fornjot VS CascadeStudio

I agree 100%.

Truck[1] and Fornjot[2] are recent attempts in the Rust space, both are WIP.

But both seem to be going the traditional way. I.e. B-Rep that can be converted to (trimmed) NURBS.

I think if one wanted to incorporate the last 50 years of computer science, particularly computer graphics, one needed to broaden the feature set considerably.

You need support for precision subdivision surface modeling with variable radius creases (either via reverse subdivision where you make sure the limit surface pass through given constraints or using an interpolating subivision scheme that but has the same perks as e.g. Catmull-Clark).

Then you need to have SDF modeling ofc.

Possibly point based representations. If only as inputs.

And traditional B-Rep.

Finally, the kernel should be able to go back and forth lossless between these representations wherever possible.

And everything must be node-based, like e.g. Houdini. Completely non-destructive.

[1] https://github.com/ricosjp/truck

[2] https://github.com/hannobraun/fornjot

Fornjot seems like this question was tailored for it: https://www.fornjot.app/

I think some interesting developments are made in that sector in the form of https://github.com/hannobraun/Fornjot and https://github.com/ricosjp/truck. Let's see whether one of those will actually get anywhere near a usable level. Fornjot in particular is shaping up really well.

E.g. Rhai[2] or Lua or whatever.

And I guess if their tech is solid enough, someone will do that eventually and open a PR or fork the project. They do not use an existing geomtry kernel but do everything from scratch which makes this a very interesting endeavour.

There also seems to be a goal overlap between Fornjot and DieselCAD

[1] https://github.com/hannobraun/Fornjot

[2] https://rhai.rs/

I have heard of yet another in-development CAD software like OpenSCAD or CADQuery, called Fornjot. Still, these are not ideal.

I'm not opposed to someone else adopting that code and creating that crate though! (Fair warning though, Fornjot might not end up using that crate. We might still go with another approach eventually.)

also it's to early to be off much use to you, but have you heard of https://www.fornjot.app/ ? it's a very in development cad kernel that is also aiming for integration into multiple host languages.

Yes! The website and repository README have a screenshot, and there are screenshots for each model in the models/ directory.

I'm kind of interested in this issue because it's what I immediately wanted when I ran fj-app.

OCCT is definitely difficult.

I am almost as far as you can get from an expert but:

For example the TNP issue derives from OCCT (or something in the stack close to it, I am not exactly sure) not really handling face naming at all.

So if you want to avoid topological naming issues (which is a hard problem in CAD), you apparently have to do some work to track before and after and reconstruct your face naming.

https://wiki.freecad.org/Topological_naming_problem

https://forum.freecad.org/viewtopic.php?t=27278

Then there are various fairly entrenched issues to do with filleting and chamfering. Basically, both these operations will fail (in FreeCAD at least, but it's OCCT at "fault") if a chamfer or fillet would completely consume an existing edge. (It also sometimes creates impossible objects when filleting, or used to).

Booleans can be slow.

And more generally, it seems if you track the FreeCAD project that OCCT can be inscrutable when things fail; error messages aren't the greatest etc.

The flip side of OpenCascade is that it seems to be highly portable and has for example been compiled to JS with Emscripten for this astonishing thing:

https://zalo.github.io/CascadeStudio/

It's a monumental open source project, for sure, and it's definitely not nothing that we have an open source CAD kernel; these are projects that perhaps have to extend beyond the working life of an individual developer if they are to be stable. And there are loads of projects built around it.

If you haven't seen it you may want to check out https://github.com/zalo/CascadeStudio

From what I see, it is exposing the OpenCascade base commands directly, versus your completely new DSL, but you might be interested in a way to implement your DSL on top of such an interface such as this which takes out a lot of the extra work of having a rendering interface, exports, etc, maybe.

It's nowhere near ready for primetime, but you should take a look at CascadeStudio (https://github.com/zalo/CascadeStudio)

FreeCAD is GUI-based though, not code-first like Fornjot. A better comparison would be CadQuery (https://cadquery.readthedocs.io/en/latest/intro.html) or Cascade Studio (https://zalo.github.io/CascadeStudio/), both of which are code-first and based on the same CAD kernel as FreeCAD.

It is an actual example from CascadeStudio, but I haven't looked into it enough to know how what actually happens under the hood, but I assume the following: