Fix depth plane clipping

[lilleyse]

Fixes #7879. Merge #8207 first.

Pushes the depth plane farther from the camera so that the depth plane does not render above primitives in the scene.

This is a lot like existing code that used to push the depth plane below classification primitives to avoid rendering artifacts. 1fda8c0

Don't merge until #8179 is fixed, otherwise pickPosition will be extremely wrong when scene.depthTestAgainstTerrain is false.

[cesium-concierge]

Thanks for the pull request @lilleyse!

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Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.
• Works (or fails gracefully) in IE11.

[mramato]

@lilleyse who should review this, @IanLilleyT?

[simonasdmd]

@lilleyse Hello. Could you please look at this question? 8181

[cesium-concierge]

Thanks again for your contribution @lilleyse!

No one has commented on this pull request in 30 days. Maintainers, can you review, merge or close to keep things tidy?

I'm going to re-bump this in 30 days. If you'd like me to stop, just comment with @cesium-concierge stop. If you want me to start again, just delete the comment.

[cesium-concierge]

Thanks again for your contribution @lilleyse!

No one has commented on this pull request in 30 days. Maintainers, can you review, merge or close to keep things tidy?

I'm going to re-bump this in 30 days. If you'd like me to stop, just comment with @cesium-concierge stop. If you want me to start again, just delete the comment.

[lilleyse]

Closing this, it's too Earth-centric. A better approach will involving finding the min/max heights based on the loaded terrain tiles / 3D Tiles kind of like #8398