LookAtTest.java

package edu.jhuapl.trinity.javafx;

/*-
 * #%L
 * ******************************* UNCLASSIFIED *******************************
 * LookAtTest.java
 * trinity:trinity
 * %%
 * Copyright (C) 2021 - 2022 Johns Hopkins University Applied Physics Laboratory
 * %%
 * (c) Johns Hopkins University Applied Physics Laboratory. All Rights Reserved.
 * This material may only be used, modified, or reproduced by or for the
 * U.S. government pursuant to the license rights granted under FAR
 * clause 52.227-14 or DFARS clauses 252.227-7013/7014.
 * For any other permission, please contact the Legal Office at JHU/APL.
 * #L%
 */

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Point3D;
import javafx.scene.AmbientLight;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.PerspectiveCamera;
import javafx.scene.Scene;
import javafx.scene.SceneAntialiasing;
import javafx.scene.SubScene;
import javafx.scene.input.MouseEvent;
import javafx.scene.input.ScrollEvent;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.paint.PhongMaterial;
import javafx.scene.shape.Box;
import javafx.scene.shape.Sphere;
import javafx.scene.transform.Rotate;
import javafx.scene.transform.Translate;
import javafx.stage.Stage;
import org.fxyz3d.geometry.MathUtils;
import org.fxyz3d.utils.CameraTransformer;

public class LookAtTest extends Application {
    PerspectiveCamera camera = new PerspectiveCamera(true);   
    public Group sceneRoot = new Group();
    public SubScene subScene;
    public CameraTransformer cameraTransform = new CameraTransformer();
    private double cameraDistance = -500;
    private final double sceneWidth = 4000;
    private final double sceneHeight = 4000;

    private double mousePosX;
    private double mousePosY;
    private double mouseOldX;
    private double mouseOldY;
    private double mouseDeltaX;
    private double mouseDeltaY;
    
    @Override
    public void start(Stage primaryStage) throws Exception {

        subScene = new SubScene(sceneRoot, sceneWidth, sceneHeight, true, SceneAntialiasing.BALANCED);
        //Start Tracking mouse movements only when a button is pressed
        subScene.setOnMouseDragged((MouseEvent me) -> mouseDragCamera(me));
        subScene.setOnScroll((ScrollEvent event) -> {
            double modifier = 2.0;
            double modifierFactor = 0.1;

            if (event.isControlDown()) {
                modifier = 1;
            }
            if (event.isShiftDown()) {
                modifier = 50.0;
            }
            double z = camera.getTranslateZ();
            double newZ = z + event.getDeltaY() * modifierFactor * modifier;
            camera.setTranslateZ(newZ);
        });        
        StackPane stackPane = new StackPane(subScene);
        subScene.widthProperty().bind(stackPane.widthProperty());
        subScene.heightProperty().bind(stackPane.heightProperty());
        subScene.setFill(Color.BLACK);

        camera = new PerspectiveCamera(true);        
        //setup camera transform for rotational support
        cameraTransform.setTranslate(0, 0, 0);
        cameraTransform.getChildren().add(camera);
        camera.setNearClip(0.1);
        camera.setFarClip(100000.0);
        camera.setTranslateZ(cameraDistance);
        cameraTransform.ry.setAngle(-45.0);
        cameraTransform.rx.setAngle(-10.0);        
        subScene.setCamera(camera);

        AmbientLight ambientLight = new AmbientLight(Color.WHITE);

        Box center = new Box(2, 2, 2);
        center.setMaterial(new PhongMaterial(Color.AQUA));

        Sphere body = new Sphere(10);
        Box pointer = new Box(2, 2, 20);
        pointer.setMaterial(new PhongMaterial(Color.TOMATO));
        pointer.setTranslateZ(10);
        Group pointyGroup = new Group(body, pointer);

        pointyGroup.setTranslateX(-100);
        
        Sphere sphereX = new Sphere(5);
        sphereX.setTranslateX(100);
        sphereX.setMaterial(new PhongMaterial(Color.RED));
        sphereX.setOnMouseClicked(e -> {
            Point3D currentPoint3D = new Point3D(
                pointyGroup.getTranslateX(), 
                pointyGroup.getTranslateY(), 
                pointyGroup.getTranslateZ());
            Point3D lookAtPoint3D = new Point3D(
                sphereX.getTranslateX(), 
                sphereX.getTranslateY(), 
                sphereX.getTranslateZ());
            lookAt(pointyGroup, currentPoint3D, lookAtPoint3D);
        });
        
        Sphere sphereY = new Sphere(5);
        sphereY.setTranslateY(-100);
        sphereY.setMaterial(new PhongMaterial(Color.GREEN));
        sphereY.setOnMouseClicked(e -> {
            Point3D currentPoint3D = new Point3D(
                pointyGroup.getTranslateX(), 
                pointyGroup.getTranslateY(), 
                pointyGroup.getTranslateZ());
            Point3D lookAtPoint3D = new Point3D(
                sphereY.getTranslateX(), 
                sphereY.getTranslateY(), 
                sphereY.getTranslateZ());
            lookAt(pointyGroup, currentPoint3D, lookAtPoint3D);
        });        
        
