How does Rotation and pivoting work in javafx? - javafx

Question

I have seen the questions asked in this website about rotation in javafx but I don't seem to grasp it. Here is some code:
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.transform.Rotate;
import javafx.scene.transform.Scale;
import javafx.scene.transform.Translate;
import javafx.stage.Stage;
public class TransformationsExample extends Application {
#Override
public void start(Stage stage) {
Rectangle rectangle = new Rectangle(50, 50, 100, 75);
rectangle.setFill(Color.BURLYWOOD);
rectangle.setStroke(Color.BLACK);
Rotate rotate = new Rotate();
rotate.setAngle(90);
rotate.setPivotX(150);
rotate.setPivotY(225);
rectangle.getTransforms().addAll(rotate);
Group root = new Group(rectangle);
Scene scene = new Scene(root, 1400, 780);
stage.setTitle("Transformations");
stage.setScene(scene);
stage.show();
}
public static void main(String args[]){
launch(args);
}
}
Why is it that when I change the angle, the rectangle starts appearing in random places? For example, when I set angle to 180, the rectangle appears in the middle. My understanding is that the rectangle moves in specified angle around X: 150 and Y:225. However, when I set the angle to 180, I am completely wrong. Can you guys help me out?
Edit: While reading and seeing the code answered to this question, I think I found a new question. How do you set a pivoting distance from pivotX and pivotY?
Edit2: This is for user #Slaw. I hope to know how you can find/set X?

Answer 1

If you replace the line
Group root = new Group(rectangle);
with the following two lines
Circle pivot = new Circle(150, 225, 5, Color.BLACK);
Group root = new Group(rectangle, pivot);
and then increment your angle in small steps 0, 10, 45, 90 degrees, the behaviour becomes clearer I think and is exactly what I would expect.