Do they work fine in EMP? If I were to use a few of these in a map, say to create a bridge that exists when the map starts, but can be destroyed (with more than just a single nuke or arty), or maybe even a building that falls down when with with enough damage? I'm a bit unsure how much this would lag the servers and or clients? if it is OK, what are good health stats on the brush?
For bridges that can be destroyed and rebuilt, use emp_eng_map_brush. Func_breakable shouldn't lag much.
Breakable is not laggy at all, and can be used in Empires without any problem. If you want things to collapse and react with physics, it won't. For that you need func_physbox, which can cause lag when overused. The best way to do it is to set the "debris" flag. That way blocks don't collide with eachother, but it is a lot less laggy. As for health values, just experiment. It depends on the material type and other factors too (I don't think stone can be damaged by small arms, for example).
While mapping for CWMP I made a house that started out burning at the start of the game, It was comprised of about 8 phys_boxes and 20+ func_breakables for the walls. It worked nicely in multiplayer and several times I played with other people and we just watched the house burn down. Happened differently each time which was cool. Didn't seem to lag too much either. Took about 5 minutes usually to fully be destroyed to rubble.
I might still have the map around on my home computer somewhere if you want to take a look. I tried using physboxes for the walls as well but they tended to shift and slide around a bit which was annoying. I ended up just using physboxes for the tin roof panels and the wooden beams across the roof to hold those up.
You remember too much... *eyes suspiciously* That entire mod died a gruesome death due to some poor leadership but I learnt a lot about the engine on the way. If I can get my hammer working again I'll make a bash at a map for empires perhaps. Can anyone give me that link to the empires wiki and how to set up hammer for empires?