heli flight sortof ok

OpenRa.Game/Game.cs

@@ -373,15 +373,24 @@ namespace OpenRa.Game
 					return;
 
 				unit = new Actor(name, (1 / 24f * producer.CenterLocation).ToInt2(), player);
-				var mobile = unit.traits.Get<Mobile>();
-				mobile.facing = 128;
-
 				var rp = producer.traits.GetOrDefault<RallyPoint>();
 				var dest = rp != null ? rp.rallyPoint : (unit.Location + new int2(0, 3));
 
+				var mobile = unit.traits.GetOrDefault<Mobile>();
+				if (mobile != null)
+				{
+					mobile.facing = 128;
 					mobile.QueueActivity(new Traits.Activities.Move(dest, 1));
 				}
 
+				var heli = unit.traits.GetOrDefault<Helicopter>();
+				if (heli != null)
+				{
+					heli.facing = 20;
+					heli.targetLocation = dest;
+				}
+			}
+
 			world.Add(unit);
 			player.FinishProduction(Rules.UnitCategory[name]);
 

OpenRa.Game/OpenRa.Game.csproj

@@ -142,6 +142,7 @@
     <Compile Include="Traits\AttackTurreted.cs" />
     <Compile Include="Traits\Building.cs" />
     <Compile Include="Traits\Harvester.cs" />
+    <Compile Include="Traits\Helicopter.cs" />
     <Compile Include="Traits\InfantrySquad.cs" />
     <Compile Include="Traits\McvDeploy.cs" />
     <Compile Include="Traits\Mobile.cs" />

OpenRa.Game/Traits/Helicopter.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRa.Game.GameRules;
+
+namespace OpenRa.Game.Traits
+{
+	class Helicopter : ITick, IOrder
+	{
+		public int facing;
+		public int altitude;
+		public int2 targetLocation;
+
+		const int CruiseAltitude = 20;
+
+		public Helicopter(Actor self)
+		{
+			targetLocation = self.Location;
+		}
+
+		public Order Order(Actor self, int2 xy, bool lmb, Actor underCursor)
+		{
+			if (lmb) return null;
+
+			if (underCursor == null)
+				return OpenRa.Game.Order.Move(self, xy,
+					!Game.IsCellBuildable(xy, UnitMovementType.Foot));
+
+			return null;
+		}
+
+		public void Tick(Actor self)
+		{
+			if (self.Location != targetLocation)
+			{
+				var dist = Game.CellSize * (targetLocation + new float2(.5f,.5f)) - self.CenterLocation;
+				var desiredFacing = Util.GetFacing(dist, facing);
+				Util.TickFacing(ref facing, desiredFacing,
+					self.unitInfo.ROT);
+
+				// .6f going the wrong way; .8f going sideways, 1f going forward.
+				var rawSpeed = .2f * (self.unitInfo as UnitInfo.VehicleInfo).Speed;
+				var angle = (facing - desiredFacing) / 128f * Math.PI;
+				var scale = .4f + .6f * (float)Math.Cos(angle);
+
+				if (altitude > CruiseAltitude / 2)		// do some movement.
+				{
+					self.CenterLocation += (rawSpeed * scale / dist.Length) * dist;
+					self.CenterLocation +=  (1f - scale) * rawSpeed 
+						* float2.FromAngle((float)angle);
+					self.Location = ((1 / 24f) * self.CenterLocation).ToInt2();
+				}
+
+				if (altitude < CruiseAltitude)
+				{
+					++altitude;
+					return;
+				}
+			}
+			else if (altitude > 0 && 
+				Game.IsCellBuildable( self.Location, UnitMovementType.Foot ))
+			{
+				--altitude;
+			}
+
+			/* todo: bob slightly when hovering */
+		}
+	}
+}

OpenRa.Game/Traits/RenderUnit.cs

@@ -18,9 +18,12 @@ namespace OpenRa.Game.Traits
 
 		void PlayFacingAnim(Actor self)
 		{
+			var mobile = self.traits.GetOrDefault<Mobile>();
+			var heli = self.traits.GetOrDefault<Helicopter>();
+
 			anim.PlayFetchIndex("idle",
 				() => Util.QuantizeFacing( 
-					self.traits.Get<Mobile>().facing, 
+					mobile != null ? mobile.facing : heli.facing, 
 					anim.CurrentSequence.Length ));
 		}
 

OpenRa.Game/Traits/RenderUnitRotor.cs

@@ -25,8 +25,6 @@ namespace OpenRa.Game.Traits
 
 		public override IEnumerable<Tuple<Sprite, float2, int>> Render(Actor self)
 		{
-			var mobile = self.traits.Get<Mobile>();
-
 			yield return Util.CenteredShadow(self, anim.Image, self.CenterLocation);
 			yield return Util.CenteredShadow(self, rotorAnim.Image, self.CenterLocation
 				+ Util.GetTurretPosition(self, self.unitInfo.PrimaryOffset, 0));
@@ -34,7 +32,8 @@ namespace OpenRa.Game.Traits
 				yield return Util.CenteredShadow(self, (secondRotorAnim ?? rotorAnim).Image, self.CenterLocation
 					+ Util.GetTurretPosition(self, self.unitInfo.SecondaryOffset, 0));
 
