JavaFX中八边形内圆的碰撞检测

Question

我是JavaFX的新手，在冲突检测方面遇到了问题。我在八边形中有一个圆圈，我希望通过从墙上反弹来保持八边形内部。目前，如果我在按键事件内检查碰撞，每当我试图移动圆圈时，它往往会跳来跳去，但如果我将碰撞检查放在按键事件外，则不会发生任何事情。此时，我的代码只检查左墙和右墙是否发生碰撞。这是我的代码：

import java.util.Vector;
import com.sun.javafx.geom.Vec2f;
import javafx.animation.AnimationTimer;
import javafx.animation.Timeline;
import javafx.animation.TranslateTransition;
import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.LongProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.property.SimpleLongProperty;
import javafx.geometry.Bounds;
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.Polygon;
import javafx.scene.shape.Shape;
import javafx.scene.transform.Rotate;
import javafx.stage.Stage;
import javafx.util.Duration;
public class Craft extends Application {
double getX; // I later declare this as circ1.getTranslateX()
double getY; // I later declare this as circ1.getTranslateY()
@Override 
public void start(Stage primaryStage) { 
    Pane pane = new Pane();
    Polygon octagon = new Polygon(500,50, 1200,50, 1600,300, 1600,800,        1200,1000, 500,1000, 100,800, 100,300 );
    octagon.setStroke(Color.BLACK);
    octagon.setFill(Color.TRANSPARENT);
    Circle circ1 = new Circle(500.0f, 500.0f, 25.0f);
    circ1.setFill(Color.BLUE);
    Polygon tri1 = new Polygon(530, 495, 530, 505, 540, 500);
    tri1.setFill(Color.BLUE);
    tri1.translateXProperty().bind(circ1.translateXProperty());
    tri1.translateYProperty().bind(circ1.translateYProperty());
    Rotate rotate = new Rotate();
    rotate.pivotXProperty().bind(circ1.centerXProperty());
    rotate.pivotYProperty().bind(circ1.centerYProperty());
    rotate.angleProperty().bind(circ1.rotateProperty());
    tri1.getTransforms().add(rotate);
    pane.getChildren().addAll(octagon, circ1, tri1);
    getX = circ1.getTranslateX();
    getY = circ1.getTranslateY();
    Bounds bounds = octagon.getBoundsInLocal();
    boolean leftWall = circ1.getTranslateX() <= (bounds.getMinX() +          circ1.getRadius());
    boolean topWall = circ1.getLayoutY() <= (bounds.getMinY() + circ1.getRadius());
    boolean rightWall = circ1.getTranslateX() >= (bounds.getMaxX() + circ1.getRadius());
    boolean bottomWall = circ1.getLayoutY() >= (bounds.getMaxY() + circ1.getRadius());
    circ1.setOnKeyPressed((e) -> {
        if(e.getCode() == KeyCode.UP) {
            DoubleProperty circ1VelX = new SimpleDoubleProperty();
            DoubleProperty circ1VelY = new SimpleDoubleProperty();
            LongProperty lastUpdateTime = new SimpleLongProperty();
            AnimationTimer circ1Animation = new AnimationTimer() {
            @Override
              public void handle(long timestamp) {
                if (lastUpdateTime.get() > 0) {
                  double elapsedSeconds = (timestamp - lastUpdateTime.get()) / 1_000_000_000.0 ;
                  double deltaX = elapsedSeconds * circ1VelX.get();
                  double deltaY = elapsedSeconds * circ1VelY.get();
                  double oldX = circ1.getTranslateX();
                  double oldY = circ1.getTranslateY();
                  double newX = oldX + deltaX;
                  double newY = oldY + deltaY;
                  circ1.setTranslateX(newX += 1 * Math.cos(Math.toRadians(circ1.getRotate())) * 0.1);
                  circ1.setTranslateY(newY += 1 * Math.sin(Math.toRadians(circ1.getRotate())) * 0.1);
                }
                lastUpdateTime.set(timestamp);
              }
            };circ1Animation.start();
        }
        else if(e.getCode() == KeyCode.LEFT) {
            circ1.setRotate(circ1.getRotate() - 5);
        }
        else if(e.getCode() == KeyCode.RIGHT) {
            circ1.setRotate(circ1.getRotate() + 5);
        }
