Animation Objects - Interactive Web-Based Virtual Reality with Java 3D - page 137

Figure 2. Code segment and result of DemoPositionPathInterpolator.java

1. public BranchGroup createSceneGraph()

2. {

3. BranchGroup objRoot = createBranchScene();

4. Transform3D t3d = new Transform3D();

5. t3d.rotY(Math.PI/4d);

6. TransformGroup objRotate = new TransformGroup(t3d);

7. TransformGroup objPositionPath = new TransformGroup();

8. objRoot.addChild(objRotate);

9. objRotate.addChild(objPositionPath);

10. objPositionPath.addChild(new Axis().getBG());

11. objPositionPath.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);

12. Point3f[] points = new Point3f[19];

13. for (int i=0;i<18;i++) {

14. float x = (float) 0.5*(float)Math.sin((float)Math.PI*2*i/17);

15. float y = (float) 0.5*(float)Math.cos((float)Math.PI*2*i/17);

16. points[i] = new Point3f(x,y,0);

17. }

18. Points[18] = new Point3f(0f,0.5f,0f);

19. float[] knots = new float[19];

20. for (int i=1;i<18;i++) knots[i] = 1.0f*i/17f;

21. knots[0] = 0f;

22. knots[18] = 1.0f;

23. Alpha posAlpha = new Alpha (-1, 5000);

24. t3d.rotY(-Math.PI/4d);

25. PositionPathInterpolator path =

26. new PositionPathInterpolator (posAlpha, objPositionPath, t3d, knots, points);

27. BoundingSphere bounds = new BoundingSphere();

28. path.setSchedulingBounds(bounds);

29. objPositionPath.addChild(path);

30. objRoot.compile();

31. return objRoot;

32. }