Track visibility modifiers on FrozenActors.

OpenRA.Game/Traits/Player/FrozenActorLayer.cs

@@ -46,7 +46,17 @@ namespace OpenRA.Traits
 		public DamageState DamageState { get; private set; }
 		readonly IHealth health;
 
+		// The Visible flag is tied directly to the actor visibility under the fog.
+		// If Visible is true, the actor is made invisible (via FrozenUnderFog/IDefaultVisibility)
+		// and this FrozenActor is rendered instead.
+		// The Hidden flag covers the edge case that occurs when the backing actor was last "seen"
+		// to be cloaked or otherwise not CanBeViewedByPlayer()ed. Setting Visible to true when
+		// the actor is hidden under the fog would leak the actors position via the tooltips and
+		// AutoTargetability, and keeping Visible as false would cause the actor to be rendered
+		// under the fog.
 		public bool Visible = true;
+		public bool Hidden = false;
+
 		public bool Shrouded { get; private set; }
 		public bool NeedRenderables { get; set; }
 		public IRenderable[] Renderables = NoRenderables;
@@ -101,6 +111,7 @@ namespace OpenRA.Traits
 		{
 			Owner = actor.Owner;
 			TargetTypes = actor.GetEnabledTargetTypes();
+			Hidden = !actor.CanBeViewedByPlayer(viewer);
 
 			if (health != null)
 			{
@@ -145,6 +156,11 @@ namespace OpenRA.Traits
 			NeedRenderables |= Visible && !wasVisible;
 		}
 
+		public void Invalidate()
+		{
+			Owner = null;
+		}
+
 		public void Flash()
 		{
 			flashTicks = 5;