Tracking of ellipsoids still not quite working.

[emackey]

Not sure if this is an incomplete fix for #4866, or something new. Check out this demo:

var czml = [
  {
    "id":"document",
    "version":"1.0",
    "clock":{
      "interval":"2016-09-01T00:00:00Z/2016-09-01T23:59:59.99Z",
      "currentTime":"2016-09-01T12:00:00Z",
      "multiplier":60,
      "range":"LOOP_STOP"
    }
  },
  {
    "id":"Test Object",
    "availability":"2016-09-01T00:00:00Z/2016-09-02T00:00:00Z",
    "name":"Test Object",
    "label":{
      "show":true,
      "text":"Test Object",
      "font":"bold 32px \"Droid Sans\",sans-serif",
      "style":"FILL_AND_OUTLINE",
      "scale":0.5,
      "pixelOffset":{
        "cartesian2":[
          5,0
        ]
      },
      "horizontalOrigin":"LEFT",
      "verticalOrigin":"CENTER",
      "fillColor":{
        "rgba":[
          255,255,0,255
        ]
      },
      "outlineColor":{
        "rgba":[
          0,0,0,255
        ]
      },
      "outlineWidth":2.4
    },
    "path":{
      "show":true,
      "width":2,
      "resolution":300,
      "leadTime":0,
      "trailTime":172800,
      "material":{
        "solidColor":{
          "color":{
            "rgba":[
              255,255,0,255
            ]
          }
        }
      }
    },
    "point":{
      "pixelSize":7,
      "color":{
        "rgba":[
          255,255,0,255
        ]
      }
    },
    "ellipsoid":{
      "radii":{
        "epoch":"2016-09-01T00:00:00Z",
        "cartesian":[
          0,279.0,632.0,17831.0,
          86400,283.0,653.0,21218.0
        ]
      },
      "material":{
        "grid":{
          "color":{
            "rgba":[
              255,255,0,255
            ]
          },
          "lineCount":{
            "cartesian2":[
              12,12
            ]
          }
        }
      }
    },
    "position":{
      "interpolationAlgorithm":"LAGRANGE",
      "interpolationDegree":5,
      "epoch":"2016-09-01T00:00:00Z",
      "cartesian":[
        0,41693056.0,-224455.0,-6354563.0,
        8640,42169152.0,-764133.0,-615413.0,
        17280,41814675.0,-1393089.0,5359758.0,
        25920,41119469.0,-1258304.0,9278534.0,
        34560,41040625.0,-560533.0,9635776.0,
        43200,41677063.0,-270318.0,6291754.0,
        51840,42135688.0,-779539.0,529501.0,
        60480,41775147.0,-1360532.0,-5436236.0,
        69120,41098752.0,-1184293.0,-9312281.0,
        77760,41054134.0,-480334.0,-9610528.0,
        86400,41713762.0,-222890.0,-6218657.0
      ]
    }
  }
];

var viewer = new Cesium.Viewer('cesiumContainer');
Cesium.CzmlDataSource.load(czml).then(function(dataSource) {
    viewer.dataSources.add(dataSource);
    viewer.selectedEntity = dataSource.entities.getById('Test Object');
    viewer.scene.camera.setView({
        destination: Cesium.Cartesian3.fromDegrees(-8, 0, 7.7e7)
    });
    viewer.clock.multiplier = 7200;
});

[emackey]

[emackey]

The red sphere above is a bit of a red herring, the real problem is the selection indicator (and the trackedEntity camera, not shown above, but which completely agrees with the portrayed selection indicator) are not correct.

If it looks like the green crosshairs are hanging out at some kind of midpoint between the entity's position and its original position, you're correct, it's the midpoint.

What's happening here is that at load time, a new bounding sphere is created for the Ellipsoid graphics, just once, based on whatever currentTime happens to be when the primitive is constructed. After that, as time animates, only the modelMatrix changes on the ellipsoid (incorporating not just size changes, but deltas from the load position as well, apparently). The ellipsoid's bounding sphere was calculated and cached into an "attributes" cache, and it never changes.

Prior to the fix in #4907, dynamic graphics would recalculate their bounding sphere every frame, by pulling a copy of the cached attribute bounding sphere and transforming it by the current modelMatrix. But the fix removed this modelMatrix transform, and as a result the ellipsoid's bounding sphere is frozen in time, correct only for the time of construction of the ellipsoid.

At a higher level, Viewer is trying to figure out what to track or select, and asks the entity. The entity then enumerates its primitives, and combines their bounding spheres. In this case, the entity's point graphics are reporting their own bounding sphere, with the correct center point, and the ellipsoid graphics are reporting an out-dated bounding sphere, with an out-dated center point. The entity then combines these two bounding spheres, and finds a center point halfway between the current position and the out-dated position. This then becomes the selected/tracked location.

[hpinkos]

Also reported here: https://groups.google.com/forum/?hl=en#!topic/cesium-dev/rCBSbMx8Xmk

[pjcozzi]

I labeled this next release; I don't think we'll be able to do it for 1.31, but we'll try for 1.32.