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Displacement of an object around a sphere with JavaFX

I have an object, like a box in this example.
I want this box to move in a sine to the left on the sphere when the Z-axis is rotated. But after the box has made a curve, i.e. the rotation of the Z-axis is back to 0. The sphere no longer rotates downwards as it did at the start, but upwards to the right.
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.image.Image;
import javafx.scene.paint.Color;
import javafx.scene.paint.PhongMaterial;
import javafx.scene.shape.Box;
import javafx.scene.shape.Sphere;
import javafx.scene.transform.*;
import javafx.stage.Stage;
import org.joml.Matrix4f;
import org.joml.Quaternionf;
import java.util.ArrayList;
public class TestFX extends Application {
public static final float WIDTH = 1400;
public static final float HEIGHT = 1000;
private final ArrayList<String> input = new ArrayList<>();
private final Sphere sphere = new Sphere(500);
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
Flugzeug flieger = new Flugzeug(30, 30, 50);
flieger.setMaterial(new PhongMaterial(Color.GREEN));
flieger.setTranslateZ(330);
flieger.getTransforms().add(new Rotate(20, Rotate.X_AXIS));
sphere.translateZProperty().set(710);
sphere.translateYProperty().set(420);
PhongMaterial phongMaterial = new PhongMaterial();
phongMaterial.setDiffuseMap(new Image(getClass().getResourceAsStream("Earth_diffuse_8k.png")));
sphere.setMaterial(phongMaterial);
PerspectiveCamera camera = new PerspectiveCamera(true);
camera.setFarClip(40000);
Group root = new Group(flieger, sphere);
Scene scene = new Scene(root, WIDTH, HEIGHT, true);
scene.setCamera(camera);
primaryStage.setTitle("FliegenFX");
primaryStage.setScene(scene);
primaryStage.show();
new AnimationTimer() {
#Override
public void handle(long now) {
initGameLogic(flieger);
dreheErde(flieger, sphere);
}
}.start();
scene.setOnKeyPressed(event -> {
String code = event.getCode().toString();
if (!input.contains(code))
input.add(code);
});
scene.setOnKeyReleased(event -> {
String code = event.getCode().toString();
input.remove(code);
});
}
// TODO Erddrehung nach Drehung beibehalten
private void dreheErde(Flugzeug flieger, Sphere erde) {
double rotationFactor = 0.005;
double drehung = flieger.getDrehung() * rotationFactor;
double amplitude = 2;
double frequency = 0.001;
float angle = (float) (Math.sin(drehung * frequency) * amplitude);
Quaternionf quat = new Quaternionf();
Matrix4f matrix4f = new Matrix4f();
Affine affine = new Affine();
quat.rotateY(angle);
quat.rotateZ(angle);
quat.rotateX(-0.001f);
quat.normalize();
quat.get(matrix4f);
float[] matrixArray = new float[16];
matrix4f.get(matrixArray);
double[] matrix = new double[16];
for (int i = 0 ; i < matrixArray.length; i++)
{
matrix[i] = matrixArray[i];
}
affine.append(matrix, MatrixType.MT_3D_4x4, 0);
erde.getTransforms().add(affine);
}
private void initGameLogic(Flugzeug flieger) {
if (input.contains("LEFT")) {
flieger.rotateByZ(-0.5);
}
if (input.contains("RIGHT")) {
flieger.rotateByZ(0.5);
}
}
private class Flugzeug extends Box{
private double drehung = 0;
private Rotate r;
private Transform t = new Rotate();
public Flugzeug(double width, double height, double depth){
super(width, height, depth);
}
public void rotateByZ(double ang){
drehung += ang;
r = new Rotate(ang, Rotate.Z_AXIS);
t = t.createConcatenation(r);
getTransforms().clear();
getTransforms().addAll(t);
}
public double getDrehung() {
return drehung;
}
}
}
I have tried many different ways with trigonometry but they have not been successful. This was for example to move the X-axis of the sphere also according to the sine or to subtract the movements of the Y and Z axis of the sphere as cosine.
I think it has to be transformed in a Rotation Matrix, but i‘ve never had matrix calculation.

