I'm trying to perform a WFS filter with a polygon in EPSG:3031, (the native projection is EPSG:4326 I think). And I'm aware that WFS/GeoServer supports reprojection on the fly. But will the features be filtered before or after they are projected into 3031? That is, does the polygon get projected to the 4326, and then the filter results are projected back, or are the features projected to 3031, where they are filtered?
How would I write a query to do the filtering in the non-native projection? Is this possible?