Supporting properties for motion path actuactors. Also adding the sta…

src/motion/actuators/MotionPathActuator.hx

@@ -18,24 +18,38 @@ class MotionPathActuator<T> extends SimpleActuator<T, T> {
 	}
 
 	private override function initialize() {
+		super.initialize();
+
+		// "x" and "y" are handled by `super.initialize()`, but there's custom behavior for those properties below,
+		// so we need to remove the details and rebuild them.
+		propertyDetails = [
+			for (detail in propertyDetails) {
+				if (detail.propertyName == "x" || detail.propertyName == "y") continue;
+				detail;
+			}
+		];
+		detailsLength = propertyDetails.length;
+
 		var details:PropertyPathDetails<T>;
 		var path:IComponentPath;
 
 		for (propertyName in Reflect.fields(properties)) {
-			path = cast(Reflect.field(properties, propertyName), IComponentPath);
+			if (propertyName == "x" || propertyName == "y") {
+				path = cast(Reflect.field(properties, propertyName), IComponentPath);
 
-			if (path != null) {
-				var isField = true;
+				if (path != null) {
+					var isField = true;
 
-				if (Reflect.hasField(target, propertyName)) {
-					path.start = Reflect.field(target, propertyName);
-				} else {
-					isField = false;
-					path.start = Reflect.getProperty(target, propertyName);
-				}
+					if (Reflect.hasField(target, propertyName)) {
+						path.start = Reflect.field(target, propertyName);
+					} else {
+						isField = false;
+						path.start = Reflect.getProperty(target, propertyName);
+					}
 
-				details = new PropertyPathDetails(target, propertyName, path, isField);
-				propertyDetails.push(details);
+					details = new PropertyPathDetails(target, propertyName, path, isField);
+					propertyDetails.push(details);
+				}
 			}
 		}
 

src/motion/actuators/SimpleActuator.hx

@@ -352,6 +352,11 @@ class SimpleActuator<T, U> extends GenericActuator<T> {
 
 			tweenPosition = (currentTime - timeOffset) / duration;
 
+			var startAt = getField(properties, "startAt");
+			if (startAt != null) {
+				tweenPosition += startAt;
+			}
+
 			if (tweenPosition > 1) {
 				tweenPosition = 1;
 			}