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> To clarify, can this method be used as a fully functional replacement to BREP for a mechanical (machine design) CAD system? I think so, but there are some op
by traverseda 4y ago
> To clarify, can this method be used as a fully functional replacement to BREP for a mechanical (machine design) CAD system?
I think so, but there are some open problems. Also it depends on the senior people. Inigo Quilez is a world class expert in this domain, and for the most part we're copying his work, get him on board and you'll be golden.
Fundamentally it makes sense, BREP is about representing boundaries and you can definitely use SDFs to represent the area under a boundary (infinite SDFs are possible, although obviously you can't turn them in to a mesh). Enclose a volume with boundaries and you can mesh that out just fine. A bit different from CSG-based SDFs, but entirely plausible.
>what approach would you recommend?
If I was to do this I'd take the constraint solver from solvespace (same one used in this post) and start using it to generate SDFs. At that point you're already 80% of the way to your end goal.
I mean if I was personally to do this I'd start by making a system that implements everything openscad can do, try to get some funding going, and than add in a solvespace based workbench for doing 2D cad that you can import into an openscad-ish language. You can see my efforts here: https://github.com/traverseda/PySdfScad https://github.com/traverseda/PySdfScad
That's tackling it from a different angle than BREP though. I think that openscad but better is a surprisingly viable thing though, especially if you use it to do things like generate the gears/screws/whatever you import into your BREP based CAD project. Use scriptable CAD as the underpinning for more advances CAD.
> How long would you estimate it would take for three full time senior developers to get a useful system out?
Well define "useful"? Honestly I think you can get 80% done in under a month. I built the first pysdfscad in a week or two and replicated 80% of openscad's features. Fogleman built the library I used for pysdfscad in under a month.
I'd expect something pretty good in under a year at that kind of rate. There would be some outstanding problems, like it would be a challenge to figure out how to apply a fillet/chamfer to an edge, but not an insurmountable challenge. Geometry import is another place where you're going to spend a lot of time/money but is very important.
So let's say two or three years with three very competent seniors working on it to get a pretty good CAD program, with a GUI.
- SequoiaHope 4y agoThank you for this. It is encouraging that something like this could be done for under $1 million. I’m just dreaming right now but I think open source mechanical CAD is one of the low level pieces that could touch billions of lives. It would be cool to put together some kind of foundation, with a working group and some kind of RFC process, to build a concrete plan which could then be used for fundraising.
- traverseda 4y agoIt definitely would, yeah. I think the SDF stuff will come to fruit eventually. There's also Matt Keeter's libfive-studio available and I saw a solvespace maintainer in this thread asking about it. I think the open source community is getting skilled up for it.
- jameskilroy427 4y agoAs far as funding is concerned, it seems like exactly kind of project FUTO is looking to back. https://futo.org/what-is-futo/ https://futo.org/what-is-futo/
- TaylorAlexander 4y agoThat’s a good point. I am planning on following up with them soon about another project I am working on. I will see if there is any room to ask about this.