Add a Reverses sequence key for TS/RA2 animations.

OpenRA.Mods.Common/Graphics/DefaultSpriteSequence.cs

@@ -129,6 +129,14 @@ namespace OpenRA.Mods.Common.Graphics
 				else
 					Length = LoadField<int>(d, "Length", 1);
 
+				// Plays the animation forwards, and then in reverse
+				if (LoadField<bool>(d, "Reverses", false))
+				{
+					var frames = Frames ?? Exts.MakeArray(Length, i => Start + i);
+					Frames = frames.Concat(frames.Skip(1).Take(frames.Length - 2).Reverse()).ToArray();
+					Length = 2 * Length - 2;
+				}
+
 				Stride = LoadField<int>(d, "Stride", Length);
 
 				if (Length > Stride)

mods/ts/sequences/structures.yaml

@@ -358,12 +358,13 @@ garadr:
 		ShadowStart: 5
 		Tick: 400
 	idle-dish: gtradr_a
-		Frames: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1
-		Length: 28
+		Length: 15
+		Reverses: True
 		Tick: 200
 	damaged-idle-dish: gtradr_a
-		Frames: 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16
-		Length: 28
+		Start: 15
+		Length: 15
+		Reverses: True
 		Tick: 240
 	make: gtradrmk
 		Length: 20