Rotating a Group inside another Group in 3d scene
In this approach Box instance doesn't seem to move 'cause it's moving with the camera . Camera and box are moving together because is it's Group parent who is rotating with keyboard event . The Sphere node is in another group and is not affected . Sphere itself is rotating in Y axis
App.java
public class App extends Application {
#Override
public void start(Stage stage) {
Shape3D sphere = new Sphere(10);
PhongMaterial mat = new PhongMaterial();
mat.setDiffuseMap(new Image("https://www.h-schmidt.net/map/map.jpg"));
sphere.setMaterial(mat);
RotateTransition sphereRotation = new RotateTransition(Duration.seconds(40), sphere);
sphereRotation.setAxis(Rotate.Y_AXIS);
sphereRotation.setToAngle(360);
sphereRotation.setInterpolator(Interpolator.LINEAR);
sphereRotation.setCycleCount(Animation.INDEFINITE);
sphereRotation.play();
Shape3D box = new Box(2, 2, 2);
box.setMaterial(new PhongMaterial(Color.ORANGE));
box.setTranslateZ(-11);
PerspectiveCamera camera = new PerspectiveCamera(true);
camera.setTranslateZ(-30);
var planeGroup = new Group(box, camera);
Group sphereGroup = new Group(sphere);
Group group3d = new Group(planeGroup, sphereGroup);
Scene scene = new Scene(group3d, 640, 480, true, SceneAntialiasing.BALANCED);
scene.setOnKeyPressed((t) -> {
if (t.getCode() == KeyCode.UP) {
Rotate r = new Rotate(-2);
r.setAxis(Rotate.X_AXIS);
planeGroup.getTransforms().add(r);
}
if (t.getCode() == KeyCode.LEFT) {
Rotate r = new Rotate(2);
r.setAxis(Rotate.Y_AXIS);
planeGroup.getTransforms().add(r);
}
if (t.getCode() == KeyCode.RIGHT) {
Rotate r = new Rotate(-2);
r.setAxis(Rotate.Y_AXIS);
planeGroup.getTransforms().add(r);
}
if (t.getCode() == KeyCode.DOWN) {
Rotate r = new Rotate(2);
r.setAxis(Rotate.X_AXIS);
planeGroup.getTransforms().add(r);
}
});
scene.setCamera(camera);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch();
}
}

How to create hexagon of hexagons as buttons in JavaFX

I want to create a hexagon of hexagons as buttons in JavaFX, I use an image and try to position some buttons to the position of each hexagon but I cannot change the position of them in a grid pane. Here is my code:
package sample;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
public class GameBoard extends GridPane {
public GameBoard(){
this.setAlignment(Pos.CENTER);
ImageView image = new ImageView();
Image hexagonImg = new Image("hexagon.jpg");
image.setFitWidth(500);
image.setFitHeight(500);
image.setImage(hexagonImg);
this.add(image,0,0);
GridPane button1Pane = new GridPane();
this.add(button1Pane,0,0);
Button button1 = new Button();
button1Pane.add(button1,1,0);
}
}

