3d CAD drafting on Ubuntu?

Sketchup isn't doing 3d drafting. The word 'drafting' seems to be used, in this context, to be about using lines and circles and such. 2D simply means, everything is on the flat plane. 3D includes the Z dimension. So you can draw, for example, a box that is formed from a frame made of parallel lines.

I mean drafting as opposed to "manipulating solid geometery". Blender lets you programatically (in python) define the vectors that make up a 3D shape. [I program 3D graphics, btw. (Amongst other things.)]

I looked at Blender some years ago, but ended using POVray. However, I found building my objects in CAD was more intuitive for me. I worked concept out on paper, then used VB to generate scripts that went into the CAD program I had. That was great for getting a look and making adjustments, then exporting that into POVray for texture and rendering. It's possible I'm barking up the wrong tree, since I did this sort of thing about 10 years ago. I'm not familiar with this python scripting in Blender, and only vaguely familiar with Python in general (but books are on the way, as I need it for some other work). The scripting I was doing was ascii stuff with basic drafting commands and parameters (line x,y,z etc). I found this made adjustments easiest, since changing a couple numbers in VB resulted in major changes in the final output.

You need not use the renderer in Blender. Just the modeling tools. And it's definitely improved since ten years ago. There is a bit of a learning curve, though. If you're programatically generating your geometry anyway, why not generate it directly into a file format that various rendering systems understand. Nearly every rendering system understands the http://en.wikipedia.org/wiki/Obj format. It's the lowest common denominator of 3D graphics file formats. It looks like POVray supports it. You could easily generate the .obj from whatever programming language you prefer, drop it into blender for manual manipulation, and then render it using POVray for all your high-quality ray-tracing needs. But Blender will let you manipulate geometry directly from python within Blender itself. I haven't used it myself, but I've seen the results. The scripting is clearly quite powerful. So powerful that people actually write games that use blender as the game engine.

See, that obj format doesn't fit me too well, for the kinds of things I'm doing. I make frames, typically geometric baubles, that may or may not have a surface applied between the edges. Sometimes, I end up with rather pretty renderings of what I create. Other times, I just get a huge buzz from doing the effort. I'm trying find a program that works the way I've done this in the past. Thinking about it, I could build the same sorts of things with polygons etc, and if that's the only means I can discover, I may just give it a whirl. But really, I was doing 3d CAD of the type I describe way back on my 286 DOS machine. Seems there has to be something that works like that in Linux. It's not like it's new!

I searched around on the ubuntu forums and there are two free ones listed: http://www.cycas.de/ and http://sourceforge.net/apps/mediawiki/free-cad/index.php?title=Main_Page. I've never used either, but I had tried out http://www.ribbonsoft.com/qcad.htmlbefore (which is not free and 2D only). http://www.varicad.com/en/home/online-store/is another 3D CAD, but it is commercial.

Sorry - I see you already mentioned FreeCAD.

Oh, FreeCAD is worth mentioning, even if it isn't ready yet! It looks like an awesome project. I hadn't yet heard of CYCAS. QCAD was easy to rule-out, due to the 2d limitation. I know I heard of VariCAD, but don't recall details (I'd buy something, if it wasn't too expensive. No justification for spending much). Oh, checking CYCAS, they want $128 for their 'basic' version, which does appear to include what I need. ::sigh:: Can't justify it. I might get deep into it for a month or 3, and then never touch it again (or, 10 years later, want to do something again, and find everything has changed)