setSchedulingBounds() question

Engines, Libraries and Tools Java 3D
#1

I’m starting a little project in Java3D and I’m trying to get a better understanding of how setSchedulingBounds() works.

To give a very simple example, consider the following lines from HelloJava3Dd.java:

// a bounding sphere specifies a region a behavior is active
      // create a sphere centered at the origin with radius of 1
      BoundingSphere bounds = new BoundingSphere();
      rotator.setSchedulingBounds(bounds);
      objSpin.addChild(rotator);

No problem so far. ColorCube rotates fine.

Now change:

BoundingSphere bounds = new BoundingSphere();

to

new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 1.0);

Still OK, as I understand things, this is pretty much the same as the empty constructor. ColorCube still rotates fine.

Now, if I comment out the following line, the ColorCube won’t rotate. Also as expected.

rotator.setSchedulingBounds(bounds);

Here’s my problem/question:
If I change the default position of the bounding sphere or give it a really small radius, the ColorCube still rotates fine. Should the bounding sphere intersect the ColorCube at any (however small) position or at all positions? I’m failing to see a tight correlation between the location/size of the bounding sphere and the rotation.

For a ColorCube constructed with a scale of 0.4, the rotation will work for the first bounding sphere below, but not for the second.

This works:

BoundingSphere bounds = new BoundingSphere(new Point3d(30.0, 30.0, 30.0), 0.0001);

This doesn’t:

BoundingSphere bounds = new BoundingSphere(new Point3d(40.0, 40.0, 40.0), 0.0001);

Thanks for your help!

#2

Think I found my answer in Selman’s book (pg. 165). “When the Bounds for a Behavior and the ViewPlatform’s activation radius intersect, the Behavior is scheduled for processing.”

My understanding (now) is that the Bounds for a Behavior don’t have to be anywhere near the actual object(s) that the Behavior is performed upon. If I place a ColorCube out of site, but my rotator Behavior bounds intersect the ViewPlatform’s activation radius, the ColorCube will spin out of sight. Likewise, if I place my ColorCube in view, but add rotator Bounds outside of the ViewPlatform’s activation radius, the ColorCube will be visible, but won’t rotate.

Hopefully a moment of clarity.