Fix FrozenUnderFog / FrozenActor visibility consistency.

This fixes cases where both objects return visible / not
when queried at the wrong time during a tick.

OpenRA.Game/Traits/Player/FrozenActorLayer.cs

@@ -18,6 +18,11 @@ using OpenRA.Primitives;
 
 namespace OpenRA.Traits
 {
+	public interface ICreatesFrozenActors
+	{
+		void OnVisibilityChanged(FrozenActor frozen);
+	}
+
 	[Desc("Required for FrozenUnderFog to work. Attach this to the player actor.")]
 	public class FrozenActorLayerInfo : Requires<ShroudInfo>, ITraitInfo
 	{
@@ -32,6 +37,7 @@ namespace OpenRA.Traits
 		public readonly PPos[] Footprint;
 		public readonly WPos CenterPosition;
 		readonly Actor actor;
+		readonly ICreatesFrozenActors frozenTrait;
 		readonly Player viewer;
 		readonly Shroud shroud;
 
@@ -70,9 +76,10 @@ namespace OpenRA.Traits
 
 		int flashTicks;
 
-		public FrozenActor(Actor actor, PPos[] footprint, Player viewer, bool startsRevealed)
+		public FrozenActor(Actor actor, ICreatesFrozenActors frozenTrait, PPos[] footprint, Player viewer, bool startsRevealed)
 		{
 			this.actor = actor;
+			this.frozenTrait = frozenTrait;
 			this.viewer = viewer;
 			shroud = viewer.Shroud;
 			NeedRenderables = startsRevealed;
@@ -153,6 +160,11 @@ namespace OpenRA.Traits
 					Shrouded = false;
 			}
 
+			// Force the backing trait to update so other actors can't
+			// query inconsistent state (both hidden or both visible)
+			if (Visible != wasVisible)
+				frozenTrait.OnVisibilityChanged(this);
+
 			NeedRenderables |= Visible && !wasVisible;
 		}
 

OpenRA.Mods.Common/Traits/Modifiers/FrozenUnderFog.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
@@ -27,7 +28,7 @@ namespace OpenRA.Mods.Common.Traits
 		public object Create(ActorInitializer init) { return new FrozenUnderFog(init, this); }
 	}
 
-	public class FrozenUnderFog : IRenderModifier, IDefaultVisibility, ITick, ITickRender, ISync, INotifyCreated
+	public class FrozenUnderFog : ICreatesFrozenActors, IRenderModifier, IDefaultVisibility, ITick, ITickRender, ISync, INotifyCreated
 	{
 		[Sync] public int VisibilityHash;
 
@@ -37,6 +38,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		PlayerDictionary<FrozenState> frozenStates;
 		bool isRendering;
+		bool created;
 
 		class FrozenState
 		{
@@ -67,7 +69,7 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			frozenStates = new PlayerDictionary<FrozenState>(self.World, (player, playerIndex) =>
 			{
-				var frozenActor = new FrozenActor(self, footprint, player, startsRevealed);
+				var frozenActor = new FrozenActor(self, this, footprint, player, startsRevealed);
 				player.PlayerActor.Trait<FrozenActorLayer>().Add(frozenActor);
 				return new FrozenState(frozenActor) { IsVisible = startsRevealed };
 			});
@@ -75,6 +77,8 @@ namespace OpenRA.Mods.Common.Traits
 			if (startsRevealed)
 				for (var playerIndex = 0; playerIndex < frozenStates.Count; playerIndex++)
 					UpdateFrozenActor(self, frozenStates[playerIndex].FrozenActor, playerIndex);
+
+			created = true;
 		}
 
 		void UpdateFrozenActor(Actor self, FrozenActor frozenActor, int playerIndex)
@@ -83,6 +87,17 @@ namespace OpenRA.Mods.Common.Traits
 			frozenActor.RefreshState();
 		}
 
+		void ICreatesFrozenActors.OnVisibilityChanged(FrozenActor frozen)
+		{
+			// Ignore callbacks during initial setup
+			if (!created)
+				return;
+
+			// Update state visibility to match the frozen actor to ensure consistency within the tick
+			// The rest of the state will be updated by ITick.Tick below
+			frozenStates[frozen.Viewer].IsVisible = !frozen.Visible;
+		}
+
 		bool IsVisibleInner(Actor self, Player byPlayer)
 		{
 			// If fog is disabled visibility is determined by shroud