Batch shroud cell changes.

By maintaining a set of changed cells we can avoid repeating work for cells that change multiple times before being rendered. The shroud renderer and radar widget now delay their work until they must render, and thus process each changed cell only once. This avoids significant repetition that was causing major slowdown when many actors were in the world.

OpenRA.Game/Traits/World/Shroud.cs

@@ -24,6 +24,8 @@ namespace OpenRA.Traits
 	{
 		[Sync] public bool Disabled;
 
+		public event Action<IEnumerable<CPos>> CellsChanged;
+
 		readonly Actor self;
 		readonly Map map;
 
@@ -31,23 +33,6 @@ namespace OpenRA.Traits
 		readonly CellLayer<short> generatedShroudCount;
 		readonly CellLayer<bool> explored;
 
-		public event Action<CPos> CellEntryChanged
-		{
-			add
-			{
-				visibleCount.CellEntryChanged += value;
-				generatedShroudCount.CellEntryChanged += value;
-				explored.CellEntryChanged += value;
-			}
-
-			remove
-			{
-				visibleCount.CellEntryChanged -= value;
-				generatedShroudCount.CellEntryChanged -= value;
-				explored.CellEntryChanged -= value;
-			}
-		}
-
 		readonly Lazy<IFogVisibilityModifier[]> fogVisibilities;
 
 		// Cache of visibility that was added, so no matter what crazy trait code does, it
@@ -88,8 +73,11 @@ namespace OpenRA.Traits
 			slowVisibleTest = IsVisible;
 		}
 
-		void Invalidate()
+		void Invalidate(IEnumerable<CPos> changed)
 		{
+			if (CellsChanged != null)
+				CellsChanged(changed);
+
 			var oldHash = Hash;
 			Hash = Sync.HashPlayer(self.Owner) + self.World.WorldTick * 3;
 
@@ -148,7 +136,7 @@ namespace OpenRA.Traits
 				throw new InvalidOperationException("Attempting to add duplicate actor visibility");
 
 			visibility[a] = visible;
-			Invalidate();
+			Invalidate(visible);
 		}
 
 		void RemoveVisibility(Actor a)
@@ -161,7 +149,7 @@ namespace OpenRA.Traits
 				visibleCount[c]--;
 
 			visibility.Remove(a);
-			Invalidate();
+			Invalidate(visible);
 		}
 
 		void UpdateVisibility(Actor a, ref CPos[] visible)
@@ -190,7 +178,7 @@ namespace OpenRA.Traits
 				throw new InvalidOperationException("Attempting to add duplicate shroud generation");
 
 			generation[a] = shrouded;
-			Invalidate();
+			Invalidate(shrouded);
 		}
 
 		void RemoveShroudGeneration(Actor a)
@@ -203,7 +191,7 @@ namespace OpenRA.Traits
 				generatedShroudCount[c]--;
 
 			generation.Remove(a);
-			Invalidate();
+			Invalidate(shrouded);
 		}
 
 		void UpdateShroudGeneration(Actor a, ref CPos[] shrouded)
@@ -241,10 +229,17 @@ namespace OpenRA.Traits
 
 		public void Explore(World world, CPos center, WRange range)
 		{
+			var changed = new List<CPos>();
 			foreach (var c in FindVisibleTiles(world, center, range))
-				explored[c] = true;
+			{
+				if (!explored[c])
+				{
+					explored[c] = true;
+					changed.Add(c);
+				}
+			}
 
-			Invalidate();
+			Invalidate(changed);
 		}
 
 		public void Explore(Shroud s)
@@ -252,27 +247,48 @@ namespace OpenRA.Traits
 			if (map.Bounds != s.map.Bounds)
 				throw new ArgumentException("The map bounds of these shrouds do not match.", "s");
 
+			var changed = new List<CPos>();
 			foreach (var uv in map.Cells.MapCoords)
-				if (s.explored[uv])
+			{
+				if (!explored[uv] && s.explored[uv])
+				{
 					explored[uv] = true;
+					changed.Add(uv.ToCPos(map));
+				}
+			}
 
-			Invalidate();
+			Invalidate(changed);
 		}
 
 		public void ExploreAll(World world)
 		{
+			var changed = new List<CPos>();
 			foreach (var uv in map.Cells.MapCoords)
-				explored[uv] = true;
+			{
+				if (!explored[uv])
+				{
+					explored[uv] = true;
+					changed.Add(uv.ToCPos(map));
+				}
+			}
 
-			Invalidate();
+			Invalidate(changed);
 		}
 
 		public void ResetExploration()
 		{
+			var changed = new List<CPos>();
 			foreach (var uv in map.Cells.MapCoords)
-				explored[uv] = visibleCount[uv] > 0;
+			{
+				var visible = visibleCount[uv] > 0;
+				if (explored[uv] != visible)
+				{
+					explored[uv] = visible;
+					changed.Add(uv.ToCPos(map));
+				}
+			}
 
-			Invalidate();
+			Invalidate(changed);
 		}
 
 		public bool IsExplored(CPos cell)