// debug function that create a displayable frustrum
  protected Geometry createFrustum(Vector3f[] pts, int i) {
    WireFrustum frustum = new WireFrustum(pts);
    Geometry frustumMdl = new Geometry("f", frustum);
    frustumMdl.setCullHint(Spatial.CullHint.Never);
    frustumMdl.setShadowMode(ShadowMode.Off);
    Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
    mat.getAdditionalRenderState().setWireframe(true);
    frustumMdl.setMaterial(mat);
    switch (i) {
      case 0:
        frustumMdl.getMaterial().setColor("Color", ColorRGBA.Pink);
        break;
      case 1:
        frustumMdl.getMaterial().setColor("Color", ColorRGBA.Red);
        break;
      case 2:
        frustumMdl.getMaterial().setColor("Color", ColorRGBA.Green);
        break;
      case 3:
        frustumMdl.getMaterial().setColor("Color", ColorRGBA.Blue);
        break;
      default:
        frustumMdl.getMaterial().setColor("Color", ColorRGBA.White);
        break;
    }

    frustumMdl.updateGeometricState();
    return frustumMdl;
  }
  @Override
  public void simpleUpdate(float tpf) {
    Quaternion q = new Quaternion();
    angle += tpf;
    angle %= FastMath.TWO_PI;
    q.fromAngles(angle, 0, angle);

    offBox.setLocalRotation(q);
    offBox.updateLogicalState(tpf);
    offBox.updateGeometricState();
  }