Gravity (#841)

Content.Client/EntryPoint.cs

@@ -12,6 +12,7 @@ using Content.Client.UserInterface.Stylesheets;
 using Content.Shared.GameObjects.Components;
 using Content.Shared.GameObjects.Components.Cargo;
 using Content.Shared.GameObjects.Components.Chemistry;
+using Content.Shared.GameObjects.Components.Gravity;
 using Content.Shared.GameObjects.Components.Markers;
 using Content.Shared.GameObjects.Components.Research;
 using Content.Shared.GameObjects.Components.VendingMachines;
@@ -161,6 +162,8 @@ namespace Content.Client
             factory.Register<SharedCargoConsoleComponent>();
             factory.Register<SharedReagentDispenserComponent>();
 
+            factory.Register<SharedGravityGeneratorComponent>();
+
             prototypes.RegisterIgnore("material");
             prototypes.RegisterIgnore("reaction"); //Chemical reactions only needed by server. Reactions checks are server-side.
             prototypes.RegisterIgnore("barSign");

Content.Client/GameObjects/Components/Gravity/GravityGeneratorBoundUserInterface.cs

@@ -0,0 +1,104 @@
+using System;
+using Content.Shared.GameObjects.Components.Gravity;
+using Robust.Client.GameObjects.Components.UserInterface;
+using Robust.Client.UserInterface.Controls;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.GameObjects.Components.UserInterface;
+using Robust.Shared.IoC;
+using Robust.Shared.Localization;
+using Robust.Shared.Maths;
+
+namespace Content.Client.GameObjects.Components.Gravity
+{
+    public class GravityGeneratorBoundUserInterface: BoundUserInterface
+    {
+        private GravityGeneratorWindow _window;
+
+        public bool IsOn;
+
+        public GravityGeneratorBoundUserInterface(ClientUserInterfaceComponent owner, object uiKey) : base (owner, uiKey)
+        {
+            SendMessage(new SharedGravityGeneratorComponent.GeneratorStatusRequestMessage());
+        }
+
+        protected override void Open()
+        {
+            base.Open();
+
+            IsOn = false;
+
+            _window = new GravityGeneratorWindow(this);
+
+            _window.Switch.OnPressed += (args) =>
+            {
+                SendMessage(new SharedGravityGeneratorComponent.SwitchGeneratorMessage(!IsOn));
+                SendMessage(new SharedGravityGeneratorComponent.GeneratorStatusRequestMessage());
+            };
+
+            _window.OpenCentered();
+        }
+
+        protected override void UpdateState(BoundUserInterfaceState state)
+        {
+            base.UpdateState(state);
+
+            var castState = (SharedGravityGeneratorComponent.GeneratorState) state;
+            IsOn = castState.On;
+            _window.UpdateButton();
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            base.Dispose(disposing);
+            if (!disposing) return;
+
+            _window?.Dispose();
+        }
+    }
+
+    public class GravityGeneratorWindow : SS14Window
+    {
+        public Label Status;
+
+        public Button Switch;
+
+        public GravityGeneratorBoundUserInterface Owner;
+
+        public GravityGeneratorWindow(GravityGeneratorBoundUserInterface gravityGeneratorInterface = null)
+        {
+            IoCManager.InjectDependencies(this);
+
+            Owner = gravityGeneratorInterface;
+
+            Title = Loc.GetString("Gravity Generator Control");
+
+            var vBox = new VBoxContainer
+            {
+                CustomMinimumSize = new Vector2(250, 100)
+            };
+            Status = new Label
+            {
+                Text = Loc.GetString("Current Status: " + (Owner.IsOn ? "On" : "Off")),
+                FontColorOverride = Owner.IsOn ? Color.ForestGreen : Color.Red
+            };
+            Switch = new Button
+            {
+                Text = Loc.GetString(Owner.IsOn ? "Turn Off" : "Turn On"),
+                TextAlign = Label.AlignMode.Center,
+                CustomMinimumSize = new Vector2(150, 60)
+            };
+
+            vBox.AddChild(Status);
+            vBox.AddChild(Switch);
+
+            Contents.AddChild(vBox);
+        }
+
+        public void UpdateButton()
+        {
+            Status.Text = Loc.GetString("Current Status: " + (Owner.IsOn ? "On" : "Off"));
+            Status.FontColorOverride = Owner.IsOn ? Color.ForestGreen : Color.Red;
+            Switch.Text = Loc.GetString(Owner.IsOn ? "Turn Off" : "Turn On");
+        }
+    }
+}

