clipping of MeshView scalafx/javafx - javafx

Question

I have the following test code, where I try to clip a MeshView with a circle.
I also tried putting the meshView into a group then clipping that, but this result in a black circle.
Is there a way to clip a MeshView, preferably without putting it into a group?
import scalafx.application.JFXApp
import scalafx.application.JFXApp.PrimaryStage
import scalafx.scene.image.Image
import scalafx.scene.paint.{Color, PhongMaterial}
import scalafx.scene.shape.{TriangleMesh, Circle, MeshView}
import scalafx.scene.{Group, PerspectiveCamera, Scene, SceneAntialiasing}
object Test4 extends JFXApp {
stage = new PrimaryStage {
scene = new Scene(500, 500, true, SceneAntialiasing.Balanced) {
fill = Color.LightGray
val clipCircle = Circle(150.0)
val meshView = new MeshView(new RectangleMesh(500,500)) {
// takes a while to load
material = new PhongMaterial(Color.White, new Image("https://peach.blender.org/wp-content/uploads/bbb-splash.png"), null, null, null)
}
// val meshGroup = new Group(meshView)
meshView.setClip(clipCircle)
root = new Group {children = meshView; translateX = 250.0; translateY = 250.0; translateZ = 560.0}
camera = new PerspectiveCamera(false)
}
}
}
class RectangleMesh(Width: Float, Height: Float) extends TriangleMesh {
points = Array(
-Width / 2, Height / 2, 0,
-Width / 2, -Height / 2, 0,
Width / 2, Height / 2, 0,
Width / 2, -Height / 2, 0
)
texCoords = Array(
1, 1,
1, 0,
0, 1,
0, 0
)
faces = Array(
2, 2, 1, 1, 0, 0,
2, 2, 3, 3, 1, 1
)

Answer 1

The clippling actually works fine over the MeshView wrapped around a Group.
If you check JavaDoc for setClip():
There is a known limitation of mixing Clip with a 3D Transform. Clipping is essentially a 2D image operation. The result of a Clip set on a Group node with 3D transformed children will cause its children to be rendered in order without Z-buffering applied between those children.
As a result of this:
Group meshGroup = new Group(meshView);
meshGroup.setClip(clipCircle);
you will have a 2D image, and it seems Material is not applied. However you can check there's a mesh, by seting this:
meshView.setDrawMode(DrawMode.LINE);
So in your case, adjusting dimensions:
#Override
public void start(Stage primaryStage) {
Circle clipCircle = new Circle(220.0);
MeshView meshView = new MeshView(new RectangleMesh(400,400));
meshView.setDrawMode(DrawMode.LINE);
Group meshGroup = new Group(meshView);
meshGroup.setClip(clipCircle);
PerspectiveCamera camera = new PerspectiveCamera(false);
StackPane root = new StackPane();
final Circle circle = new Circle(220.0);
circle.setFill(Color.TRANSPARENT);
circle.setStroke(Color.RED);
root.getChildren().addAll(meshGroup, circle);
Scene scene = new Scene(root, 500, 500, true, SceneAntialiasing.BALANCED);
scene.setCamera(camera);
primaryStage.setTitle("Hello World!");
primaryStage.setScene(scene);
primaryStage.show();
}
will give this:
In the end, clipping doesn't make sense with 3D shapes. For that you can use just 2D shape to get the result you want.
If you want 3D clipping have a look at CSG operations. Check this question for a JavaFX based solution.