Legally distinct gravity gun (#8114)

Content.Client/Weapons/Ranged/TetherGunCommand.cs

@@ -0,0 +1,14 @@
+using Robust.Shared.Console;
+
+namespace Content.Client.Weapons.Ranged;
+
+public sealed class TetherGunCommand : IConsoleCommand
+{
+    public string Command => "tethergun";
+    public string Description => "Allows you to drag mobs around with your mouse.";
+    public string Help => $"{Command}";
+    public void Execute(IConsoleShell shell, string argStr, string[] args)
+    {
+        IoCManager.Resolve<IEntitySystemManager>().GetEntitySystem<TetherGunSystem>().Enabled ^= true;
+    }
+}

Content.Client/Weapons/Ranged/TetherGunSystem.cs

@@ -0,0 +1,107 @@
+using Content.Client.Clickable;
+using Content.Shared.Weapons.Ranged;
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Client.Input;
+using Robust.Shared.Input;
+using Robust.Shared.Map;
+using Robust.Shared.Timing;
+
+namespace Content.Client.Weapons.Ranged;
+
+public sealed class TetherGunSystem : SharedTetherGunSystem
+{
+    [Dependency] private readonly IEyeManager _eyeManager = default!;
+    [Dependency] private readonly IGameTiming _gameTiming = default!;
+    [Dependency] private readonly IInputManager _inputManager = default!;
+    [Dependency] private readonly EntityLookupSystem _lookup = default!;
+    [Dependency] private readonly InputSystem _inputSystem = default!;
+
+    public bool Enabled { get; set; }
+
+    /// <summary>
+    /// The entity being dragged around.
+    /// </summary>
+    private EntityUid? _dragging;
+
+    private MapCoordinates? _lastMousePosition;
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+
+        if (!Enabled || !_gameTiming.IsFirstTimePredicted) return;
+
+        var state = _inputSystem.CmdStates.GetState(EngineKeyFunctions.Use);
+
+        if (state != BoundKeyState.Down)
+        {
+            StopDragging();
+            return;
+        }
+
+        var mouseScreenPos = _inputManager.MouseScreenPosition;
+        var mousePos = _eyeManager.ScreenToMap(mouseScreenPos);
+
+        if (_dragging == null)
+        {
+            var bodyQuery = GetEntityQuery<PhysicsComponent>();
+            var lowest = new List<(int DrawDepth, EntityUid Entity)>();
+
+            foreach (var ent in _lookup.GetEntitiesIntersecting(mousePos))
+            {
+                if (!bodyQuery.HasComponent(ent) ||
+                    !TryComp<ClickableComponent>(ent, out var clickable) ||
+                    !clickable.CheckClick(mousePos.Position, out var drawDepth, out _)) continue;
+
+                lowest.Add((drawDepth, ent));
+            }
+
+            lowest.Sort((x, y) => y.DrawDepth.CompareTo(x.DrawDepth));
+
+            foreach (var ent in lowest)
+            {
+                StartDragging(ent.Entity, mousePos);
+                break;
+            }
+
+            if (_dragging == null) return;
+        }
+
+        if (!TryComp<TransformComponent>(_dragging!.Value, out var xform) ||
+            _lastMousePosition!.Value.MapId != xform.MapID)
+        {
+            StopDragging();
+            return;
+        }
+
+        if (_lastMousePosition.Value.Position.EqualsApprox(mousePos.Position)) return;
+
+        _lastMousePosition = mousePos;
+
+        RaiseNetworkEvent(new TetherMoveEvent()
+        {
+            Coordinates = _lastMousePosition!.Value,
+        });
+    }
+
+    private void StopDragging()
+    {
+        if (_dragging == null) return;
+
+        RaiseNetworkEvent(new StopTetherEvent());
+        _dragging = null;
+        _lastMousePosition = null;
+    }
+
+    private void StartDragging(EntityUid uid, MapCoordinates coordinates)
+    {
+        _dragging = uid;
+        _lastMousePosition = coordinates;
+        RaiseNetworkEvent(new StartTetherEvent()
+        {
+            Entity = _dragging!.Value,
+            Coordinates = coordinates,
+        });
+    }
+}