add the Hovercraft wake animation

OpenRA.Mods.Common/OpenRA.Mods.Common.csproj

@@ -366,6 +366,7 @@
     <Compile Include="Traits\ProximityCapturable.cs" />
     <Compile Include="Traits\RadarColorFromTerrain.cs" />
     <Compile Include="Traits\Render\Hovers.cs" />
+    <Compile Include="Traits\Render\LeavesTrails.cs" />
     <Compile Include="Traits\Render\RenderBuilding.cs" />
     <Compile Include="Traits\Render\RenderBuildingCharge.cs" />
     <Compile Include="Traits\Render\RenderBuildingTurreted.cs" />

OpenRA.Mods.Common/Traits/Render/LeavesTrails.cs

@@ -0,0 +1,53 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2015 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System.Linq;
+using OpenRA.Effects;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Renders a sprite effect when leaving a cell.")]
+	public class LeavesTrailsInfo : ITraitInfo
+	{
+		public readonly string Image = null;
+		public readonly string Palette = "effect";
+
+		[Desc("Only do so when the terrain types match with the previous cell.")]
+		public readonly string[] TerrainTypes = { };
+
+		public object Create(ActorInitializer init) { return new LeavesTrails(this, init.Self); }
+	}
+
+	public class LeavesTrails : ITick
+	{
+		readonly LeavesTrailsInfo info;
+
+		public LeavesTrails(LeavesTrailsInfo info, Actor self)
+		{
+			this.info = info;
+		}
+
+		CPos cachedLocation;
+
+		public void Tick(Actor self)
+		{
+			if (cachedLocation != self.Location)
+			{
+				var type = self.World.Map.GetTerrainInfo(cachedLocation).Type;
+				var pos = self.World.Map.CenterOfCell(cachedLocation);
+				if (info.TerrainTypes.Contains(type) && !string.IsNullOrEmpty(info.Image))
+					self.World.AddFrameEndTask(w => w.Add(new SpriteEffect(pos, self.World, info.Image, info.Palette)));
+
+				cachedLocation = self.Location;
+			}
+		}
+	}
+}

mods/ts/rules/gdi-vehicles.yaml

@@ -70,6 +70,10 @@ HVR:
 	WithVoxelBody:
 	WithVoxelTurret:
 	Hovers:
+	LeavesTrails:
+		Image: wake
+		Palette: effect
+		TerrainTypes: Water
 
 SMECH:
 	Inherits: ^Tank

mods/ts/sequences/misc.yaml

@@ -220,6 +220,11 @@ moveflsh:
 		Length: *
 		Tick: 30
 
+wake:
+	idle: wake2
+		Length: *
+		Tick: 180
+
 resources:
 	Defaults:
 		UseTilesetExtension: true