Have you implemented the multi-polygon interfaces for the union and intersection operations?
Polygons with holes (not being multi-polygons) are there already.
I'm busy with the overlay operations, it is somewhat delayed but the plan was to have it in the sandbox again soon. Including multi's.
Kef didn't specify whether he wanted to merge 2 polygons with holes or N polygons with holes. I would expect it is the latter.
Interesting. What do you mean by overlay operations, exactly? Two layer map-overlay or N-layer?
Sorry, I interpreted your question wrongly. We call a multi polygon a geometry object having more than one polygon. That one is supported. N-layer will be supported once and is (theoretically) feasable by the same algorithm-set but not supported now. Overlay operations are currently still intersection / union, that state didn't change after review. Barend