Content.IntegrationTests/Tests/GravityGridTest.cs

@@ -0,0 +1,64 @@
+using System.Threading.Tasks;
+using Content.Client.GameObjects.Components.Gravity;
+using Content.Server.GameObjects.Components.Gravity;
+using Content.Server.GameObjects.Components.Power;
+using NUnit.Framework;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Interfaces.Map;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+
+namespace Content.IntegrationTests.Tests
+{
+    /// Tests the behavior of GravityGeneratorComponent,
+    /// making sure that gravity is applied to the correct grids.
+    [TestFixture]
+    [TestOf(typeof(GravityGeneratorComponent))]
+    public class GravityGridTest : ContentIntegrationTest
+    {
+        [Test]
+        public async Task Test()
+        {
+            var server = StartServerDummyTicker();
+
+            IEntity generator = null;
+
+            IMapGrid grid1 = null;
+            IMapGrid grid2 = null;
+
+            // Create grids
+            server.Assert(() =>
+            {
+                var mapMan = IoCManager.Resolve<IMapManager>();
+
+                mapMan.CreateMap(new MapId(1));
+                grid1 = mapMan.CreateGrid(new MapId(1));
+                grid2 = mapMan.CreateGrid(new MapId(1));
+
+                var entityMan = IoCManager.Resolve<IEntityManager>();
+
+                generator = entityMan.SpawnEntity("GravityGenerator", new GridCoordinates(new Vector2(0, 0), grid2.Index));
+                Assert.That(generator.HasComponent<GravityGeneratorComponent>());
+                Assert.That(generator.HasComponent<PowerDeviceComponent>());
+                var generatorComponent = generator.GetComponent<GravityGeneratorComponent>();
+                var powerComponent = generator.GetComponent<PowerDeviceComponent>();
+                Assert.AreEqual(generatorComponent.Status, GravityGeneratorStatus.Unpowered);
+                powerComponent.ExternalPowered = true;
+            });
+            server.RunTicks(1);
+
+            server.Assert(() =>
+            {
+                var generatorComponent = generator.GetComponent<GravityGeneratorComponent>();
+
+                Assert.AreEqual(generatorComponent.Status, GravityGeneratorStatus.On);
+
+                Assert.That(!grid1.HasGravity);
+                Assert.That(grid2.HasGravity);
+            });
+
+            await server.WaitIdleAsync();
+        }
+    }
+}

