This Java tip shows how to draw an offscreen image created by Java3D system on screen after a button is clicked.

 import com.sun.j3d.utils.geometry.ColorCube;
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import javax.media.j3d.*;
import javax.vecmath.*;

/**
 * PrintFromButton tests renderOffScreenBuffer from a button
 */
public class PrintFromButton extends Applet implements ActionListener {

  OffScreenCanvas3D c;

    private SimpleUniverse u = null;

  public BranchGroup createSceneGraph(Raster drawRaster)
  {
    // Create the root of the branch graph
    BranchGroup objRoot = new BranchGroup();

    // spin object has composited transformation matrix
    Transform3D spin = new Transform3D();
    Transform3D tempspin = new Transform3D();

    spin.rotX(Math.PI/4.0d);
    tempspin.rotY(Math.PI/5.0d);
    spin.mul(tempspin);
    spin.setScale(0.7);
    spin.setTranslation(new Vector3d(-0.4, 0.3, 0.0));

    TransformGroup objTrans = new TransformGroup(spin);
    objRoot.addChild(objTrans);

    // Create a simple shape leaf node, add it to the scene graph.
    // ColorCube is a Convenience Utility class
    objTrans.addChild(new ColorCube(0.4));

    //Create a raster obj
    Shape3D shape = new Shape3D(drawRaster);
    objRoot.addChild(shape);

    // Let Java 3D perform optimizations on this scene graph.
    objRoot.compile();

    return objRoot;
  }

  public PrintFromButton ()
  {
  }

    public void init() {
  setLayout(new BorderLayout());
  GraphicsConfiguration config =
      SimpleUniverse.getPreferredConfiguration();
  BufferedImage bImage = new BufferedImage(200, 200 ,
             BufferedImage.TYPE_INT_ARGB);

  ImageComponent2D buffer =
      new ImageComponent2D(ImageComponent.FORMAT_RGBA, bImage);
  buffer.setCapability(ImageComponent2D.ALLOW_IMAGE_READ);

  Raster drawRaster = new Raster(new Point3f(0.0f, 0.0f, 0.0f),
               Raster.RASTER_COLOR,
               0, 0, 200, 200, buffer, null);
  drawRaster.setCapability(Raster.ALLOW_IMAGE_WRITE);
  // create the main scene graph
  BranchGroup scene = createSceneGraph(drawRaster);
  // create the on-screen canvas
  Canvas3D d = new Canvas3D(config, false);
  add("Center", d);
  // create a simple universe
  u = new SimpleUniverse(d);
  // This will move the ViewPlatform back a bit so the
  // objects in the scene can be viewed.
  u.getViewingPlatform().setNominalViewingTransform();
  // create an off Screen Buffer
  c = new OffScreenCanvas3D(config, true, drawRaster);
  // set the offscreen to match the onscreen
  Screen3D sOn = d.getScreen3D();
  Screen3D sOff = c.getScreen3D();
  sOff.setSize(sOn.getSize());
  sOff.setPhysicalScreenWidth(sOn.getPhysicalScreenWidth());
  sOff.setPhysicalScreenHeight(sOn.getPhysicalScreenHeight());
  // attach the same view to the offscreen canvas
  u.getViewer().getView().addCanvas3D(c);
  // create the gui
  Button b = new Button ("Print");
  b.addActionListener(this);
  Panel p = new Panel();
  p.add(b);
  add("North", p);
  u.addBranchGraph(scene);
    }

    public void destroy() {
  u.cleanup();
    }
  public void actionPerformed(ActionEvent e)
  {
    // perform the print action
    c.print(false);
  }
  public static void main(String argv[])
  {
    new MainFrame(new PrintFromButton(), 500, 500);
  }
}

class OffScreenCanvas3D extends Canvas3D {

  Raster drawRaster;

  boolean printing = false;

  public OffScreenCanvas3D(GraphicsConfiguration gconfig,
      boolean offscreenflag, Raster drawRaster) {

    super(gconfig, offscreenflag);
    this.drawRaster = drawRaster;
  }

  public void print(boolean toWait) {

    if (!toWait)
      printing = true;

    BufferedImage bImage = new BufferedImage(200, 200,
        BufferedImage.TYPE_INT_ARGB);

    ImageComponent2D buffer = new ImageComponent2D(
        ImageComponent.FORMAT_RGBA, bImage);
    buffer.setCapability(ImageComponent2D.ALLOW_IMAGE_READ);

    this.setOffScreenBuffer(buffer);
    this.renderOffScreenBuffer();

    if (toWait) {
      this.waitForOffScreenRendering();
      drawOffScreenBuffer();
    }
  }

  public void postSwap() {

    if (printing) {
      super.postSwap();
      drawOffScreenBuffer();
      printing = false;
    }
  }

  void drawOffScreenBuffer() {

    BufferedImage bImage = this.getOffScreenBuffer().getImage();
    ImageComponent2D newImageComponent = new ImageComponent2D(
        ImageComponent.FORMAT_RGBA, bImage);

    drawRaster.setImage(newImageComponent);
  }
}

class OnScreenCanvas3D extends Canvas3D {

  OffScreenCanvas3D c;

  boolean print = false;

  boolean imageReady = false;

  public OnScreenCanvas3D(GraphicsConfiguration gconfig, boolean offscreenflag) {
    super(gconfig, offscreenflag);
  }

  public void setOffScreenCanvas(OffScreenCanvas3D c) {
    this.c = c;
  }

  public void setImageReady() {
    imageReady = true;
  }

  public void postSwap() {
    if (imageReady && !print) {
      c.print(false);
      print = true;
    }
  }
}