How to draw text on a sphere in javafx

Question

I want to draw a text onto a sphere in javafx.

I try to keep it purely javafx. I'm using a PerspectiveCamera.

One option would be to just draw 3D-text (if that exists) touching the sphere and being parallel to the viewer for good readability. The better option would be to draw a curved text right onto the sphere, also facing the viewer.

Answer 1

Solution 1. Text3D

There is no built-in JavaFX 3D Text node. However you can use a Text3DMesh node from the FXyz library.

Something like this:

build.gradle

plugins {
  id 'application'
  id 'org.openjfx.javafxplugin' version '0.0.7'
}

repositories {
    jcenter()
    mavenCentral()
}

dependencies {
    implementation 'org.fxyz3d:fxyz3d:0.4.0'
}

javafx {
    version = "12"
    modules = [ 'javafx.controls' ]
}

mainClassName = 'text3d.Text3D'

text3d.Text3D.java

public class Text3D extends Application {

    private final Rotate rotateX = new Rotate(10, Rotate.X_AXIS);
    private final Rotate rotateY = new Rotate(-10, Rotate.Y_AXIS);
    private double mousePosX, mousePosY, mouseOldX, mouseOldY;

    @Override
    public void start(Stage stage) throws Exception {
        PerspectiveCamera camera = new PerspectiveCamera(true);
        camera.setNearClip(0.1);
        camera.setFarClip(10000.0);
        camera.getTransforms().addAll (rotateX, rotateY, new Translate(-100, 100, -1000));

        Text3DMesh text3D = new Text3DMesh("Text3D");
        text3D.setFont(Font.getFamilies().get(new Random().nextInt(Font.getFamilies().size())));
        text3D.setFontSize(200);
        text3D.setTextureModeVertices3D(1530, p -> p.y);
        Bounds bounds = text3D.getBoundsInParent();
        text3D.setTranslateX(- bounds.getWidth() / 2d);
        text3D.setTranslateY(bounds.getHeight() / 2d);
        text3D.setTranslateZ(-bounds.getDepth());

        double radius = Math.max(bounds.getWidth(), bounds.getHeight()) * 1.2;
        SpheroidMesh spheroid = new SpheroidMesh(radius);
        spheroid.setTextureModeVertices3D(1530, p -> p.x * p.y);
        spheroid.setTranslateZ(radius);

        Group group = new Group(spheroid, text3D);

        Scene scene = new Scene(group, 400, 300, true, SceneAntialiasing.BALANCED);
        scene.setFill(Color.BISQUE);
        scene.setCamera(camera);

        scene.setOnMousePressed(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
        });

        scene.setOnMouseDragged(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
            rotateX.setAngle(rotateX.getAngle() - (mousePosY - mouseOldY));
            rotateY.setAngle(rotateY.getAngle() + (mousePosX - mouseOldX));
            mouseOldX = mousePosX;
            mouseOldY = mousePosY;
        });

        stage.setScene(scene);
        stage.setTitle("FXyz3D Sample");
        stage.show();
    }
}

Solution 2. Image

Another approach can be done by adding an image as diffuse map of the sphere. Again, this can be done with FXyz.

First, you need to render a regular Text 2D node on a scene, and do a snapshot of it to generate the image.

text3d.Image3D

public class Image3D extends Application {

    private final Rotate rotateX = new Rotate(10, Rotate.X_AXIS);
    private final Rotate rotateY = new Rotate(-10, Rotate.Y_AXIS);

    private double mousePosX;
    private double mousePosY;
    private double mouseOldX;
    private double mouseOldY;

    @Override
    public void start(Stage stage) throws Exception {
        PerspectiveCamera camera = new PerspectiveCamera(true);
        camera.setNearClip(0.1);
        camera.setFarClip(10000.0);
        camera.setFieldOfView(20);
        camera.getTransforms().addAll (rotateX, rotateY, new Translate(-100, 100, -2000));

        Text text = new Text(" Text3D ");
        text.setStroke(Color.DARKGOLDENROD);
        text.setFill(Color.DARKGOLDENROD);
        text.setFont(Font.font(Font.getFamilies().get(new Random().nextInt(Font.getFamilies().size())), 30));
        Group root = new Group(text);
        Scene sceneAux = new Scene(root, root.getBoundsInLocal().getWidth(), root.getBoundsInLocal().getHeight());
        SnapshotParameters sp = new SnapshotParameters();
        double s = Screen.getPrimary().getOutputScaleX();
        sp.setTransform(new Scale(s, s));
        sp.setFill(Color.DARKMAGENTA);
        Image image = root.snapshot(sp, null);

        double radius = 400;
        SpheroidMesh spheroid = new SpheroidMesh(radius);
        ((PhongMaterial) spheroid.getMaterial()).setDiffuseMap(image);
        Group group = new Group(spheroid);

