace Content.Shared.Physics
 {
@@ -10,7 +13,7 @@ namespace Content.Shared.Physics
     {
         public override IPhysicsComponent? ControlledComponent { protected get; set; }
 
-        public void Move(Vector2 velocityDirection, float speed)
+        public void Move(Vector2 velocityDirection, float speed, Vector2 itemRelativeToConveyor)
         {
             if (ControlledComponent?.Owner.IsWeightless() ?? false)
             {
@@ -23,6 +26,33 @@ namespace Content.Shared.Physics
             }
 
             LinearVelocity = velocityDirection * speed;
+
+            //gravitating item towards center
+            //http://csharphelper.com/blog/2016/09/find-the-shortest-distance-between-a-point-and-a-line-segment-in-c/
+            Vector2 centerPoint;
+
+            var t = 0f;
+            if (velocityDirection.Length > 0) //if velocitydirection is 0, this calculation will divide by 0
+            {
+                t = Vector2.Dot(itemRelativeToConveyor, velocityDirection) /
+                    Vector2.Dot(velocityDirection, velocityDirection);
+            }
+
+            if (t < 0)
+            {
+                centerPoint = new Vector2();
+            }
+            else if(t > 1)
+            {
+                centerPoint = velocityDirection;
+            }
+            else
+            {
+                centerPoint = velocityDirection * t;
+            }
+
+            var delta = centerPoint - itemRelativeToConveyor;
+            LinearVelocity += delta * (4 * delta.Length);
         }
 
         public override void UpdateAfterProcessing()

Resources/Maps/saltern.yml

@@ -1388,15 +1388,12 @@ entities:
         type: Robust.Server.GameObjects.Components.Container.Container
     type: ContainerContainer
 - uid: 163
-  type: ConveyorSwitch
+  type: TwoWayLever
   components:
   - parent: 855
     pos: -23.467268,-14.347846
     rot: 3.141592653589793 rad
     type: Transform
-  - conveyors: []
-    switches: []
-    type: ConveyorSwitch
 - uid: 164
   type: DisposalJunctionFlipped
   components:

Resources/Prototypes/Catalog/LatheRecipes/cargo.yml

@@ -0,0 +1,10 @@
+- type: latheRecipe
+  id: ConveyorAssembly
+  icon:
+    sprite: Constructible/Power/conveyor.rsi
+    state: conveyor_loose
+  result: ConveyorBeltAssembly
+  completetime: 1000
+  materials:
+    steel: 1000
+    glass: 50

Resources/Prototypes/Catalog/Research/technologies.yml

@@ -42,6 +42,8 @@
   requiredPoints: 1000
   requiredTechnologies:
     - BasicResearch
+  unlockedRecipes:
+    - ConveyorAssembly
 
 - type: technology
   name: material sheet printing

Resources/Prototypes/Entities/Constructible/Power/lathe.yml

@@ -102,6 +102,7 @@
       - CableStack
       - Crowbar
       - Multitool
+      - ConveyorAssembly
   - type: UserInterface
     interfaces:
     - key: enum.LatheUiKey.Key

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

@@ -0,0 +1,57 @@
+- type: constructionGraph
+  id: ConveyorGraph
+  start: start
+  graph:
+    - node: start
+      edges:
+        - to: entity
+          steps:
+            - component: ConveyorAssembly
+              icon:
+                sprite: Constructible/Power/conveyor.rsi
+                state: conveyor_loose
+              name: conveyor belt assembly
+              doAfter: 2
+    - node: item
+      entity: ConveyorBeltAssembly
+      actions:
+        - !type:SetAnchor
+          value: false
+    - node: entity
+      entity: ConveyorBelt
+      actions:
+        - !type:SetAnchor
+          value: true
+        - !type:SnapToGrid
+          offset: Center
+      edges:
+        - to: item
+          steps:
+            - tool: Prying
+              doAfter: 3
+
+- type: constructionGraph
+  id: leverGraph
+  start: start
+  graph:
+  - node: start
+    actions:
+      - !type:SpawnPrototype
+        prototype: SteelSheet1
+        amount: 2
+      - !type:DeleteEntity {}
+    edges:
+      - to: lever
+        completed:
+          - !type:SnapToGrid {}
+        steps:
+          - material: Metal
+            amount: 2
+            doAfter: 1
+  - node: lever
+    entity: TwoWayLever
+    edges:
+      - to: start
+        steps:
+          - tool: Anchoring
+            doAfter: 1

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

@@ -0,0 +1,26 @@
+- type: construction
+  name: conveyor belt
+  id: conveyorbelt
+  graph: ConveyorGraph
+  startNode: start
+  targetNode: entity
+  category: Structures
+  description: A conveyor belt, commonly used to transport large numbers of items elsewhere quite quickly.
+  objectType: Structure
+  placementMode: SnapgridCenter
+  icon:
+    sprite: Constructible/Power/conveyor.rsi
+    state: conveyor_stopped_cw
+
+- type: construction
+  name: two-way lever
+  id: twowaylever
+  graph: leverGraph
+  startNode: start
+  targetNode: lever
+  category: Structures
+  description: A lever to control machines. It has 3 modes.
+  objectType: Structure
+  icon:
+    sprite: Constructible/Power/conveyor.rsi
+    state: switch-off

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

@@ -25,7 +25,8 @@
     sprite: Constructible/Power/conveyor.rsi
     state: conveyor_started_cw
     drawdepth: FloorObjects
-
+  - type: SignalReceiver
+    maxTransmitters: 1
   - type: Conveyor
   - type: Appearance
     visuals:
@@ -33,26 +34,23 @@
       state_running: conveyor_started_cw
       state_stopped: conveyor_stopped_cw
       state_reversed: conveyor_started_cw_r
-      state_loose: conveyor_loose
   - type: PowerReceiver
+  - type: Construction
+    graph: ConveyorGraph
+    node: entity
 
 - type: entity
-  id: ConveyorSwitch
+  id: ConveyorBeltAssembly
-  name: conveyor switch
+  parent: BaseItem
-  description: A conveyor control switch.
+  name: conveyor belt
+  suffix: assembly
+  description: A conveyor belt assembly. Used to construct a conveyor belt.
   components:
-  - type: Clickable
+    - type: Sprite
-  - type: InteractionOutline
+      netsync: false
-  - type: Sprite
+      sprite: Constructible/Power/conveyor.rsi
-    netsync: false
+      state: conveyor_loose
-    sprite: Constructible/Power/conveyor.rsi
+    - type: ConveyorAssembly
-    state: switch-off
+    - type: Construction
-
+      graph: ConveyorGraph
-  - type: ConveyorSwitch
+      node: item
-  - type: Appearance
-    visuals:
-      - type: ConveyorSwitchVisualizer
-        state_forward: switch-fwd
-        state_off: switch-off
-        state_reversed: switch-rev
-        state_loose: switch

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

@@ -0,0 +1,21 @@
+- type: entity
+  id: TwoWayLever
+  name: two way switch
+  description: A two way switch.
+  components:
+    - type: Clickable
+    - type: InteractionOutline
+    - type: Sprite
+      netsync: false
+      sprite: Constructible/Power/conveyor.rsi
+      state: switch-off
+    - type: TwoWayLever
+    - type: Appearance
+      visuals:
+        - type: TwoWayLeverVisualizer
+          state_forward: switch-fwd
+          state_off: switch-off
+          state_reversed: switch-rev
+    - type: Construction
+      graph: leverGraph
+      node: lever