polygon hexagons
Since you need to use as buttons ; I added mouse click event wich changes stage's tittle . If you want to place hexagons side to side you may need to concider radius for x axis and apothem for y axis .
this is afunctional single class javafx app you can try
App.java
public class App extends Application {
#Override
public void start(Stage stage) {
double HexagonRadius = 100;
Hexagon hexagon1 = new Hexagon(HexagonRadius, Color.CADETBLUE);
Hexagon hexagon2 = new Hexagon(HexagonRadius, Color.MEDIUMPURPLE);
hexagon2.setTranslateY(hexagon1.getOffsetY() * 2);
Hexagon hexagon3 = new Hexagon(HexagonRadius, Color.MEDIUMSEAGREEN);
hexagon3.setTranslateY(-hexagon1.getOffsetY() * 2);
Hexagon hexagon4 = new Hexagon(HexagonRadius, Color.CORNFLOWERBLUE);
hexagon4.setTranslateY(-hexagon1.getOffsetY());
hexagon4.setTranslateX(hexagon1.getOffsetX());
Hexagon hexagon5 = new Hexagon(HexagonRadius, Color.YELLOW);
hexagon5.setTranslateY(-hexagon1.getOffsetY());
hexagon5.setTranslateX(-hexagon1.getOffsetX());
Hexagon hexagon6 = new Hexagon(HexagonRadius, Color.ORANGE);
hexagon6.setTranslateY(hexagon1.getOffsetY());
hexagon6.setTranslateX(-hexagon1.getOffsetX());
Hexagon hexagon7 = new Hexagon(HexagonRadius, Color.SKYBLUE);
hexagon7.setTranslateY(hexagon1.getOffsetY());
hexagon7.setTranslateX(hexagon1.getOffsetX());
Group hexagonsGroup = new Group(hexagon1, hexagon2, hexagon3, hexagon4, hexagon5, hexagon6, hexagon7);
StackPane stackPane = new StackPane(hexagonsGroup);
var scene = new Scene(stackPane, 640, 480);
scene.setFill(Color.ANTIQUEWHITE);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch();
}
public class Hexagon extends Group {
private Polygon polygon;
private double radius;
private double radianStep = (2 * Math.PI) / 6;
private double offsetY;
private double offsetX;
public Hexagon(double radius, Paint color) {
this.radius = radius;
makeHexagon(radius, color);
offsetY = calculateApothem();
offsetX = radius * 1.5;
changeTittle();
}
private void makeHexagon(double radius, Paint color) {
polygon = new Polygon();
this.getChildren().add(polygon);
polygon.setFill(color);
polygon.setStroke(Color.WHITESMOKE);
polygon.setEffect(new DropShadow(10, Color.BLACK));
polygon.setStrokeWidth(10);
polygon.setStrokeType(StrokeType.INSIDE);
for (int i = 0; i < 6; i++) {
double angle = radianStep * i;
polygon.getPoints().add(Math.cos(angle) * radius / 1.1);
polygon.getPoints().add(Math.sin(angle) * radius / 1.1);
}
}
public void changeTittle() {
polygon.setOnMouseClicked(e -> {
Stage stage = (Stage) this.getScene().getWindow();
stage.setTitle(polygon.getFill().toString());
});
}
public double getOffsetY() {
return offsetY;
}
public double getOffsetX() {
return offsetX;
}
private double calculateApothem() {
return (Math.tan(radianStep) * radius) / 2;
}
}
}

I would just create a Path for each Hexagon and put them in Group which you can then place in the middle of some Pane. Dealing with images and a GridPane only complicates things. Just doing some graphics directly is much easier.

JavaFX: How to move 2 Rectangles at the same time?

