how do structual and detail brushes work and how do i use them?
detail and structual
Structural brushes as I understand it seal your world from the “void” of space. These brushes also stop the engine from drawing other parts of the level.
Detail brushes are cosmetic only and do not protect your world from the “void” of space or prevent the engine from drawing another area of the level.
Use strucutral brushes sparingly. If you were going to make room with computer equipment inside it you might want to make the wallks, floor and roof structual and all the computer equipment and furiniture a detail brush.
For more information you can open up the Oasis map that came with SD Radient. You’ll notice the buildings in the courtyard are structual brushes wile all the detail (and large parts of the visible buildings themselves) are detail brushes. You can hide detail bruses by clicking CRTL+D.
I hope that explanation helps. I invite others to elaborate.
Thanks,
-Aaron
In the time it took for me to post the reply Ifurita posted a link from Nibbs world that says it best.
Thanks.
For those that are too lazy to click the link…
Structural: Blocks visibility, light, players and so on. HAVE to be used to block the void as CrazedFan said. But since it’s used to block vis, all ceiling, walls and floors should be structural. That means it will lower the tris count (triangles being drawn) and hide stuff you don’t want to be drawn by the engine. If you only have your hull structural, that would mean that everything inside the map would be drawn, even if you’re far away from it.
Detail: Block light, clip players, etc but NOT visibility! It’s mostly, as the name implies, detailing stuff…
That was quick wasn’t it? 
ok, i read it and i have a batter understanding of it all now, thanks