java - 我应该如何让我的玩家矩形跳跃？

Question

我只是想让我的红色矩形在你按下跳跃按钮时跳起来。我似乎找不到任何类似动画的东西，甚至找不到上升，等待一定时间然后返回的东西。

import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.paint.Color;
import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.control.Button;
import javafx.event.EventHandler;
import javafx.event.ActionEvent;
import javafx.animation.PathTransition;
import javafx.scene.shape.*;
import javafx.util.Duration;

public class GUIPractice extends Application{

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

public void start (Stage primaryStage)
{
    Rectangle screen = new Rectangle(20, 20, 986, 500);
    Button JumpBtn = new Button("Jump");
        JumpBtn.setLayoutX(410);
        JumpBtn.setLayoutY(530);
        JumpBtn.setMinWidth(200);
        JumpBtn.setMinHeight(100);
    Rectangle player = new Rectangle(450, 420, 50, 100);
        player.setFill(Color.RED);

    Path path = new Path();

我相信下面就是跳跃的地方，但我唯一能弄清楚的是如何让矩形在屏幕上向上移动而不是向下移动。

    JumpBtn.setOnAction(new EventHandler<ActionEvent>()
    {
        public void handle(ActionEvent e) {
            player.setTranslateY(-40);
        }
    });

    Group root =  new Group(screen, JumpBtn, player);

    Scene scene = new Scene(root, 1024, 768);
    scene.setFill(Color.GREY);

    primaryStage.setTitle("GUIPractice");
    primaryStage.setScene(scene);
    primaryStage.show();
}

}

Answer 1

使用时间轴等动画来移动节点，例如

double ty = player.getTranslateY();

// quadratic interpolation to simulate gravity
Interpolator interpolator = new Interpolator() {
    @Override
    protected double curve​(double t) {
        return t * (2 - t);
    }

};
Timeline timeline = new Timeline(new KeyFrame(Duration.ZERO,
                                              new KeyValue(player.translateYProperty(), ty, interpolator)),
                                 new KeyFrame(Duration.seconds(1),
                                              new KeyValue(player.translateYProperty(), ty-40, interpolator)));

// play forward once, then play backward once
timeline.setCycleCount(2);
timeline.setAutoReverse(true);

JumpBtn.setDisable(true);
timeline.setOnFinished(evt -> JumpBtn.setDisable(false));

timeline.play();