I have a GeoJson feature that is rendered with leaflet and proj4(ESPG:31467). Now I want to rotate that feature so that it NW corner points to NE, e.g. 90 deg rotation. Is there a way to do this? Or can you give me hints how to address this issue and develop a LL plugin for such functionality.
For points you can do it using CSS, in the layer you can use the pointToLayer function and return a DivIcon with the CSS class you want. Then the CSS has the rotation applied. See http://davetimmins.com/2015/10/07/Rotated-icons-with-leaflet/ for more details.