如何检查一条线是否与图像相交

Question

这是我的以下代码：

  public void start(Stage primaryStage) throws Exception {
        Pane root = new Pane();
        Scene scene = new Scene(root, 500, 500, Color.WHITE);

        ImageView image = new ImageView(new Image(getClass().getResourceAsStream("dice.jpeg")));
        image.setX(35);
        image.setY(225);
        image.setFitWidth(50);
        image.setFitHeight(70);
        root.getChildren().add(image);

        Line line = new Line(20, 40, 120, 40);
        line.setStroke(Color.RED);
        line.setStrokeWidth(10);
        root.getChildren().add(line);

        if (line.getBoundsInParent().intersects(image.getBoundsInParent())) {
            System.out.println("intersect");
        }

        Timeline timeline = new Timeline(
                new KeyFrame(
                        Duration.seconds(2),
                        new KeyValue(line.translateYProperty(), 600)
                ));
        timeline.setCycleCount(Animation.INDEFINITE);
        timeline.setAutoReverse(false);

        timeline.play();
        primaryStage.setScene(scene);
        primaryStage.show();
    }

我希望在线条和图像相交时打印此System.out.println("intersect") 消息，但是当我运行我的代码时它不起作用。谁能告诉我我做错了什么？任何帮助表示赞赏！

Answer 1

我想出了一个解决方案。这涉及在其他代码仍在运行时使用线程一直检查。您的代码中的错误是仅在动画尚未开始运行时检查一次。

显然，我的代码并不完美，因此您可能需要对其进行清理以满足您的需求：

public class Test extends Application{

public static void main(String[] args) {
    Test.launch(args);
    //The thread which checks continues to run so you have to stop it 
    //(There is definitly a better way to do this)
    System.exit(0);
}

@Override
public void start(Stage primaryStage) throws Exception {
    Pane root = new Pane();
    Scene scene = new Scene(root, 500, 500, Color.WHITE);

    ImageView image = new ImageView(new Image(getClass().getResourceAsStream("dice.jpeg")));
    image.setX(35);
    image.setY(225);
    image.setFitWidth(50);
    image.setFitHeight(70);
    root.getChildren().add(image);

    Line line = new Line(20, 40, 120, 40);
    line.setStroke(Color.RED);
    line.setStrokeWidth(10);
    root.getChildren().add(line);

    //new code
    Thread t = new Thread(){
        @Override
        public void run(){
            while(true){               
                try {
                    //you could add a Thread.sleep so it only checks every x miliseconds 
                    Thread.sleep(40);
                    if (line.getBoundsInParent().intersects(image.getBoundsInParent())) {
                        System.out.println("intersect");
                    }
                } catch (InterruptedException ex) {
                    Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
                }
            }

        }
    };
    t.start();
    //end of new code

    Timeline timeline = new Timeline(
            new KeyFrame(
                    Duration.seconds(2),
                    new KeyValue(line.translateYProperty(), 600)
            ));
    timeline.setCycleCount(Animation.INDEFINITE);
    timeline.setAutoReverse(false);
    timeline.play();

    primaryStage.setScene(scene);
    primaryStage.show();
}

}