        Scene scene = new Scene(group, 400, 300, true, SceneAntialiasing.BALANCED);
        scene.setFill(Color.BISQUE);
        scene.setCamera(camera);

        scene.setOnMousePressed(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
        });

        scene.setOnMouseDragged(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
            rotateX.setAngle(rotateX.getAngle() - (mousePosY - mouseOldY));
            rotateY.setAngle(rotateY.getAngle() + (mousePosX - mouseOldX));
            mouseOldX = mousePosX;
            mouseOldY = mousePosY;
        });

        stage.setScene(scene);
        stage.setTitle("FXyz3D Sample");
        stage.show();
    }

}

EDIT

Solution 3

While this is not part of FXyz, you can also apply some transforms to wrap the Text3DMesh around the sphere.

Each letter basically is a TriangleMesh with a translate transform in X (offset).

So we take all the points for each letter, remove the transform, and apply the offset, so we have absolute coordinates:

 x = x + offset;

Then we calculate the bending angle based on a given arc length we want and the actual width w of the text node.

 t = (x - w/2) / (w/2) * Pi/2;

Then, for each point, its new coordinates will be:

 x = (R + z) * cos(t);
 z = (R + z) * Sin(t);

text3d.CurvedText3D.java

public class CurvedText3D extends Application {

    private final Rotate rotateX = new Rotate(10, Rotate.X_AXIS);
    private final Rotate rotateY = new Rotate(-10, Rotate.Y_AXIS);

    private double mousePosX, mousePosY, mouseOldX, mouseOldY;

    @Override
    public void start(Stage stage) throws Exception {
        PerspectiveCamera camera = new PerspectiveCamera(true);
        camera.setNearClip(0.1);
        camera.setFarClip(10000.0);
        camera.setFieldOfView(40);
        camera.getTransforms().addAll (rotateX, rotateY, new Translate(-100, 100, -2000));

        Text3DMesh text3D = new Text3DMesh("Round Text3D",
                Font.getFamilies().get(new Random().nextInt(Font.getFamilies().size())), 100, true);
        text3D.setHeight(30);
        text3D.setTextureModeNone(Color.CRIMSON);
        Bounds bounds = text3D.getBoundsInParent();
        double width = bounds.getWidth();

        double radius = Math.max(width, bounds.getHeight());

        text3D.getMeshes().stream()
                .forEach(m -> {
                    ObservableFloatArray points = ((TriangleMesh) m.getMesh()).getPoints();
                    float[] v = new float[points.size()];
                    points.toArray(v);
                    double offset = m.getTransforms().get(0).getTx();
                    m.getTransforms().clear();
                    for (int i = 0; i < v.length; i += 3) {
                        v[i] += offset;
                        double t0 =  (v[i] - width / 2d) / (width / 2d) *  Math.PI / 2;
                        double t1 = (radius + v[i + 2]) * Math.cos(t0);
                        double t2 = (radius + v[i + 2]) * Math.sin(t0);
                        v[i] = (float) t1;
                        v[i + 2] = (float) t2;
                    }
                    ((TriangleMesh) m.getMesh()).getPoints().setAll(v);
                });

        SpheroidMesh spheroid = new SpheroidMesh(radius * 0.9);
        spheroid.setTextureModeVertices3D(1530, p -> p.x * p.y);

        Group group = new Group(spheroid, text3D);

        Scene scene = new Scene(group, 400, 300, true, SceneAntialiasing.BALANCED);
        scene.setFill(Color.BISQUE);
        scene.setCamera(camera);

        scene.setOnMousePressed(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
        });

        scene.setOnMouseDragged(event -> {
            mousePosX = event.getSceneX();
            mousePosY = event.getSceneY();
            rotateX.setAngle(rotateX.getAngle() - (mousePosY - mouseOldY));
            rotateY.setAngle(rotateY.getAngle() + (mousePosX - mouseOldX));
            mouseOldX = mousePosX;
            mouseOldY = mousePosY;
        });

        stage.setScene(scene);
        stage.setTitle("FXyz3D Sample");
        stage.show();
    }

}

Answer 2

One idea that comes to my mind is to render the text normally in an appropriate node like (TextField/Area/Flow) and then take a snapshot of this node. The resulting image could then be used as a texture to wrap around your sphere.