Question

我有两个Polygon类对象，我想使用javafx.scene.shape.Shape中的union（）方法联合起来，我需要输出也是Polygon类对象。我找到了几个输出为Path对象的例子：

Path path = Path.union(shape1, shape2)

或者可以将路径转换为多边形吗？我试着去谷歌，但没有运气。

Answer 1

这就是我所说的。

import java.util.ArrayList;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Polygon;
import javafx.scene.shape.Shape;
import javafx.stage.Stage;



public class JavaFXApplication31 extends Application {

    @Override
    public void start(Stage primaryStage) {

        Polygon p1 = new Polygon();
        p1.getPoints().addAll(new Double[]{
            60.0, 60.0,
            80.0, 70.0,
            70.0, 80.0 });

        Polygon p2 = new Polygon();
        p2.getPoints().addAll(new Double[]{
            40.0, 40.0,
            60.0, 50.0,
            50.0, 60.0 });        

        AnchorPane root = new AnchorPane();


        Button btn = new Button();
        btn.setText("Click me!'");
        btn.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                System.out.println("Polygon unioned!");
                Shape union = Polygon.union(p1, p2);
                union.setFill(Color.BLUE);
                root.getChildren().add(union);
            }
        });

        Button btn2 = new Button();
        btn2.setText("New Polygon union!'");
        btn2.setLayoutX(100);
        btn2.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent event) {
                Polygon p3 = createNewPolygonUnion(p1, p2);
                p3.setFill(Color.RED);
                root.getChildren().add(p3);
            }
        });

        root.getChildren().addAll(p1, p2, btn, btn2);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }


    Polygon createNewPolygonUnion(Polygon one, Polygon two)
    {
        Polygon p3 = new Polygon();

        ArrayList<Double> onePoints = new ArrayList();
        ArrayList<Double> twoPoints = new ArrayList();
        ArrayList<Double> threePoints = new ArrayList();

        for(int i = 0; i < one.getPoints().size(); i++)
        {
            onePoints.add(one.getPoints().get(i));   
            twoPoints.add(two.getPoints().get(i));            
        }

        for(int i = 0; i < onePoints.size(); i++)
        {
            threePoints.add(onePoints.get(i) + twoPoints.get(i));
        }

        p3.getPoints().addAll(threePoints);

        return p3;
    }
}

原始的两个多边形。

两个原始多边形的联盟。两个多边形的联合没有导致多边形。

从我创建的方法联合。这个方法使用了来自的点原始的两个多边形并创建一个新的多边形。

Answer 2

当您获取两个多边形的并集时，您将获得一个Path对象，如您所述。可以将此路径对象转换为Polygon对象（不是最好的代码，但可行）。

//createing both polygon objects p1 and p2
Polygon p1 = new Polygon();
p1.getPoints().addAll(new Double[]{
            0.0, 0.0,
            20.0, 10.0,
            10.0, 20.0 });

Polygon p2 = new Polygon();
p2.getPoints().addAll(new Double[]{
            10.0, 0.0,
            25.0, 10.0,
            5.0, 20.0 });

// Taking the union that results in a Path object
Path p3 = (Path) Polygon.union(p1, p2);

// Array of points for the new polygon
Double[] points = new Double[(p3.getElements().size() - 1)*2];

int i = 0;
// going through all the path elements in the path and adding the x and y coordinates to points
for(PathElement el : p3.getElements()){
    if(el instanceof MoveTo){
        MoveTo mt = (MoveTo) el;
        points[i] = mt.getX();
        points[i+1] = mt.getY();
    }
    if(el instanceof LineTo){
        LineTo lt = (LineTo) el;
        points[i] = lt.getX();
        points[i+1] = lt.getY();
    }
    i += 2;
}

// creating new Polygon with these points
Polygon newPolygon = new Polygon();
newPolygon.getPoints().addAll(points);

如果多边形不相交，这可能不起作用，但应该起作用。如果没有交集，您将有两个MoveTo语句而不是一个。

如何将两个多边形联合起来使输出为多边形而不是路径（javafx）？

2 个答案: