Provide both old and new value in variables changed event.

Author: freezy

Editor/Descriptors/VariableChangedEventUnitDescriptor.cs

@@ -39,7 +39,10 @@ protected override void DefinedPort(IUnitPort port, UnitPortDescription desc)
 			base.DefinedPort(port, desc);
 
 			switch (port.key) {
-				case nameof(PlayerVariableChangedEventUnit.Value):
+				case nameof(PlayerVariableChangedEventUnit.OldValue):
+					desc.summary = "The previous value of the player variable.";
+					break;
+				case nameof(PlayerVariableChangedEventUnit.NewValue):
 					desc.summary = "The new value of the player variable.";
 					break;
 			}
@@ -66,7 +69,10 @@ protected override void DefinedPort(IUnitPort port, UnitPortDescription desc)
 			base.DefinedPort(port, desc);
 
 			switch (port.key) {
-				case nameof(TableVariableChangedEventUnit.Value):
+				case nameof(TableVariableChangedEventUnit.OldValue):
+					desc.summary = "The previous value of the table variable.";
+					break;
+				case nameof(TableVariableChangedEventUnit.NewValue):
 					desc.summary = "The new value of the table variable.";
 					break;
 			}

Runtime/Gamelogic/State.cs

@@ -100,7 +100,7 @@ public void Set<T>(string variableId, T value) where T : class
 			if (currentValue != value) {
 				EventBus.Trigger(
 					VariableChangedEventName,
-					new VariableChangedArgs(variableId)
+					new VariableChangedArgs(variableId, currentValue, value)
 				);
 			}
 		}
@@ -157,9 +157,14 @@ public readonly struct VariableChangedArgs
 	{
 		public readonly string VariableId;
 
-		public VariableChangedArgs(string variableId)
+		public readonly object OldValue;
+		public readonly object NewValue;
+
+		public VariableChangedArgs(string variableId, object oldValue, object newValue)
 		{
 			VariableId = variableId;
+			OldValue = oldValue;
+			NewValue = newValue;
 		}
 	}
 }

Runtime/Gamelogic/VisualScriptingGamelogicEngine.cs

@@ -104,15 +104,15 @@ public void SetCurrentPlayer(int value, bool forceNotify = false)
 
 			// also trigger updates for each variable
 			foreach (var varDef in PlayerVariableDefinitions) {
+				var before = PlayerStates[previousPlayer].GetVariable(varDef.Id);
+				var now = PlayerStates[_currentPlayer].GetVariable(varDef.Id);
 				if (PlayerStates.ContainsKey(previousPlayer)) {
-					var before = PlayerStates[previousPlayer].GetVariable(varDef.Id);
-					var now = PlayerStates[_currentPlayer].GetVariable(varDef.Id);
 					if (forceNotify || before != now) {
-						EventBus.Trigger(VisualScriptingEventNames.PlayerVariableChanged, new VariableChangedArgs(varDef.Id));
+						EventBus.Trigger(VisualScriptingEventNames.PlayerVariableChanged, new VariableChangedArgs(varDef.Id, before.Get<object>(), now.Get<object>()));
 					}
 
 				} else {
-					EventBus.Trigger(VisualScriptingEventNames.PlayerVariableChanged, new VariableChangedArgs(varDef.Id));
+					EventBus.Trigger(VisualScriptingEventNames.PlayerVariableChanged, new VariableChangedArgs(varDef.Id, before.Get<object>(), now.Get<object>()));
 				}
 			}
 		}

Runtime/Nodes/PlayerState/VariableChangedEventUnit.cs

@@ -47,8 +47,11 @@ public class TableVariableChangedEventUnit : VariableChangedEventUnit
 
 	public abstract class VariableChangedEventUnit : GleEventUnit<VariableChangedArgs>
 	{
-		[DoNotSerialize, PortLabel("Value"), Inspectable]
-		public ValueOutput Value { get; private set; }
+		[DoNotSerialize, PortLabel("Old Value"), Inspectable]
+		public ValueOutput OldValue { get; private set; }
+
+		[DoNotSerialize, PortLabel("New Value"), Inspectable]
+		public ValueOutput NewValue { get; private set; }
 
 		public override EventHook GetHook(GraphReference reference) => new(EventHookName);
 		protected override bool register => true;
@@ -65,11 +68,19 @@ protected override void Definition()
 				return;
 			}
 
-			Value = VariableDefinition.Type switch {
-				VariableType.String => ValueOutput<string>(nameof(Value)),
-				VariableType.Integer => ValueOutput<int>(nameof(Value)),
-				VariableType.Float => ValueOutput<float>(nameof(Value)),
-				VariableType.Boolean => ValueOutput<bool>(nameof(Value)),
+			OldValue = VariableDefinition.Type switch {
+				VariableType.String => ValueOutput<string>(nameof(OldValue)),
+				VariableType.Integer => ValueOutput<int>(nameof(OldValue)),
+				VariableType.Float => ValueOutput<float>(nameof(OldValue)),
+				VariableType.Boolean => ValueOutput<bool>(nameof(OldValue)),
+				_ => throw new ArgumentOutOfRangeException()
+			};
+
+			NewValue = VariableDefinition.Type switch {
+				VariableType.String => ValueOutput<string>(nameof(NewValue)),
+				VariableType.Integer => ValueOutput<int>(nameof(NewValue)),
+				VariableType.Float => ValueOutput<float>(nameof(NewValue)),
+				VariableType.Boolean => ValueOutput<bool>(nameof(NewValue)),
 				_ => throw new ArgumentOutOfRangeException()
 			};
 		}
@@ -87,16 +98,20 @@ protected override void AssignArguments(Flow flow, VariableChangedArgs args)
 
 			switch (VariableDefinition.Type) {
 				case VariableType.String:
-					flow.SetValue(Value,  State.Get<string>(VariableDefinition.Id));
+					flow.SetValue(OldValue,  (string)args.OldValue);
+					flow.SetValue(NewValue,  (string)args.NewValue);
 					break;
 				case VariableType.Integer:
-					flow.SetValue(Value,  (int)State.Get<Integer>(VariableDefinition.Id));
+					flow.SetValue(OldValue,  (int)(Integer)args.OldValue);
+					flow.SetValue(NewValue, (int)(Integer)args.NewValue);
 					break;
 				case VariableType.Float:
-					flow.SetValue(Value,  (float)State.Get<Float>(VariableDefinition.Id));
+					flow.SetValue(OldValue,  (float)(Float)args.OldValue);
+					flow.SetValue(NewValue,  (float)(Float)args.NewValue);
 					break;
 				case VariableType.Boolean:
-					flow.SetValue(Value,  (bool)State.Get<Bool>(VariableDefinition.Id));
+					flow.SetValue(OldValue,  (bool)(Bool)args.OldValue);
+					flow.SetValue(NewValue,  (bool)(Bool)args.NewValue);
 					break;
 				default:
 					throw new ArgumentOutOfRangeException();