ok, I have a BSP tree-based engine up and running, with the tree calculated just after I load the file. Now, my question is this - let''s say I want there to be switches in the world, and when these switches are activated, things move (doors open, bridges go across pits, etc...). How do I do this since BSP Trees handle only static polygons? I _could_ recalculate the tree after doing this, but that seems terribly slow. I know there must be a better way, but I haven''t the faintest idea where to begin. And while we''re on the subject - once I get this working I plan on putting monsters of some type in the world. They''ll be moving around, so how do I use them with by renderer, since they''ll move around the tree? Thanks for any help (source code would be greatly appreciated, OGL preferred but anything is useful gameguru4@yahoo.com

Your dynamic objects aren''t actually in the BSP tree.

After rendering the BSP with back to front, you should render the dynamic objects using the z-buffer. That is how Quake does it.