通过鼠标最简单的旋转相机不起作用

Question

好吧，这快把我逼疯了。文档很薄弱，Oracle 的示例应用程序很奇怪，有一个巨大的令人费解的帮助类，甚至这里的问题都没有答案！

我在很大程度上遵循并简化了this tutorial，但我没有旋转对象，而是尝试旋转相机，所以当你拖动鼠标时，它应该围绕相机旋转。

但是，尽管我已经通过控制台日志和调试确认正在调用事件处理程序，并且一切似乎都有正确的值，但我的轮换永远不会发生！我错过了什么？

此外，我根本无法移动相机，即使（注释掉）translateX 之类的也不起作用，所以我很困惑，但无法让轴看起来喜欢除了左上角的任何地方！

import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.scene.Camera;
import javafx.scene.Group;
import javafx.scene.PerspectiveCamera;
import javafx.scene.paint.Color;
import javafx.scene.paint.PhongMaterial;
import javafx.scene.shape.Box;
import javafx.scene.transform.Rotate;

public class RotateCameraExample extends Group {

    private double anchorX, anchorY;
    private double anchorAngleX = 0;
    private double anchorAngleY = 0;
    private DoubleProperty angleX = new SimpleDoubleProperty(0);
    private DoubleProperty angleY = new SimpleDoubleProperty(0);

    Camera camera;
    Group axes;

    public RotateCameraExample() {
        axes = buildAxes();
        getChildren().add(axes);

        camera = new PerspectiveCamera(true);
        camera.setFarClip(6000);
        camera.setNearClip(0.01);
        //camera.translateYProperty().set(300); // this doesn't do anything!  why?

        getChildren().add(camera);
        initMouseControl();
    }

    private void initMouseControl() {
        Rotate xRotate = new Rotate(0, Rotate.X_AXIS);
        Rotate yRotate = new Rotate(0, Rotate.Y_AXIS);
        camera.getTransforms().addAll(xRotate, yRotate);

        xRotate.angleProperty().bind(angleX);
        yRotate.angleProperty().bind(angleY);

        setOnMousePressed(event -> {
            anchorX = event.getSceneX();
            anchorY = event.getSceneY();
            anchorAngleX = angleX.get();
            anchorAngleY = angleY.get();
        });

        setOnMouseDragged(event -> {
            angleX.set(anchorAngleX - (anchorY - event.getSceneY()));
            angleY.set(anchorAngleY + anchorX - event.getSceneX());
        });
    }

    private Group buildAxes() {
        final Box xAxis = new Box(1200, 10, 10);
        final Box yAxis = new Box(10, 1200, 10);
        final Box zAxis = new Box(10, 10, 1200);

        xAxis.setMaterial(new PhongMaterial(Color.RED));
        yAxis.setMaterial(new PhongMaterial(Color.GREEN));
        zAxis.setMaterial(new PhongMaterial(Color.BLUE));

        Group axisGroup = new Group();
        axisGroup.getChildren().addAll(xAxis, yAxis, zAxis);
        return axisGroup;
    }
}

这里可以看到轴在左上角可见，我希望它在围绕它移动相机时保持在 (0, 0, 0)。

这是Application 的启动代码，这显然不是问题：

public class TestApp extends Application {
    @Override
    public void start(Stage stage) throws IOException {
        RotateCameraExample g = new RotateCameraExample();
        Scene scene = new Scene(g, 800, 800, Color.BLACK);
        stage.setScene(scene);
        stage.show();
    }
    public static void main(String[] args) {
        launch();
    }
}

Answer 1

而不是添加相机到Group的孩子，

getChildren().add(camera);

你应该设置场景的相机。

scene.setCamera(g.camera);

您将立即看到屏幕中心的坐标轴。同样，鼠标处理程序应应用于场景。然后，您可以在场景的处理程序中更新组的变换。

例如，下面的变体改变了相机的旋转以响应鼠标滚动事件。请注意垂直鼠标滚动如何影响围绕 X 轴的旋转，而水平鼠标滚动如何影响围绕 Y 轴的旋转。同样的手势也将整个群体翻译成一个整体。各种键盘命令使您能够围绕 Z 轴旋转相机，沿 Z 轴旋转相机，并重置场景。

你可以平移和旋转圆上的点，如图here；相比之下，这个相关的example 为对象围绕轴的旋转设置动画。

import javafx.application.Application;
import javafx.scene.Camera;
import javafx.scene.Group;
import javafx.scene.PerspectiveCamera;
import javafx.scene.Scene;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.input.ScrollEvent;
import javafx.scene.paint.Color;
import javafx.scene.paint.PhongMaterial;
import javafx.scene.shape.Box;
import javafx.scene.transform.Rotate;
import javafx.stage.Stage;

/**
 * @see https://stackoverflow.com/a/69260181/230513
 */
public class RotateCameraExample extends Application {

    private static class RotateCamera extends Group {

        private final Camera camera;
        private final Rotate xRotate = new Rotate(0, Rotate.X_AXIS);
        private final Rotate yRotate = new Rotate(0, Rotate.Y_AXIS);
        private final Rotate zRotate = new Rotate(0, Rotate.Z_AXIS);

        public RotateCamera() {
            buildAxes();
            camera = new PerspectiveCamera(true);
            camera.setFarClip(6000);
            camera.setNearClip(0.01);
            camera.setTranslateZ(-2000);
            camera.getTransforms().addAll(xRotate, yRotate, zRotate);
        }

        private void buildAxes() {
            final Box xAxis = new Box(1200, 10, 10);
            final Box yAxis = new Box(10, 1200, 10);
            final Box zAxis = new Box(10, 10, 1200);

            xAxis.setMaterial(new PhongMaterial(Color.RED));
            yAxis.setMaterial(new PhongMaterial(Color.GREEN));
            zAxis.setMaterial(new PhongMaterial(Color.BLUE));

            Group axisGroup = new Group();
            axisGroup.getChildren().addAll(xAxis, yAxis, zAxis);
            this.getChildren().add(axisGroup);
        }
    }

    @Override
    public void start(Stage stage) {
        RotateCamera g = new RotateCamera();
        Scene scene = new Scene(g, 800, 800, Color.BLACK);
        scene.setCamera(g.camera);
        stage.setScene(scene);
        stage.show();
        scene.setOnScroll((final ScrollEvent e) -> {
            g.xRotate.setAngle(g.xRotate.getAngle() + e.getDeltaY() / 10);
            g.yRotate.setAngle(g.yRotate.getAngle() - e.getDeltaX() / 10);
            g.setTranslateX(g.getTranslateX() + e.getDeltaX());
            g.setTranslateY(g.getTranslateY() + e.getDeltaY());
        });
        scene.setOnKeyPressed((KeyEvent e) -> {
            KeyCode code = e.getCode();
            switch (code) {
                case LEFT:
                    g.zRotate.setAngle(g.zRotate.getAngle() + 10);
                    break;
                case RIGHT:
                    g.zRotate.setAngle(g.zRotate.getAngle() - 10);
                    break;
                case UP:
                    g.setTranslateZ(g.getTranslateZ() - 100);
                    break;
                case DOWN:
                    g.setTranslateZ(g.getTranslateZ() + 100);
                    break;
                case HOME:
                    g.xRotate.setAngle(0);
                    g.yRotate.setAngle(0);
                    g.zRotate.setAngle(0);
                    g.setTranslateX(0);
                    g.setTranslateY(0);
                    g.setTranslateZ(0);
                    break;
                default:
                    break;
            }
        });
    }

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