Dynamic boxes don't track correctly

[emackey]

Noticed during testing of #5133.

Boxes with dynamic geometry don't track correctly when the clock is animating. You can pause the clock, and track such a box with the camera, and that works fine. But when the clock moves, the box flies away from the camera.

Note that boxes are believed to be representative of almost all "dynamic" geometry with the exception of ellipsoids in 3D mode. Ellipsoids in 3D mode are actually not "dynamic" in the normal Cesium sense of rebuilding vertex data every frame, instead they modify their matrices for better performance. Boxes could be made to do that too, but this issue is specifically to track geometry that must be rebuilt every frame, and dynamic boxes are currently a good test case for that.

This is a very old bug, dating back at least to the introduction of boxes themselves. The most recent version of Cesium that doesn't show this bug is 1.22, because there is no dynamic box:

Working, but no box: Cesium 1.22 test

Box present, tracking broken: Cesium 1.23 test

More recent, same behavior: Cesium 1.31 test

[mc-allen]

I am hitting this in a use case of tracking a moving object with a "keepout box" around it. An ellipsoid works fine, but if I use a box the tracking doesn't work and the camera is pointed at the original entity position at T0.

I would appreciate prioritizing this issue.

[hpinkos]

Related to #6631

DynamicEllipsoidGeometryUpdater was optimized so that it only recreates the EllipsoidGeometry when certain properties that require a recreation change. DynamicBoxGeometryUpdater could be optimized similarly. @mc-allen if you open a pull request, we would be happy to review it! I'm not sure how soon someone from our team would be able to look into this. Thanks

[hpinkos]

Also reported by @461255824 in #8800

See test case here: #8800 (comment)

[461255824]

thank you! the project is amazing

[OmarShehata]

Reported again on the forum: https://community.cesium.com/t/problem-of-tracking-entity-with-dynamic-polygon-hierarchy/9809

When I have a tracked entity without dynamic polygon hierarchy, it runs correctly.

Once I added the dynamic polygon hierarchy in the way of callback property, the tracking camera seemed to be still at the start moment that never tracking the entity.
Sandcastle

[dzungpng]

A potential fix is to change the second argument in getBoundingSphere in Viewer.js (

cesium/Source/Widgets/Viewer/Viewer.js

Line 1820 in 81f1306

false,

) to true, as mentioned in #9455:

Viewer.prototype._onTick = function (clock) {
  var time = clock.currentTime;

  var isUpdated = this._dataSourceDisplay.update(time);
  if (this._allowDataSourcesToSuspendAnimation) {
    this._clockViewModel.canAnimate = isUpdated;
  }

  var entityView = this._entityView;
  if (defined(entityView)) {
    var trackedEntity = this._trackedEntity;
    var trackedState = this._dataSourceDisplay.getBoundingSphere(
      trackedEntity,
      // false,
      true, //switch false to true
      boundingSphereScratch
    );
    if (trackedState === BoundingSphereState.DONE) {
      entityView.update(time, boundingSphereScratch);
    }
  }
...

This sets allowPartial to true. Definition for allowPartial:
pending bounding spheres are ignored and an answer will be returned from the currently available data

This may not be the best fix since it could incorrectly return when the data is not ready yet.

More here:

cesium/Source/DataSources/DataSourceDisplay.js

Line 346 in 81f1306

DataSourceDisplay.prototype.getBoundingSphere = function (

[ggetz]

Reported in #10517