PySdfScad
sdf
PySdfScad | sdf | |
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6 | 18 | |
16 | 1,485 | |
- | - | |
10.0 | 0.0 | |
about 1 year ago | 3 months ago | |
OpenSCAD | Python | |
- | MIT License |
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PySdfScad
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CAD Sketcher, free and open-source project bringing CAD like tools to Blender3d
> 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
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.
- I created an openscad interpreter that supports chamfers and fillets
- Show HN: PySdfScad,an openSCAD interpretor using signed-distance-functions
- Show HN: PySdfScad, my early work on an openscad interpretor with fillets
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Ask HN: What would be your stack if you are building an MVP today?
Depends on exactly what I'm making, the answer is probably different if I'm making like a chat app or something more data centric.
For something really minimal, an internal tool, I'd probably use grist. Grist is a "no code" spreadsheet program that is open source and works on a relational database. I just threw together an inventory management system for my weekly dnd group in a few minutes, and I've shared it with the group. I find the relational mindset grist uses a lot easier to reason about than traditional spreadsheets.
The next level up would be django with htmx. Very minimal javascript, I might embed a javascript "applet" like a map into it if needed. This covers 99% of data driven apps.
If I wanted to build something like say discord I'd probably use a pretty similar stack for the MVP, but with server-sent-events (htmx with server sent events is nice) and web components for more complicated interactions. That's probably why I'm not in charge for building complicated single page webapps with a lot of interdependent state though. I maintain this approach should work but haven't had a real chance to test it in the wild.
If I'm writing CAD software I'm probably going with QT/python/(numpy/jax/compute-shaders/sympy/etc). Python might not be the fastest, but when you're accelerating it with one of those machine learning libraries it can be really powerful. I've actually been working on something CAD-ish using that stack here: https://github.com/traverseda/PySdfScad
That's probably roughly the same stack I'd use for things like computer vision, machine learning, etc. Ironically anything where performance is important I'd probably choose python over a compiled language.
Mind you the QT python documentation is really not great, for a really minimal MVP I might swap qt out for pyimgui which is amazing for rapid prototyping but is going to be a real pain to do things like syntax highlight a text editor or embed HTML content.
Embedded electronics? Probably micropython on an ESP32 for an MVP. A REPL on your microcontroller is really nice. Robotics I'd probably use buildroot to build a custom linux distro.
I don't have much experience with mobile development, so I'd probably end up using QT with python and pyqtdeploy, but that's not an approach I'd recommend anyone else follow. I'm keeping an eye on Tauri in that space, although I really wish they made it easier to bundle in things that aren't single page javascript web apps (like a python application).
So yeah, mostly I'd use python. Master of some trades, jack of a bunch of others, it's flexible and powerful enough that I feel happy to have specialized in it, even if deploying apps to end users can be finicky and annoying. I'd avoid the javascript ecosystem as much as possible, and where I'd have to use javascript I'd prefer to make self-contained web components.
- GitHub - traverseda/PySdfScad: Openscad interpretor written in python and using signed-distance-functions
sdf
- Sdf – Generate 3D meshes based on SDFs
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FreeCAD User Book (2019)
I used to like OpenSCAD for its simple approach but then I discovered SDF-based modelling with Python made possible with this neat library: [1]. This is perfect if you are a programmer that doesn't know anything about CAD-Software.
1.: https://github.com/fogleman/sdf
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CAD Sketcher, free and open-source project bringing CAD like tools to Blender3d
>these the the central core that understands BREP and implements the geometric operations.
I've seen people quote a good modern CAD kernal as a 100 man year project. It's probably not going to happen, maybe there's some avenue for government funding?
Alternatively Signed-Distance-Functions are pretty nice. They're not BREP, but they're a lot easier to implement, and it might be possible to shove them into a BREP-shaped hole.
Here's a signed-distance-function based CAD kernal written in a few thousand lines of python+numpy, that seems to be about as fast as openscad. Maybe faster. https://github.com/fogleman/sdf
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Signed distance functions in 46 lines of Python
Excellent. You might be interested in a Python library that I wrote for generating 3D meshes (STL files) from SDFs : https://github.com/fogleman/sdf
It just uses marching cubes for triangulation but the SDFs are all numpy'd and the SDF is evaluated in batches on multiple threads so it's relatively fast.
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Plot of triangle mesh with py5
I used the SDF repo by Michael Fogleman. Check out his website, there's a ton of useful stuff on there. He contributes a lot to the open source community and has been mentioned in r/PlotterArt before.
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10 ways to get the best out of OpenSCAD
Try out fogleman/sdf[1]. It is like OpenSCAD in many ways but the distance field model gives you offsets and fillets more easily.
[1] https://github.com/fogleman/sdf
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Is it possible to 3d print signed distance functions?
https://github.com/fogleman/sdf this python project can create mesh from sdf
- Curated Code CAD
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Guerrilla guide to CNC machining, mold making, and resin casting (2015)
> https://github.com/fogleman/sdf
Holy crap, why have I not seen this before?!?!!? I was even planning to start coding something like this myself. This is awesome!
- I am planning on creating a programming language for my Informatics Bachelor Thesis. What are your ideas for such a project?
What are some alternatives?
manifold - Geometry library for topological robustness
meshlab - The open source mesh processing system
SolveSpace-Daily-Engineering - app4soft's engineering experiments in SolveSpace — FLOSS parametric 2D/3D CAD & CAE (.slvs files repository) Follow ➡ https://twitter.com/search?q=solvespace+from%3Aapp4soft
trimesh - Python library for loading and using triangular meshes.
supabase - The open source Firebase alternative.
sdfx - A simple CAD package using signed distance functions
deno - A modern runtime for JavaScript and TypeScript.
meshio - :spider_web: input/output for many mesh formats
jetstream - Tailwind scaffolding for the Laravel framework.
vedo - A python module for scientific analysis of 3D data based on VTK and Numpy
redwood - The App Framework for Startups
opencascade-emscripten-port - Open CASCADE - Emscripten / Webassembly port