i have made a 3d engine, but now I want to add a "indoors" engine in it, I know some thoeory behind portal rendering and BSP trees but not enough to start coding with.. so before heading into a long web search for code I wanted to ask the experts first. Where can I find info about this: What is the theory nehind modern BSP trees per example what is a "brush"? (I have made some quake levels and I still dont know what that means) What is faster or easier to make a BSP or a Portal engine? How come BSP''s are supposed to be solid and inmovile and some games have moving parts, like doors or rotating floors? How do you check collisions against a bsp tree? Where can I find some good theory on this subjects, theres a lot of code but I can only find pretty basic theory.. any help will be most apreciated! thanks on advance!

BSPs are generally very static, I''ve read that dynamic BSP trees are possible but I''ve never seen any examples of how to create them and I don''t believe it would be worth the trouble. After all, in most games the levels are fairly static, with only small parts moving.

Engines that contain moving doors/elevators/etc do not store these in the BSP tree for the level. Either they are stored as a ''regular'' 3d-object or they are stored as an individual BSP tree (i.e., not in the big BSP that makes up the rest of the level). From what I understand Quake uses small BSP trees for moving parts of the level and a big one for all the static geometry.

Hmm... Mostly ramblings, There are alot of good FAQs/tuts out there about BSPs and portals, thats how I''ve learned what (little) I know.....

Check out http://crystalspace.org for a working opensource portal renderer (It can use BSP trees too). It might give you some ideas...

//Jesse