categorize traits better

OpenRa.Game/Traits/Modifiers/WithShadow.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRa.Graphics;
+
+namespace OpenRa.Traits
+{
+	class WithShadowInfo : StatelessTraitInfo<WithShadow> {}
+
+	class WithShadow : IRenderModifier
+	{
+		public IEnumerable<Renderable> ModifyRender(Actor self, IEnumerable<Renderable> r)
+		{
+			var unit = self.traits.Get<Unit>();
+
+			var shadowSprites = r.Select(a => a.WithPalette("shadow"));
+			var flyingSprites = (unit.Altitude <= 0) ? r 
+				: r.Select(a => a.WithPos(a.Pos - new float2(0, unit.Altitude)).WithZOffset(3));
+
+			return shadowSprites.Concat(flyingSprites);
+		}
+	}
+}