-			var p = self.CenterLocation - new float2( 0, altitude );
+			var heli = self.traits.Get<Helicopter>();
+			var p = self.CenterLocation - new float2( 0, heli.altitude );
 
 			yield return Util.Centered(self, anim.Image, p);
 			yield return Util.Centered(self, rotorAnim.Image, p 
@@ -44,10 +43,6 @@ namespace OpenRa.Game.Traits
 					+ Util.GetTurretPosition(self, self.unitInfo.SecondaryOffset, 0));
 		}
 
-		int altitude = 0;
-		const int climbRate = 1;
-		const int cruiseAltitude = 20;
-
 		public override void Tick(Actor self)
 		{
 			base.Tick(self);
@@ -55,20 +50,17 @@ namespace OpenRa.Game.Traits
 			if (secondRotorAnim != null)
 				secondRotorAnim.Tick();
 
-			var mobile = self.traits.Get<Mobile>();
-			var isFlying = mobile.HasActivity;
+			var heli = self.traits.GetOrDefault<Helicopter>();
+			if (heli == null) return;
 			
-			if (isFlying && altitude < cruiseAltitude)
-				altitude = Math.Min(altitude + climbRate, cruiseAltitude);
-			else if (!isFlying && altitude > 0)
-				altitude = Math.Max(altitude - climbRate, 0);
+			var isFlying = heli.altitude > 0;
 
-			if ((altitude >0) ^ (rotorAnim.CurrentSequence.Name != "rotor")) 
+			if (isFlying ^ (rotorAnim.CurrentSequence.Name != "rotor")) 
 				return;
 
-			rotorAnim.PlayRepeatingPreservingPosition((altitude>0) ? "rotor" : "slow-rotor");
+			rotorAnim.PlayRepeatingPreservingPosition(isFlying ? "rotor" : "slow-rotor");
 			if (secondRotorAnim != null)
-				secondRotorAnim.PlayRepeatingPreservingPosition((altitude>0) ? "rotor2" : "slow-rotor2");
+				secondRotorAnim.PlayRepeatingPreservingPosition(isFlying ? "rotor2" : "slow-rotor2");
 		}
 	}
 }

OpenRa.Game/Traits/Util.cs

@@ -91,7 +91,7 @@ namespace OpenRa.Game.Traits
 			var ru = self.traits.WithInterface<RenderUnit>().FirstOrDefault();
 			if (ru == null) return int2.Zero;	/* things that don't have a rotating base don't need the turrets repositioned */
 
-			var bodyFacing = self.traits.Get<Mobile>().facing;
+			var bodyFacing = self.traits.Contains<Mobile>() ? self.traits.Get<Mobile>().facing : self.traits.Get<Helicopter>().facing;
 			var quantizedFacing = QuantizeFacing(bodyFacing, ru.anim.CurrentSequence.Length) * (256 / ru.anim.CurrentSequence.Length);
 
 			return (RotateVectorByFacing(new float2(offset[0], offset[1]), quantizedFacing, .7f) + GetRecoil(self, recoil))

OpenRa.Game/UnitOrders.cs

@@ -15,9 +15,16 @@ namespace OpenRa.Game
 			{
 			case "Move":
 				{
-					var mobile = order.Subject.traits.Get<Mobile>();
-					mobile.Cancel( order.Subject );
-					mobile.QueueActivity( new Traits.Activities.Move( order.TargetLocation, 8 ) );
+					var mobile = order.Subject.traits.GetOrDefault<Mobile>();
+					if (mobile != null)
+					{
+						mobile.Cancel(order.Subject);
+						mobile.QueueActivity(new Traits.Activities.Move(order.TargetLocation, 8));
+					}
+
+					var heli = order.Subject.traits.GetOrDefault<Helicopter>();
+					if (heli != null)
+						heli.targetLocation = order.TargetLocation;
 
 					var attackBase = order.Subject.traits.WithInterface<AttackBase>().FirstOrDefault();
 					if( attackBase != null )

units.ini

@@ -128,16 +128,17 @@ Description=Transport Helicopter
 PrimaryOffset=0,14,0,-4
 SecondaryOffset=0,-14,0,-2
 BuiltAt=hpad
-Traits=Mobile, RenderUnitRotor
+Traits=Helicopter, RenderUnitRotor
 SecondaryAnim=rotor2
 [HELI]
 Description=Longbow
 BuiltAt=hpad
-Traits=Mobile, RenderUnitRotor
+Traits=Helicopter, RenderUnitRotor
+PrimaryOffset=0,0,0,-2
 [HIND]
 Description=Hind
 BuiltAt=hpad
-Traits=Mobile, RenderUnitRotor
+Traits=Helicopter, RenderUnitRotor