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Antimony – A fresh look at CAD software

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Re: Antimony – A fresh look at CAD software

#61
post #27

Okay, I'm a CAD software developer instead of an actual CAD engineer, so my perspective may be a bit biased. But this CSG (constructive solid geometry) idea is not in any way new. The reason it's kind of obscure now is that spline-based boundary representation systems (B-reps) took over the market decades ago. If you think about, say, the latest car designs, those free-flowing shapes are pretty easy to do in B-rep, a…

> the latest car designs

Is that a history joke you snuck in there?

http://en.wikipedia.org/wiki/Pierre_B%C3%A9zier#B.C3.A9zier_...

Re: Antimony – A fresh look at CAD software

#62
post #27

Okay, I'm a CAD software developer instead of an actual CAD engineer, so my perspective may be a bit biased. But this CSG (constructive solid geometry) idea is not in any way new. The reason it's kind of obscure now is that spline-based boundary representation systems (B-reps) took over the market decades ago. If you think about, say, the latest car designs, those free-flowing shapes are pretty easy to do in B-rep, a…

> the latest car designs

Is that a history joke you snuck in there?

http://en.wikipedia.org/wiki/Pierre_B%C3%A9zier#B.C3.A9zier_...

Re: Antimony – A fresh look at CAD software

#63
post #7

Looks nice. I have been working ten years professionally developing a CAD program, and if I could time travel and give my ten years younger self a single tip it would be to use a proper geometrical kernel (like CGAL) rather than doing anything with floating point. The tree rep is very cool. It could probably render implicitly using distance fields without even needing triangulation. http://iquilezles.org/www/articles…

> proper geometrical kernel (like CGAL) Wow, that looks amazing. Thanks for the pointer! http://www.cgal.org/ (Pretending to add value, it's eminently googleable)

Does anyone know a CGAL-like library with an iOS App Store-compatible open source license?

Re: Antimony – A fresh look at CAD software

#64

What's the best free cad modelling tool for osx?

AutoCAD has an free education version:

http://www.autodesk.com/education/free-software/all

Very easy to obtain, but it can't be used for commercial applications obviously.

There's also OpenSCAD (GPL):

http://www.openscad.org

Re: Antimony – A fresh look at CAD software

#65
This is very interesting, there is definitely a big opportunity for CAD software that does things differently. A lot of the supposedly 'BIM enabled' and 'parametric' CAD software in use in the construction industry suffers from over defined and inflexible representations of real world objects, which often fail in the edge cases. I don't think software should be defining what it thinks a wall or a slab is or how they connect to each other, I think they should be giving architects and engineers better tools for defining and categorising these things ourselves.

Re: Antimony – A fresh look at CAD software

#66
post #19

Having used OpenSCAD, Solidworks and NX fairly extensively, I can say that "code-based" solid modelling systems are good for some specific things - anything that is highly parametric, for example: * Gears and sprockets * Fasteners (nuts & bolts) * Electrical components (ICs, etc) For anything else they aren't at all suitable. It's just a million times easier to be able to click on dimensions on the actual sketch and…

> The main reason they exist is that it is much (like 100 times) easier to write a code-drive CAD system than a GUI-driven one. The reason they exist is because they are very well suited for making changes on the model ... on shallow and deep level. It might be easer to "click on dimensions on the actual sketch and change them" for a few elements, but try making a fundamental change without code. GUI vs. code/config…

Being a career software developer who has recently learned to use parametric CAD (specifically, Geomagic Design, formerly known as Alibre Design), this is just not true. On the software side, I'm one of those who generally prefers code vs. GUI config. But that's an utterly terrible analogy to parametric CAD, which is really a touch closer to a kind of end-user programming language.

Parametric CAD is far better about keeping relevant dimension values, formulas, and model constraints right where they're relevant and trivial to visually comprehend in terms of their function in the model.

A better analogy for the uninitiated would be the frustration of a spreadsheet where the cell values and formulas had to be edited on some entirely separate text code UI sheet, requiring flipping back and forth and holding stuff in short-term memory to do anything to the model.

That said, I'm actually quite interested to play with Antimony. At first blush, it looks far more appealing than OpenSCAD for practical applications. Over time, it's UI might be able to converge functionally to the mature CAD packages, but allow for greater insight into how the engine is really building up the model, especially in complex projects. Constraint debugging in parametric CAD can occasionally be a frustrating kind of hell. Antimony and/or its descendents may be able to help out with that.

Re: Antimony – A fresh look at CAD software

#67
post #59

Earlier quoted context omitted.

AutoCad got AutoLisp as an update to R6 in January 1986. AutoCad got solid modelling in R11 with the "Advanced Modelling Extension" add-on in 1990. The whole history of AutoCad's feature evolution is that of a successful startup. There's an overview on AutoDesk's website: http://autodesk.blogs.com/between_the_lines/autocad-release-...

I think it was release 2.18, retroactively named R6 maybe. John Walker and I hacked up a p.d. thing called xlisp by David Betz, removing some of the best bits (the 'X' parts) and fitting it into its own 64k 'small model' (x86) segment. I was a bit of a lisp nut, but even I (product manager at the time too) thought lisp as a 'macro language' for AutoCAD was a tinge crackers. Glad we did it though!

Yes, according to the timeline, it was 2.18, but it lists 2.1 as R6, so despite it's huge impact in allowing the creation of tools like AEC-Architectural it apparently doesn't get its own integer. As a scripting language it seemed to me a pretty good choice, because sat reasonably well with the command-line based interface in that it somewhat reflected its * format.

And of course in the 1980's Lisps were tech's "the sharing economy". One of the reasons I went to vocational school to study drafting was to get my hands on AutoCad to get my hands on AutoLisp to get my hands on a Lisp. In 1991, I was doing timed Cad competitions using R10. My secret weapon was twenty minutes writing my own "PGP" command aliases in AutoLisp with edlin before I started drawing. That's how I won my copy of R11.

So I'm glad you did it too. Thanks.

Re: Antimony – A fresh look at CAD software

#69

Having used OpenSCAD, Solidworks and NX fairly extensively, I can say that "code-based" solid modelling systems are good for some specific things - anything that is highly parametric, for example: * Gears and sprockets * Fasteners (nuts & bolts) * Electrical components (ICs, etc) For anything else they aren't at all suitable. It's just a million times easier to be able to click on dimensions on the actual sketch and…

"You're never going to see a power tool or a tractor or whatever designed in OpenSCAD." I beg to differ on this, I've been using OpenSCAD for a couple of years now, and the two most complicated designs I have done were for a dual drive robot base and a simple 3-axis CNC machine. Many of the parts were COTS (which I built modules for) and the rest were designed for these projects, including some parts which were sent…

i also use open scad, but mostly because solid works is too expensive (and i like to have my data on a free format, human readable if possible, always)

i bet if you look at your design code, most of the parametrization and solid are there just to work around the fact that you can't tie one side of a cube to another.

to me at least, that's the killer feature that open scad lacks.

Re: Antimony – A fresh look at CAD software

#70

What's the best free cad modelling tool for osx?

I haven't found a free, native Mac CAD software that I like as much as Autodesk Inventor for Windows yet, but there are a number of free one available for the Mac.

123Design comes to mind [1]

You can also peruse the comparison of CAD software at Wikipedia. [2]

1. http://www.123dapp.com/design 2. http://en.wikipedia.org/wiki/Comparison_of_computer-aided_de...

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