Let’s say you have one or more of those oddly shaped thingies:
How can you break it up into tris/quads?
And what’s the best way for applying a seamless (tiling) texture? (opengl)
I know it would be easier with convex shapes, but I have my reasons (faster level building). Also performance isn’t an issue (one time operation).
Since it’s a rather common problem there have to be a bunch of usual ways to do it. Well, y’know, searching is hard if you don’t know the correct term 
[quote]And what’s the best way for applying a seamless (tiling) texture? (opengl)
[/quote]
Easiest would be to just use the vertex positions as texture coords. Then your textures end up tiled and aligned to your coordinate system which makes it easy to line things up. You probably want to add some kind of scale factor as well so you get the right frequency of tiling.
If its for some kind of geometry editor, I found setting texture coords by letting the user drag them around works great (especially combined with the previous). I used both methods in V-Script if you want to see them working… 
I can’t do anything in the V-Script Editor :-/
However, thanks for the hints
Its not the most intuitive to get started with. I’ll pm you with some details of how to do the texture stuff.
Erm… ok. Seems like glu can do this kind of stuff automatically for you ;D
See here:
http://www.geocities.com/foetsch/extrude/extrude.htm#glutess