This is a pixel accurate implementation of picking. Picking queries
can be created on view, and upon completion a user provided callback
is called with the Entity of the renderable at the queried coordinates
in the viewport.
Picking queries typically have 1 or 2 frame of latency and may impact
performance on some drivers.
It is mostly intended for use by editors, or when latency is not a major
concern. This api should not be used for dragging/moving objects, it is
intended for initial picking only.
Picking is implemented in the structure pass.
The depth buffer value is retrieved and the fragment coordinate is
reconstructed and passed to PickingQueryResult. This can be used in
turn to calculate the view and/or world space position.
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