Investigate options for fading out distance culled objects

[Aitolda]

At the moment, culled meshes will simple pop out of existence. If possible, a fade out (such as we currently do with the sit object icon using) would be far less jarring.

I would suggest having the beginning of the fade out immediately at the specified distance, for example, if the property is "vircadia_lod_hide = 30" , once the camera is 30 meters/units from the object it would switch to "alpha blend" mode and gradually transition to an alpha of 0 before being culled completely. Perhaps a property for the fade distance would be necessessary. Something like "vircadia_hide_transition = (n)" in meters. Where (n) is the distance beyond those 30 meters where said transition occurs.

[Gigabyte5671]

For reference, the code for fading the labels in/out is here.

This begins to fade the labels out about 1m before they pop, and completes the fadeout (visibility = 0) at the pop distance. This ensures the popping is not visible.