Mouse rotator system (#19267)

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Client/MouseRotator/MouseRotatorSystem.cs

@@ -0,0 +1,61 @@
+using Content.Shared.MouseRotator;
+using Robust.Client.Graphics;
+using Robust.Client.Input;
+using Robust.Client.Player;
+using Robust.Shared.Map;
+using Robust.Shared.Timing;
+
+namespace Content.Client.MouseRotator;
+
+/// <inheritdoc/>
+public sealed class MouseRotatorSystem : SharedMouseRotatorSystem
+{
+    [Dependency] private readonly IInputManager _input = default!;
+    [Dependency] private readonly IPlayerManager _player = default!;
+    [Dependency] private readonly IGameTiming _timing = default!;
+    [Dependency] private readonly IEyeManager _eye = default!;
+    [Dependency] private readonly SharedTransformSystem _transform = default!;
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+
+        if (!_timing.IsFirstTimePredicted || !_input.MouseScreenPosition.IsValid)
+            return;
+
+        var player = _player.LocalPlayer?.ControlledEntity;
+
+        if (player == null || !TryComp<MouseRotatorComponent>(player, out var rotator))
+            return;
+
+        var xform = Transform(player.Value);
+
+        // Get mouse loc and convert to angle based on player location
+        var coords = _input.MouseScreenPosition;
+        var mapPos = _eye.PixelToMap(coords);
+
+        if (mapPos.MapId == MapId.Nullspace)
+            return;
+
+        var angle = (mapPos.Position - xform.MapPosition.Position).ToWorldAngle();
+
+        var curRot = _transform.GetWorldRotation(xform);
+
+        // Don't raise event if mouse ~hasn't moved (or if too close to goal rotation already)
+        var diff = Angle.ShortestDistance(angle, curRot);
+        if (Math.Abs(diff.Theta) < rotator.AngleTolerance.Theta)
+            return;
+
+        if (rotator.GoalRotation != null)
+        {
+            var goalDiff = Angle.ShortestDistance(angle, rotator.GoalRotation.Value);
+            if (Math.Abs(goalDiff.Theta) < rotator.AngleTolerance.Theta)
+                return;
+        }
+
+        RaisePredictiveEvent(new RequestMouseRotatorRotationEvent
+        {
+            Rotation = angle
+        });
+    }
+}