What's nice about this is that it allows for programmatic CAD, enabling things like web applications that can download an .stl file based on user input. I hope I can find a weekend or two to play with it.
BTW: I spent a few weekends playing with Microcad (https://microcad.xyz/). It was cool, and had a similar rust feel. I just, for the life of me, couldn't figure out how to do 3d ellipses.
The opening paragraph is very telling; the author doesn't seem to understand typical pro-level parametric CAD programs available on the market:
> I keep designing physical parts for our robots. Motor mounts, sensor brackets, wheel hubs. Every time, the workflow is the same: open a GUI CAD program, click around for an hour, export an STL, realize the bolt pattern is 2mm off, repeat.
This doesn't make sense. When you realize the bolt pattern is 2mm off, you just edit that dimension and let the CAD program recalculate. You don't need to click around for an hour again. That's the beauty of contstraint-based parametric modeling as opposed to, say, modeling in Blender.
The author's program is akin to writing vim to replace Publisher. They're solving entirely different problems. Not to mention, this code-as-model paradigm already exists: OpenSCAD
> That's the beauty of constraint-based parametric modeling as opposed to, say, modeling in Blender.
I was thinking the same thing. This looks more like an API that makes 3d modeling look closer to CAD, but without realizing that CAD is about constraints, parametrizing, and far more.
I've even already asked an LLM to generate designs in openscad, and there's plenty of examples out there. Obviously there's a complexity limit, but there's also a cheat sheet that makes it pretty easy to discover how to do almost anything that's possible within.
The pull request is to delete the project and open SOLIDWORKS or FreeCAD.
But don't actually delete it. It looks like a nice alternative to OpenSCAD. But like OpenSCAD it's really a niche thing for designs that are highly parametric like fasteners, gears, 3D printed boxes, etc.
Like OpenSCAD using it for normal "irregular" CAD is going to be extremely frustrating. Like editing an SVG in notepad instead of Inkscape.
I still feel like there's a unexplored space where you combine the benefits of both somehow though. Like a code-based CAD but it also has a GUI editor that stays in sync and avoids the need to type in coordinates by hand. That would be extremely difficult though.
>I still feel like there's an unexplored space where you combine the benefits of both somehow though. Like a code-based CAD but it also has a GUI editor that stays in sync and avoids the need to type in coordinates by hand. That would be extremely difficult though.
I think you can do this if the data representation of operations and values is human readable. The simplest implementation would restrict the language/data format to operations representable in the gui.
Unlike trying to solve the "visual programming" problems, we don't need or desire Turing completeness.
SketchUp was my go to for a while but I'm done with parametric personally, trying to fix meshes for 3D printing... time I grow up and use something like Fusion360 seems like or onshape. Still it was good/simple enough for non-round shapes in SketchUp except they have some kind of memory leak/bug at least for the 2017 version. But I guess quit being cheap and buy a modern copy on my part.
Edit: oh I guess sketchup is a surface modeler weird thought it was parametric this whole time, lol someone else said it's a polygon modeler
Yeah I don't know what parametric modeling is apparently, I use a mouse/calipers to model stuff not parameters
There is a solid validator plugin you use before you export an STL to make sure the mesh is closed/a manifold
It's using a constructive solid geometry system. You can add and subtract volumes. Making a hole is subtracting a volume. This has classically been numeric roundoff hell, where points that should coincide and surfaces which should touch don't get handled properly due to numerical error.
The geometry engine is Manifold, which guarantees watertight meshes from boolean operations.
Ah. That's what's doing the constructive solid geometry. Here's the 2009 PhD thesis behind the object merge and difference algorithms inside Manifold. Nice. At last, soundness.
This is a long-standing problem. And now there's an open source implementation. Manifold itself is in C++, not Rust, though.
None of this is parametric. That's a different problem. That's where you put in constraints such as A is perpendicular to B, B is 100mm from C, etc., and the constraint solver tries to satisfy all the constraints. Change a dimension and everything adjusts to preserve the constraints. Parametric CAD is all about constraint solving and expressing conflicts to the user. Autodesk Inventor, Fusion, etc. have good constraint solvers.