I have 2 rectangles representing the paddles for my Pong game. I use W/S for one rectangle and UP/DOWN for the second rectangle. When I press W to move one rectangle and then press UP to move the second rectangle, the first rectangle will stop moving and then the second rectangle will move. How do I make it so both rectangles can move simultaneously?
GraphicsContext gc;
Rectangle player11;
Rectangle player22;
Circle ball;
private int y1;
private int p1y = 381;
private int y2;
private int p2y = 381;
AnimateObjects animate;
Canvas canvas;
private AnimationTimer timer = new AnimationTimer() {
public void handle(long now) {
// update paddle positions
p1y += y1;
p2y += y2;
if (p1y < 0) {
p1y = 0;
}
if (p2y < 0) {
p2y = 0;
}
player11.setY(p1y);
player22.setY(p2y);
}
};
public EventHandler<KeyEvent> keyReleased = new EventHandler<KeyEvent>() {
public void handle(KeyEvent event) {
// set movement to 0, if the released key was responsible for the paddle
switch (event.getCode()) {
case W:
case S:
y1 = 0;
break;
case UP:
case DOWN:
y2 = 0;
break;
}
}
};
private EventHandler<KeyEvent> keyPressed = new EventHandler<KeyEvent>() {
public void handle(KeyEvent event) {
// start movement according to key pressed
switch (event.getCode()) {
case W:
y1 = -6;
break;
case S:
y1 = 6;
break;
case UP:
y2 = -6;
break;
case DOWN:
y2 = 6;
break;
}
}
};
public static void main(String[] args) {
launch();
}//main
public void start(Stage stage) {
stage.setTitle("Pong");
Group root = new Group();
canvas = new Canvas(1000, 800);
root.getChildren().add(canvas);
Scene scene = new Scene(root, Color.GREEN);
stage.setScene(scene);
player11 = new Rectangle(30, p1y, 20, 70);
player11.setFill(Color.RED);
player22 = new Rectangle(750, p2y, 20, 70);
player22.setFill(Color.BLUE);
root.getChildren().add(player11);
root.getChildren().add(player22);
scene.setOnKeyPressed(keyPressed);
scene.setOnKeyReleased(keyReleased);
ball = new Circle(10, Color.DARKSLATEBLUE);
root.getChildren().add(ball);
ball.relocate(500,350);
gc = canvas.getGraphicsContext2D();
animate = new AnimateObjects();
animate.start();
stage.show();
}//start
public class AnimateObjects extends AnimationTimer {
public void handle(long now) {
}//handle method in AnimateObjects class
}//AnimateObjects class
}//pong class

You need to capture KeyCodes. Use up, down, z, and x to control paddles. The right paddle will not move beyond the upper and lower bounds of the gameboard. The left paddle will. More comments in the code! Here is a working example.
import java.util.HashSet;
import java.util.Set;
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.input.KeyCode;
import javafx.scene.layout.Pane;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;
/**
*
* #author blj0011
*/
public class App extends Application
{
Rectangle leftPaddle, rightPaddle;
AnimationTimer gameLoop;
Set<KeyCode> input;
Pane gameBoard;
#Override
public void start(Stage primaryStage)
{
leftPaddle = new Rectangle(7, 100, Color.BLACK);
leftPaddle.setX(3);
leftPaddle.setY(0);
rightPaddle = new Rectangle(7, 100, Color.BLACK);
rightPaddle.setX(500 - 10);
rightPaddle.setY(0);
input = new HashSet(); //This set is used to keep up with keys that are currently being pressed.
gameBoard = new Pane(leftPaddle, rightPaddle);
VBox.setVgrow(gameBoard, Priority.ALWAYS);
gameBoard.setOnKeyPressed(event -> input.add(event.getCode()));//add keys that are currently being pressed to the set
gameBoard.setOnKeyReleased(event -> input.remove(event.getCode()));//remove keys from the set after they are released
gameLoop = new AnimationTimer()
{
#Override
public void handle(long l)
{
movePaddle();//Call method to move paddle based on certain keys in the set
//System.out.println("playing");
}
};
Button btnStartGame = new Button("Play");
btnStartGame.setMaxWidth(Double.MAX_VALUE);
btnStartGame.setOnAction((event) -> {
gameBoard.requestFocus();//Request gameboard focus to capture keyevents
gameLoop.start();
btnStartGame.setDisable(true);
});
VBox root = new VBox(gameBoard, btnStartGame);
Scene scene = new Scene(root, 500, 500);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
launch(args);
}
//Use to move paddles based on keycodes in set
private void movePaddle()
{
if (input.contains(KeyCode.UP)) {
rightPaddle.setY(rightPaddle.getY() - 10);
if (rightPaddle.getY() < 0) {
rightPaddle.setY(0);
}
}
else if (input.contains(KeyCode.DOWN)) {
rightPaddle.setY(rightPaddle.getY() + 10);
if (rightPaddle.getY() + rightPaddle.getHeight() > gameBoard.getHeight()) {
rightPaddle.setY(gameBoard.getHeight() - rightPaddle.getHeight());
}
}
if (input.contains(KeyCode.Z)) {
leftPaddle.setY(leftPaddle.getY() - 10);
}
else if (input.contains(KeyCode.X)) {
leftPaddle.setY(leftPaddle.getY() + 10);
}
}
}

