Camera tilt does not work in ICRF

[pjcozzi]

via @emackey

Zoom in to the Earth surface, and use the middle-mouse-drag to tilt the view down so you can see the horizon.

It tilts crazily and doesn't show a level surface view. I presume this is something to do with ICRF frame...

@bagnell when you need a break from the polyline work, we should address this. I'm sure some data is out-of-sync.

[mramato]

You don't even have to zoom in, just using the middle mouse button in the default view causes issues. This is definitely an ICRF problem. I would not debug it in the 2012DA14 asteroid branch because that was a one-off and is pretty out of date. In order to reproduce the issue in any branch, just replace CesiumViewerWidget update function with this. (the else block is the only new code).

        update : function() {
            var currentTime;
            if (this.clockViewModel.owner === this) {
                currentTime = this.clock.tick();
            } else {
                currentTime = this.clock.currentTime;
            }
            this.visualizers.update(currentTime);

            // Update the camera to stay centered on the selected object, if any.
            var viewFromTo = this._viewFromTo;
            if (typeof viewFromTo !== 'undefined') {
                viewFromTo.update(currentTime);
            } else {
                var mode = this.scene.mode;

                var camera = this.scene.getCamera();
                if (mode === SceneMode.SCENE3D) {
                    this.foo = Transforms.computeIcrfToFixedMatrix(currentTime, this.foo);
                    if (typeof this.foo !== 'undefined') {
                        Matrix4.fromRotationTranslation(this.foo, Cartesian3.ZERO, camera.transform);
                    }
                }
            }
            return currentTime;
        },