        else if(e.getCode() == KeyCode.DOWN) {
            DoubleProperty circ1VelX = new SimpleDoubleProperty();
            DoubleProperty circ1VelY = new SimpleDoubleProperty();
            LongProperty lastUpdateTime = new SimpleLongProperty();
            AnimationTimer circ1Animation = new AnimationTimer() {
            @Override
              public void handle(long timestamp) {
                if (lastUpdateTime.get() > 0) {
                  double elapsedSeconds = (timestamp - lastUpdateTime.get()) / 1_000_000_000.0 ;
                  double deltaX = elapsedSeconds * circ1VelX.get();
                  double deltaY = elapsedSeconds * circ1VelY.get();
                  double oldX = circ1.getTranslateX();
                  double oldY = circ1.getTranslateY();
                  double newX = oldX + deltaX;
                  double newY = oldY + deltaY;
                  circ1.setTranslateX(newX -= 1 * Math.cos(Math.toRadians(circ1.getRotate())) * 0.1);
                  circ1.setTranslateY(newY -= 1 * Math.sin(Math.toRadians(circ1.getRotate())) * 0.1);
                }
                lastUpdateTime.set(timestamp);
              }
            };circ1Animation.start();
        }
    });
    circ1.setOnKeyReleased((e) -> {
        if(e.getCode() == KeyCode.UP) {
            DoubleProperty circ1VelX = new SimpleDoubleProperty();
            DoubleProperty circ1VelY = new SimpleDoubleProperty();
            LongProperty lastUpdateTime = new SimpleLongProperty();
            AnimationTimer circ1Animation = new AnimationTimer() {
            @Override
              public void handle(long timestamp) {
                if (lastUpdateTime.get() > 0) {
                  double elapsedSeconds = (timestamp - lastUpdateTime.get()) / 1_000_000_000.0 ;
                  double deltaX = elapsedSeconds * circ1VelX.get();
                  double deltaY = elapsedSeconds * circ1VelY.get();
                  double oldX = circ1.getTranslateX();
                  double oldY = circ1.getTranslateY();
                  double newX = oldX + deltaX;
                  double newY = oldY + deltaY;
                  circ1.setTranslateX(newX += 0.5 *      Math.cos(Math.toRadians(circ1.getRotate())));
                  circ1.setTranslateY(newY += 0.5 * Math.sin(Math.toRadians(circ1.getRotate())));
                }
                lastUpdateTime.set(timestamp);
              }
            };circ1Animation.start();
        }
        else if(e.getCode() == KeyCode.DOWN) {
            DoubleProperty circ1VelX = new SimpleDoubleProperty();
            DoubleProperty circ1VelY = new SimpleDoubleProperty();
            LongProperty lastUpdateTime = new SimpleLongProperty();
            AnimationTimer circ1Animation = new AnimationTimer() {
            @Override
              public void handle(long timestamp) {
                if (lastUpdateTime.get() > 0) {
                  double elapsedSeconds = (timestamp - lastUpdateTime.get()) / 1_000_000_000.0 ;
                  double deltaX = elapsedSeconds * circ1VelX.get();
                  double deltaY = elapsedSeconds * circ1VelY.get();
                  double oldX = circ1.getTranslateX();
                  double oldY = circ1.getTranslateY();
                  double newX = oldX + deltaX;
                  double newY = oldY + deltaY;
                  circ1.setTranslateX(newX -= 0.5 * Math.cos(Math.toRadians(circ1.getRotate())));
                  circ1.setTranslateY(newY -= 0.5 *       Math.sin(Math.toRadians(circ1.getRotate())));
                }
                lastUpdateTime.set(timestamp);
              }
            };circ1Animation.start();
        }
    });
    if(leftWall || rightWall) {
          circ1.setTranslateX(getX *= -1);
      }