Content.Server/GameObjects/Components/Gravity/GravityGeneratorComponent.cs

@@ -0,0 +1,206 @@
+using Content.Server.GameObjects.Components.Damage;
+using Content.Server.GameObjects.Components.Interactable.Tools;
+using Content.Server.GameObjects.Components.Power;
+using Content.Server.GameObjects.EntitySystems;
+using Content.Server.Interfaces;
+using Content.Shared.GameObjects.Components.Gravity;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Robust.Server.GameObjects;
+using Robust.Server.GameObjects.Components.UserInterface;
+using Robust.Server.GameObjects.EntitySystems;
+using Robust.Server.Interfaces.GameObjects;
+using Robust.Server.Interfaces.Player;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Localization;
+using Robust.Shared.Serialization;
+
+namespace Content.Server.GameObjects.Components.Gravity
+{
+    [RegisterComponent]
+    public class GravityGeneratorComponent: SharedGravityGeneratorComponent, IAttackBy, IBreakAct, IAttackHand
+    {
+        private BoundUserInterface _userInterface;
+
+        private PowerDeviceComponent _powerDevice;
+
+        private SpriteComponent _sprite;
+
+        private bool _switchedOn;
+
+        private bool _intact;
+
+        private GravityGeneratorStatus _status;
+
+        public bool Powered => _powerDevice.Powered;
+
+        public bool SwitchedOn => _switchedOn;
+
+        public bool Intact => _intact;
+
+        public GravityGeneratorStatus Status => _status;
+
+        public bool NeedsUpdate
+        {
+            get
+            {
+                switch (_status)
+                {
+                    case GravityGeneratorStatus.On:
+                        return !(Powered && SwitchedOn && Intact);
+                    case GravityGeneratorStatus.Off:
+                        return SwitchedOn || !(Powered && Intact);
+                    case GravityGeneratorStatus.Unpowered:
+                        return SwitchedOn || Powered || !Intact;
+                    case GravityGeneratorStatus.Broken:
+                        return SwitchedOn || Powered || Intact;
+                    default:
+                        return true; // This _should_ be unreachable
+                }
+            }
+        }
+
+        public override string Name => "GravityGenerator";
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            _userInterface = Owner.GetComponent<ServerUserInterfaceComponent>()
+                .GetBoundUserInterface(GravityGeneratorUiKey.Key);
+            _userInterface.OnReceiveMessage += HandleUIMessage;
+            _powerDevice = Owner.GetComponent<PowerDeviceComponent>();
+            _sprite = Owner.GetComponent<SpriteComponent>();
+            _switchedOn = true;
+            _intact = true;
+            _status = GravityGeneratorStatus.On;
+            UpdateState();
+        }
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            serializer.DataField(ref _switchedOn, "switched_on", true);
+            serializer.DataField(ref _intact, "intact", true);
+        }
+
+        bool IAttackHand.AttackHand(AttackHandEventArgs eventArgs)
+        {
+            if (!eventArgs.User.TryGetComponent<IActorComponent>(out var actor))
+                return false;
+            if (Status != GravityGeneratorStatus.Off && Status != GravityGeneratorStatus.On)
+            {
+                return false;
+            }
+            OpenUserInterface(actor.playerSession);
+            return true;
+        }
+
+        public bool AttackBy(AttackByEventArgs eventArgs)
+        {
+            if (!eventArgs.AttackWith.TryGetComponent<WelderComponent>(out var welder)) return false;
+            if (welder.TryUse(5.0f))
+            {
+                // Repair generator
+                var damagable = Owner.GetComponent<DamageableComponent>();
+                var breakable = Owner.GetComponent<BreakableComponent>();
+                damagable.HealAllDamage();
+                breakable.broken = false;
+                _intact = true;
+
+                var entitySystemManager = IoCManager.Resolve<IEntitySystemManager>();
+                var notifyManager = IoCManager.Resolve<IServerNotifyManager>();
+
+                entitySystemManager.GetEntitySystem<AudioSystem>().Play("/Audio/items/welder2.ogg", Owner);
+                notifyManager.PopupMessage(Owner, eventArgs.User, Loc.GetString("You repair the gravity generator with the welder"));
+
+                return true;
+            } else
+            {
+                return false;
+            }
+        }
+
+        public void OnBreak(BreakageEventArgs eventArgs)
+        {
+            _intact = false;
+            _switchedOn = false;
+        }
+
+        public void UpdateState()
+        {
+            if (!Intact)
+            {
+                MakeBroken();
+            } else if (!Powered)
+            {
+                MakeUnpowered();
+            } else if (!SwitchedOn)
+            {
+                MakeOff();
+            } else
+            {
+                MakeOn();
+            }
+        }
+
+        private void HandleUIMessage(ServerBoundUserInterfaceMessage message)
+        {
+            switch (message.Message)
+            {
+                case GeneratorStatusRequestMessage _:
+                    _userInterface.SetState(new GeneratorState(Status == GravityGeneratorStatus.On));
+                    break;
+                case SwitchGeneratorMessage msg:
+                    _switchedOn = msg.On;
+                    UpdateState();
+                    break;
+                default:
+                    break;
+            }
+        }
+
+        private void OpenUserInterface(IPlayerSession playerSession)
+        {
+            _userInterface.Open(playerSession);
+        }
+
+        private void MakeBroken()
+        {
+            _status = GravityGeneratorStatus.Broken;
+            _sprite.LayerSetState(0, "broken");
+            _sprite.LayerSetVisible(1, false);
+        }
+
+        private void MakeUnpowered()
+        {
+            _status = GravityGeneratorStatus.Unpowered;
+            _sprite.LayerSetState(0, "off");
+            _sprite.LayerSetVisible(1, false);
+        }
+
+        private void MakeOff()
+        {
+            _status = GravityGeneratorStatus.Off;
+            _sprite.LayerSetState(0, "off");
+            _sprite.LayerSetVisible(1, false);
+        }
+
+        private void MakeOn()
+        {
+            _status = GravityGeneratorStatus.On;
+            _sprite.LayerSetState(0, "on");
+            _sprite.LayerSetVisible(1, true);
+        }
+    }
+
+    public enum GravityGeneratorStatus
+    {
+        Broken,
+        Unpowered,
+        Off,
+        On
+    }
+}

