FindUnitPathToRange

OpenRa.Game/Game.cs

@@ -160,6 +160,17 @@ namespace OpenRa.Game
 				.Where(x => (x.CenterLocation - a).LengthSquared < r * r);
 		}
 
+		public static IEnumerable<int2> FindTilesInCircle(int2 a, int r)
+		{
+			var min = a - new int2(r, r);
+			var max = a + new int2(r, r);
+
+			for (var j = min.Y; j <= max.Y; j++)
+				for (var i = min.X; i <= max.X; i++)
+					if (r * r >= (new int2(i, j) - a).LengthSquared)
+						yield return new int2(i, j);
+		}
+
 		public static IEnumerable<Actor> SelectUnitsInBox(float2 a, float2 b)
 		{
 			return FindUnits(a, b).Where(x => x.Owner == LocalPlayer && x.traits.Contains<Traits.Mobile>());

OpenRa.Game/PathFinder.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using IjwFramework.Collections;
+using System.Linq;
 using OpenRa.FileFormats;
 using OpenRa.Game.Graphics;
 
@@ -30,21 +31,32 @@ namespace OpenRa.Game
 			return FindUnitPath(src, DefaultEstimator(dest), umt);
 		}
 
+		public List<int2> FindUnitPathToRange(int2 src, int2 dest, UnitMovementType umt, int range)
+		{
+			var tilesInRange = Game.FindTilesInCircle(dest, range)
+				.Where(t => Game.IsCellBuildable(t, umt))
+				.Select(t => t + map.Offset);
+
+			var path = FindUnitPath(tilesInRange, DefaultEstimator(dest), umt);
+			path.Reverse();
+			return path;
+		}
+
 		List<int2> FindUnitPath( int2 unitLocation, Func<int2,double> estimator, UnitMovementType umt )
 		{
 			var startLocation = unitLocation + map.Offset;
+			return FindUnitPath( new[] {startLocation}, estimator, umt );
+		}
 
+		List<int2> FindUnitPath(IEnumerable<int2> startLocations, Func<int2, double> estimator, UnitMovementType umt)
+		{
 			var cellInfo = new CellInfo[128, 128];
+			var offset = map.Offset;
 
 			for (int x = 0; x < 128; x++)
 				for (int y = 0; y < 128; y++)
 					cellInfo[x, y] = new CellInfo(double.PositiveInfinity, new int2(x, y), false);
 
-			return FindUnitPath( new[] {startLocation}, estimator, umt, map.Offset, cellInfo );
-		}
-
-		List<int2> FindUnitPath(IEnumerable<int2> startLocations, Func<int2, double> estimator, UnitMovementType umt, int2 offset, CellInfo[,] cellInfo)
-		{
 			var queue = new PriorityQueue<PathDistance>();
 
 			foreach (var sl in startLocations)