        
        Sphere sphereZ = new Sphere(5);
        sphereZ.setTranslateZ(100);
        sphereZ.setMaterial(new PhongMaterial(Color.BLUE));
        sphereZ.setOnMouseClicked(e -> {
            Point3D currentPoint3D = new Point3D(
                pointyGroup.getTranslateX(), 
                pointyGroup.getTranslateY(), 
                pointyGroup.getTranslateZ());
            Point3D lookAtPoint3D = new Point3D(
                sphereZ.getTranslateX(), 
                sphereZ.getTranslateY(), 
                sphereZ.getTranslateZ());
            lookAt(pointyGroup, currentPoint3D, lookAtPoint3D);
        });
        
        sceneRoot.getChildren().addAll(cameraTransform, ambientLight, 
            center, sphereX, sphereY, sphereZ, pointyGroup);

        BorderPane bpOilSpill = new BorderPane(subScene);
        stackPane.getChildren().clear();
        stackPane.getChildren().addAll(bpOilSpill);
        stackPane.setPadding(new Insets(10));
        stackPane.setBackground(new Background(new BackgroundFill(Color.rgb(255, 255, 255), CornerRadii.EMPTY, Insets.EMPTY)));
        Scene scene = new Scene(stackPane, 1000, 1000);
        scene.setOnMouseEntered(event -> subScene.requestFocus());
        
        primaryStage.setTitle("Multiple SpotLight Test");
        primaryStage.setScene(scene);
        primaryStage.show();
               
    }
    public void lookAt(Node node, javafx.geometry.Point3D currentPosition, javafx.geometry.Point3D lookAtPos) {          
        //Create direction vector  
        javafx.geometry.Point3D lookDirection = lookAtPos.subtract(currentPosition.getX(), currentPosition.getY(), currentPosition.getZ());  
        lookDirection = lookDirection.normalize();  

        double xRotation = Math.toDegrees(Math.asin(-lookDirection.getY()));  
        double yRotation =  Math.toDegrees(Math.atan2( lookDirection.getX(), lookDirection.getZ()));  
        
        Rotate ry = new Rotate(yRotation, currentPosition.getX(), currentPosition.getY(), currentPosition.getZ(),  Rotate.Y_AXIS);  
        Rotate rx = new Rotate(xRotation, currentPosition.getX(), currentPosition.getY(), currentPosition.getZ(), Rotate.X_AXIS);  
        node.getTransforms().setAll( ry, rx, new Translate( 
            currentPosition.getX(), currentPosition.getY(), currentPosition.getZ())); 
    }       
    private void mouseDragCamera(MouseEvent me) {
        mouseOldX = mousePosX;
        mouseOldY = mousePosY;
        mousePosX = me.getSceneX();
        mousePosY = me.getSceneY();
        mouseDeltaX = (mousePosX - mouseOldX);
        mouseDeltaY = (mousePosY - mouseOldY);
        double modifier = 5.0;
        double modifierFactor = 0.1;

        if (me.isControlDown()) {
            modifier = 1;
        }
        if (me.isShiftDown()) {
            modifier = 10.0;
        }
        if (me.isPrimaryButtonDown()) {
            if(me.isAltDown()) { //roll
                cameraTransform.rz.setAngle(((cameraTransform.rz.getAngle() + mouseDeltaX * modifierFactor * modifier * 2.0) % 360 + 540) % 360 - 180); // +
            } else {
                cameraTransform.ry.setAngle(((cameraTransform.ry.getAngle() + mouseDeltaX * modifierFactor * modifier * 2.0) % 360 + 540) % 360 - 180); // +
                cameraTransform.rx.setAngle(
                        MathUtils.clamp(-60, 
                        (((cameraTransform.rx.getAngle() - mouseDeltaY * modifierFactor * modifier * 2.0) % 360 + 540) % 360 - 180),
                        60)); // - 
            }
        } else if (me.isMiddleButtonDown() ) {
            cameraTransform.t.setX(cameraTransform.t.getX() + mouseDeltaX * modifierFactor * modifier * 0.3); // -
            cameraTransform.t.setY(cameraTransform.t.getY() + mouseDeltaY * modifierFactor * modifier * 0.3); // -
        }
    }    

    public static void main(String[] args){
        Application.launch(LookAtTest.class, args);
    }
}

if i set the initial translation of the group to something other than 0,0,0 (arbitrary... image is translateX(-100) it seems to add the existing translation to the original?

Not sure if I get it right... but have you tried adding the transforms of the parent?

node.getTransforms().setAll(...);
+ node.getTransforms().addAll(0, node.getParent().getTransforms());

this didn't work either... :-/

   node.getTransforms().setAll( ry, rx, new Translate( 

        currentPosition.getX(), currentPosition.getY(), currentPosition.getZ())); 
    node.getTransforms().addAll(0, node.getParent().getTransforms());  

its close... the problem is that its adding the original translation I think... and I'm not sure if its because the "node" is actually a Group?

So this worked:
Rotate ry = new Rotate(yRotation, 0, 0, 0, Rotate.Y_AXIS);
Rotate rx = new Rotate(xRotation, 0, 0, 0, Rotate.X_AXIS);

    node.getTransforms().setAll( ry, rx);

Doing the rotation around 0,0,0 as the pivot point but then not adding in a translate after