HasSight -> RevealsShroud and used everywhere

OpenRA.Game/OpenRA.Game.csproj

@@ -82,7 +82,7 @@
     <Compile Include="Orders\GenericSelectTarget.cs" />
     <Compile Include="Traits\AI\EmitInfantryOnSell.cs" />
     <Compile Include="Traits\AI\ReturnOnIdle.cs" />
-    <Compile Include="Traits\HasSight.cs" />
+    <Compile Include="Traits\RevealsShroud.cs" />
     <Compile Include="Traits\Player\VictoryConditions.cs" />
     <Compile Include="Traits\Modifiers\HiddenUnderFog.cs" />
     <Compile Include="Traits\Render\RenderFlare.cs" />

OpenRA.Game/Traits/Mobile.cs

@@ -53,7 +53,6 @@ namespace OpenRA.Traits
 				{
 					self.World.WorldActor.traits.Get<UnitInfluence>().Remove(self, this);
 					self.Location = value;
-					self.World.WorldActor.traits.Get<Shroud>().UpdateActor(self);
 				}
 				self.World.WorldActor.traits.Get<UnitInfluence>().Add(self, this);
 			}

OpenRA.Game/Traits/RevealsShroud.cs

@@ -20,16 +20,19 @@
 
 namespace OpenRA.Traits
 {
-	class HasSightInfo : TraitInfo<HasSight> { }
+	class RevealsShroudInfo : TraitInfo<RevealsShroud> { }
 
-	// for random non-mobile movers
-
-	class HasSight : ITick
+	class RevealsShroud : ITick
 	{
+		int2 previousLocation;
+
 		public void Tick(Actor self)
 		{
-			if (!self.IsIdle)
+			if (!self.IsIdle && previousLocation != self.Location)
+			{
+				previousLocation = self.Location;
 				self.World.WorldActor.traits.Get<Shroud>().UpdateActor(self);
+			}
 		}
 	}
 }

OpenRA.Game/Traits/World/Shroud.cs

@@ -87,6 +87,8 @@ namespace OpenRA.Traits
 				vis = GetVisOrigins(a).ToArray()
 			};
 
+			if (v.range == 0) return;		// don't bother for things that can't see
+
 			foreach (var p in v.vis)
 			{
 				foreach (var q in FindVisibleTiles(a.World, p, v.range))