I had a lot of fun playing around with antimony (also from Keeter) a few years ago, but unfortunately it has been mostly abandoned. I heard libfive is supposed to be the next generation, but I haven't experimented with it yet.
My whole CAD experience is with OpenSCAD, which apparently uses the same kernel; Honest question -- what is the alternative? I would assume the vast majority of 3D model processing relies on triangle meshes...
Meshes are an output, not a source, and not a good internal representation.
Meshes are only a lossy approximation of the actual geometry, and the errors accumulate as features reference off of earlier features.
A simple example is a line tangent to an arc. The line will only be the correct distance from the center of the arc at one point (one angle) per segment.
In openscad you don't notice the problem because since it's code and you have variables and programming ways of expressing relationships, you would usually not try to derive one thing from another by geometry, instead both things would reference a common ancestor variable. But that's a technical implimentation detail that works around the problem by just not doing a thing that doesn't work. The problem is still there that a valid geometry constraint would produce invalid results.
I've built something very similar (also based on triangle meshes, but in TS), and while it wouldn't work for say 3D printing, my target is game object modeling. I guess people have specific use cases in mind when referring to "CAD".
An example of common terms that disagrees with that somewhat, is "CAD/CAM" where the design component is clearly distinct from the manufacturing component.
I do agree that historically, software aimed at building 3d models for games/animations and other digital use was usually called modeling and not cad. I'm thinking of software like 3D Studio Max back in the 90s here.
I notice though that the Wikipedia article for CAD says: "This software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing."
Is anyone else put off by the AI-sounding text? Two things that give it away for me are the excessive use of punctuation-emphasized sentence fragments ex:
> No clicking. No undo. Just recompile.
> That's our mascot. Entirely CSG.
> No garbage collection pauses. No floating point surprises from a scripting layer.
I've found LLMs perform surprisingly well here if you target CSG or OpenSCAD. It seems to frame the 3D modeling challenge as a logic and syntax problem rather than a spatial one, which plays to the model's strengths. You avoid the spatial hallucinations common in image generation because it's effectively just writing code.
Amazing work! This is what I was looking for, I thought of this few months ago and didn't have the time to create it myself. Thanks will explore it and give my feedback!
I've been doing a similar thing using GhostSCAD[1], which is a relatively thin wrapper around OpenSCAD in Go. Not as typesafe, but my language of choice.
definitely learn solidworks or something in that vein first
that, and as a prior skill, learn to draw by hand on paper orthogonal and isometric views of 3d objects.
cad is another theory building excercise, but instead of being about processes, its about objects. you want to start from a strong manual/first principles base
If you're more interested int the result than the process, Onshape or Fusion are great, free (with use restrictions) parametric CAD. And both support scripting, to some extent.
I wouldn't call a FOSS project that you compare to some 2,620 USD/year software a dead-end. It's good enough for simple modeling, especially when it comes to scripting, and has been for 10 years already.
I am constantly designing parts myself. I just wish that instead of having many unfinished, unpolished products we had something with the level of Solidworks / Onshape / whatever.
FreeCad is getting somewhere but it is still way behind. The last thing I care about is what language was it implemented with.
GP perhaps did not say it in a polite manner, but their criticism is valid.
Please have a check on a different monitor and browser than you are currently using, as most of the article is unreadable. Code blocks are nigh unreadable, and the screenshots are washed out as if they were HDR with improper tone mapping (I tested both with Firefox on Linux and Safari on iOS).
It's a shame, because it made me gloss over the article.
Oh, and the screenshots have the same issue both on the blog post and on the main vcad.io website. Funnily enough, code snippets on vcad.io have proper readable colors as opposed to your blog (they're still too dim to be comfortable though, but they're readable).
I agree the UI on the screenshot is not very accessible. I'm also think that language and tone choice matter a lot when delivering (even constructive) criticism.
