Show HN: LuaCAD – Parametric CAD Scripted in Lua
luacad.ad-si.comLuaCAD models solids in Lua rather than the OpenSCAD language, with operator overloading for CSG (`a + b`, `a - b`, `a * b`).
It ships with a CLI and a desktop app, including a preview area and a text editor.
I've always been a big fan of OpenSCAD, but the SCAD language itself is unfortunately quite cobbled-together and is a very poorly designed programming language.
LuaCAD takes all the good parts of OpenSCAD and combines them with one of the best scripting languages. It has now completely replaced OpenSCAD for me, and I think it provides a better experience than OpenSCAD for all use cases. I'd love to hear any reasons why LuaCAD shouldn't fully replace OpenSCAD!
It’s fully open source and you can find the repo here: https://github.com/ad-si/LuaCAD
Tech stack:
- It's implemented in Rust and uses mlua (https://github.com/mlua-rs/mlua) to execute the Lua code.
- Uses OpenCSG (https://opencsg.org) for fast and correct rendering of the 3D models (like OpenSCAD)
- Uses Manifold (https://github.com/elalish/manifold) to create the manifold triangle meshes
- Native support for all BOSL2 functions (i.e. implemented in Rust for better performance)
Does this have a web-based playground? I find https://www.pythonscad.org/playground/ to be nice to try out the project.
Agreed! I’m already working on it, but it’s not quite ready yet. ETA is 1-2 weeks.
Really interesting! I actually use freecad so I'm use to that layer of the process but I'll check this out. Also good to see the work being done in modeling software these days
Love it! OpenSCAD has very painful syntax. Is it possible to easily do bevels/chamfers or does it have the same limitations as OpenSCAD there?
Thanks! It natively supports all BOSL2 functions which include a chamfer argument (https://github.com/revarbat/BOSL/wiki#common-arguments). So that makes it quite straightforward to add chamfers to everything!
Which is what separates us from the animals.
Can you fillet unions? Like, if I union a cube with a smaller cube sticking out of its side, can I make a fillet so that the edge where the two cubes' faces intersect doesn't become a stress concentration point for cracks to start at? This is OpenSCAD's primary weakness from my point of view.
Quite easy to add chamfers to everything in the CAD file. But your manufacturing guy is going to strangle you...
So ill strangle myself while the 3d printer goes back and forth.
Is it able to access the file system and write/read files?
I've been doing that via PythonSCAD for my current project https://github.com/WillAdams/gcodepreview and it might be interesting to do a re-write in another language.
Yes, it executes in a full fledged Lua environment. So you can do all the things you expect do be able to do with Lua!
I’d pick Lua over Python any day, but maybe that’s just me. ;-)
I've had good success w/ using Lua in LuaLaTeX, so hopefully a good fit for me to exercise my programming chops. I think it will be interesting to maintain two parallel versions for comparison/contrast. Thanks!
The change history on this repository is fascinating
Isn't OpenSCAD's limited (non-Turing complete) language a feature?
I'm pretty sure it's Turing complete by now. If it was conceptualized as a limited language and only became a full fledged programming language over time, it would certainly explain all its weird warts. (Here is some more details: https://github.com/ad-si/LuaCAD#why-lua) I guess 3D modeling is just too complex for a simple, but limited DSL.
Lua is easier to use, faster, and more feature-rich. It's one of those rare occasions when a new solution is actually better in every single way.
In the pedantic sense, yes. You can use recursive functions with tail-call optimization, or list comprehensions to emulate a universal Turing machine.
But my point is that OpenSCAD's expression purity and one-way compilation model are purposefully limited, and not historical accident: models are a deterministic function of their parameters, subtrees can be cached and reused during preview without invalidation logic, designs diff and merge as text, etc.
Sometimes making things "more programmable" is an anti-feature.
AFAIK OpenSCAD does not do any meaningful optimizations that are enabled by having a limited DSL, despite that normally being a good reason to do a DSL. And ironically you often have use a general purpose language (python and C++) to do custom optimizations not possible in the DSL.