Cloak trait now implements IRenderModifier, so we can compose cloaking with pretty much anything.

OpenRa.Game/Actor.cs

@@ -73,7 +73,9 @@ namespace OpenRa.Game
 
 		public IEnumerable<Tuple<Sprite, float2, int>> Render()
 		{
-			return traits.WithInterface<IRender>().SelectMany( x => x.Render( this ) );
+			var mods = traits.WithInterface<IRenderModifier>();
+			var sprites = traits.WithInterface<IRender>().SelectMany(x => x.Render(this));
+			return mods.Aggregate(sprites, (m, p) => p.ModifyRender(this, m));
 		}
 
 		public Order Order( int2 xy, MouseInput mi )

OpenRa.Game/Combat.cs

@@ -56,7 +56,7 @@ namespace OpenRa.Game
 		{
 			var projectile = Rules.ProjectileInfo[weapon.Projectile];
 
-			if (projectile.ASW && target.traits.Contains<RenderSubmarine>()) return true;
+			if (projectile.ASW && target.traits.Contains<Cloak>()) return true;
 			if (projectile.AA && target.traits.Contains<Helicopter>()) return true;
 			if (projectile.UnderWater && !target.Info.WaterBound) return false;
 			return projectile.AG;

OpenRa.Game/OpenRa.Game.csproj

@@ -175,7 +175,7 @@
     <Compile Include="Traits\RenderBuildingTurreted.cs" />
     <Compile Include="Traits\RenderBuildingWarFactory.cs" />
     <Compile Include="Traits\RenderSimple.cs" />
-    <Compile Include="Traits\RenderSubmarine.cs" />
+    <Compile Include="Traits\Cloak.cs" />
     <Compile Include="Traits\RenderUnit.cs" />
     <Compile Include="Traits\RenderUnitMuzzleFlash.cs" />
     <Compile Include="Traits\RenderUnitReload.cs" />

OpenRa.Game/Traits/Cloak.cs

@@ -0,0 +1,50 @@
+using System.Collections.Generic;
+using System.Linq;
+using OpenRa.Game.Graphics;
+
+namespace OpenRa.Game.Traits
+{
+	class Cloak : IRenderModifier, INotifyAttack, ITick
+	{
+		int remainingSurfaceTime = 2;		/* setup for initial dive */
+
+		public Cloak(Actor self) {}
+
+		public void Attacking(Actor self)
+		{
+			if (remainingSurfaceTime <= 0)
+				OnSurface();
+
+			remainingSurfaceTime = (int)(Rules.General.SubmergeDelay * 60 * 25);
+		}
+
+		public IEnumerable<Tuple<Sprite, float2, int>>
+			ModifyRender(Actor self, IEnumerable<Tuple<Sprite, float2, int>> rs)
+		{
+			if (remainingSurfaceTime > 0)
+				return rs;
+
+			if (self.Owner == Game.LocalPlayer)
+				return rs.Select(a => Tuple.New(a.a, a.b, 8));
+			else
+				return new Tuple<Sprite, float2, int>[] { };
+		}
+
+		public void Tick(Actor self)
+		{
+			if (remainingSurfaceTime > 0)
+				if (--remainingSurfaceTime <= 0)
+					OnDive();
+		}
+
+		void OnSurface()
+		{
+			Sound.Play("subshow1.aud");
+		}
+
+		void OnDive()
+		{
+			Sound.Play("subshow1.aud");		/* is this the right sound?? */
+		}
+	}
+}

OpenRa.Game/Traits/RenderSubmarine.cs

@@ -1,54 +0,0 @@
-using System.Collections.Generic;
-using OpenRa.Game.Graphics;
-
-namespace OpenRa.Game.Traits
-{
-	class RenderSubmarine : RenderSimple, INotifyAttack, ITick
-	{
-		int remainingSurfaceTime = 2;		/* setup for initial dive */
-
-		public RenderSubmarine(Actor self)
-			: base(self)
-		{
-			anim.PlayFacing("idle", () => self.traits.Get<Unit>().Facing);
-		}
-
-		public void Attacking(Actor self)
-		{
-			if (remainingSurfaceTime <= 0)
-				OnSurface();
-
-			remainingSurfaceTime = (int)(Rules.General.SubmergeDelay * 60 * 25);
-		}
-
-		public override IEnumerable<Tuple<Sprite, float2, int>> Render(Actor self)
-		{
-			var s = Util.Centered(self, anim.Image, self.CenterLocation);
-			if (remainingSurfaceTime <= 0)
-			{
-				s.c = 8;	/* shadow only palette */
-				if (self.Owner != Game.LocalPlayer)
-					yield break;	/* can't see someone else's submerged subs */
-			}
-			yield return s;
-		}
-
-		public override void Tick(Actor self)
-		{
-			base.Tick(self);
-			if (remainingSurfaceTime > 0)
-				if (--remainingSurfaceTime <= 0)
-					OnDive();
-		}
-
-		void OnSurface()
-		{
-			Sound.Play("subshow1.aud");
-		}
-
-		void OnDive()
-		{
-			Sound.Play("subshow1.aud");		/* is this the right sound?? */
-		}
-	}
-}

OpenRa.Game/Traits/TraitsInterfaces.cs

@@ -9,7 +9,7 @@ namespace OpenRa.Game.Traits
 	interface ITick { void Tick(Actor self); }
 	interface IRender { IEnumerable<Tuple<Sprite, float2, int>> Render(Actor self); }
 	interface INotifyDamage { void Damaged(Actor self, DamageState ds); }
-	interface INotifyDamageEx : INotifyDamage { void Damaged(Actor self, int damage, WarheadInfo warhead); }
+	interface INotifyDamageEx { void Damaged(Actor self, int damage, WarheadInfo warhead); }
 	interface INotifyBuildComplete { void BuildingComplete (Actor self); }
 	interface IOrder
 	{
@@ -19,4 +19,6 @@ namespace OpenRa.Game.Traits
 	interface IProducer { bool Produce( Actor self, UnitInfo producee ); }
 	interface IOccupySpace { IEnumerable<int2> OccupiedCells(); }
 	interface INotifyAttack { void Attacking(Actor self); }
+	interface IRenderModifier { IEnumerable<Tuple<Sprite, float2, int>> 
+		ModifyRender( Actor self, IEnumerable<Tuple<Sprite, float2, int>> r ); }
 }

units.ini

@@ -94,7 +94,7 @@ PT
 Description=Submarine
 WaterBound=yes
 BuiltAt=spen
-Traits=Unit, Mobile, RenderSubmarine, AttackBase
+Traits=Unit, Mobile, RenderUnit, Cloak, AttackBase
 FireDelay=2
 [DD]
 Description=Destroyer