Mouse rotator system (#19267)

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

Content.Shared/MouseRotator/MouseRotatorComponent.cs

@@ -0,0 +1,43 @@
+using System.Numerics;
+using Robust.Shared.GameStates;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.MouseRotator;
+
+/// <summary>
+/// This component allows overriding an entities local rotation based on the client's mouse movement
+/// </summary>
+/// <see cref="SharedMouseRotatorSystem"/>
+[RegisterComponent, NetworkedComponent, AutoGenerateComponentState]
+public sealed partial class MouseRotatorComponent : Component
+{
+    /// <summary>
+    ///     How much the desired angle needs to change before a predictive event is sent
+    /// </summary>
+    [DataField]
+    [ViewVariables(VVAccess.ReadWrite)]
+    public Angle AngleTolerance = Angle.FromDegrees(5.0);
+
+    /// <summary>
+    ///     The angle that will be lerped to
+    /// </summary>
+    [AutoNetworkedField, DataField]
+    public Angle? GoalRotation;
+
+    /// <summary>
+    ///     Max degrees the entity can rotate per second
+    /// </summary>
+    [DataField]
+    [ViewVariables(VVAccess.ReadWrite)]
+    public double RotationSpeed = float.MaxValue;
+}
+
+/// <summary>
+///     Raised on an entity with <see cref="MouseRotatorComponent"/> as a predictive event on the client
+///     when mouse rotation changes
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class RequestMouseRotatorRotationEvent : EntityEventArgs
+{
+    public Angle Rotation;
+}

Content.Shared/MouseRotator/SharedMouseRotatorSystem.cs

@@ -0,0 +1,60 @@
+using Content.Shared.Interaction;
+using Robust.Shared.Timing;
+
+namespace Content.Shared.MouseRotator;
+
+/// <summary>
+/// This handles rotating an entity based on mouse location
+/// </summary>
+/// <see cref="MouseRotatorComponent"/>
+public abstract class SharedMouseRotatorSystem : EntitySystem
+{
+    [Dependency] private readonly RotateToFaceSystem _rotate = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeAllEvent<RequestMouseRotatorRotationEvent>(OnRequestRotation);
+    }
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+
+        // TODO maybe `ActiveMouseRotatorComponent` to avoid querying over more entities than we need?
+        // (if this is added to players)
+        // (but arch makes these fast anyway, so)
+        var query = EntityQueryEnumerator<MouseRotatorComponent, TransformComponent>();
+        while (query.MoveNext(out var uid, out var rotator, out var xform))
+        {
+            if (rotator.GoalRotation == null)
+                continue;
+
+            if (_rotate.TryRotateTo(
+                    uid,
+                    rotator.GoalRotation.Value,
+                    frameTime,
+                    rotator.AngleTolerance,
+                    MathHelper.DegreesToRadians(rotator.RotationSpeed),
+                    xform))
+            {
+                // Stop rotating if we finished
+                rotator.GoalRotation = null;
+                Dirty(uid, rotater);
+            }
+        }
+    }
+
+    private void OnRequestRotation(RequestMouseRotatorRotationEvent msg, EntitySessionEventArgs args)
+    {
+        if (args.SenderSession.AttachedEntity is not { } ent || !TryComp<MouseRotatorComponent>(ent, out var rotator))
+        {
+            Log.Error($"User {args.SenderSession.Name} ({args.SenderSession.UserId}) tried setting local rotation without a mouse rotator component attached!");
+            return;
+        }
+
+        rotator.GoalRotation = msg.Rotation;
+        Dirty(ent, rotator);
+    }
+}