Hi,

i can't add an object in runtime to a Java 3D environment.

I'm trying to construct a kind of hollow cube, and when you click
somewhere along the axis of the cube, a square appears inside the cube.

See screenshot : http://www.seo-web-hosting.be/hypercube/screenshot.jpg

Now i'm trying to make a square appear by adding a behavior to the
branchgroup and telling it to add a square at runtime, when any key is
pressed.

The results so far have been discouraging :-(.
Sometimes i get an error telling me that only a branchgroup can be
added, and when i try placing the square in a branchgroup, nothing
happens.

I'll add my code below.

   public BranchGroup createSceneGraph() {

       // Create the root of the branch graph
       BranchGroup objRoot = new BranchGroup();
       //BranchGroup addBehavior = new BranchGroup();
       Transform3D rotate = new Transform3D();
       Transform3D tempRotate = new Transform3D();
       rotate.rotX(Math.PI/7.0d);
       tempRotate.rotY(Math.PI/4.0d);
       rotate.mul(tempRotate);
       TransformGroup objRotate = new TransformGroup(rotate);
       objRoot.setCapability(BranchGroup.ALLOW_CHILDREN_WRITE);
       objRoot.setCapability(BranchGroup.ALLOW_CHILDREN_EXTEND);
       objRoot.setCapability(BranchGroup.ALLOW_CHILDREN_READ);
       SimpleBehavior myRotationBehavior = new
SimpleBehavior(objRoot);
       myRotationBehavior.setSchedulingBounds(new BoundingSphere());

       objRoot.addChild(myRotationBehavior);
       objRoot.addChild(objRotate);

// this is the important code from createSceneGraph(), the rest is to
construct the hollow cube.

//And this is the code from the SimpleBehavior class

import java.awt.event.KeyEvent;
import javax.media.j3d.Behavior;
import javax.media.j3d.TransformGroup;
import javax.media.j3d.WakeupOnAWTEvent;
import java.util.Enumeration;
import javax.media.j3d.QuadArray;
import javax.media.j3d.Appearance;
import javax.media.j3d.ColoringAttributes;
import javax.media.j3d.Shape3D;
import javax.media.j3d.BranchGroup;

public class SimpleBehavior extends Behavior {
       private BranchGroup objRoot;
       SimpleBehavior(BranchGroup objRoot){
           this.objRoot = objRoot;
       }

   //initialize the behavior
   // set initial wakeup condition
   // called when behavior becomes live
   public void initialize(){
       //set initial wakeup condition
       this.wakeupOn(new WakeupOnAWTEvent(KeyEvent.KEY_PRESSED));
   }

   //called by Java3D when appropriate stimulus occurs
   public void processStimulus(Enumeration criteria){
       //create square environment
        QuadArray qaEnvironment = new QuadArray(4,
QuadArray.COORDINATES);
        float coordsSquareEnvironment [] = {
                                      -0.2f, -0.4f, 0.4f, //de eerste
coordinaat van elk punt bepaalt waar
                                      -0.2f, 0.4f, 0.4f, //de "plaat"
zich bevindt op de environment-as
                                      -0.2f, 0.4f, -0.4f,
                                      -0.2f, -0.4f, -0.4f,
       };
       qaEnvironment.setCoordinates(0, coordsSquareEnvironment);
       Appearance appEnvironment = new Appearance();
       ColoringAttributes caEnvironment = new ColoringAttributes(); //
opmaak environment vierkant
       caEnvironment.setColor(1.0f, 0.0f, 0.0f); // opmaak environment
vierkant
       appEnvironment.setColoringAttributes(caEnvironment);
       Shape3D squareEnvironment = new Shape3D(qaEnvironment,
appEnvironment);
       Transform3D rotate = new Transform3D();
       Transform3D tempRotate = new Transform3D();
       rotate.rotX(Math.PI / 7.0d);
       tempRotate.rotY(Math.PI / 4.0d);
       rotate.mul(tempRotate);
       TransformGroup objRotate = new TransformGroup(rotate);
       objRotate.addChild(squareEnvironment);
       objRoot.addChild(objRotate);

       this.wakeupOn(new WakeupOnAWTEvent(KeyEvent.KEY_PRESSED));
   }
}

What am i doing wrong?