JavaFx：在運行時檢查PathTransition的當前位置

Question

我想通過PathTransition獲取Circle（javafx.scene.shape.Circle）的當前位置（x，y），而轉換正在運行/正在發生。

所以我需要某種任務，每隔50毫秒檢查一次圓的位置（例如）。

我也試過這個解決方案Current circle position of javafx transition這是在Stack Overflow上建議的，但我似乎沒有爲我工作。

Circle projectile = new Circle(Playground.PROJECTILE_SIZE, Playground.PROJECTILE_COLOR); 

root.getChildren().add(projectile); 

double duration = distance/Playground.PROJECTILE_SPEED; 

double xOff = (0.5-Math.random())*Playground.WEAPON_OFFSET; 
double yOff = (0.5-Math.random())*Playground.WEAPON_OFFSET; 

Line shotLine = new Line(player.getCurrentX(), player.getCurrentY(), aimLine.getEndX() + xOff, aimLine.getEndY() + yOff); 

shotLine.setEndX(shotLine.getEndX() + (Math.random()*Playground.WEAPON_OFFSET)); 

PathTransition pt = new PathTransition(Duration.seconds(duration), shotLine, projectile); 

// Linear movement for linear speed 
pt.setInterpolator(Interpolator.LINEAR); 

pt.setOnFinished(new EventHandler<ActionEvent>() { 
    public void handle(ActionEvent event) { 
    // Remove bullet after hit/expiration 
    projectile.setVisible(false); 
    root.getChildren().remove(projectile); 
    } 
}); 

projectile.translateXProperty().addListener(new ChangeListener<Number>() { 

    @Override 
    public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) { 
    double x = collider.getTranslateX() - projectile.getTranslateX(); 
    double y = collider.getTranslateY() - projectile.getTranslateY(); 

    double distance = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2)); 

    System.out.println("Distance: "+ distance); 

    if (distance < 50) { 
     System.out.println("hit"); 
    } 
    } 
}); 

pt.play(); 

Answer 1

甲PathTransition將通過操縱其translateX和translateY特性移動的節點。 （A TranslateTransition以同樣的方式。）

很難明確地回答你的問題是你的代碼是如此不完整的，但如果projectile和collider在場景圖中相同的父，轉換projectile的初始座標和collider通過調用localToParent將給出父母的座標，包括翻譯。因此，您可以觀察translateX和translateY屬性並使用該轉換來檢查衝突。如果他們有不同的父母，您可以使用localToScene來做同樣的事情，只需將它們轉換爲相對於場景的座標即可。

這是一個快速的SSCCE。使用左，右箭頭瞄準，空間拍攝：

import javafx.animation.Animation; 
import javafx.animation.TranslateTransition; 
import javafx.application.Application; 
import javafx.beans.binding.Bindings; 
import javafx.beans.binding.BooleanBinding; 
import javafx.geometry.Point2D; 
import javafx.scene.Scene; 
import javafx.scene.input.KeyCode; 
import javafx.scene.layout.Pane; 
import javafx.scene.paint.Color; 
import javafx.scene.shape.Circle; 
import javafx.scene.shape.Line; 
import javafx.scene.transform.Rotate; 
import javafx.stage.Stage; 
import javafx.util.Duration; 

public class ShootingGame extends Application { 

    @Override 
    public void start(Stage primaryStage) { 
     final double width = 400 ; 
     final double height = 400 ; 

     final double targetRadius = 25 ; 
     final double projectileRadius = 5 ; 

     final double weaponLength = 25 ; 

     final double weaponX = width/2 ; 
     final double weaponStartY = height ; 
     final double weaponEndY = height - weaponLength ; 

     final double targetStartX = targetRadius ; 
     final double targetY = targetRadius * 2 ;; 

     Pane root = new Pane(); 
     Circle target = new Circle(targetStartX, targetY, targetRadius, Color.BLUE); 
     TranslateTransition targetMotion = new TranslateTransition(Duration.seconds(2), target); 
     targetMotion.setByX(350); 
     targetMotion.setAutoReverse(true); 
     targetMotion.setCycleCount(Animation.INDEFINITE); 
     targetMotion.play(); 

     Line weapon = new Line(weaponX, weaponStartY, weaponX, weaponEndY); 
     weapon.setStrokeWidth(5); 
     Rotate weaponRotation = new Rotate(0, weaponX, weaponStartY); 
     weapon.getTransforms().add(weaponRotation); 

     Scene scene = new Scene(root, width, height); 
     scene.setOnKeyPressed(e -> { 
      if (e.getCode() == KeyCode.LEFT) { 
       weaponRotation.setAngle(Math.max(-45, weaponRotation.getAngle() - 2)); 
      } 
      if (e.getCode() == KeyCode.RIGHT) { 
       weaponRotation.setAngle(Math.min(45, weaponRotation.getAngle() + 2)); 
      } 
      if (e.getCode() == KeyCode.SPACE) { 

       Point2D weaponEnd = weapon.localToParent(weaponX, weaponEndY); 

       Circle projectile = new Circle(weaponEnd.getX(), weaponEnd.getY(), projectileRadius); 

       TranslateTransition shot = new TranslateTransition(Duration.seconds(1), projectile); 
       shot.setByX(Math.tan(Math.toRadians(weaponRotation.getAngle())) * height); 
       shot.setByY(-height); 
       shot.setOnFinished(event -> root.getChildren().remove(projectile)); 

       BooleanBinding hit = Bindings.createBooleanBinding(() -> { 
        Point2D targetLocation = target.localToParent(targetStartX, targetY); 
        Point2D projectileLocation = projectile.localToParent(weaponEnd); 
        return (targetLocation.distance(projectileLocation) < targetRadius + projectileRadius) ; 
       }, projectile.translateXProperty(), projectile.translateYProperty()); 

       hit.addListener((obs, wasHit, isNowHit) -> { 
        if (isNowHit) { 
         System.out.println("Hit"); 
         root.getChildren().remove(projectile); 
         root.getChildren().remove(target); 
         targetMotion.stop(); 
         shot.stop(); 
        } 
       }); 

       root.getChildren().add(projectile); 
       shot.play(); 
      } 
     }); 

     root.getChildren().addAll(target, weapon); 

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

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