91–100 of 124 posts
I find openscad quite painful to use, I whish I learned about Antimony before. I think this has lot of potential, as a lightweigth, intuitive, free software, notably in the maker/diyer scene.
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…
Btw any advices for those who are interested in CAD/CAM software development? (refs/books/lectures/(remote)jobs)
I enjoy every new CAD program (solvespace, implicitCAD, nanoCAD, ...) when they come but each time it lacks this vital function. Even fat dinausors like CATIA, Pro/E, Inventor & co have a very poor ux at that level.
So I will recommend to master the rules of technical drawings and geometric dimensionning and tolerancing before going to deep in 3D. Likewise, BRep, CSG, constraints solvers, code/GUI will be just straightforward "plugins". It's safer and more useable in real life.
By the way, the Purdue University have some good innovative lectures, ie. Erep [1]
Computer Aided Engineering Design by Anupam Saxena & Birendra Sahay is cool and informative.
In general, the Indian Institute of Technology of Kampur [2] has some pretty intense books on the subject.
Finally, Knowledge-based engineering [127] will extend a lot your future awesome opensource haskell CAD package!
[1] https://www.cs.purdue.edu/homes/cmh/distribution/papers/Erep...
[2] http://www.iitk.ac.in/cad/
[127] https://en.wikipedia.org/wiki/Knowledge-based_engineering
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…
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You can still run Lisp commands on the commandline interface in AutoCAD. Or even as you type out command inputs. So for example, if you know that you just put in 187 for length, but the next line needs to be double that, you can type (* 2 187) when it's time to put in the length and AutoCAD calculates it.
I thought they turned it into a license feature (so LT doesn't have it, only the full version does)? But yes, I found AutoLisp to be very useful for automating things. The place I used to work for had to have the CNC machines cut out differently sized shapes from a library of shapes, so I created functions to draw each library shape for me quickly. This is a lot easier than trying to form four mutually tangent circul…
Impressive. Wonder how long it took to develop.
I've been working on tools of this nature for about four years, though the only thing that's made it through mostly-unchanged is the geometry kernel. This grew out of my thesis work (2011-2013); in rough chronological order, here are a few documents from that time period: http://fab.cba.mit.edu/classes/S62.12/people/keeter.matt/ind... http://www.mattkeeter.com/projects/kokopelli/ http://www.mattkeeter.com/research/th…
BTW I was ray tracing CSG objects for RT chess back in 2001. Here's a pic:http://www.caiman.us/scripts/fw/f282.html I implemented a primitive called quadratic lathe which took 3 points on a curve and revolved them around the vertical axis as an implicit surface intersected with a slab to limit the vertical span. Most of the chess pieces were created by sketching them on graph paper and putting the profile coordinates into code.
If you want to run it, beware of potential malware from sites that have it. Also, replace the SDL dll in there - somehow a bad version got in our original zip. I may not have source for the game any more, but the renderer has progressed a bit and now supports multithreading.
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> 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_...
I think you missed his/her point... OP wasn't saying that Bézier curves in car models were something new. What OP said is that (as an example) latest car desings are hard to do with constructive solid geometry but easy to do with B-rep
Bézier curves are ubiquitous in computer graphics. They were introduced implicitly into theoretical mathematics long before computers, primarily by the French mathematician Charles Hermite and the Russian mathematician Sergei Bernstein. But it was only the work of Pierre Bézier, an employee of the automobile maker Renault, and of Paul de Casteljau, of Citroen, that made these curves familiar to graphics specialists. Recently, the polynomials defined by Bernstein have become again of interest to mathematicians. http://www.ams.org/samplings/feature-column/fcarc-bezier
Wikipedia expands:
Bézier curves were adopted as the standard curve of the PostScript language and subsequently were adopted by vector programs such as Adobe Illustrator, CorelDRAW and Inkscape. Most outline fonts, including TrueType and PostScript Type 1, are defined with Bézier curves. http://en.wikipedia.org/wiki/Pierre_B%C3%A9zier#B.C3.A9zier_...
... though almost certainly CorelDraw (and Quark xPress?) came before Illustrator, and PostScript's popularization came through the rather embrace-and-extend PDF format it spawned.
FWIW, I have fond memories of doing CSG with Povray - http://povray.org/ - as an 11 year old. When the supply of new DOS games ran out, it sure beat writing batch file viruses, the other primary form of entertainment.
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You can still run Lisp commands on the commandline interface in AutoCAD. Or even as you type out command inputs. So for example, if you know that you just put in 187 for length, but the next line needs to be double that, you can type (* 2 187) when it's time to put in the length and AutoCAD calculates it.
I thought they turned it into a license feature (so LT doesn't have it, only the full version does)? But yes, I found AutoLisp to be very useful for automating things. The place I used to work for had to have the CNC machines cut out differently sized shapes from a library of shapes, so I created functions to draw each library shape for me quickly. This is a lot easier than trying to form four mutually tangent circul…
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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!
https://www.fourmilab.ch/autofile/www/chapter2_35.html
"Lisp?!?! Why the Hell did you pick the most arcane, obscure, and hopelessly-rooted-in-the-computer-science-department language in the world for an AutoCAD programming language? Over the next six months, all of us will have the opportunity to answer this question."
That was in 1985. Not so much has changed in 30 years :P
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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!
John Walker's The Autodesk File has his original strategy paper on this topic: https://www.fourmilab.ch/autofile/www/chapter2_35.html "Lisp?!?! Why the Hell did you pick the most arcane, obscure, and hopelessly-rooted-in-the-computer-science-department language in the world for an AutoCAD programming language? Over the next six months, all of us will have the opportunity to answer this question." That was in 1985. No…