some basic plane behavior on Yak

OpenRa.Game/Traits/Activities/Fly.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace OpenRa.Game.Traits.Activities
+{
+	class Fly : IActivity
+	{
+		readonly int2 Cell;
+		bool isCanceled;
+
+		public Fly(int2 cell) { Cell = cell; }
+
+		public IActivity NextActivity { get; set; }
+
+		const int CruiseAltitude = 20;
+		
+		public IActivity Tick(Actor self)
+		{
+			if (isCanceled) return NextActivity;
+
+			var d = Util.CenterOfCell(Cell) - self.CenterLocation;
+			if (d.LengthSquared < 50)		/* close enough */
+				return NextActivity;
+
+			var unit = self.traits.Get<Unit>();
+
+			if (unit.Altitude < CruiseAltitude)
+				++unit.Altitude;
+
+			var desiredFacing = Util.GetFacing(d, unit.Facing);
+			if (unit.Altitude == CruiseAltitude)
+				Util.TickFacing(ref unit.Facing, desiredFacing, self.Info.ROT);
+			var speed = .2f * Util.GetEffectiveSpeed(self);
+			var angle = unit.Facing / 128f * Math.PI;
+
+			self.CenterLocation += speed * -float2.FromAngle((float)angle);
+			self.Location = ((1 / 24f) * self.CenterLocation).ToInt2();
+
+			return null;
+		}
+
+		public void Cancel(Actor self) { isCanceled = true; NextActivity = null; }
+	}
+
+	class FlyTimed : IActivity
+	{
+		public IActivity NextActivity { get; set; }
+		int remainingTicks;
+
+		public FlyTimed(int ticks) { remainingTicks = ticks; }
+		
+		public IActivity Tick(Actor self)
+		{
+			if (remainingTicks == 0)
+				return NextActivity;
+
+			--remainingTicks;
+
+			var unit = self.traits.Get<Unit>();
+			var speed = .2f * Util.GetEffectiveSpeed(self);
+			var angle = unit.Facing / 128f * Math.PI;
+
+			self.CenterLocation += speed * -float2.FromAngle((float)angle);
+			self.Location = ((1 / 24f) * self.CenterLocation).ToInt2();
+
+			return null;
+		}
+
+		public void Cancel(Actor self) { remainingTicks = 0; NextActivity = null; }
+	}
+
+	class Circle : IActivity
+	{
+		public IActivity NextActivity { get; set; }
+		bool isCanceled;
+		readonly int2 Cell;
+
+		public Circle(int2 cell) { Cell = cell; }
+		
+		public IActivity Tick(Actor self)
+		{
+			if (isCanceled) return NextActivity;
+			return new Fly(Cell)
+			{
+				NextActivity =
+					new FlyTimed(50)
+					{
+						NextActivity = this
+					}
+			};
+		}
+
+		public void Cancel(Actor self) { isCanceled = true; NextActivity = null; }
+	}
+}