[JAVA3D] Creating a Background with a color gradient

[Ashwini Chougule]

Hi All, I am trying to create a background with a color gradient. I am working with HelloUniverse example for this. I am trying to use Background geometry. The problem is that when I give the branchgroup , to which the geometry is added as an argument  to setGeometry method of Background class ,I cannot see the effect. The code  is : import java.applet.Applet; import java.awt.BorderLayout; import java.awt.event.*; import java.awt.Color; 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.*; import com.sun.j3d.utils.geometry.Sphere;   public class HelloUniverse extends Applet {     private SimpleUniverse u = null;   Color3f white = new Color3f(1.0f,1.0f,1.0f);   Color3f blue = new Color3f(0.0f,0.0f,1.0f);     private final float[] vertices =           { 1.0f,-1.0f,1.0f,             1.0f, 1.0f,1.0f,            -1.0f, 1.0f,1.0f,            -1.0f,-1.0f,1.0f};     public BranchGroup createSceneGraph() {      BranchGroup objRoot = new BranchGroup();      TransformGroup objTrans = new TransformGroup();    objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);    objRoot.addChild(objTrans);      // Create a simple Shape3D node; add it to the scene graph.    objTrans.addChild(new ColorCube(0.4));      Transform3D yAxis = new Transform3D();    Alpha rotationAlpha = new Alpha(-1, 4000);      RotationInterpolator rotator =    new RotationInterpolator(rotationAlpha, objTrans, yAxis,    0.0f, (float) Math.PI*2.0f);    BoundingSphere bounds =    new BoundingSphere(new Point3d(0.0,0.0,0.0), 100.0);    rotator.setSchedulingBounds(bounds);    objRoot.addChild(rotator);      BranchGroup branch = new BranchGroup();    branch.setCapability(BranchGroup.ALLOW_CHILDREN_EXTEND);    branch.setCapability(BranchGroup.ALLOW_CHILDREN_READ);    branch.setCapability(BranchGroup.ALLOW_CHILDREN_WRITE);      Shape3D rectangle = new Shape3D();    rectangle.setCapability(Shape3D.ALLOW_GEOMETRY_READ);    rectangle.setCapability(Shape3D.ALLOW_GEOMETRY_WRITE);    rectangle.setCapability(Shape3D.ALLOW_APPEARANCE_WRITE);    rectangle.setCapability(Shape3D.ALLOW_APPEARANCE_READ);    rectangle.setCapability(Shape3D.ALLOW_APPEARANCE_OVERRIDE_WRITE);    rectangle.setCapability(Shape3D.ALLOW_APPEARANCE_OVERRIDE_READ);    rectangle.setCapability(Shape3D.ALLOW_LOCAL_TO_VWORLD_READ);      QuadArray aQuadArray = new QuadArray(4,QuadArray.COORDINATES|QuadArray.NORMALS|QuadArray.COLOR_3);    aQuadArray.setCapability(QuadArray.ALLOW_COLOR_READ);    aQuadArray.setCapability(QuadArray.ALLOW_COLOR_WRITE);    aQuadArray.setCapability(QuadArray.ALLOW_COORDINATE_WRITE);    aQuadArray.setCapability(QuadArray.ALLOW_COORDINATE_READ);      aQuadArray.setCoordinates(0,vertices);      Vector3f vector=new Vector3f( 0.0f,0.7f,0.7f);    for( int i = 0; i < 4; i++ )    {aQuadArray.setNormal( i,vector);}      aQuadArray.setColor(0,white);    aQuadArray.setColor(1,white);    aQuadArray.setColor(2,blue);    aQuadArray.setColor(3,blue);        rectangle.addGeometry(aQuadArray);    branch.addChild(rectangle);    Background background = "" Background();    background.setApplicationBounds(bounds);    background.setCapability(Background.ALLOW_GEOMETRY_READ);    background.setCapability(Background.ALLOW_GEOMETRY_WRITE);    background.setGeometry(branch);      objRoot.addChild(background);      objRoot.compile();    return objRoot;    }     public HelloUniverse() {    }     public void init() {      setLayout(new BorderLayout());    GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();      Canvas3D c = new Canvas3D(config);    add("Center", c);      // Create a simple scene and attach it to the virtual universe    BranchGroup scene = createSceneGraph();    u = new SimpleUniverse(c);      u.getViewingPlatform().setNominalViewingTransform();      u.addBranchGraph(scene);  }     public void destroy() {      u.removeAllLocales();    }   public static void main(String[] args) {    new MainFrame(new HelloUniverse(), 256, 256);  }   }