    Scene scene = new Scene(pane, 1700, 1050);
    scene.getStylesheets().add("custom_craft.css");
    primaryStage.setScene(scene);
    primaryStage.setTitle("Craft");
    primaryStage.show();
    circ1.requestFocus();
}
public static void main(String[] args) {
    launch(args);
}
}

Answer 1

你要搜索的是几个问题的答案，例如，我想你的球应该连续移动，移动时不要结结巴巴。此外，球应该一直移动，而不仅仅是在按键时。并且您对AnimationTimer的使用是错误的。

关于交叉点：如果你只有一个矩形，那么答案很简单。但你没有。因此，您需要检查八边形或单独的线。这本身就是非常数学化的。SO上已经有几个关于第<->行的问题和答案圆形交叉点。然后你就有了从对角墙上反弹的角度问题，等等。

这里有一个快速&肮脏的例子：

• 我把你的多边形转换成单独的线
• 我用圆和每条线创建一个新的形状，这样可以检查它们是否相交

您可以拖动圆形，并通过更改颜色来查看相交处。

import java.util.ArrayList;
import java.util.List;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.scene.shape.Polygon;
import javafx.scene.shape.Shape;
import javafx.stage.Stage;
public class CircleLineIntersection extends Application {
    Circle circle;
    List<Line> lines = new ArrayList<>();
    Color defaultStroke = Color.GREEN;
    Color defaultFill = defaultStroke.deriveColor(1, 1, 1, 0.3);
    Color hitStroke = Color.RED;
    Color hitFill = hitStroke.deriveColor(1, 1, 1, 0.3);
    public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void start(Stage primaryStage) {
        Group root = new Group();
        circle = new Circle(100, 100, 50);
        circle.setStroke( defaultStroke);
        circle.setFill( defaultFill);
        Polygon octagon = new Polygon(500, 50, 1200, 50, 1600, 300, 1600, 800, 1200, 1000, 500, 1000, 100, 800, 100, 300);
        // create lines out of the octagon
        int size = octagon.getPoints().size();
        for (int i = 0; i < size; i += 2) {
            double startX = octagon.getPoints().get(i);
            double startY = octagon.getPoints().get(i + 1);
            double endX = octagon.getPoints().get((i + 2) % size);
            double endY = octagon.getPoints().get((i + 3) % size);
            Line line = new Line(startX, startY, endX, endY);
            lines.add(line);
        }
        MouseGestures mg = new MouseGestures();
        mg.makeDraggable(circle);
        root.getChildren().addAll(lines);
        root.getChildren().addAll(circle);
        primaryStage.setScene(new Scene(root, 1920, 1080));
        primaryStage.show();
    }

    public class MouseGestures {
        class DragContext {
            double x;
            double y;
        }
        DragContext dragContext = new DragContext();
        public void makeDraggable(Node node) {
            node.setOnMousePressed(onMousePressedEventHandler);
            node.setOnMouseDragged(onMouseDraggedEventHandler);
            node.setOnMouseReleased(onMouseReleasedEventHandler);
        }
        EventHandler<MouseEvent> onMousePressedEventHandler = new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                Circle circle = ((Circle) (event.getSource()));
                dragContext.x = circle.getCenterX() - event.getSceneX();
                dragContext.y = circle.getCenterY() - event.getSceneY();
            }
        };
        EventHandler<MouseEvent> onMouseDraggedEventHandler = new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                Circle circle = ((Circle) (event.getSource()));
                circle.setCenterX(dragContext.x + event.getSceneX());
                circle.setCenterY(dragContext.y + event.getSceneY());
                // check intersection of lines vs circle
                boolean intersects = false;
                for (Line line : lines) {
                    // TODO: this is heavy on performance, better implement your own line <-> circle intersection algorithm
                    Shape shape = Shape.intersect( line, circle);
                    intersects = shape.getBoundsInLocal().getWidth() >= 0 || shape.getBoundsInLocal().getHeight() >= 0;
                    if( intersects) {
                        break;
                    }
                }
                // set color depending on intersection
                if( intersects) {
                    circle.setStroke( hitStroke);
                    circle.setFill( hitFill);
                }  else {
                    circle.setStroke( defaultStroke);
                    circle.setFill( defaultFill);
                }
            }
        };
        EventHandler<MouseEvent> onMouseReleasedEventHandler = new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
            }
        };
    }
}

Answer 2

我当然知道awt的答案。。。将多边形投射到区域，并使用相交方法。

http://docs.oracle.com/javase/7/docs/api/java/awt/geom/Area.html

你可能需要在你的八边形周围定义一个小的非零厚度的新多边形和（区域）新的多边形框架（…）

frame.intersect((Area)circ1).isEmpty()!=true

圆圈和框架相撞了。

编辑：javafx（2d迷宫）中的碰撞检测器提供了一些关于使用javafxCanvas 处理对象碰撞的说明