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GenCAD

gencad.github.io

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Re: GenCAD

#71

Post by vincent-uden »

ecto wrote: post #22

Readers may also enjoy my open source Rust BRep CAD kernel https://github.com/ecto/vcad or the hosted version at https://vcad.io . I also wrote a bit about what goes into CAD apps! https://campedersen.com/tessellation

Seeing as I'm attempting to build my own CAD program in Rust I checked out the hosted website. I'm not really sure what is supposed to be working and what isn't.

I can't help but to be skeptical of one person writing ~115k LOC in 4 months which is just the Rust crates, nevermind the frontend (which is another 100k LOC!!!).

I'm curious why you decided to go with "eager" tessellation. Creating a circle immediately results in a bunch of lines which resemble a circle but would fail under tangency constraints quickly. Is this a current limitation or part of the strategy for the kernel?

Re: GenCAD

#72

Post by whazor »

jrflo wrote: post #37

Neat, but I don't really see the utility. The time consuming part of CAD drawing comes from figuring out the correct dimensions of each feature, spacing, sizing, tolerances, etc., and constraining the drawing in a way so that it's easy to tweak later on- which this doesn't do at all. Maybe you could draw a 2d sketch of what you want then generate it, but you'd still have to do the hard part.

Strangely, it would work better if it generates CAD as code with clear labels. Then you can grab your caliper and make sure its all the right size.

Re: GenCAD

#73

Post by physicsguy »

john_minsk wrote: post #69
physicsguy wrote: post #67

This is over a year old now, why post now? There have been other advancements in this area.

Could you please share?

For e.g.:

https://arxiv.org/abs/2603.04337 https://arxiv.org/abs/2603.05607 https://arxiv.org/abs/2605.01171

For a more detailed review: https://github.com/lichengzhanguom/LLMs-CAD-Survey-Taxonomy

Re: GenCAD

#74

Post by dajt »

I'm stumped by things like this. The drawing & modelling are not the difficult bit - the CAM programming is.

That seems difficult enough that I have not found an open source program to load a 3D model and allow me to set the toolpaths in a UI, never mind have an LLM generate them from the model.

Re: GenCAD

#76

Post by clmul »

vincent-uden wrote: post #71
ecto wrote: post #22

Readers may also enjoy my open source Rust BRep CAD kernel https://github.com/ecto/vcad or the hosted version at https://vcad.io . I also wrote a bit about what goes into CAD apps! https://campedersen.com/tessellation

Seeing as I'm attempting to build my own CAD program in Rust I checked out the hosted website. I'm not really sure what is supposed to be working and what isn't. I can't help but to be skeptical of one person writing ~115k LOC in 4 months which is just the Rust crates, nevermind the frontend (which is another 100k LOC!!!). I'm curious why you decided to go with "eager" tessellation. Creating a circle immediately resu…

As someone also working on CAD in their spare time, also tried the hosted app. I get the feeling that this is made by someone who has never opened a (professional) CAD app at all. It feels like a mix between a tool like blender and CSG-style CAD, but even all of that doesn't seem to work. Maybe this is the proof that vibe coding does not work, at least not for this kind of application.

In my own project I use LLMs very sparingly and hesitantly, but made the observation that they are not very useful on the hard parts of CAD. I expect this is because of a lack of training material. Most professional CAD applications are proprietary and books on the topic are usually sparse on implementation details. The non-BRep CAD applications such as OpenSCAD and family are probably overrepresented in the training data.

This might also explain why people's experiences with LLMs are very varied. If you stay in the happy path of CRUD web development and stuff all is nice and well, but if you start to veer off this path you get more and more challenged.

Re: GenCAD

#77

Post by Arch-TK »

stck wrote: post #65
jrflo wrote: post #37

Neat, but I don't really see the utility. The time consuming part of CAD drawing comes from figuring out the correct dimensions of each feature, spacing, sizing, tolerances, etc., and constraining the drawing in a way so that it's easy to tweak later on- which this doesn't do at all. Maybe you could draw a 2d sketch of what you want then generate it, but you'd still have to do the hard part.

If you can just take a pencil and draw a piece of furniture, press a button and get a semi-decent CAD drawing to tweak, that'd be a huge tool for carpenters and such.

"to tweak" is probably quite far away even if "get a semi-decent CAD drawing" was remotely reliable which it isn't.

Re: GenCAD

#78

Post by willis936 »

smartmic wrote: post #61
jrflo wrote: post #37

Neat, but I don't really see the utility. The time consuming part of CAD drawing comes from figuring out the correct dimensions of each feature, spacing, sizing, tolerances, etc., and constraining the drawing in a way so that it's easy to tweak later on- which this doesn't do at all. Maybe you could draw a 2d sketch of what you want then generate it, but you'd still have to do the hard part.

As is often the case in the GenAI space, this also appears to be a solution to a non-existent problem.

I very much have this problem. I am uninterested in the art of sketching and constraining. I have spent many hours attempting and am content with the knowledge that I don't have the touch but still sometimes have problems I want to solve with 3D prints. LLMs could offer a solution, but they are bullshit machines and by their nature over promise. Drafting is not a trivial skill that we just wave a wand and magically have it automated. We'll get there eventually, but we're not there.

Re: GenCAD

#79

Post by nextlevelwizard »

satvikpendem wrote: post #64
nextlevelwizard wrote: post #45

Earlier quoted context omitted.

If down the line this model could create 3D model from 2D images that would be very neat way to pay less for war gaming models

Gaussian splats and neural radiance fields already exist.

I dont know how that solves this. How do you get STLs out of gausian splats?

Re: GenCAD

#80

Post by nextlevelwizard »

semi-extrinsic wrote: post #50
nextlevelwizard wrote: post #45

Earlier quoted context omitted.

If down the line this model could create 3D model from 2D images that would be very neat way to pay less for war gaming models

You can already do this with apps like Kira. I believe it is especially good on the iPhone variants with LiDAR.

I dont know that app specifically, but from all videos of different lidar and other 3d scanning tools I have seen the results are pretty bad and require a lot of sculpting after the scan. Whole point was that with few images the ML model could construct the actual 3d model for you
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