The clipping "ratio" is based on the zbuffer resolution you are using.
The 3000 to 1 recommendation comes from the fact that most users still
are using a 16 bit zbuffer.  If your video card (and setup) provide you
with a 32 bit zbuffer you should be able to make this ratio much larger
without inducing problems.  But I think most of us stick with 3000 to 1
because we have no control (nor any way to test) over the user's PC
configuration.

- John Wright
Starfire Research

"ZACZEK, MARIUSZ P. (JSC-DM) (NASA)" wrote:
>
> I believe it might be that the default back clipping plane is too
> close...you may try setting the
> back-clip distance farther back....using:
>
>   u.getViewer().getView().setBackClipDistance( 1000.0 );
>
> Also, you may want to change the front-clipping plane as well if it's too
> far away...with:
>
>   u.getViewer().getView().setFrontClipDistance( 0.001 );
>
> I'm not sure of the actual ratio, but there is a recommendation that the
> ratio of the
> backclip distance to the frontclip distance should be around 3000, at
> worst....but I actually
> don't know the number so you may want to check on that...or maybe someone
> can correct me.
>
>    Mario
>
> Mariusz Zaczek
> NASA - Johnson Space Center
> Automated Vehicles and Orbit Analysis / DM35
> Flight Design and Dynamics Division
> Mission Operations Directorate
> Bldg: 30A     Room: 3048B
>
> Disclaimer: "The opinions, observations and comments expressed in my email
>                    are strictly my own and do not necessarily reflect those
> of NASA."
>
>
> -----Original Message-----
> From: St�phane Vanacker [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, October 03, 2002 5:12 PM
> To: [EMAIL PROTECTED]
> Subject: [JAVA3D] Problem of visualisation when changing distance of a
> ViewPlatform
>
> Hello,
>
> I'm french, so sorry for bad english.
> I have problems when I view an object like a ColorCube and this problem
> appears when I change the distance of the viewingPlatform.
> This is very particular :
>
> With the next Code
>
> trans.setTranslation(new Vector3d(0, 0, 50));
>
> I can see easily the color cube (with the mouse and NavigatorBehavior), but
> when I write
>
> trans.setTranslation(new Vector3d(0, 0, 60));
>
> I see the half of the cube : all is like there would be an opaque black
> object which hides a part of the color cube (you see it when you rotate the
> cube). I don't understand why because my code is just an small adaptation of
> the Basic Sample :
> "HelloUnivers", and I have only one Object, there is no special Appearance,
> no special Material ...
>
> Thanks.
>
> import java.applet.Applet;
> import java.awt.BorderLayout;
> import java.awt.GraphicsConfiguration;
>
> import javax.media.j3d.BoundingSphere;
> import javax.media.j3d.BranchGroup;
> import javax.media.j3d.Canvas3D;
> import javax.media.j3d.Transform3D;
> import javax.media.j3d.TransformGroup;
> import javax.vecmath.Point3d;
> import javax.vecmath.Vector3d;
>
> import com.sun.j3d.utils.applet.MainFrame;
> import com.sun.j3d.utils.behaviors.vp.OrbitBehavior;
> import com.sun.j3d.utils.geometry.ColorCube;
> import com.sun.j3d.utils.universe.SimpleUniverse;
>
> public class HelloUniverse extends Applet {
>
>     private SimpleUniverse u = null;
>
>     public BranchGroup createSceneGraph() {
>   BranchGroup objRoot = new BranchGroup();
>   TransformGroup objTrans = new TransformGroup();
>   objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
>   objRoot.addChild(objTrans);
>   objTrans.addChild(new ColorCube(5));
>      objRoot.compile();
>
>   return objRoot;
>     }
>
>     public HelloUniverse() {
>     }
>
>     public void init() {
>   setLayout(new BorderLayout());
>          GraphicsConfiguration config =
>             SimpleUniverse.getPreferredConfiguration();
>
>   Canvas3D c = new Canvas3D(config);
>   add("Center", c);
>
>   OrbitBehavior orbitBehavior = new OrbitBehavior(c,
> OrbitBehavior.REVERSE_ALL);
>   orbitBehavior.setEnable(true);
>
>   BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0),
> 5000.0);
>   orbitBehavior.setSchedulingBounds(bounds);
>
>   // Create a simple scene and attach it to the virtual universe
>   BranchGroup scene = createSceneGraph();
>   u = new SimpleUniverse(c);
>
>   u.getViewingPlatform().setViewPlatformBehavior(orbitBehavior);
>
>         // This will move the ViewPlatform back a bit so the
>         // objects in the scene can be viewed.
>   Transform3D trans = new Transform3D();
>   trans.setIdentity();
>   trans.setTranslation(new Vector3d(0, 0, 50));
>
>   TransformGroup tg = u.getViewingPlatform().getViewPlatformTransform();
>   tg.setTransform(trans);
>
> //        u.getViewingPlatform().setNominalViewingTransform();
>
>   u.addBranchGraph(scene);
>     }
>
>     public void destroy() {
>   u.removeAllLocales();
>     }
>
>     public static void main(String[] args) {
>   new MainFrame(new HelloUniverse(), 256, 256);
>     }
> }
>
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> [EMAIL PROTECTED] and include in the body of the message "help".

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