How to identify objects with the same variable name in javaFX? [duplicate]

I have a set of Nodes, Circles, on the stage.
I want to be able to click on one of them and 'select it' (just get a reference to it so I can move it around, change color etc.)
Pane root = new Pane();
root.getChildren().addAll( /* an array of Circle objects */ );
Scene scene = new Scene(root, 500, 500, BACKGROUND_COLOR);
scene.setOnMouseClicked(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
// how do I get which Circle I clicked on?
}
});
stage.setTitle(TITLE);
stage.setScene(scene);
stage.show();

I would simply register a listener with each circle itself. Then you already have the reference to the circle with which the listener was registered.
This example pushes the limit a little as to usability, because it has 10,000 circles shown all at once, but it demonstrates the technique:
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.css.PseudoClass;
import javafx.geometry.Point2D;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
public class GridOfCircles extends Application {
private static final PseudoClass SELECTED_P_C = PseudoClass.getPseudoClass("selected");
private final int numColumns = 100 ;
private final int numRows = 100 ;
private final double radius = 4 ;
private final double spacing = 2 ;
private final ObjectProperty<Circle> selectedCircle = new SimpleObjectProperty<>();
private final ObjectProperty<Point2D> selectedLocation = new SimpleObjectProperty<>();
#Override
public void start(Stage primaryStage) {
selectedCircle.addListener((obs, oldSelection, newSelection) -> {
if (oldSelection != null) {
oldSelection.pseudoClassStateChanged(SELECTED_P_C, false);
}
if (newSelection != null) {
newSelection.pseudoClassStateChanged(SELECTED_P_C, true);
}
});
Pane grid = new Pane();
for (int x = 0 ; x < numColumns; x++) {
double gridX = x*(spacing + radius + radius) + spacing ;
grid.getChildren().add(new Line(gridX, 0, gridX, numRows*(spacing + radius + radius)));
}
for (int y = 0; y < numRows ; y++) {
double gridY = y*(spacing + radius + radius) + spacing ;
grid.getChildren().add(new Line(0, gridY, numColumns*(spacing + radius + radius), gridY));
}
for (int x = 0 ; x < numColumns; x++) {
for (int y = 0 ;y < numRows ; y++) {
grid.getChildren().add(createCircle(x, y));
}
}
Label label = new Label();
label.textProperty().bind(Bindings.createStringBinding(() -> {
Point2D loc = selectedLocation.get();
if (loc == null) {
return "" ;
}
return String.format("Location: [%.0f, %.0f]", loc.getX(), loc.getY());
}, selectedLocation));
BorderPane root = new BorderPane(new ScrollPane(grid));
root.setTop(label);
Scene scene = new Scene(root);
scene.getStylesheets().add("grid.css");
primaryStage.setScene(scene);
primaryStage.show();
}
private Circle createCircle(int x, int y) {
Circle circle = new Circle();
circle.getStyleClass().add("intersection");
circle.setCenterX(x * (spacing + radius + radius) + spacing);
circle.setCenterY(y * (spacing + radius + radius) + spacing);
circle.setRadius(radius);
circle.addEventHandler(MouseEvent.MOUSE_CLICKED, e -> {
selectedCircle.set(circle);
selectedLocation.set(new Point2D(x, y));
});
return circle ;
}
public static void main(String[] args) {
launch(args);
}
}
with the file grid.css:
.intersection {
-fx-fill: blue ;
}
.intersection:selected {
-fx-fill: gold ;
}

