After a bit of trial and error, I understand the oft-written advice for UT3 maps: Keep the BSP simple.

On many UT3 maps, BSP is only used to force occlusion (block the view intentionally for framerate). I’m porting a map from the days when the architecture was done entirely in BSP, typical for “corridor” shooters. So it’s tempting to do all of the level that way, but I’m finding things break in the complex spots.

Either UT3′s BSP is quite basic (why not, all the complexity is expected from meshes) or Sketchup’s occasional odd polygons are importing strangely. Either way I’m learning to follow that advice above.

I’m now using BSP only for my simple wall structure. I’m importing floors and any sort of curves or height changes (stairs, ramps) via ASE as meshes. Floors are a key part, since they were getting holes as part of the BSP and that meant randomly falling into oblivion. They work better as meshes, I just set them to per-poly collision (as described in Hourences’ Modeling Tutorial).

As you can see, I’ve got the BSP done and it’s probably still more complex than it should be as a ‘modern’ UT3 map. I haven’t textured anything, nor added any details or even ceilings / skyboxes, but I’m pretty pleased with my learn-as-I-go progress so far.

Next up: Stairs and ramps so I can navigate the level without resorting to ‘fly’ mode.