Create a small, cheap to copy (non-qobject) class
Qgs3DMapSettingsSnapshot which is designed to store
just cheap properties of Qgs3DMapSettings. Then use this
object wherever possible to avoid accessing the (non-thread
safe) Qgs3DMapSettings object for retrieval of simple
map properties (eg crs, extent, ...)
Refs https://github.com/qgis/QGIS-Enhancement-Proposals/issues/301
The 3D scene's CRS is not necessarily the same as the project's
CRS. For example, it can be "EPSG:3857" if the project's CRS is
geographic.
The stored extent in the settings is always the 3D scene's extent.
See:
b0d1a4f8b1
