I’ve written a proposal for an alternative paradigm:
- GUI-first, like KiCad - visual modeling is the default
- Text-based source files (YAML/JSON) — readable, diffable, Git-friendly
- Separation of source and result - .step, .stl and previews are built artifacts
- Parametric logic is explicit - slot width = tab width + clearance
Works with Git, CI, or scripting — no more PDM lock-in The proposal is called SplitCAD, and it's just a concept for now — not a working tool. But I’d love to hear from anyone frustrated by the limitations of current mechanical CAD.
GitHub: https://github.com/yuanxun-yx/SplitCAD
ddingus•1d ago
But I am just going to put this here so the general thoughts incorporate a fundamental problem before significant labor investments go too far:
What is a probable, viable, possible answer to the geometry kernel problem?
Parasolid, arguably the leader and generally most capable geometry kernel we have today, is or at least I can't see past...
...is just not something easily duplicated.
There are a bazillion man months of time in that body of code. And those are hard hours!
For those unfamiliar, the geometry kernel is the piece that resolves geometry cases to make operations possible. Imagine a cylinder and rectangle. Now imagine they have some common volume. They intersect, in other words.
Put a fillet on one edge to blend the edge.
How many literal edge and corner cases can you come up with?
There are way more than you think!
Now multiply that tiny problem space with all the geometry used every day.
And then multiple that time again by what it takes to make it robust.
And the whole thing, as it stand today is not even multi-threaded!
Any CAD that we expect to see even moderate general use in a professional sense, needs this piece.
How do we, meaning anyone interested in CAD this way, get past this?
I wish there were some OSS type license for Parasolid. It could be treated like the Linux kernel.
Whatever replaces Parasolid and friends, should be treated like the Linux kernel.
The closest we have is Open Cascade.
Sorry. I do not want to piss on a good vision. But this has to be said.
Peace and good luck!
I used voice input on this. Pleqse forgive typos.
thinkmachyx•22h ago
Although building such engine requires tons of work, but the engine we’re having is indeed a bit of old. Except for the problems I mentioned, you also mentioned they’re still single threaded. That’s why I think it’s still worth building a new one, especially when there’s no good open sourced one currently.
I’m a big supporter of open source. If we have something like that in the future, we should of course make it open source like Linux kernel and allow everyone to enjoy the benefit of it.
ddingus•12h ago
CAD is close to my heart. I jumped in during the 80's as a high schooler running on an Apple 2! Even back then, limited 8 bit CAD could do a lot. And it was one application that helped me see the future! Product design was gonna change as manufacturing already was and the people who knew CAD were gonna be there.
Now here we are, and the CAD companies own design and manufacturing.
I had a flash of an idea this morning reading your comment:
Perhaps we could license Parasolid for a year, or maybe we try what tomfoolery I am about to put here with Open Cascade.
Maybe an AI model of some kind can get us a leg up?
Going back to the fillet example I put here earlier, I want to share a bit of backstory...
I was at SDRC, who had built out a fantastic concurrent engineering and analysis system called I-DEAS. I loved that CAD software and was an applications engineer and trainer on it. Taught many groups of engineers how CAD works, and I got to do that on a system that had collaboration built in from the beginning! Fully revision controlled concurrent engineering and analysis. Fun stuff.
But it died.
My years of skills gone. Kernel could not keep up. So I moved all that onto what is NX today and many of the best parts of the software I loved ended up being implemented because some mergers resulted in the same smart people being product managers! I am particularly redeemed!
And therein lies the lesson of the geometry kernel. You build your true skill on Parasolid systems or risk seeing them lying dormant, cast aside.
The kernel upon which I-DEAS was built was written in Fortran 90. Beautiful software too. It offered capabilities well ahead of Parasolid in some ways, but consistently failed on some common geometry cases that come up rather frequently. Things tangent to things, touching a a point was a big one.
One thing I taught was overbuild or underbuild. Rather than draw a rectangle tangent to a circle to prepare for an extrude, place that end of the rectangle inside the circle and let a boolean operator sort out the two resulting solids.
So yeah, build it kind of wrong so the kernel can build solids. Messy. :)
I was in a room talking to the people who do fillers. Edge blend to some of us.
We talked about my fillet gauntlet. It was a collection of geometry cases that fillet operations failed to complete.
Parasolid could always resolve more of them, and it did that with fairly sloppy tolerances. The SDRC kernel was catching up each rev, but the trend line looked like a decade of analysis of the successful resolutions, and coding for those, wash, rinse repeat a lot.
I wonder if it might be possible to generate geometry cases using parameters such that whole problem spaces could or can be created. Have good kernels solve and train an AI on all that to see what it may then solve differently?
Maybe man years boils down to compute/watt hours?