Content.Server/GameObjects/Components/Movement/AiControllerComponent.cs

@@ -90,6 +90,15 @@ namespace Content.Server.GameObjects.Components.Movement
             }
         }
 
+        /// <inheritdoc />
+        [ViewVariables]
+        public float CurrentPushSpeed => 5.0f;
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public float GrabRange => 0.2f;
+
+
         /// <summary>
         ///     Is the entity Sprinting (running)?
         /// </summary>

Content.Server/GameObjects/Components/Movement/PlayerInputMoverComponent.cs

@@ -67,6 +67,14 @@ namespace Content.Server.GameObjects.Components.Movement
             }
         }
 
+        /// <inheritdoc />
+        [ViewVariables]
+        public float CurrentPushSpeed => 5.0f;
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public float GrabRange => 0.2f;
+
         /// <summary>
         ///     Is the entity Sprinting (running)?
         /// </summary>

Content.Server/GameObjects/Components/Movement/ShuttleControllerComponent.cs

@@ -34,6 +34,15 @@ namespace Content.Server.GameObjects.Components.Movement
         [ViewVariables(VVAccess.ReadWrite)]
         public float CurrentWalkSpeed { get; set; } = 8;
         public float CurrentSprintSpeed { get; set; }
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public float CurrentPushSpeed => 0.0f;
+
+        /// <inheritdoc />
+        [ViewVariables]
+        public float GrabRange => 0.0f;
+
         public bool Sprinting { get; set; }
         public Vector2 VelocityDir { get; } = Vector2.Zero;
         public GridCoordinates LastPosition { get; set; }