What's nice about this is that it allows for programmatic CAD, enabling things like web applications that can download an .stl file based on user input. I hope I can find a weekend or two to play with it.
BTW: I spent a few weekends playing with Microcad (https://microcad.xyz/). It was cool, and had a similar rust feel. I just, for the life of me, couldn't figure out how to do 3d ellipses.
The opening paragraph is very telling; the author doesn't seem to understand typical pro-level parametric CAD programs available on the market:
> I keep designing physical parts for our robots. Motor mounts, sensor brackets, wheel hubs. Every time, the workflow is the same: open a GUI CAD program, click around for an hour, export an STL, realize the bolt pattern is 2mm off, repeat.
This doesn't make sense. When you realize the bolt pattern is 2mm off, you just edit that dimension and let the CAD program recalculate. You don't need to click around for an hour again. That's the beauty of contstraint-based parametric modeling as opposed to, say, modeling in Blender.
The author's program is akin to writing vim to replace Publisher. They're solving entirely different problems. Not to mention, this code-as-model paradigm already exists: OpenSCAD
> That's the beauty of constraint-based parametric modeling as opposed to, say, modeling in Blender.
I was thinking the same thing. This looks more like an API that makes 3d modeling look closer to CAD, but without realizing that CAD is about constraints, parametrizing, and far more.
Read a bit before critisizing:
> One thing I care about that most CAD tools don't: vcad is designed to be used by AI coding agents.
AI coding agents are notoriously bad at anything that involves spatial awareness.
For that there’s openscad
I've even already asked an LLM to generate designs in openscad, and there's plenty of examples out there. Obviously there's a complexity limit, but there's also a cheat sheet that makes it pretty easy to discover how to do almost anything that's possible within.
You're correct, I'm completely uneducated! Pull requests welcome :)
The pull request is to delete the project and open SOLIDWORKS or FreeCAD.
But don't actually delete it. It looks like a nice alternative to OpenSCAD. But like OpenSCAD it's really a niche thing for designs that are highly parametric like fasteners, gears, 3D printed boxes, etc.
Like OpenSCAD using it for normal "irregular" CAD is going to be extremely frustrating. Like editing an SVG in notepad instead of Inkscape.
I still feel like there's a unexplored space where you combine the benefits of both somehow though. Like a code-based CAD but it also has a GUI editor that stays in sync and avoids the need to type in coordinates by hand. That would be extremely difficult though.
>I still feel like there's an unexplored space where you combine the benefits of both somehow though. Like a code-based CAD but it also has a GUI editor that stays in sync and avoids the need to type in coordinates by hand. That would be extremely difficult though.
I think you can do this if the data representation of operations and values is human readable. The simplest implementation would restrict the language/data format to operations representable in the gui.
Unlike trying to solve the "visual programming" problems, we don't need or desire Turing completeness.
Very interesting indeed!
> Like editing an SVG in notepad instead of Inkscape.
Speaking of which, I would love to have parametric capabilities in Inkscape.
Are you aware of Rhino 3D with grasshopper?
SketchUp was my go to for a while but I'm done with parametric personally, trying to fix meshes for 3D printing... time I grow up and use something like Fusion360 seems like or onshape. Still it was good/simple enough for non-round shapes in SketchUp except they have some kind of memory leak/bug at least for the 2017 version. But I guess quit being cheap and buy a modern copy on my part.
Edit: oh I guess sketchup is a surface modeler weird thought it was parametric this whole time, lol someone else said it's a polygon modeler
Yeah I don't know what parametric modeling is apparently, I use a mouse/calipers to model stuff not parameters
There is a solid validator plugin you use before you export an STL to make sure the mesh is closed/a manifold
It's using a constructive solid geometry system. You can add and subtract volumes. Making a hole is subtracting a volume. This has classically been numeric roundoff hell, where points that should coincide and surfaces which should touch don't get handled properly due to numerical error. The geometry engine is Manifold, which guarantees watertight meshes from boolean operations.
