vertical polyline cannot be explored

[yaozhih...@googlemail.com]

Hi,

the following code can be run in the Cesium Sandcastle to render a vertical polyline.
But when panning or zooming the map, the polyline disappears. Could this be a bug?

var viewer = new Cesium.Viewer('cesiumContainer');

var dashedLine = viewer.entities.add({
name : 'Blue dashed line',
polyline : {
positions : Cesium.Cartesian3.fromDegreesArrayHeights([-75, 45, 500000,
-75, 45, 500100]),
width : 4,
material : new Cesium.PolylineDashMaterialProperty({
color: Cesium.Color.CYAN
})
}
});

viewer.zoomTo(viewer.entities);

Zhihang

[Omar Shehata]

It disappears just because the camera moves too fast with any click. Try setting the first point's height to 0 to see that it doesn't disappear.

Another thing you can do is set the camera's reference frame to be on the line so you never lose it:

var center = Cesium.Cartesian3.fromDegrees(-75, 45, 500050);

var transform = Cesium.Transforms.eastNorthUpToFixedFrame(center);

viewer.scene.camera.lookAtTransform(transform, new Cesium.HeadingPitchRange(0, -Math.PI/4, 200));

Here's a Sandcastle link to the camera orbitting this line.

To reset the transform you can then do:

viewer.scene.camera.lookAtTransform(Cesium.Matrix4.IDENTITY)