You can get the reference by using getSource of the MouseEvent.
Example in which you can drag a Circle and any other Node:
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
Circle circle = new Circle( 100,100,50);
circle.setStroke(Color.BLUE);
circle.setFill(Color.BLUE.deriveColor(1, 1, 1, 0.3));
Rectangle rectangle = new Rectangle( 0,0,100,100);
rectangle.relocate(200, 200);
rectangle.setStroke(Color.GREEN);
rectangle.setFill(Color.GREEN.deriveColor(1, 1, 1, 0.3));
Text text = new Text( "Example Text");
text.relocate(300, 300);
Pane root = new Pane();
root.getChildren().addAll(circle, rectangle, text);
MouseGestures mouseGestures = new MouseGestures();
mouseGestures.makeDraggable(circle);
mouseGestures.makeDraggable(rectangle);
mouseGestures.makeDraggable(text);
Scene scene = new Scene(root, 1024, 768);
primaryStage.setScene(scene);
primaryStage.show();
}
public static 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 = event -> {
if( event.getSource() instanceof Circle) {
Circle circle = (Circle) (event.getSource());
dragContext.x = circle.getCenterX() - event.getSceneX();
dragContext.y = circle.getCenterY() - event.getSceneY();
} else {
Node node = (Node) (event.getSource());
dragContext.x = node.getTranslateX() - event.getSceneX();
dragContext.y = node.getTranslateY() - event.getSceneY();
}
};
EventHandler<MouseEvent> onMouseDraggedEventHandler = event -> {
if( event.getSource() instanceof Circle) {
Circle circle = (Circle) (event.getSource());
circle.setCenterX( dragContext.x + event.getSceneX());
circle.setCenterY( dragContext.y + event.getSceneY());
} else {
Node node = (Node) (event.getSource());
node.setTranslateX( dragContext.x + event.getSceneX());
node.setTranslateY( dragContext.y + event.getSceneY());
}
};
EventHandler<MouseEvent> onMouseReleasedEventHandler = event -> {
};
}
public static void main(String[] args) {
launch(args);
}
}

Javafx click on a Circle and get it's reference

I have a set of Nodes, Circles, on the stage.
I want to be able to click on one of them and 'select it' (just get a reference to it so I can move it around, change color etc.)
Pane root = new Pane();
root.getChildren().addAll( /* an array of Circle objects */ );
Scene scene = new Scene(root, 500, 500, BACKGROUND_COLOR);
scene.setOnMouseClicked(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
// how do I get which Circle I clicked on?
}
});
stage.setTitle(TITLE);
stage.setScene(scene);
stage.show();