Content.Server/GameObjects/EntitySystems/GravitySystem.cs

@@ -0,0 +1,134 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Content.Server.GameObjects.Components.Gravity;
+using Content.Server.GameObjects.Components.Mobs;
+using JetBrains.Annotations;
+using Robust.Server.GameObjects.EntitySystems;
+using Robust.Server.Interfaces.Player;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Interfaces.Map;
+using Robust.Shared.Interfaces.Random;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Random;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    [UsedImplicitly]
+    public class GravitySystem: EntitySystem
+    {
+#pragma warning disable 649
+        [Dependency] private readonly IMapManager _mapManager;
+        [Dependency] private readonly IPlayerManager _playerManager;
+        [Dependency] private readonly IEntitySystemManager _entitySystemManager;
+        [Dependency] private readonly IRobustRandom _random;
+#pragma warning restore 649
+
+        private const float GravityKick = 100.0f;
+
+        private const uint ShakeTimes = 10;
+
+        private Dictionary<GridId, uint> _gridsToShake;
+
+        private float internalTimer = 0.0f;
+
+        public override void Initialize()
+        {
+            EntityQuery = new TypeEntityQuery<GravityGeneratorComponent>();
+            _gridsToShake = new Dictionary<GridId, uint>();
+        }
+
+        public override void Update(float frameTime)
+        {
+            internalTimer += frameTime;
+            var gridsWithGravity = new List<GridId>();
+            foreach (var entity in RelevantEntities)
+            {
+                var generator = entity.GetComponent<GravityGeneratorComponent>();
+                if (generator.NeedsUpdate)
+                {
+                    generator.UpdateState();
+                }
+                if (generator.Status == GravityGeneratorStatus.On)
+                {
+                    gridsWithGravity.Add(entity.Transform.GridID);
+                }
+            }
+
+            foreach (var grid in _mapManager.GetAllGrids())
+            {
+                if (grid.HasGravity && !gridsWithGravity.Contains(grid.Index))
+                {
+                    grid.HasGravity = false;
+                    ScheduleGridToShake(grid.Index, ShakeTimes);
+                } else if (!grid.HasGravity && gridsWithGravity.Contains(grid.Index))
+                {
+                    grid.HasGravity = true;
+                    ScheduleGridToShake(grid.Index, ShakeTimes);
+                }
+            }
+
+            if (internalTimer > 0.2f)
+            {
+                ShakeGrids();
+                internalTimer = 0.0f;
+            }
+        }
+
+        private void ScheduleGridToShake(GridId gridId, uint shakeTimes)
+        {
+            if (!_gridsToShake.Keys.Contains(gridId))
+            {
+                _gridsToShake.Add(gridId, shakeTimes);
+            }
+            else
+            {
+                _gridsToShake[gridId] = shakeTimes;
+            }
+            // Play the gravity sound
+            foreach (var player in _playerManager.GetAllPlayers())
+            {
+                if (player.AttachedEntity == null
+                    || player.AttachedEntity.Transform.GridID != gridId) continue;
+                _entitySystemManager.GetEntitySystem<AudioSystem>().Play("/Audio/effects/alert.ogg", player.AttachedEntity);
+            }
+        }
+
+        private void ShakeGrids()
+        {
+            // I have to copy this because C# doesn't allow changing collections while they're
+            // getting enumerated.
+            var gridsToShake = new Dictionary<GridId, uint>(_gridsToShake);
+            foreach (var gridId in _gridsToShake.Keys)
+            {
+                if (_gridsToShake[gridId] == 0)
+                {
+                    gridsToShake.Remove(gridId);
+                    continue;
+                }
+                ShakeGrid(gridId);
+                gridsToShake[gridId] -= 1;
+            }
+            _gridsToShake = gridsToShake;
+        }
+
+        private void ShakeGrid(GridId gridId)
+        {
+            foreach (var player in _playerManager.GetAllPlayers())
+            {
+                if (player.AttachedEntity == null
+                    || player.AttachedEntity.Transform.GridID != gridId
+                    || !player.AttachedEntity.TryGetComponent(out CameraRecoilComponent recoil))
+                {
+                    continue;
+                }
+
+                recoil.Kick(new Vector2(_random.NextFloat(), _random.NextFloat()) * GravityKick);
+            }
+        }
+    }
+}

Content.Server/GameObjects/EntitySystems/MoverSystem.cs

@@ -1,4 +1,6 @@
-using Content.Server.GameObjects.Components;
+using System;
+using System.Net;
+using Content.Server.GameObjects.Components;
 using Content.Server.GameObjects.Components.Mobs;
 using Content.Server.GameObjects.Components.Movement;
 using Content.Server.GameObjects.Components.Sound;
@@ -15,6 +17,7 @@ using Robust.Server.Interfaces.Player;
 using Robust.Server.Interfaces.Timing;
 using Robust.Shared.Configuration;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.Transform;
 using Robust.Shared.GameObjects.Systems;
 using Robust.Shared.Input;
@@ -28,6 +31,7 @@ using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
 using Robust.Shared.Network;
+using Robust.Shared.Physics;
 using Robust.Shared.Players;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Random;
@@ -44,6 +48,7 @@ namespace Content.Server.GameObjects.EntitySystems
         [Dependency] private readonly IMapManager _mapManager;
         [Dependency] private readonly IRobustRandom _robustRandom;
         [Dependency] private readonly IConfigurationManager _configurationManager;
+        [Dependency] private readonly IEntityManager _entityManager;
 #pragma warning restore 649
 
         private AudioSystem _audioSystem;
@@ -130,13 +135,43 @@ namespace Content.Server.GameObjects.EntitySystems
                 }
                 var mover = entity.GetComponent<IMoverComponent>();
                 var physics = entity.GetComponent<PhysicsComponent>();
-
-                UpdateKinematics(entity.Transform, mover, physics);
+                if (entity.TryGetComponent<CollidableComponent>(out var collider))
+                {
+                    UpdateKinematics(entity.Transform, mover, physics, collider);
+                }
+                else
+                {
+                    UpdateKinematics(entity.Transform, mover, physics);
+                }
             }
         }
 
