Transparent stuff won't work right now since the drawing order is basically random. If it draws a ship with transparent polygons in the front of the screen, even transparent pixels get their depth written in the Z-buffer, meaning that objects behind transparent areas won't be drawn since they'll be rejected by the Z-buffer. That's why drawing transparent textures MUST be sorted, which is, of course, why textures with alpha channels cannot be currently implemented. BSPs generally lend themselves nicely to easily creating a back-to-front drawing order, but afaik the FS2 BSPs are non-subdividing BSPs, and I don't know how to deal with those, since my knowledge of BSPs is very limited... Perhaps Kazan could give some insights...