truck 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

I think you confuse the book/tutorial with the documentation on docs.rs.

My impression is that the former is very much a work in progress. I never looked at it until now.

The latter (and the examples in the resp. crates) is what you want to look at to see the kernel being used. E.g. https://github.com/ricosjp/truck/blob/master/truck-modeling/...

The main README has links to all the documentation of the crates.

There are two Rust projects working on parametric kernels I'm aware of.

The first one, Truck[1] seems to have a company behind it, Ricos Ltd, that look like they to know what they're doing[2]. The tweet shows their product using functionality from Truck (the frontend is not OSS AFAIK).

Fornjot is an ambitious project IMHO. Their kernel is in a separate crate[3].

As for OSS code that could be a good base to either use (or port to something like Rust) for someone to write their own kernel is Ayam [4], the oldest OSS 3D NURBS modeler that is still being developed.

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

[2] https://twitter.com/RICOS_ltd/status/1550390552482693120

[3] https://crates.io/crates/fj-kernel

[4] https://ayam.sourceforge.net/

I've been following your project with interest and was wondering if you were familiar with Truck. Its another project implementing a CAD kernel in Rust.

I will definitely keep reading and learning, as well as gaining practical implementation experience. We'll have to see how that goes, and what the solution will end up being.

> Another direction you could take is to define just the API, and use the opencascade kernel (like FreeCAD) until the rest of your code is ready.

A CAD kernel is the central dependency for any CAD program, and I feel that it would be wrong to just use one and accept its limitations. I need to be able to take ownership, to work on it directly. OpenCASCADE is a huge pile of C++ code, which is the opposite of all that. (Not saying it's wrong to use in general, just that I'm the wrong guy to work on a huge pile of C++ code.)

I've considered using Truck[1], but decided not to do that for now. I really want to see what I can come up with. If that doesn't work out, at least I'll be in a much better decision to decide what other option would be best.

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

For a specific example: I am interested in working with 3D objects using Rust (maybe this is too ambitious for a newbie!) so I found a CAD kernel crate called truck which seems to be crate built of smaller crates and implementations of other libraries. How would you go about finding the most relevant info and where to start? Should I start by understanding all the smaller parts such as the gui/gpu rendering modules, or is that irrelevant and I can focus on figuring out the top level?

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: