Jordan90 wrote in Sat Mar 27, 2021 12:43 pm:How do I know where hills are on the server-side? How do I know when object collisions happen?
Basically, you don't - unless you do some client-size calculations and forward those to the server.
Alternatively, you could hack fgms to access a local copy of the whole terrain/scenery database (aka ALL terrain tiles)
and then use the fgelev tool and related sources to compute the corresponding bounding boxes.
Also note that while most people will be satisfied using a simple BB approach, those doing aerobatics or military flying will require very different methods/data resolutions. Similairly, helicopter/VTOL folks will have different "collision detection" requirements, too.