Reorganize shroud cell queries.

This is in preparation for a future PR that will
remove GetVisOrigins.

OpenRA.Game/Traits/World/Shroud.cs

@@ -72,21 +72,20 @@ namespace OpenRA.Traits
 				Hash += 1;
 		}
 
-		static CPos[] FindVisibleTiles(Actor actor, WRange range)
+		public static IEnumerable<CPos> CellsInRange(Map map, WPos pos, WRange range)
 		{
-			return GetVisOrigins(actor).SelectMany(o => FindVisibleTiles(actor.World, o, range)).Distinct().ToArray();
+			var r = (range.Range + 1023) / 1024;
+			var limit = range.RangeSquared;
+			var cell = map.CellContaining(pos);
+
+			foreach (var c in map.FindTilesInCircle(cell, r, true))
+				if ((map.CenterOfCell(c) - pos).HorizontalLengthSquared <= limit)
+					yield return c;
 		}
 
-		public static IEnumerable<CPos> FindVisibleTiles(World world, CPos position, WRange radius)
+		public static IEnumerable<CPos> CellsInRange(Map map, CPos cell, WRange range)
 		{
-			var map = world.Map;
+			return CellsInRange(map, map.CenterOfCell(cell), range);
-			var r = (radius.Range + 1023) / 1024;
-			var limit = radius.RangeSquared;
-			var pos = map.CenterOfCell(position);
-
-			foreach (var cell in map.FindTilesInCircle(position, r, true))
-				if ((map.CenterOfCell(cell) - pos).HorizontalLengthSquared <= limit)
-					yield return cell;
 		}
 
 		public void AddVisibility(Actor a, CPos[] visible)
@@ -184,6 +183,8 @@ namespace OpenRA.Traits
 			}
 		}
 
+		// TODO: Actor vis will be split into separate cases for
+		// "cells that I reveal from" and "cells that reveal me"
 		public static IEnumerable<CPos> GetVisOrigins(Actor a)
 		{
 			var ios = a.OccupiesSpace;
@@ -197,10 +198,10 @@ namespace OpenRA.Traits
 			return new[] { a.World.Map.CellContaining(a.CenterPosition) };
 		}
 
-		public void Explore(World world, CPos center, WRange range)
+		public void Explore(World world, IEnumerable<CPos> cells)
 		{
-			var changed = new List<CPos>();
+			var changed = new HashSet<CPos>();
-			foreach (var c in FindVisibleTiles(world, center, range))
+			foreach (var c in cells)
 			{
 				if (!explored[c])
 				{

OpenRA.Mods.Common/Traits/RevealsShroud.cs

@@ -46,12 +46,13 @@ namespace OpenRA.Mods.Common.Traits
 
 		CPos[] Cells(Actor self)
 		{
+			var map = self.World.Map;
 			var range = Range;
 			if (range == WRange.Zero)
 				return NoCells;
 
 			return Shroud.GetVisOrigins(self)
-				.SelectMany(o => Shroud.FindVisibleTiles(self.World, o, range))
+				.SelectMany(c => Shroud.CellsInRange(map, c, range))
 				.Distinct().ToArray();
 		}
 

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

@@ -17,14 +17,23 @@ using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits
 {
-	public class MPStartLocationsInfo : TraitInfo<MPStartLocations>
+	public class MPStartLocationsInfo : ITraitInfo
 	{
 		public readonly WRange InitialExploreRange = WRange.FromCells(5);
+
+		public virtual object Create(ActorInitializer init) { return new MPStartLocations(this); }
 	}
 
 	public class MPStartLocations : IWorldLoaded
 	{
-		public Dictionary<Player, CPos> Start = new Dictionary<Player, CPos>();
+		readonly MPStartLocationsInfo info;
+
+		public readonly Dictionary<Player, CPos> Start = new Dictionary<Player, CPos>();
+
+		public MPStartLocations(MPStartLocationsInfo info)
+		{
+			this.info = info;
+		}
 
 		public void WorldLoaded(World world, WorldRenderer wr)
 		{
@@ -52,15 +61,18 @@ namespace OpenRA.Mods.Common.Traits
 			}
 
 			// Explore allied shroud
-			var explore = world.WorldActor.Info.Traits.Get<MPStartLocationsInfo>().InitialExploreRange;
+			var map = world.Map;
 			foreach (var p in Start.Keys)
+			{
+				var cells = Shroud.CellsInRange(map, Start[p], info.InitialExploreRange);
 				foreach (var q in world.Players)
 					if (p.IsAlliedWith(q))
-						q.Shroud.Explore(world, Start[p], explore);
+						q.Shroud.Explore(world, cells);
+			}
 
 			// Set viewport
 			if (world.LocalPlayer != null && Start.ContainsKey(world.LocalPlayer))
-				wr.Viewport.Center(world.Map.CenterOfCell(Start[world.LocalPlayer]));
+				wr.Viewport.Center(map.CenterOfCell(Start[world.LocalPlayer]));
 		}
 
 		static Player FindPlayerInSlot(World world, string pr)