Introduce IDefaultVisibility.

OpenRA.Game/Player.cs

@@ -154,12 +154,7 @@ namespace OpenRA
 			if (a.TraitsImplementing<IVisibilityModifier>().Any(t => !t.IsVisible(a, this)))
 				return false;
 
-			if (a.Owner.IsAlliedWith(this))
-				return true;
-
-			// Actors are hidden under shroud, but not under fog by default
-			// TODO: Shroud exploration should be implemented as an IVisibility modifier!
-			return Shroud.GetVisOrigins(a).Any(Shroud.IsExplored);
+			return a.Trait<IDefaultVisibility>().IsVisible(a, this);
 		}
 
 		#region Scripting interface

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -167,6 +167,8 @@ namespace OpenRA.Traits
 		IEnumerable<Pair<CPos, Color>> RadarSignatureCells(Actor self);
 	}
 
+	public interface IDefaultVisibilityInfo { }
+	public interface IDefaultVisibility { bool IsVisible(Actor self, Player byPlayer); }
 	public interface IVisibilityModifier { bool IsVisible(Actor self, Player byPlayer); }
 	public interface IFogVisibilityModifier { bool HasFogVisibility(Player byPlayer); }
 

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

@@ -676,6 +676,8 @@
     <Compile Include="Widgets\EditorViewportControllerWidget.cs" />
     <Compile Include="Traits\World\PaletteFromPaletteWithAlpha.cs" />
     <Compile Include="Traits\World\PaletteFromPlayerPaletteWithAlpha.cs" />
+    <Compile Include="Traits\Modifiers\HiddenUnderShroud.cs" />
+    <Compile Include="Traits\Modifiers\AlwaysVisible.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>

OpenRA.Mods.Common/Traits/Modifiers/AlwaysVisible.cs

@@ -0,0 +1,24 @@
+#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 OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("The actor is always considered visible for targeting and rendering purposes.")]
+	public class AlwaysVisibleInfo : TraitInfo<AlwaysVisible>, IDefaultVisibilityInfo { }
+	public class AlwaysVisible : IDefaultVisibility
+	{
+		public bool IsVisible(Actor self, Player byPlayer)
+		{
+			return true;
+		}
+	}
+}

OpenRA.Mods.Common/Traits/Modifiers/FrozenUnderFog.cs

@@ -17,17 +17,21 @@ using OpenRA.Traits;
 namespace OpenRA.Mods.Common.Traits
 {
 	[Desc("This actor will remain visible (but not updated visually) under fog, once discovered.")]
-	public class FrozenUnderFogInfo : ITraitInfo, Requires<BuildingInfo>
+	public class FrozenUnderFogInfo : ITraitInfo, Requires<BuildingInfo>, IDefaultVisibilityInfo
 	{
 		public readonly bool StartsRevealed = false;
 
+		[Desc("Players with these stances can always see the actor.")]
+		public readonly Stance AlwaysVisibleStances = Stance.Ally;
+
 		public object Create(ActorInitializer init) { return new FrozenUnderFog(init, this); }
 	}
 
-	public class FrozenUnderFog : IRenderModifier, IVisibilityModifier, ITick, ISync
+	public class FrozenUnderFog : IRenderModifier, IDefaultVisibility, ITick, ISync
 	{
 		[Sync] public int VisibilityHash;
 
+		readonly FrozenUnderFogInfo info;
 		readonly bool startsRevealed;
 		readonly MPos[] footprint;
 
