Posted by philjord on Feb 05, 2016; 11:33pm
URL: https://forum.jogamp.org/Canvas3D-disappears-when-resizing-JComponets-on-Windows10-tp4036118p4036124.html

Tom,
I can't tell you the exact cause but I can tell you how to work around the issue.

It appears to have been around since 2002
https://www.mail-archive.com/java3d-interest@java.sun.com/msg18026.html

The issue is that the renderer decides not to update the Canvas3D in the name of efficiency. However something else comes in and clears the Canvas3D to grey in a race condition with the Renderer, so you get the crazy sometimes grey output.

The work around is to always have at least 1 non passive behavior in the scene graph

Like this:




import java.awt.Frame;
import java.util.Enumeration;

import javax.media.j3d.Behavior;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.WakeupCondition;
import javax.media.j3d.WakeupOnElapsedFrames;
import javax.swing.SwingUtilities;
import javax.vecmath.Point3d;

import com.sun.j3d.utils.geometry.ColorCube;
import com.sun.j3d.utils.universe.SimpleUniverse;

public class Java3DSimpleTest
{
        public static void createAndShowGUI()
        {
                BranchGroup root = new BranchGroup();
                root.addChild(new ColorCube(0.5f));
                root.addChild(go);
                Canvas3D canvas = new Canvas3D(SimpleUniverse.getPreferredConfiguration()) {
                        public void postSwap()
                        {
                                System.out.println("swap called");
                        }
                };

                SimpleUniverse universe = new SimpleUniverse(canvas);
                universe.getViewingPlatform().setNominalViewingTransform();
                universe.addBranchGraph(root);

                Frame frame = new Frame("Java3DSimpleTest");
                frame.add(canvas);
                frame.setSize(400, 400);
                frame.setVisible(true);
        }

        public static void main(String[] args)
        {
                SwingUtilities.invokeLater(new Runnable() {
                        public void run()
                        {
                                createAndShowGUI();
                        }
                });
        }

        private static GoBehavior go = new GoBehavior();

        private static class GoBehavior extends Behavior
        {
                private WakeupCondition FPSCriterion = new WakeupOnElapsedFrames(0, false);

                public GoBehavior()
                {
                        setSchedulingBounds(new BoundingSphere(new Point3d(0.0, 0.0, 0.0), Double.POSITIVE_INFINITY));
                        setEnable(true);
                }

                public void initialize()
                {
                        wakeupOn(FPSCriterion);
                }

                @SuppressWarnings("rawtypes")
                public void processStimulus(Enumeration criteria)
                {

                        wakeupOn(FPSCriterion);
                }
        }

}


Notice if you comment out the line
 root.addChild(go);

then the console no longer fills with swap called.

Sorry I don't don't the actual cause and a decent way around whatever is painting the grey.
Phil.