heli flight sortof ok

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 */
+		}
+	}
+}