@@ -41,6 +45,8 @@ namespace OpenRA.Mods.Common.Traits
 
 		public FrozenUnderFog(ActorInitializer init, FrozenUnderFogInfo info)
 		{
+			this.info = info;
+
 			// Spawned actors (e.g. building husks) shouldn't be revealed
 			startsRevealed = info.StartsRevealed && !init.Contains<ParentActorInit>();
 			var footprintCells = FootprintUtils.Tiles(init.Self).ToList();
@@ -54,7 +60,11 @@ namespace OpenRA.Mods.Common.Traits
 
 		public bool IsVisible(Actor self, Player byPlayer)
 		{
-			return byPlayer == null || visible[byPlayer];
+			if (byPlayer == null)
+				return true;
+
+			var stance = self.Owner.Stances[byPlayer];
+			return info.AlwaysVisibleStances.HasFlag(stance) || visible[byPlayer];
 		}
 
 		public void Tick(Actor self)

OpenRA.Mods.Common/Traits/Modifiers/HiddenUnderFog.cs

@@ -16,18 +16,22 @@ using OpenRA.Traits;
 namespace OpenRA.Mods.Common.Traits
 {
 	[Desc("The actor stays invisible under fog of war.")]
-	public class HiddenUnderFogInfo : TraitInfo<HiddenUnderFog> { }
-
-	public class HiddenUnderFog : IRenderModifier, IVisibilityModifier
+	public class HiddenUnderFogInfo : HiddenUnderShroudInfo
 	{
-		public bool IsVisible(Actor self, Player byPlayer)
-		{
-			return byPlayer == null || Shroud.GetVisOrigins(self).Any(byPlayer.Shroud.IsVisible);
+		public override object Create(ActorInitializer init) { return new HiddenUnderFog(this); }
 	}
 
-		public IEnumerable<IRenderable> ModifyRender(Actor self, WorldRenderer wr, IEnumerable<IRenderable> r)
+	public class HiddenUnderFog : HiddenUnderShroud
 	{
-			return IsVisible(self, self.World.RenderPlayer) ? r : SpriteRenderable.None;
+		public HiddenUnderFog(HiddenUnderFogInfo info)
+			: base(info) { }
+
+		protected override bool IsVisibleInner(Actor self, Player byPlayer)
+		{
+			if (!VisibilityFootprint(self).Any(byPlayer.Shroud.IsVisible))
+				return false;
+
+			return base.IsVisibleInner(self, byPlayer);
 		}
 	}
 }

OpenRA.Mods.Common/Traits/Modifiers/HiddenUnderShroud.cs

@@ -0,0 +1,60 @@
+#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.Collections.Generic;
+using System.Linq;
+using OpenRA.Graphics;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("The actor stays invisible under the shroud.")]
+	public class HiddenUnderShroudInfo : ITraitInfo, IDefaultVisibilityInfo
+	{
+		[Desc("Players with these stances can always see the actor.")]
+		public readonly Stance AlwaysVisibleStances = Stance.Ally;
+
+		public virtual object Create(ActorInitializer init) { return new HiddenUnderShroud(this); }
+	}
+
+	public class HiddenUnderShroud : IDefaultVisibility, IRenderModifier
+	{
+		readonly HiddenUnderShroudInfo info;
+
+		public HiddenUnderShroud(HiddenUnderShroudInfo info)
+		{
+			this.info = info;
+		}
+
+		protected IEnumerable<CPos> VisibilityFootprint(Actor self)
+		{
+			return Shroud.GetVisOrigins(self);
+		}
+
+		protected virtual bool IsVisibleInner(Actor self, Player byPlayer)
+		{
+			return VisibilityFootprint(self).Any(byPlayer.Shroud.IsExplored);
+		}
+
+		public bool IsVisible(Actor self, Player byPlayer)
+		{
+			if (byPlayer == null)
+				return true;
+
+			var stance = self.Owner.Stances[byPlayer];
+			return info.AlwaysVisibleStances.HasFlag(stance) || IsVisibleInner(self, byPlayer);
+		}
+
+		public IEnumerable<IRenderable> ModifyRender(Actor self, WorldRenderer wr, IEnumerable<IRenderable> r)
+		{
+			return IsVisible(self, self.World.RenderPlayer) ? r : SpriteRenderable.None;
+		}
+	}
+}