Limiting Camera Tilting

This issue stems from the following community forum post: https://community.cesium.com/t/how-to-limit-tilt/14459

There has been a significant history of community forum questions/complaints related to camera functionality in CesiumJS. Limiting the camera tilt can help prevent users from ending up “underground” or getting lost in the scene by moving the mouse rapidly to tilt the camera to view both extremes (+90 degrees, -90 degrees). Adding an additional function called limitTilt() to the Camera object may make sense, although other suggestions are welcome.

In offline discussion, both @lilleyse and @ebogo1 seem to support this feature as well. Here is a sandcastle demo that showcases how this feature might perform:

https://sandcastle.cesium.com/#c=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

While this demo is not perfect, it should give readers an idea of what we are looking for.

[ebogo1]

@robmilton At this time it doesn’t seem like we’ll be able to get to this in the near future, but we have this and other Camera fixes in mind for when we get a chance to work on them.

[lilleyse]

This would be a really welcome feature.

My thinking is that it would a property called minimumTiltAngle in ScreenSpaceCameraController. The implementation would be almost completely be in ScreenSpaceCameraController instead of Camera.