Hi John,
The multiple renders when something happens is an artifact of our current
implementation. It also isn't very smart about which canvases need
rendered. This will be fixed in the Java 3D 1.2 implementation.
The visual artifacts sounds like a bug.
Doug Twillager
Java 3D Team
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> Subject: [java3d] Flashing, multiple swapping, etc...
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>
>
> So, I've got a problem. Well, my girlfriend tells me I have several, but
> that's for another list.
>
> We have a nice 4 view applet running with a bunch of manipulation and
> picking behaviors going on. We've always noticed a bit of flashing
> sometimes (not predictable, but forcible if transparency values are
> tweaked on the fly). It wasn't a big problem, just one of those things
> to fix someday. This was with 1 view.
>
> Now that we have 4 views things have become a little more serious given that
> some of our models are complicated. I dug in and found that each view was
> rendering 4 times. That means that anytime some action happens there are
> 16(!!!) renders. I don't know if it does a full render, but I do know that
> postSwap is called 16 times for any change. I have a few problems with this.
>
> 1. It should only render once for any change and then only in one
> window if I'm only modifying the view of one window. If I manipulate
> an object, it should do 4 renders.
>
> 2. Not all the rendered images swapped in are the same. Sometimes we
> get flashing geometry (that isn't supposed to). Sometimes Transform
> nodes don't seem to be respected resulting in dancing geometry or
> sometimes blipping monster geometry (an object flashes between tiny
> and huge 2 times (each). While it's sort of cool to see, it's not
> a great thing for demos...
>
> So, #1 on my nice fast machine is passable (NT: P2 450, 256M, ATI...)
> a more compute bound machine (W95: P1 266 80MB, ???) is painful to use or
watch.
>
> #2 is right out.
>
> I started stripping stuff out of our code, disabling this and that and
> came up with the appended test program. Behaves the same on NT, W95, or
> Solaris: four postSwaps (preRenders & postRenders too) for any major
> event. Click the window, click another window, click the window again...
>
> Any ideas? Is this part of the design or ???
>
> -- John
>
>
>
> import java.applet.Applet;
> import java.awt.BorderLayout;
> import java.awt.event.*;
> import java.awt.GraphicsConfiguration;
> import com.sun.j3d.utils.applet.MainFrame;
> import com.sun.j3d.utils.geometry.ColorCube;
> import com.sun.j3d.utils.universe.*;
> import javax.media.j3d.*;
> import javax.vecmath.*;
>
> public class MyHello extends Applet {
>
>
> public BranchGroup createSceneGraph () {
>
> BranchGroup objRoot = new BranchGroup ();
> objRoot.addChild (new ColorCube (0.4));
> objRoot.compile ();
>
> return objRoot;
> }
>
> public MyHello () {
> setLayout (new BorderLayout ());
>
> MyCanvas3D c = new MyCanvas3D ();
> add ("Center", c);
>
> BranchGroup scene = createSceneGraph ();
> SimpleUniverse u = new SimpleUniverse (c);
>
> u.getViewingPlatform ().setNominalViewingTransform ();
>
> u.addBranchGraph (scene);
> }
>
> public static void main (String[] args) {
> new MainFrame (new MyHello (), 256, 256);
> }
>
>
> public class MyCanvas3D extends Canvas3D {
>
> public MyCanvas3D () {
> super (null);
> }
>
> public void postSwap () {
> System.out.println ("MyCanvas3D: postSwap "+
> ((System.currentTimeMillis () / 1000)%1000));
> }
> }
> }
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