-        private void UpdateKinematics(ITransformComponent transform, IMoverComponent mover, PhysicsComponent physics)
+        private void UpdateKinematics(ITransformComponent transform, IMoverComponent mover, PhysicsComponent physics, CollidableComponent collider = null)
         {
+            bool weightless = false;
+
+            var tile = _mapManager.GetGrid(transform.GridID).GetTileRef(transform.GridPosition).Tile;
+
+            if ((!_mapManager.GetGrid(transform.GridID).HasGravity || tile.IsEmpty) && collider != null)
+            {
+                weightless = true;
+                // No gravity: is our entity touching anything?
+                var touching = false;
+                foreach (var entity in _entityManager.GetEntitiesInRange(transform.Owner, mover.GrabRange, true))
+                {
+                    if (entity.TryGetComponent<CollidableComponent>(out var otherCollider))
+                    {
+                        if (otherCollider.Owner == transform.Owner) continue; // Don't try to push off of yourself!
+                        touching |= ((collider.CollisionMask & otherCollider.CollisionLayer) != 0x0
+                                     || (otherCollider.CollisionMask & collider.CollisionLayer) != 0x0) // Ensure collision
+                                    && !entity.HasComponent<ItemComponent>(); // This can't be an item
+                    }
+                }
+                if (!touching)
+                {
+                    return;
+                }
+            }
             if (mover.VelocityDir.LengthSquared < 0.001 || !ActionBlockerSystem.CanMove(mover.Owner))
             {
                 if (physics.LinearVelocity != Vector2.Zero)
@@ -145,6 +180,13 @@ namespace Content.Server.GameObjects.EntitySystems
             }
             else
             {
+                if (weightless)
+                {
+                    physics.LinearVelocity = mover.VelocityDir * mover.CurrentPushSpeed;
+                    transform.LocalRotation = mover.VelocityDir.GetDir().ToAngle();
+                    return;
+                }
+
                 physics.LinearVelocity = mover.VelocityDir * (mover.Sprinting ? mover.CurrentSprintSpeed : mover.CurrentWalkSpeed);
                 transform.LocalRotation = mover.VelocityDir.GetDir().ToAngle();
 

Content.Server/Interfaces/GameObjects/Components/Movement/IMoverComponent.cs

@@ -19,6 +19,17 @@ namespace Content.Server.Interfaces.GameObjects.Components.Movement
         /// </summary>
         float CurrentSprintSpeed { get; }
 
+
+        /// <summary>
+        ///     The movement speed (m/s) of the entity when it pushes off of a solid object in zero gravity.
+        /// </summary>
+        float CurrentPushSpeed { get; }
+
+        /// <summary>
+        ///     How far an entity can reach (in meters) to grab hold of a solid object in zero gravity.
+        /// </summary>
+        float GrabRange { get; }
+
         /// <summary>
         ///     Is the entity Sprinting (running)?
         /// </summary>

Content.Server/Throw/ThrowHelper.cs

@@ -65,6 +65,14 @@ namespace Content.Server.Throw
             var spd = a / (1f / timing.TickRate); // acceleration is applied in 1 tick instead of 1 second, scale appropriately
 
             physComp.LinearVelocity = angle.ToVec() * spd;
+
+            if (throwSourceEnt != null)
+            {
+                var p = throwSourceEnt.GetComponent<PhysicsComponent>();
+                var playerAccel = 5 * throwForce / (float) Math.Max(0.001, p.Mass);
+                p.LinearVelocity = Angle.FromDegrees(angle.Degrees + 180).ToVec()
+                                   * playerAccel / (1f / timing.TickRate);
+            }
         }
     }
 }

