Collision detector in javafx (2d maze)

问题

How do I make my ball bounce off objects on the screen?

The picture below is a good example of how the program should be working once the ball runs into an obstacle.

I made the ball bounce off the walls, but what's left is making it also bounce off objects. Thanks for the help!

Here's the source code:

public class 2DGAME extends Application {

    public static Circle circle;
    public static Pane canvas;
    private long counter = 0;
    double X = 0;
    double Y = 0;

    @Override
    public void start(Stage primaryStage) {

        canvas = new Pane();
        Scene scene = new Scene(canvas, 800, 600);

        primaryStage.setTitle("2D Ball Game");
        primaryStage.setScene(scene);
        primaryStage.show();

        circle = new Circle(20, Color.BLUE);
        circle.relocate(100, 100);

        final Rectangle r = new Rectangle(20, 20, Color.DARKMAGENTA);
        r.setLayoutX(400);
        r.setLayoutY(300);

        canvas.getChildren().addAll(circle);
        canvas.getChildren().addAll(r);


        Timeline loop = new Timeline(new KeyFrame(Duration.millis(5), new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent t) {
                if (counter++ % 5 == 0) {
                    // Moves the ball depending on the values of X and Y
                    circle.setLayoutX(circle.getLayoutX() + X);
                    circle.setLayoutY(circle.getLayoutY() + Y);

//Code to bounce off walls
                    final Bounds bounds = canvas.getBoundsInLocal();
                    boolean leftWall = circle.getLayoutX() <= (bounds.getMinX() + circle.getRadius());
                    boolean topWall = circle.getLayoutY() <= (bounds.getMinY() + circle.getRadius());
                    boolean rightWall = circle.getLayoutX() >= (bounds.getMaxX() - circle.getRadius());
                    boolean bottomWall = circle.getLayoutY() >= (bounds.getMaxY() - circle.getRadius());

   //Bugged and not sure how to make it work
                    final Bounds rectangleBounds = r.getLayoutBounds();
                    boolean rectangle_left = circle.getLayoutX() <= (rectangleBounds.getMinX() + circle.getRadius());
                    boolean rectangle_right = circle.getLayoutX() >= (rectangleBounds.getMaxX() - circle.getRadius());


   //If the bottom or top wall has been touched, the ball reverses direction.
                    if (bottomWall || topWall) {

                        Y = Y * -1; 
                    }
    // If the left or right wall has been touched, the ball reverses direction.
                    if (leftWall || rightWall) {
                        X = X * -1;
                    }

    //Bugged code for boucning off obstacle object
                    if (rectangle_left || rectangle_right) {
                       // X = X * - 1;
                    }

                }
            }

        }));

        loop.setCycleCount(Timeline.INDEFINITE);
        loop.play();
    }

    public static void main(String[] args) {
        launch(args);
    }

}

回答1:

You could do that with the intersects() method.

boolean movingDown = true;

void checkforCollision(){
if(circle.intersects(bottomWall.getBoundsInLocal()){
      movingDown = !movingDown;
      // do something
    }

else if(circle.intersects(rectangle.getBoundsInParent()) && !movingDown{
      movingDown = !movingDown;
      // do something
    }
// etc..
}

来源：https://stackoverflow.com/questions/20047379/collision-detector-in-javafx-2d-maze