Change scene.pickPosition to globe.pick on Sandcastle

[OmarShehata]

It came up on the forum that setting baseLayerPicker: false makes scene.pickPosition report an incorrect position.

I was about to open a bug for this since I don't think turning off the widget should change this behavior (right?) when I tried @hpinkos 's suggestion here to use globe.pick instead, and that works pretty well.

You can test this in this Sandcastle by turning off the widget and trying to draw:

https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/?src=Drawing%20on%20Terrain.html

This issue is to at least change the Sandcastle to use globe.pick if that's a more stable function. Should there be a separate issue for the baseLayerPicker or should I just make a comment in the scene.pickPosition returns incorrect position issue?

[hpinkos]

For turning off the widget, see #6991
BaseLayerPicker secretly sets globe.depthTestAgainstTerrain = true. pickPosition only works decently well when it's set to true, so when the widget isn't included depthTestAgainstTerrain is false and pickPosition stops working.

I agree that the example would be better using globe.pick instead for picking terrain. I would only recommend using pickPosition for picking the exact position on a 3D tiles or glTF model.

[ggetz]

Closing this as the root issue is #4368.