Content.Shared/GameObjects/Components/Gravity/SharedGravityGeneratorComponent.cs

@@ -0,0 +1,57 @@
+using System;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components.UserInterface;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.GameObjects.Components.Gravity
+{
+    public class SharedGravityGeneratorComponent: Component
+    {
+        public override string Name => "GravityGenerator";
+
+        public override uint? NetID => ContentNetIDs.GRAVITY_GENERATOR;
+
+        /// <summary>
+        ///     Sent to the server to set whether the generator should be on or off
+        /// </summary>
+        [Serializable, NetSerializable]
+        public class SwitchGeneratorMessage : BoundUserInterfaceMessage
+        {
+            public bool On;
+
+            public SwitchGeneratorMessage(bool on)
+            {
+                On = on;
+            }
+        }
+
+        /// <summary>
+        ///     Sent to the server when requesting the status of the generator
+        /// </summary>
+        [Serializable, NetSerializable]
+        public class GeneratorStatusRequestMessage : BoundUserInterfaceMessage
+        {
+            public GeneratorStatusRequestMessage()
+            {
+
+            }
+        }
+
+        [Serializable, NetSerializable]
+        public class GeneratorState : BoundUserInterfaceState
+        {
+            public bool On;
+
+            public GeneratorState(bool on)
+            {
+                On = on;
+            }
+        }
+
+        [Serializable, NetSerializable]
+        public enum GravityGeneratorUiKey
+        {
+            Key
+        }
+    }
+}

Content.Shared/GameObjects/ContentNetIDs.cs

@@ -42,5 +42,6 @@
         public const uint PAPER = 1037;
         public const uint REAGENT_INJECTOR = 1038;
         public const uint GHOST = 1039;
+        public const uint GRAVITY_GENERATOR = 1040;
     }
 }

Resources/Prototypes/Entities/Buildings/gravity_generator.yml

@@ -0,0 +1,36 @@
+- type: entity
+  id: GravityGenerator
+  name: Gravity Generator
+  description: It's what keeps you to the floor.
+  components:
+    - type: Sprite
+      sprite: Buildings/gravity_generator.rsi
+      layers:
+        - state: on
+        - sprite: Buildings/gravity_generator_core.rsi
+          state: activated
+          shader: unshaded
+    - type: Icon
+      sprite: Buildings/gravity_generator.rsi
+      state: on
+    - type: SnapGrid
+      offset: Center
+    - type: PowerDevice
+      load: 500
+    - type: Collidable
+      shapes:
+        - !type:PhysShapeAabb
+          bounds: "-1.5,-1.5,1.5,1.5"
+          layer: 15
+    - type: Clickable
+    - type: InteractionOutline
+    - type: Damageable
+    - type: Breakable
+      threshold: 150
+    - type: GravityGenerator
+    - type: UserInterface
+      interfaces:
+        - key: enum.GravityGeneratorUiKey.Key
+          type: GravityGeneratorBoundUserInterface
+  placement:
+    mode: AlignTileAny

Resources/Textures/Buildings/gravity_generator.rsi/meta.json

@@ -0,0 +1,23 @@
+{
+    "version":1,
+    "size":{
+        "x":96,
+        "y":96
+    },
+    "license":"CC-BY-SA-3.0",
+    "copyright":"Taken from https://github.com/tgstation/tgstation",
+    "states":[
+        {
+            "name":"on",
+            "directions": 1
+        },
+        {
+            "name": "off",
+            "directions": 1
+        },
+        {
+            "name": "broken",
+            "directions": 1
+        }
+    ]
+}

Resources/Textures/Buildings/gravity_generator_core.rsi/meta.json

@@ -0,0 +1,20 @@
+{
+    "version":1,
+    "size":{
+        "x":32,
+        "y":32
+    },
+    "license":"CC-BY-SA-3.0",
+    "copyright":"Taken from https://github.com/tgstation/tgstation",
+    "states":[
+        {
+            "name": "activated",
+            "directions": 1,
+            "delays": [
+                [0.1,
+                0.1,
+                0.1]
+            ]
+        }
+    ]
+}