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))
+			{
+				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)
+			{
+				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)

OpenRA.Mods.Common/Traits/World/ShroudRenderer.cs

@@ -9,6 +9,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using OpenRA.Graphics;
 using OpenRA.Traits;
 
@@ -85,6 +86,8 @@ namespace OpenRA.Mods.Common.Traits
 
 		readonly CellLayer<TileInfo> tileInfos;
 		readonly CellLayer<bool> shroudDirty;
+		readonly HashSet<CPos> cellsDirty;
+		readonly HashSet<CPos> cellsAndNeighborsDirty;
 
 		readonly Vertex[] fogVertices, shroudVertices;
 		readonly Sprite[] fogSprites, shroudSprites;
@@ -113,6 +116,8 @@ namespace OpenRA.Mods.Common.Traits
 
 			tileInfos = new CellLayer<TileInfo>(map);
 			shroudDirty = new CellLayer<bool>(map);
+			cellsDirty = new HashSet<CPos>();
+			cellsAndNeighborsDirty = new HashSet<CPos>();
 			var verticesLength = map.MapSize.X * map.MapSize.Y * 4;
 			fogVertices = new Vertex[verticesLength];
 			shroudVertices = new Vertex[verticesLength];
@@ -209,20 +214,38 @@ namespace OpenRA.Mods.Common.Traits
 			if (currentShroud != newShroud)
 			{
 				if (currentShroud != null)
-					currentShroud.CellEntryChanged -= MarkCellAndNeighborsDirty;
+					currentShroud.CellsChanged -= MarkCellsDirty;
 
 				if (newShroud != null)
 				{
 					shroudDirty.Clear(true);
-					newShroud.CellEntryChanged += MarkCellAndNeighborsDirty;
+					newShroud.CellsChanged += MarkCellsDirty;
 				}
 
+				cellsDirty.Clear();
+				cellsAndNeighborsDirty.Clear();
+
 				currentShroud = newShroud;
 			}
 
 			if (currentShroud != null)
 			{
 				mapBorderShroudIsCached = false;
+
+				// We need to mark newly dirtied areas of the shroud.
+				// Expand the dirty area to cover the neighboring cells, since shroud is affected by neighboring cells.
+				foreach (var cell in cellsDirty)
+				{
+					cellsAndNeighborsDirty.Add(cell);
+					foreach (var direction in CVec.Directions)
+						cellsAndNeighborsDirty.Add(cell + direction);
+				}
+
+				foreach (var cell in cellsAndNeighborsDirty)
+					shroudDirty[cell] = true;
+
+				cellsDirty.Clear();
+				cellsAndNeighborsDirty.Clear();
 			}
 			else if (!mapBorderShroudIsCached)
 			{
@@ -231,9 +254,9 @@ namespace OpenRA.Mods.Common.Traits
 			}
 		}
 
-		void MarkCellAndNeighborsDirty(CPos cell)
+		void MarkCellsDirty(IEnumerable<CPos> cellsChanged)
 		{
-			// Mark this cell and its 8 neighbors as being out of date.
+			// Mark changed cells as being out of date.
 			// We don't want to do anything more than this for several performance reasons:
 			// - If the cells remain off-screen for a long time, they may change several times before we next view
 			// them, so calculating their new vertices is wasted effort since we may recalculate them again before we
@@ -242,15 +265,7 @@ namespace OpenRA.Mods.Common.Traits
 			// leaves a trail of fog filling in behind). If we recalculated a cell and its neighbors when the first
 			// cell in a group changed, many cells would be recalculated again when the second cell, right next to the
 			// first, is updated. In fact we might do on the order of 3x the work we needed to!
-			shroudDirty[cell + new CVec(-1, -1)] = true;
-			shroudDirty[cell + new CVec(0, -1)] = true;
-			shroudDirty[cell + new CVec(1, -1)] = true;
-			shroudDirty[cell + new CVec(-1, 0)] = true;
-			shroudDirty[cell] = true;
-			shroudDirty[cell + new CVec(1, 0)] = true;
-			shroudDirty[cell + new CVec(-1, 1)] = true;
-			shroudDirty[cell + new CVec(0, 1)] = true;
-			shroudDirty[cell + new CVec(1, 1)] = true;
+			cellsDirty.UnionWith(cellsChanged);
 		}
 
 		void CacheMapBorderShroud()

OpenRA.Mods.Common/Widgets/RadarWidget.cs

@@ -9,6 +9,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
 using OpenRA.Graphics;
@@ -33,6 +34,8 @@ namespace OpenRA.Mods.Common.Widgets
 		readonly WorldRenderer worldRenderer;
 		readonly RadarPings radarPings;
 
+		readonly HashSet<CPos> dirtyShroudCells = new HashSet<CPos>();
+
 		float radarMinimapHeight;
 		int frame;
 		bool hasRadar;
@@ -130,6 +133,11 @@ namespace OpenRA.Mods.Common.Widgets
 			}
 		}
 
+		void MarkShroudDirty(IEnumerable<CPos> cellsChanged)
+		{
+			dirtyShroudCells.UnionWith(cellsChanged);
+		}
+
 		public override string GetCursor(int2 pos)
 		{
 			if (world == null || !hasRadar)
@@ -194,6 +202,15 @@ namespace OpenRA.Mods.Common.Widgets
 			if (world == null)
 				return;
 
+			if (renderShroud != null)
+			{
+				foreach (var cell in dirtyShroudCells)
+					UpdateShroudCell(cell);
+				dirtyShroudCells.Clear();
+			}
+
+			radarSheet.CommitData();
+
 			var o = new float2(mapRect.Location.X, mapRect.Location.Y + world.Map.Bounds.Height * previewScale * (1 - radarMinimapHeight) / 2);
 			var s = new float2(mapRect.Size.Width, mapRect.Size.Height * radarMinimapHeight);
 
@@ -255,7 +272,7 @@ namespace OpenRA.Mods.Common.Widgets
 				if (newRenderShroud != renderShroud)
 				{
 					if (renderShroud != null)
-						renderShroud.CellEntryChanged -= UpdateShroudCell;
+						renderShroud.CellsChanged -= MarkShroudDirty;
 
 					if (newRenderShroud != null)
 					{
@@ -264,9 +281,11 @@ namespace OpenRA.Mods.Common.Widgets
 							OpenRA.Graphics.Util.FastCopyIntoSprite(shroudSprite, bitmap);
 
 						// Update the notification binding
-						newRenderShroud.CellEntryChanged += UpdateShroudCell;
+						newRenderShroud.CellsChanged += MarkShroudDirty;
 					}
 
+					dirtyShroudCells.Clear();
+
 					renderShroud = newRenderShroud;
 				}
 
@@ -299,8 +318,6 @@ namespace OpenRA.Mods.Common.Widgets
 						}
 					}
 				}
-
-				radarSheet.CommitData();
 			}
 
 			var targetFrame = enabled ? AnimationLength : 0;