Add state-based effect.

Assets/Cryville/Crtr/Skin.cs

@@ -60,7 +60,9 @@ namespace Cryville.Crtr {
 				var effect = e.Value;
 				etor.ContextCascadeInsert();
 				etor.ContextCascadeUpdate(EffectInstance._VAR_EFFECT_INDEX, PropSrc.Error);
-				etor.Optimize(effect.duration);
+				foreach(var s in effect.states) {
+					etor.Optimize(s.Value.duration);
+				}
 				effect.elements.Optimize(etor);
 				etor.ContextCascadeDiscard();
 			}
@@ -99,10 +101,30 @@ namespace Cryville.Crtr {
 	}
 
 	public class EffectDefinition {
-		public PdtExpression duration;
+		static Identifier _ident_init = new Identifier("init");
+#pragma warning disable IDE1006
+		public PdtExpression duration {
+			set {
+				EffectState s;
+				if (!states.TryGetValue(_ident_init, out s))
+					throw new InvalidOperationException("Cannot set duration and states at the same time");
+				s.duration = value;
+			}
+		}
+#pragma warning restore IDE1006
+		public Identifier init = _ident_init;
+		public Dictionary<Identifier, EffectState> states = new Dictionary<Identifier, EffectState> {
+			{ _ident_init, new EffectState() { rewind = _ident_init } }
+		};
 		public SkinElement elements;
 	}
 
+	public class EffectState {
+		public PdtExpression duration;
+		public Identifier rewind;
+		public Identifier next;
+	}
+
 	public class AnimationSpan {
 		[ElementList]
 		public Dictionary<Clip, AnimationSpan> spans