I would simply register a listener with each circle itself. Then you already have the reference to the circle with which the listener was registered.
This example pushes the limit a little as to usability, because it has 10,000 circles shown all at once, but it demonstrates the technique:
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.css.PseudoClass;
import javafx.geometry.Point2D;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
public class GridOfCircles extends Application {
private static final PseudoClass SELECTED_P_C = PseudoClass.getPseudoClass("selected");
private final int numColumns = 100 ;
private final int numRows = 100 ;
private final double radius = 4 ;
private final double spacing = 2 ;
private final ObjectProperty<Circle> selectedCircle = new SimpleObjectProperty<>();
private final ObjectProperty<Point2D> selectedLocation = new SimpleObjectProperty<>();
#Override
public void start(Stage primaryStage) {
selectedCircle.addListener((obs, oldSelection, newSelection) -> {
if (oldSelection != null) {
oldSelection.pseudoClassStateChanged(SELECTED_P_C, false);
}
if (newSelection != null) {
newSelection.pseudoClassStateChanged(SELECTED_P_C, true);
}
});
Pane grid = new Pane();
for (int x = 0 ; x < numColumns; x++) {
double gridX = x*(spacing + radius + radius) + spacing ;
grid.getChildren().add(new Line(gridX, 0, gridX, numRows*(spacing + radius + radius)));
}
for (int y = 0; y < numRows ; y++) {
double gridY = y*(spacing + radius + radius) + spacing ;
grid.getChildren().add(new Line(0, gridY, numColumns*(spacing + radius + radius), gridY));
}
for (int x = 0 ; x < numColumns; x++) {
for (int y = 0 ;y < numRows ; y++) {
grid.getChildren().add(createCircle(x, y));
}
}
Label label = new Label();
label.textProperty().bind(Bindings.createStringBinding(() -> {
Point2D loc = selectedLocation.get();
if (loc == null) {
return "" ;
}
return String.format("Location: [%.0f, %.0f]", loc.getX(), loc.getY());
}, selectedLocation));
BorderPane root = new BorderPane(new ScrollPane(grid));
root.setTop(label);
Scene scene = new Scene(root);
scene.getStylesheets().add("grid.css");
primaryStage.setScene(scene);
primaryStage.show();
}
private Circle createCircle(int x, int y) {
Circle circle = new Circle();
circle.getStyleClass().add("intersection");
circle.setCenterX(x * (spacing + radius + radius) + spacing);
circle.setCenterY(y * (spacing + radius + radius) + spacing);
circle.setRadius(radius);
circle.addEventHandler(MouseEvent.MOUSE_CLICKED, e -> {
selectedCircle.set(circle);
selectedLocation.set(new Point2D(x, y));
});
return circle ;
}
public static void main(String[] args) {
launch(args);
}
}
with the file grid.css:
.intersection {
-fx-fill: blue ;
}
.intersection:selected {
-fx-fill: gold ;
}

You can get the reference by using getSource of the MouseEvent.
Example in which you can drag a Circle and any other Node:
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
Circle circle = new Circle( 100,100,50);
circle.setStroke(Color.BLUE);
circle.setFill(Color.BLUE.deriveColor(1, 1, 1, 0.3));
Rectangle rectangle = new Rectangle( 0,0,100,100);
rectangle.relocate(200, 200);
rectangle.setStroke(Color.GREEN);
rectangle.setFill(Color.GREEN.deriveColor(1, 1, 1, 0.3));
Text text = new Text( "Example Text");
text.relocate(300, 300);
Pane root = new Pane();
root.getChildren().addAll(circle, rectangle, text);
MouseGestures mouseGestures = new MouseGestures();
mouseGestures.makeDraggable(circle);
mouseGestures.makeDraggable(rectangle);
mouseGestures.makeDraggable(text);
Scene scene = new Scene(root, 1024, 768);
primaryStage.setScene(scene);
primaryStage.show();
}
public static 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 = event -> {
if( event.getSource() instanceof Circle) {
Circle circle = (Circle) (event.getSource());
dragContext.x = circle.getCenterX() - event.getSceneX();
dragContext.y = circle.getCenterY() - event.getSceneY();
} else {
Node node = (Node) (event.getSource());
dragContext.x = node.getTranslateX() - event.getSceneX();
dragContext.y = node.getTranslateY() - event.getSceneY();
}
};
EventHandler<MouseEvent> onMouseDraggedEventHandler = event -> {
if( event.getSource() instanceof Circle) {
Circle circle = (Circle) (event.getSource());
circle.setCenterX( dragContext.x + event.getSceneX());
circle.setCenterY( dragContext.y + event.getSceneY());
} else {
Node node = (Node) (event.getSource());
node.setTranslateX( dragContext.x + event.getSceneX());
node.setTranslateY( dragContext.y + event.getSceneY());
}
};
EventHandler<MouseEvent> onMouseReleasedEventHandler = event -> {
};
}
public static void main(String[] args) {
launch(args);
}
}