fix heli repusion from grounded helis. cleanup flight code

OpenRA.Mods.RA/Air/Aircraft.cs

@@ -11,6 +11,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using OpenRA.Traits;
+using System;
 
 namespace OpenRA.Mods.RA.Air
 {
@@ -96,5 +97,11 @@ namespace OpenRA.Mods.RA.Air
 		int2[] noCells = new int2[] { };
 		public IEnumerable<int2> OccupiedCells() { return noCells; }
 		public int2 PxPosition { get { return center.ToInt2(); } }
+
+		public void TickMove( float speed, int facing )
+		{
+			var angle = facing / 128f * Math.PI;
+			center += speed * -float2.FromAngle((float)angle);
+		}
 	}
 }

OpenRA.Mods.RA/Air/Fly.cs

@@ -58,8 +58,7 @@ namespace OpenRA.Mods.RA.Air
 		{
 			var aircraft = self.Trait<Aircraft>();
 			var speed = .2f * aircraft.MovementSpeed;
-			var angle = aircraft.Facing / 128f * Math.PI;
-			aircraft.center += speed * -float2.FromAngle((float)angle);
+			aircraft.TickMove( speed, aircraft.Facing );
 			aircraft.Altitude += Math.Sign(desiredAltitude - aircraft.Altitude);
 		}
 	}

OpenRA.Mods.RA/Air/HeliAttack.cs

@@ -26,10 +26,7 @@ namespace OpenRA.Mods.RA.Air
 
 			var limitedAmmo = self.TraitOrDefault<LimitedAmmo>();
 			if (limitedAmmo != null && !limitedAmmo.HasAmmo())
-			{	
-				self.QueueActivity(new HeliReturn());
-				return NextActivity;
-			}
+				return Util.SequenceActivities( new HeliReturn(), NextActivity );
 			
 			var aircraft = self.Trait<Aircraft>();
 			var info = self.Info.Traits.Get<HelicopterInfo>();

OpenRA.Mods.RA/Air/Helicopter.cs

@@ -138,7 +138,7 @@ namespace OpenRA.Mods.RA.Air
 				.Where(a => a.HasTrait<Helicopter>());
 
 			var f = otherHelis
-				.Select(h => self.Trait<Helicopter>().GetRepulseForce(self, h))
+				.Select(h => self.Trait<Helicopter>().GetRepulseForce(self, h, h.Trait<Helicopter>()))
 				.Aggregate(float2.Zero, (a, b) => a + b);
 
 			aircraft.center += rawSpeed * f;
@@ -152,10 +152,12 @@ namespace OpenRA.Mods.RA.Air
 		}
 
 		const float Epsilon = .5f;
-		public float2 GetRepulseForce(Actor self, Actor h)
+		public float2 GetRepulseForce(Actor self, Actor h, Aircraft hAir)
 		{
 			if (self == h)
 				return float2.Zero;
+			if( hAir.Altitude < Altitude )
+				return float2.Zero;
 			var d = self.CenterLocation - h.CenterLocation;
 			
 			if (d.Length > Info.IdealSeparation)

OpenRA.Mods.RA/Air/Land.cs

@@ -39,9 +39,8 @@ namespace OpenRA.Mods.RA.Air
 			var desiredFacing = Util.GetFacing(d, aircraft.Facing);
 			aircraft.Facing = Util.TickFacing(aircraft.Facing, desiredFacing, aircraft.ROT);
 			var speed = .2f * aircraft.MovementSpeed;
-			var angle = aircraft.Facing / 128f * Math.PI;
 
-			aircraft.center += speed * -float2.FromAngle((float)angle);
+			aircraft.TickMove( speed, aircraft.Facing );
 
 			return this;
 		}