Textures - Interactive Web-Based Virtual Reality with Java 3D - page 111

Apart from this difference, there are also other minor differences between programming
for applets and applications. For example, the method init is used instead of the construc-
tor in applets. Further information on this issue can be found from the Java Applet API
documentation at http://java.sun.com/products/jdk/1.2/docs/api/java/applet/Applet.html
and http://mercury.tvu.ac.uk/oop/oop_11.html. Figures 16 and 17 present an example code
segment for an applet. Note the use of the method Load starting from line 29, and the fact
that java.net.* has to be imported for using the URL class. Lastly, the code segment should
be run as an index.html file in the context of a browser.

Figure 16. First code segment for Myearth_applet.java

1. import java.applet.Applet; import java.awt.BorderLayout; import java.awt.Frame;

2. import java.awt.event.*; import java.awt.GraphicsConfiguration;

3. import com.sun.j3d.utils.applet.MainFrame; import com.sun.j3d.utils.universe.*;

4. import com.sun.j3d.utils.image.TextureLoader; import com.sun.j3d.utils.geometry.*;

5. import javax.media.j3d.*; import java.net.*;

6.

7. public class Myearth_applet extends Applet {

8. private java.net.URL go = null;

9. private Texture texture = null;

10. private SimpleUniverse simpleU= null;

11.

12. public void init() { // initialize applet, equivalent to constructor in application

13. setLayout(new BorderLayout());

14. GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();

15. Canvas3D canvas3D = new Canvas3D(config);

16. add("Center", canvas3D); canvas3D.setStereoEnable(false);

17. BranchGroup scene = createSceneGraph();

18. simpleU = new SimpleUniverse(canvas3D);

19. simpleU.getViewingPlatform().setNominalViewingTransform();

20. simpleU.addBranchGraph(scene); }

21.
22. public void destroy() { simpleU.removeAllLocales(); }

23.
24. Appearance createAppearance() {

25. Appearance Appear = new Appearance();

26. Appear.setTexture(Load());

27. return Appear; }

28.
29. public Texture Load() { // load texture

30. try go= new java.net.URL(getCodeBase().toString()+"earth.jpg");

31. catch (java.net.MalformedURLException ex) {

32. System.out.println(ex.getMessage());

33. System.exit(1); }

34. texture = new TextureLoader(go, this).getTexture();

35. return texture; }

36.