real crate spawning

OpenRa.Game/Traits/World/CrateSpawner.cs

@@ -11,17 +11,49 @@ namespace OpenRa.Traits
 		public readonly int CrateMaximum = 255; // Maximum number of crates
 		public readonly int CrateRadius = 3; // Radius of crate effect TODO: This belongs on the crate effect itself
 		public readonly int CrateRegen = 180; // Average time (seconds) between crate spawn
-		public readonly float WaterCrateChance = 0.2f; // Change of generating a water crate instead of a land crate
-		
-		public object Create(Actor self) { return new CrateSpawner(self); }
+		public readonly float WaterCrateChance = .2f; // Chance of generating a water crate instead of a land crate
+
+		public object Create(Actor self) { return new CrateSpawner(); }
 	}
 	
-	class CrateSpawner
+	// assumption: there is always at least one free water cell, and one free land cell.
+
+	class CrateSpawner : ITick
 	{
-		Actor self;
-		public CrateSpawner(Actor self)
+		List<Actor> crates = new List<Actor>();
+		int ticks = 0;
+
+		public void Tick(Actor self)
 		{
-			this.self = self;
+			if (--ticks <= 0)
+			{
+				var info = self.Info.Traits.Get<CrateSpawnerInfo>();
+				ticks = info.CrateRegen * 25;		// todo: randomize
+			
+				crates.RemoveAll(c => !c.IsInWorld);
+
+				while (crates.Count < info.CrateMinimum)
+					SpawnCrate(self, info);
+				if (crates.Count < info.CrateMaximum)
+					SpawnCrate(self, info);
+			}
+		}
+
+		void SpawnCrate(Actor self, CrateSpawnerInfo info)
+		{
+			var inWater = Game.SharedRandom.NextDouble() < info.WaterCrateChance;
+			var umt = inWater ? UnitMovementType.Float : UnitMovementType.Wheel;
+
+			for (; ; )
+			{
+				var p = new int2(Game.SharedRandom.Next(128), Game.SharedRandom.Next(128));
+				if (self.World.IsCellBuildable(p, umt))
+				{
+					self.World.AddFrameEndTask(
+						w => crates.Add(w.CreateActor("crate", p, self.Owner)));
+					break;
+				}
+			}
 		}
 	}
 }