JavaFX中抛物线轨迹的时间线 [英] Timeline for parabolic trajectory in JavaFX
问题描述
对不起，但我还是不理解。我的问题是我对物理学一无所知，但我的老师给我这个项目。
private void shoot（）{
Group group = new Group（）;
double angle = cannon.getRotate（）;
double speed = slider.getValue（）;
double x = cannon.getLayoutX（）;
double y = cannon.getLayoutY（）;
double v0X = Math.cos（angle）* speed;
double voY = Math.sin（angle）* speed;
Circle c = new Circle（x，y，8，Color.BLACK）;
/ * t是时间，但我不知道它的
值或者它与KeyFrame持续时间的值是否相同？ * /
double x2 = x + voX * t;
double y2 = y + v0Y * t - 0.5 * gravity * t * t;
线l =新线（x，y，x2，y2）;
l.setStroke（Color.BLACK）;
group.getChildren（）。addAll（c，l）;
final时间轴时间轴=新时间轴（）;
KeyValue xKV = new KeyValue（c.centerXProperty（），x2）;
KeyValue yKV = new KeyValue（c.centerYProperty（），y2，new Interpolator（）{
@Override
//也许我需要分裂，而不是曲线（？）
受保护的双曲线（双t）{
//这应该是轨迹的公式
返回Math.tan（角度）* x * - （重力/（2 *速度* Math.cos（角度））） * x * x;
}
}）;
KeyFrame xKF = new KeyFrame（Duration.millis（2000），xKV）;
KeyFrame yKF = new KeyFrame（Duration.millis（2000），yKV）;
timeline.getKeyFrames（）。addAll（xKF，yKF）;
timeline.play（）;
}
我处于停滞状态。请帮助meeee
在
import javafx.animation.Interpolator;
import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
import javafx.util.Duration;
/ **
* @see https://stackoverflow.com/a/38031826/230513
* /
公共类测试扩展应用程序{
@Override
public void start（Stage primaryStage）{
primaryStage.setTitle（Test）;
Group group = new Group（）;
场景场景=新场景（组，600,350）;
scene.setFill（Color.BLACK）;
primaryStage.setScene（scene）;
primaryStage.show（）;
Circle c = new Circle（100,300,16，Color.AQUA）;
线l =新线（100,300,500,300）;
l.setStroke（Color.AQUA）;
group.getChildren（）。addAll（c，l）;
final时间轴时间轴=新时间轴（）;
timeline.setCycleCount（Timeline.INDEFINITE）;
timeline.setAutoReverse（false）;
KeyValue xKV = new KeyValue（c.centerXProperty（），500）;
KeyValue yKV = new KeyValue（c.centerYProperty（），100，new Interpolator（）{
@Override
protected double curve（double t）{
return -4 *（ t - .5）*（t - .5）+ 1;
}
}）;
KeyFrame xKF = new KeyFrame（Duration.millis（2000），xKV）;
KeyFrame yKF = new KeyFrame（Duration.millis（2000），yKV）;
timeline.getKeyFrames（）。addAll（xKF，yKF）;
timeline.play（）;
}
public static void main（String [] args）{
launch（args）;
}
}
I'm sorry, but I continue not understanding. My problem is I know nothing about physics but my teacher assigned to me this project.
private void shoot() {
Group group = new Group();
double angle = cannon.getRotate();
double speed = slider.getValue();
double x = cannon.getLayoutX();
double y = cannon.getLayoutY();
double v0X = Math.cos(angle)*speed;
double voY = Math.sin(angle)*speed;
Circle c = new Circle(x, y, 8, Color.BLACK);
/*t is the time, but I don't know its
value or has it the same value of the KeyFrame duration? */
double x2 = x + voX*t;
double y2 = y + v0Y * t - 0.5 * gravity * t * t;
Line l = new Line(x, y, x2, y2);
l.setStroke(Color.BLACK);
group.getChildren().addAll(c, l);
final Timeline timeline = new Timeline();
KeyValue xKV = new KeyValue(c.centerXProperty(), x2);
KeyValue yKV = new KeyValue(c.centerYProperty(), y2 , new Interpolator() {
@Override
//Maybe I need I splite, not a curve (?)
protected double curve(double t) {
//thisshould be trajectory's formula
return Math.tan(angle) * x*-(gravity/(2*speed*Math.cos(angle)))*x*x;
}
});
KeyFrame xKF = new KeyFrame(Duration.millis(2000), xKV);
KeyFrame yKF = new KeyFrame(Duration.millis(2000), yKV);
timeline.getKeyFrames().addAll(xKF, yKF);
timeline.play();
}
I'm at a standstill. Please, help meeee
In a KeyValue, the first parameter should be a WritableValue, e.g. circle.centerXProperty(), which represents the initial coordinate, say x. The second parameter should be a type compatible value, in this case the x coordinate toward which the projectile should move. As the timeline plays, the WritableValue will be updated accordingly. Add a second KeyValue to drive the y coordinate.
In the first example seen here, three instances of KeyValue move a figure from it's initial position to its destination position, which is size units away along each coordinate axis. In this related example, a figure moves form point p1 to p2.
In the example below, a Circle moves parallel to the x axis between 100 and 500. At the same time, that same Circle moves parallel to the y axis between 300 and 100 following the curve() defined by the parabola y = –4(x – ½)2 + 1, which has vertex (½, 1) and x intercepts at 0 and 1. This implementation of curve() models a parabolic path on a unit square, as required by the curve() API. You can change the angle of elevation by changing the ratio of height to width in the keys frames, e.g.
KeyValue xKV = new KeyValue(c.centerXProperty(), 200);
KeyValue yKV = new KeyValue(c.centerYProperty(), 0, new Interpolator() {…});
import javafx.animation.Interpolator;
import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
import javafx.util.Duration;
/**
* @see https://stackoverflow.com/a/38031826/230513
*/
public class Test extends Application {
@Override
public void start(Stage primaryStage) {
primaryStage.setTitle("Test");
Group group = new Group();
Scene scene = new Scene(group, 600, 350);
scene.setFill(Color.BLACK);
primaryStage.setScene(scene);
primaryStage.show();
Circle c = new Circle(100, 300, 16, Color.AQUA);
Line l = new Line(100, 300, 500, 300);
l.setStroke(Color.AQUA);
group.getChildren().addAll(c, l);
final Timeline timeline = new Timeline();
timeline.setCycleCount(Timeline.INDEFINITE);
timeline.setAutoReverse(false);
KeyValue xKV = new KeyValue(c.centerXProperty(), 500);
KeyValue yKV = new KeyValue(c.centerYProperty(), 100, new Interpolator() {
@Override
protected double curve(double t) {
return -4 * (t - .5) * (t - .5) + 1;
}
});
KeyFrame xKF = new KeyFrame(Duration.millis(2000), xKV);
KeyFrame yKF = new KeyFrame(Duration.millis(2000), yKV);
timeline.getKeyFrames().addAll(xKF, yKF);
timeline.play();
}
public static void main(String[] args) {
launch(args);
}
}
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