How to add multiple light effects on a pane?

Question

I have a problem with JavaFX light effects. I have a game that needs multiple pointlights on the same pane, but I haven't managed to do that, if its even possible. Right now I have a pane and all the elements on top of it.

This seems to be bad method, so if someone knows better way to add lightsources for 2D game, I would really appreciate the help!

It also seems that only one light effect can be attached to a pane, because whenever I try to set a new one, the other gets deleted. One light just isn't enough for this project. If there is better way of adding lights, let me know! Maybe attach the light to a block and then somehow make it shine on the pane? Here is the code:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.effect.Light;
import javafx.scene.effect.Lighting;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class game extends Application{

@Override
public void start(Stage alku) throws Exception {
    Pane test=new Pane();
    Rectangle box = new Rectangle(200,200);
    box.setFill(Color.WHITE);
    box.setTranslateX(50);
    box.setTranslateY(50);
    test.getChildren().add(box);
    
    Rectangle box2 = new Rectangle(200,200);
    box2.setFill(Color.WHITE);
    box2.setTranslateX(50);
    box2.setTranslateY(300);
    test.getChildren().add(box2);
    
    Scene scene = new Scene(test,400,400);
    
Lighting light = new Lighting();
Light.Point l = new Light.Point();
l.xProperty().set(70);
l.yProperty().set(200);
l.setZ(50);
l.setColor(Color.GREEN);
light.setLight(l);
test.setEffect(light);


  Lighting light2 = new Lighting();
Light.Point l2 = new Light.Point();
l2.xProperty().set(20);
l2.yProperty().set(200);
l2.setZ(50);
l2.setColor(Color.RED);
light2.setLight(l2);
test.setEffect(light2);



    alku.setTitle("light test");
    alku.setScene(scene);
    alku.show();
}


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


}


    

this is how it looks at the moment

So the "light" gets overwritten.

Answer 1

The effect property is a property like any other in Java. If you set it to one value, and then immediately set it to a second value, it will have the second value.

To combine two effects, use a Blend:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.effect.Blend;
import javafx.scene.effect.BlendMode;
import javafx.scene.effect.Light;
import javafx.scene.effect.Lighting;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class Game extends Application {

    @Override
    public void start(Stage alku) throws Exception {
        Pane test = new Pane();
        Rectangle box = new Rectangle(200, 200);
        box.setFill(Color.WHITE);
        box.setTranslateX(50);
        box.setTranslateY(50);
        test.getChildren().add(box);

        Rectangle box2 = new Rectangle(200, 200);
        box2.setFill(Color.WHITE);
        box2.setTranslateX(50);
        box2.setTranslateY(300);
        test.getChildren().add(box2);

        Scene scene = new Scene(test, 400, 400);

        Lighting light = new Lighting();
        Light.Point l = new Light.Point();
        l.xProperty().set(70);
        l.yProperty().set(200);
        l.setZ(50);
        l.setColor(Color.GREEN);
        light.setLight(l);
        //test.setEffect(light);

        Lighting light2 = new Lighting();
        Light.Point l2 = new Light.Point();
        l2.xProperty().set(20);
        l2.yProperty().set(200);
        l2.setZ(50);
        l2.setColor(Color.RED);
        light2.setLight(l2);
        //test.setEffect(light2);

        Blend blend = new Blend(BlendMode.ADD);
        blend.setTopInput(light);
        blend.setBottomInput(light2);
        
        test.setEffect(blend);

        alku.setTitle("light test");
        alku.setScene(scene);
        alku.show();
    }

    public static void main(String[] args) {

        launch(args);
    }

}

You can basically do the same thing for an arbitrary number of lights:

Lighting[] lotsOfLights = ... ;

Effect allLights = lotsOfLights[0] ;

for (int i = 1 ; i < lotsOfLights.length ; i++) 
    allLights = new Blend(BlendMode.ADD, allLights, lotsOfLights[i]);

someNode.setEffect(allLights);