Add the ability for mappers to drag grids around. (#7769)

* Add the ability for mappers to drag grids around.

* Less message spam

* Also flinging

Content.Client/Maps/GridDraggingSystem.cs

@@ -0,0 +1,114 @@
+using Content.Client.Administration.Managers;
+using Content.Shared.Maps;
+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.Maps;
+
+/// <inheritdoc />
+public sealed class GridDraggingSystem : SharedGridDraggingSystem
+{
+    [Dependency] private readonly IEyeManager _eyeManager = default!;
+    [Dependency] private readonly IGameTiming _gameTiming = default!;
+    [Dependency] private readonly IInputManager _inputManager = default!;
+    [Dependency] private readonly IMapManager _mapManager = default!;
+    [Dependency] private readonly InputSystem _inputSystem = default!;
+
+    public bool Enabled { get; set; }
+
+    private EntityUid? _dragging;
+    private Vector2 _localPosition;
+    private MapCoordinates? _lastMousePosition;
+
+    private void StartDragging(EntityUid grid, Vector2 localPosition)
+    {
+        _dragging = grid;
+        _localPosition = localPosition;
+
+        if (TryComp<PhysicsComponent>(grid, out var body))
+        {
+            RaiseNetworkEvent(new GridDragVelocityRequest()
+            {
+                Grid = grid,
+                LinearVelocity = Vector2.Zero
+            });
+        }
+    }
+
+    private void StopDragging()
+    {
+        if (_dragging == null) return;
+
+        if (_lastMousePosition != null && TryComp<TransformComponent>(_dragging.Value, out var xform) &&
+            TryComp<PhysicsComponent>(_dragging.Value, out var body) &&
+            xform.MapID == _lastMousePosition.Value.MapId)
+        {
+            var tickTime = _gameTiming.TickPeriod;
+            var distance = _lastMousePosition.Value.Position - xform.WorldPosition;
+            RaiseNetworkEvent(new GridDragVelocityRequest()
+            {
+                Grid = _dragging.Value,
+                LinearVelocity = distance.LengthSquared > 0f ? (distance / (float) tickTime.TotalSeconds) * 0.25f : Vector2.Zero,
+            });
+        }
+
+        _dragging = null;
+        _localPosition = Vector2.Zero;
+        _lastMousePosition = null;
+    }
+
+    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)
+        {
+            if (!_mapManager.TryFindGridAt(mousePos, out var grid))
+                return;
+
+            StartDragging(grid.GridEntityId, Transform(grid.GridEntityId).InvWorldMatrix.Transform(mousePos.Position));
+        }
+
+        if (!TryComp<TransformComponent>(_dragging, out var xform))
+        {
+            StopDragging();
+            return;
+        }
+
+        if (xform.MapID != mousePos.MapId)
+        {
+            StopDragging();
+            return;
+        }
+
+        var localToWorld = xform.WorldMatrix.Transform(_localPosition);
+
+        if (localToWorld.EqualsApprox(mousePos.Position, 0.01f)) return;
+
+        var requestedGridOrigin = mousePos.Position - xform.WorldRotation.RotateVec(_localPosition);
+        _lastMousePosition = new MapCoordinates(requestedGridOrigin, mousePos.MapId);
+
+        RaiseNetworkEvent(new GridDragRequestPosition()
+        {
+            Grid = _dragging.Value,
+            WorldPosition = requestedGridOrigin,
+        });
+    }
+}