I've written an AnimPlasma application that animates a colorful plasma image on JavaFX's canvas. The source code appears below (and an explanation of the problem follows):

import javafx.animation.PauseTransition;

import javafx.application.Application;

import javafx.event.ActionEvent;
import javafx.event.EventHandler;

import javafx.geometry.VPos;

import javafx.scene.Group;
import javafx.scene.Scene;

import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;

import javafx.scene.effect.DropShadow;
import javafx.scene.effect.Reflection;

import javafx.scene.paint.Color;
import javafx.scene.paint.CycleMethod;
import javafx.scene.paint.LinearGradient;
import javafx.scene.paint.Stop;

import javafx.scene.text.Font;
import javafx.scene.text.Text;

import javafx.stage.Stage;

import javafx.util.Duration;

public class AnimPlasma extends Application
{
   private int[] palette;
   private byte[][] plasma;
   private int[] colors;

   private GraphicsContext gc;

   @Override
   public void start(final Stage primaryStage)
   {
      primaryStage.setTitle("Animated Plasma");
      primaryStage.setWidth(600);
      primaryStage.setHeight(600);

      final Group group = new Group();

      Text text = new Text();
      text.setText("Animated Plasma");
      text.setFill(Color.YELLOW);
      text.setFont(new Font("Arial BOLD", 24.0));
      text.setEffect(new DropShadow());
      text.xProperty().bind(primaryStage.widthProperty()
                      .subtract(text.layoutBoundsProperty().getValue().getWidth())
                      .divide(2));
      text.setY(30.0);
      text.setTextOrigin(VPos.TOP);
      group.getChildren().add(text);

      Canvas canvas = new Canvas(400, 400);
      canvas.setTranslateX(100);
      canvas.setTranslateY(100);
      gc = canvas.getGraphicsContext2D();
      group.getChildren().add(canvas);
/*
DropShadow ds = new DropShadow();
ds.setInput(new Reflection());
group.setEffect(ds);
*/
      Reflection r = new Reflection();
      r.setInput(new DropShadow()); // This line leads to NullPointerException.
      group.setEffect(r);

      LinearGradient lg = new LinearGradient(0.0, 0.0, 0.0, 1.0, true,
                                             CycleMethod.NO_CYCLE,
                                             new Stop(0, Color.BLUE),
                                             new Stop(1.0, Color.BLUEVIOLET));
      Scene scene = new Scene(group, lg);
      primaryStage.setScene(scene);

      primaryStage.setResizable(false);
      primaryStage.show();

      setup(canvas);

      final PauseTransition pt = new PauseTransition(Duration.millis(30));
      pt.setCycleCount(1);
      pt.setOnFinished(new EventHandler<ActionEvent>()
                       {
                          @Override
                          public void handle(ActionEvent ae)
                          {
                             update(canvas);
                             pt.play();
                          }
                       });
      pt.play();
   }

   void setup(Canvas canvas)
   {
      palette = new int[256];
      for (int i = 0; i < palette.length; i++)
      {
          Color color = Color.hsb(i/255.0*360, 1.0, 1.0);
          int red = (int) (color.getRed()*255);
          int grn = (int) (color.getGreen()*255);
          int blu = (int) (color.getBlue()*255);
          palette[i] = (red << 16)|(grn << 8)|blu;
      }

      plasma = new byte[(int) canvas.getHeight()][];
      for (int i = 0; i < plasma.length; i++)
          plasma[i] = new byte[(int) canvas.getWidth()];

      colors = new int[(int) (canvas.getWidth()*canvas.getHeight())];
   }

   void update(Canvas canvas)
   {
      int width = (int) canvas.getWidth();
      int height = (int) canvas.getHeight();
      for (int row = 0; row < height; row++)
          for (int col = 0; col < width; col++)
              plasma[row][col] =
                     (byte) ((128.0+128.0*Math.cos(row/8.0)+
                            128.0+128.0*Math.cos(col/8.0))/2);

      int shift = (int) System.currentTimeMillis()/5;
      int base = 0;
      for (int row = 0; row < height; row++)
      {
          for (int col = 0; col < width; col++)
          {
              colors[base+col] = palette[(plasma[row][col]+shift)&255];
              int r = (colors[base+col]>>16)&255;
              int g = (colors[base+col]>>8)&255;
              int b = colors[base+col]&255;
              gc.setFill(Color.rgb(r, g, b));
              gc.fillRect(row, col, 1, 1);
          }
         
          base += width;
      }
   }

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

In the following code sequence, r.setInput(new DropShadow()); leads to repeated runtime error messages:

Reflection r = new Reflection();
r.setInput(new DropShadow()); // This line leads to NullPointerException.
group.setEffect(r);

The error message appears below:

java.lang.NullPointerException
at com.sun.scenario.effect.FilterEffect.getBounds(FilterEffect.java:67)
at com.sun.scenario.effect.BoxShadow.getBounds(BoxShadow.java:367)
at com.sun.scenario.effect.Offset.getBounds(Offset.java:145)
at com.sun.scenario.effect.FilterEffect.getBounds(FilterEffect.java:72)
at com.sun.scenario.effect.DelegateEffect.getBounds(DelegateEffect.java:60)
at com.sun.scenario.effect.Effect.getBounds(Effect.java:325)
at com.sun.scenario.effect.Reflection.getDirtyRegions(Reflection.java:271)
at com.sun.javafx.sg.prism.NGNode.applyEffect(NGNode.java:2471)
at com.sun.javafx.sg.prism.NGNode.accumulateGroupDirtyRegion(NGNode.java:1209)
at com.sun.javafx.sg.prism.NGNode.accumulateDirtyRegions(NGNode.java:1033)
at com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:236)
at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:89)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:129)
at java.lang.Thread.run(Thread.java:744)

When I comment out r.setInput(new DropShadow());, everything works fine except that there is no drop shadow. Interestingly, if I replace the three-line code sequence with the following code sequence:

DropShadow ds = new DropShadow();
ds.setInput(new Reflection());
group.setEffect(ds);

there is no problem.

Jeff