Ah. That's what's doing the constructive solid geometry. Here's the 2009 PhD thesis behind the object merge and difference algorithms inside Manifold. Nice. At last, soundness. This is a long-standing problem. And now there's an open source implementation. Manifold itself is in C++, not Rust, though.
None of this is parametric. That's a different problem. That's where you put in constraints such as A is perpendicular to B, B is 100mm from C, etc., and the constraint solver tries to satisfy all the constraints. Change a dimension and everything adjusts to preserve the constraints. Parametric CAD is all about constraint solving and expressing conflicts to the user. Autodesk Inventor, Fusion, etc. have good constraint solvers.
[1] https://github.com/elalish/manifold/blob/master/docs/RobustB...
Manifold (which is doing the heavy lifting in this) uses triangles, which are an approximation.
This is never going to have the accuracy seen in higher-end CAD circles, which use b-Reps: highly accurate mathematic representation.
Manifold is good for visualization, but to use it as an engine for manufacturing .. its limits will be hit.
SketchUp uses direct modelling, not parametric modelling. I think they even got some patents on direct modelling.
This sounds a lot like Fidget (https://github.com/mkeeter/fidget) and libfive (https://github.com/libfive/libfive) by the amazing Matt Keeter!
I had a lot of fun playing around with antimony (also from Keeter) a few years ago, but unfortunately it has been mostly abandoned. I heard libfive is supposed to be the next generation, but I haven't experimented with it yet.
Do you know how it compares?
Hadn't ran into these, thanks!
Unfortunately, using a geometry kernel [1] that operates on triangle meshes means this is a no-go for serious CAD usage.
[1]: https://github.com/elalish/manifold
My whole CAD experience is with OpenSCAD, which apparently uses the same kernel; Honest question -- what is the alternative? I would assume the vast majority of 3D model processing relies on triangle meshes...
Breps. Nearly all commercial cad packages operate on boundary representations of objects.
I would start with CSG if you are new to these ideas:
https://en.wikipedia.org/wiki/Constructive_solid_geometry
Meshes are an output, not a source, and not a good internal representation.
Meshes are only a lossy approximation of the actual geometry, and the errors accumulate as features reference off of earlier features.
A simple example is a line tangent to an arc. The line will only be the correct distance from the center of the arc at one point (one angle) per segment.
In openscad you don't notice the problem because since it's code and you have variables and programming ways of expressing relationships, you would usually not try to derive one thing from another by geometry, instead both things would reference a common ancestor variable. But that's a technical implimentation detail that works around the problem by just not doing a thing that doesn't work. The problem is still there that a valid geometry constraint would produce invalid results.
OpenCASCADE?
https://dev.opencascade.org/
Notably wrapped by build123d into cad as a code package
libfive
I've built something very similar (also based on triangle meshes, but in TS), and while it wouldn't work for say 3D printing, my target is game object modeling. I guess people have specific use cases in mind when referring to "CAD".
In my mind, cad that you’re not going to manufacture is “modeling”. Not sure if that’s a common verbal distinction.
An example of common terms that disagrees with that somewhat, is "CAD/CAM" where the design component is clearly distinct from the manufacturing component.
I do agree that historically, software aimed at building 3d models for games/animations and other digital use was usually called modeling and not cad. I'm thinking of software like 3D Studio Max back in the 90s here.
https://en.wikipedia.org/wiki/CAD/CAM
I notice though that the Wikipedia article for CAD says: "This software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing."
https://en.wikipedia.org/wiki/Computer-aided_design
Not sure either but sharing the sentiment.
Great work! Please consider adding a RSS/Atom Feed to your site. I would like to include it in my Tech Content Platform: https://insidestack.it
Done, thanks for the kind words!
Great, I already added you!
