Animation Objects - Interactive Web-Based Virtual Reality with Java 3D - page 136

Figure 1. Code segment and result of DemoPositionInterpolator.java

1. public BranchGroup createSceneGraph()

2. {

3. BranchGroup objRoot = createBranchScene();

4.

5. BoundingSphere bound = new BoundingSphere();

6. Alpha alpha = new Alpha(-1, Alpha.INCREASING_ENABLE|Alpha.DECREASING_ENABLE, 0, 0,

4000,2000,1000, 4000, 2000, 1000);

7.

8. TransformGroup objPosition = new TransformGroup();

9. objPosition.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);

10. objPosition.addChild(new Quad());

11.
12. Transform3D axisPosition = new Transform3D();

13. axisPosition.rotZ(Math.PI/2.0);

14. PositionInterpolator positionInterpol = new PositionInterpolator(alpha,

objPosition,axisPosition, 0f, 0.8f);

15. positionInterpol.setSchedulingBounds(bound);

16.
17. TransformGroup objTilt = new TransformGroup();

18.
19. Transform3D tiltX = new Transform3D();

20. Transform3D tiltY = new Transform3D();

21. tiltX.rotX(Math.PI/5.0d);

22. tiltY.rotY(Math.PI/5.0d);

23. tiltX.mul(tiltY);

24. objTilt.setTransform(tiltX);

25.
26. objRoot.addChild(objTilt);

27. objTilt.addChild(objPosition);

28. objPosition.addChild(positionInterpol);

29.
30. objRoot.compile();

31.
32. return objRoot;

33.
34. }

positionpathInterpolator

The code segment and results in Figure 2 show how PositionPathInterpolator can be used
together with the alpha values to change the translational position of the target Transfor-