[JAVA3D] PickTool always returns null

[Jurg c]

I'm trying to find out whether and where a line segment and a Shape3D
intersect using PickTool. However, i get null back instead of a PickResult
every time. I've tried just about every capability i can think of on both
the Shape3D and any Group nodes and have also tried the
PickTool.setCapabilities(node, PickTool.INTERSECT_FULL) and setPickable
(true). I've been messing around with this for 3 days now - any help would
be very appreciated. I've listed my code below.
Thanks, Jurg

import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import java.awt.GraphicsConfiguration;
import com.sun.j3d.utils.picking.*;
import javax.swing.*;
import java.awt.*;

class DrawPanel extends JPanel
{
 BranchGroup scene;

   DrawPanel()
   {
      setBackground(Color.WHITE);
      setLayout(new BorderLayout());

      GraphicsConfiguration config =
SimpleUniverse.getPreferredConfiguration();
      Canvas3D canvas3D = new Canvas3D(config);

      add("Center", canvas3D);

      scene = createSceneGraph();

      SimpleUniverse simpleU = new SimpleUniverse(canvas3D);
      simpleU.getViewingPlatform().setNominalViewingTransform();
      simpleU.addBranchGraph(scene);
   }


   public BranchGroup createSceneGraph()
   {
      BranchGroup objRoot = new BranchGroup();

      Appearance a = new Appearance();
      a.setColoringAttributes(new ColoringAttributes
(0.7f,0.9f,0.9f,ColoringAttributes.FASTEST));

      Cylinder c = new Cylinder(0.1f,0.8f, Cylinder.GENERATE_NORMALS |
Cylinder.ENABLE_GEOMETRY_PICKING,a);

      //I only want a tube, but can't be bothered to write my own class
      Shape3D sh = new Shape3D(c.getShape(Cylinder.BODY).getGeometry(),a);
      sh.setBoundsAutoCompute(true);
      PickTool.setCapabilities(sh,PickTool.INTERSECT_FULL);

      objRoot.addChild(sh);
      objRoot.setCapability(Node.ENABLE_PICK_REPORTING);

      return objRoot;
   }

   //Call this after the scene has been made visible (i don't know if this
is actually necessary)
   public void intersects()
   {
      PickTool pt = new PickTool(scene);
      pt.setMode(PickTool.GEOMETRY);
      pt.setShapeSegment(new Point3d(0,0.04,0.3),new Point3d(0,0.04,-0.3));
      PickResult pr = pt.pickAny();


      if (pr == null)
       System.out.println("Nothing intersects "+pr);
      else
       System.out.println("Found an intersection "+pr);

   }
}

public class L3D extends JApplet
{
   public static void main(String[] args)
   {
      JFrame f = new JFrame("Intersect Test");

      DrawPanel dp = new DrawPanel();

      f.getContentPane().add(dp);
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.pack();
      f.setSize(600,400);
      f.setVisible(true);

      //Check if the line segment intersects the tube
      dp.intersects();
   }
}

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