Modeling Tools: Unfold3D
Originally written by oDDity on http://forums.thedarkmod.com/topic/2052
Here's the free version, it has a limit of a 1000 polys, but you can just cut your object into parts and UV them separately.
It literally produces perfect UV maps instantly, no work required.
In LW go to file-export and save your object as an .obj, load that into unfold3d, hit automap and export it out again. Simple as that. Here's a more indepth tutorial for cutting comple objects into parts are indicating seams for unfold3d.
If your are uv mapping a cylinder for example, you have to unweld the vertices down one side. Imagine if you were trying to unfold a paper tube in real life. The best way way to do it would be to cut it down one side and fold it into a flat square.
Unfold3d does the same thing, but you have to make the cut in it yourself first.
The object also has to be one continuous mesh, yoiu can't have a loose polygon cut off from the rest, and all the vertices have to be welded - you can't have two verts sharing the same space, or two polys sharing the same space, or any 2 point polys. It has to be tris or quads.
It's the same for every object, though it gets more complicated.
Always imagine the objects in real life, they are made of paper and you have a pair of sissors. You want to fold the paper shape out flat on a table. Decide the fewest cuts you'd have to make in order to do that, and try to hide them in unseen places if you can. It's basically origami in reverse.