CSG in Sketchup

noelwarr · 28 Jan 2012, 10:32

I bumped into this (http://en.wikipedia.org/wiki/Constructive_solid_geometry ) wikipedia article. I don't have Sketchup pro so I can't check but I can't imagine how CSG would fit into sketchup. I would've thought that Sketchup worked only with B-rep structures. Surely this article mistaken.

oganocali · 28 Jan 2012, 10:51

SU Pro has solid tools.

noelwarr · 28 Jan 2012, 11:07

I know. That doesn't mean it uses CSG. As I said, I'm pretty sure it uses B-rep structures to perform it's boolean operations. In fact I would even put money on them using large parts of the CGAL library.

oganocali · 28 Jan 2012, 12:45

SU pro has 8 hours free trial. You should be able to verify your suspicions in that time.
cheers

noelwarr · 28 Jan 2012, 19:52

Wow. That's the shortest trial I ever heard of. I'll have to set a day aside for trying out all its features. That said, using Sketchup wont tell me weather they use CSG or not. CSG and B-rep are two different ways of representing 3d solid data. The first uses primitive solids to construct more complex shapes, the latter uses polyhedral surfaces. Google it, it's interesting stuff. This has more to do with the internal workings of Sketchup rather than its capabilities. I was hoping someone on the SU team (Or someone who knows someone who knows someone...) would see the post and enlighten me.

I'm reasonably familiar with the ruby API and there are no functions or classes that relate to CSG. It seems pretty clear that it uses an exclusively B-rep model. So, should I take it up with wikipedia? Anyone?

Gaieus · 28 Jan 2012, 20:09

8 hours to actively work with it (even when it is open but you are idle, it won't run the clock).

Dave R · 28 Jan 2012, 21:24

When you find get the answer to your question, what will you do with that information?

noelwarr · 29 Jan 2012, 00:46

Do with the information? The only thing I will do as a direct result of getting an answer is having the wikipedia page changed. After all, we want wikipedia to be as accurate as possible now, don't we?

I should mention that I am developping a SU plugin that involves using the CGAL library (Minkowski sums, boolean operations, envelopes...) and though knowing weather SU uses CSG is not imperative for my project it certainly helps me have a better understanding of how SU works under the hood.