Add UnionRectangles extension method.

OpenRA.Game/Exts.cs

@@ -151,6 +151,26 @@ namespace OpenRA
 				return xs.ElementAt(r.Next(xs.Count));
 		}
 
+		public static Rectangle Union(this IEnumerable<Rectangle> rects)
+		{
+			// PERF: Avoid LINQ.
+			var first = true;
+			var result = Rectangle.Empty;
+			foreach (var rect in rects)
+			{
+				if (first)
+				{
+					first = false;
+					result = rect;
+					continue;
+				}
+
+				result = Rectangle.Union(rect, result);
+			}
+
+			return result;
+		}
+
 		public static float Product(this IEnumerable<float> xs)
 		{
 			return xs.Aggregate(1f, (a, x) => a * x);

OpenRA.Game/Traits/World/ScreenMap.cs

@@ -219,31 +219,6 @@ namespace OpenRA.Traits
 			return partitionedRenderableFrozenActors[p].InBox(RectWithCorners(a, b)).Where(frozenActorIsValid);
 		}
 
-		Rectangle AggregateBounds(IEnumerable<Rectangle> screenBounds)
-		{
-			if (!screenBounds.Any())
-				return Rectangle.Empty;
-
-			var bounds = screenBounds.First();
-			foreach (var b in screenBounds.Skip(1))
-				bounds = Rectangle.Union(bounds, b);
-
-			return bounds;
-		}
-
-		Rectangle AggregateBounds(IEnumerable<int2> vertices)
-		{
-			if (!vertices.Any())
-				return Rectangle.Empty;
-
-			var first = vertices.First();
-			var rect = new Rectangle(first.X, first.Y, 0, 0);
-			foreach (var v in vertices.Skip(1))
-				rect = Rectangle.Union(rect, new Rectangle(v.X, v.Y, 0, 0));
-
-			return rect;
-		}
-
 		public void TickRender()
 		{
 			foreach (var a in addOrUpdateActors)
@@ -261,7 +236,7 @@ namespace OpenRA.Traits
 				else
 					partitionedMouseActors.Remove(a);
 
-				var screenBounds = AggregateBounds(a.ScreenBounds(worldRenderer));
+				var screenBounds = a.ScreenBounds(worldRenderer).Union();
 				if (!screenBounds.Size.IsEmpty)
 				{
 					if (partitionedRenderableActors.Contains(a))
@@ -298,7 +273,7 @@ namespace OpenRA.Traits
 					else
 						partitionedMouseFrozenActors[kv.Key].Remove(fa);
 
-					var screenBounds = AggregateBounds(fa.ScreenBounds);
+					var screenBounds = fa.ScreenBounds.Union();
 					if (!screenBounds.Size.IsEmpty)
 					{
 						if (partitionedRenderableFrozenActors[kv.Key].Contains(fa))