This example shows how to switch the map from one projection to another.
Three zones are defined: World, Metropolitan France and Overseas. And each zone has its own projection.
Switching zone is done either manually by selecting a new zone using the HTML select, or automatically by zooming or paning the map to a new zone.
For example, by drawing a zoom box (hold SHIFT and drag) inside France, the map will switch from ESPG:4326 to EPSG:27582.