Animation Objects - Interactive Web-Based Virtual Reality with Java 3D - page 140

Figure 4. Code segment and result of RotPathInter.java

1. public BranchGroup createSceneGraph()

2. {

3. BranchGroup objRoot = new BranchGroup();

4.

5. TransformGroup objTrans = new TransformGroup();

6. objTrans.setCapability( TransformGroup.ALLOW_TRANSFORM_WRITE );

7. // this is essential for transformation in a live scene graph

8. objRoot.addChild( objTrans );

9.
10. Transform3D coordRot = new Transform3D(); //local coordinate system is set to default
11.
12. float[] knots = { 0.0f, 0.25f, 0.5f, 0.75f, 1.0f }; //knot values to determine animation
13.
14. Quat4f[] quats = new Quat4f[5]; // quaternions values needed to determine the rotation
15. quats[0] = new Quat4f( 0.0f, -1.0f, 0.0f, 1.0f );
16. quats[1] = new Quat4f( 0.0f, 1.0f, 0.0f, 1.0f );
17. quats[2] = new Quat4f( 1.0f, 0.0f, 0.0f, 1.0f );
18. quats[3] = new Quat4f( -1.0f, 0.0f, 0.0f, 1.0f );
19. quats[4] = new Quat4f( 0.0f, -1.0f, 0.0f, 1.0f );
20.
21. Alpha rotationAlpha = new Alpha( -1, 4000 ); //continuous loop of period 4000 miliseconds
22. RotationPathInterpolator rotator =
23. new RotationPathInterpolator( rotationAlpha, objTrans, coordRot, knots, quats );
24.
25. BoundingSphere bounds = new BoundingSphere();
26. rotator.setSchedulingBounds( bounds );
27. objTrans.addChild ( rotator );

28. // being a node leaf object, rotator have to be added to the appropriate group node.

29.
30. objTrans.addChild( new createRotPathInter() ); //a RotPathInter shape node is added.
31.
32. objRoot.compile();
33.
34. return objRoot;
35. }

rotpospathInterpolator

Combining the effects of both translation and rotation, the class RotPosPathInterpolator
allows a visual object to undergo both translation and rotation along a specified path. Figure