Note that there's an existing CAD-in-Rust project, Fornjot, which has been quietly developing since 2020: https://www.fornjot.app/
Also Truck https://github.com/ricosjp/truck
Is anyone else put off by the AI-sounding text? Two things that give it away for me are the excessive use of punctuation-emphasized sentence fragments ex:
> No clicking. No undo. Just recompile.
> That's our mascot. Entirely CSG.
> No garbage collection pauses. No floating point surprises from a scripting layer.
And worst of all, the dreaded "and/but honestly":
> But honestly, the main reason is the toolchain.
Am I misreading things?
Thanks for the feedback
Curious to how well LLM's work in this context! (mentioned as one of the reasons to embed CAD in Rust)
I only know of another text -> STL AI model, I'm quite a bit more excited about this idea.
Does someone have experience with this?
I've found LLMs perform surprisingly well here if you target CSG or OpenSCAD. It seems to frame the 3D modeling challenge as a logic and syntax problem rather than a spatial one, which plays to the model's strengths. You avoid the spatial hallucinations common in image generation because it's effectively just writing code.
Amazing work! This is what I was looking for, I thought of this few months ago and didn't have the time to create it myself. Thanks will explore it and give my feedback!
Based on a geometry engine written in C++ ...
https://github.com/elalish/manifold
I've been doing a similar thing using GhostSCAD[1], which is a relatively thin wrapper around OpenSCAD in Go. Not as typesafe, but my language of choice.
[1]: https://github.com/ljanyst/ghostscad
I get the sense that this author is looking for a DSL (domain specific language) and landed quite close.
Why not use OpenSCAD?
Because it is not written in Rust, I suppose.
Anyway, I think using only code for designing 3D objects is a poor design choice. You really need something that is between pure code and pure GUI.
Interesting, because I am trying to learn OpenSCAD for some simple modeling.
definitely learn solidworks or something in that vein first
that, and as a prior skill, learn to draw by hand on paper orthogonal and isometric views of 3d objects.
cad is another theory building excercise, but instead of being about processes, its about objects. you want to start from a strong manual/first principles base
If you're more interested int the result than the process, Onshape or Fusion are great, free (with use restrictions) parametric CAD. And both support scripting, to some extent.
Both have really great documentation/examples.
Note: This is probably a dead-end; it is not on the same level as SolidWorks, Fusion etc.
I wouldn't call a FOSS project that you compare to some 2,620 USD/year software a dead-end. It's good enough for simple modeling, especially when it comes to scripting, and has been for 10 years already.
You're probably right, OpenSCAD seems to be limited both in speed and in exactness of the surfaces.
However purely programmatic interface allows doing surprising things which might be hard to achieve with a mouse.
How could I make it better?
Sorry about the confusion - I'm referring to OpenSCAD; not your project.
I am constantly designing parts myself. I just wish that instead of having many unfinished, unpolished products we had something with the level of Solidworks / Onshape / whatever.
FreeCad is getting somewhere but it is still way behind. The last thing I care about is what language was it implemented with.
Absolutely atrocious and piss-poor contrast. Can barely read a thing.
Are you feeling alright?
GP perhaps did not say it in a polite manner, but their criticism is valid.
Please have a check on a different monitor and browser than you are currently using, as most of the article is unreadable. Code blocks are nigh unreadable, and the screenshots are washed out as if they were HDR with improper tone mapping (I tested both with Firefox on Linux and Safari on iOS).
It's a shame, because it made me gloss over the article.
Oh, and the screenshots have the same issue both on the blog post and on the main vcad.io website. Funnily enough, code snippets on vcad.io have proper readable colors as opposed to your blog (they're still too dim to be comfortable though, but they're readable).
Yes, I am alright, the website attempts to support dark-mode but does such a poor job of it that renders it completely useless.
https://i.ibb.co/VppSx4mc/pisspoor.png
I agree the UI on the screenshot is not very accessible. I'm also think that language and tone choice matter a lot when delivering (even constructive) criticism.
Thank for the feedback. Have a nice day.
Yet another rewrite-it-in-rust-just-because project. I'll stick with OpenSCAD