/*

* Complete implementation of the following fractal program to display snow flake

*/

import javafx.application.Application; import javafx.geometry.Point2D; import javafx.geometry.Pos; import javafx.scene.Scene; import javafx.scene.control.Label; import javafx.scene.control.TextField; import javafx.scene.layout.BorderPane; import javafx.scene.layout.HBox; import javafx.scene.layout.Pane; import javafx.scene.shape.Line; import javafx.stage.Stage;

public class SnowSample extends Application { @Override // Override the start method in the Application class public void start(Stage primaryStage) { KochSnowFlakePane trianglePane = new KochSnowFlakePane(); TextField tfOrder = new TextField(); tfOrder.setOnAction( e -> trianglePane.setOrder(Integer.parseInt(tfOrder.getText()))); tfOrder.setPrefColumnCount(4); tfOrder.setAlignment(Pos.BOTTOM_RIGHT);

// Pane to hold label, text field, and a button HBox hBox = new HBox(10); hBox.getChildren().addAll(new Label("Enter an order: "), tfOrder); hBox.setAlignment(Pos.CENTER); BorderPane borderPane = new BorderPane(); borderPane.setCenter(trianglePane); borderPane.setBottom(hBox); // Create a scene and place it in the stage Scene scene = new Scene(borderPane, 400, 410); primaryStage.setTitle("Snow Flake"); // Set the stage title primaryStage.setScene(scene); // Place the scene in the stage primaryStage.show(); // Display the stage scene.widthProperty().addListener(ov -> trianglePane.paint()); scene.heightProperty().addListener(ov -> trianglePane.paint()); }

/** Pane for displaying fractal */ static class KochSnowFlakePane extends Pane { private int order = 0;

/** Set a new order */ public void setOrder(int order) { this.order = order; paint(); }

KochSnowFlakePane() { }

protected void paint() { double side = Math.min(getWidth(), getHeight()) * 0.8; double triangleHeight = side * Math.sin(Math.toRadians(60)); // Set initial three points Point2D p1 = new Point2D(getWidth() / 2, 10); Point2D p2 = new Point2D(getWidth() / 2 - side / 2, 10 + triangleHeight); Point2D p3 = new Point2D(getWidth() / 2 + side / 2, 10 + triangleHeight);

this.getChildren().clear(); // Clear the pane before redisplay displayKochSnowFlake(order, p1, p2); displayKochSnowFlake(order, p2, p3); displayKochSnowFlake(order, p3, p1); }

private void displayKochSnowFlake(int order, Point2D p1, Point2D p2) { if (order == 0) { this.getChildren().add(new Line(p1.getX(), p1.getY(), p2.getX(), p2.getY())); } else { // order > 0 double deltaX = p2.getX() - p1.getX(); double deltaY = p2.getY() - p1.getY();

Point2D x = new Point2D(p1.getX() + deltaX / 3, p1.getY() + deltaY / 3); Point2D y = new Point2D(p1.getX() + deltaX * 2 / 3, p1.getY() + deltaY * 2 / 3); Point2D z = new Point2D( (p1.getX() + p2.getX()) / 2 + Math.cos(Math.toRadians(30)) * (p1.getY() - p2.getY()) / 3, (p1.getY() + p2.getY()) / 2 + Math.cos(Math.toRadians(30)) * (p2.getX() - p1.getX()) / 3);

// Recursively display snow flakes on lines

} } } /** * The main method is only needed for the IDE with limited * JavaFX support. Not needed for running from the command line. */ public static void main(String[] args) { launch(args); } }