Nevertheless it feels like brlcad is maybe the best foss cad at this time.

From what I understand, FreeCAD is limited by the OpenCascade kernel. I wonder if brlcad could help to address this issue in any way.

It's limited more by the way it uses it.

No, OpenCascade just kinda sucks to use.

In what ways is freecad using opencascade incorrectly?

brl-cad is CSG modeler with some BRep support. Opencascade is a BRep modeler that supports boolean operations. The industry gave up on CSG and went BRep decades ago.

openSCAD is also a CSG modeller, and quite popular in 3d printing.

Not entirely true. As an explicit edit method, sure, but several of the big-name non-parametric (i.e., solid modeling) commercial CAD systems are fundamentally still CSG representation under the hood. They just hide it well, typically under the guise of feature edit nomenclatures or editing constraints.

Can find indications it's CSG under the hood if it won't let you directly modify a surface without selecting some "convert to editable representation" option. TinkerCAD is an extreme example that's basically a pure CSG modeler (and probably the most popular CAD system to date, but I digress), but you won't find the term union, intersection, or CSG anywhere in its GUI. Solidworks and NX do a really good job hiding it.

I guess we have a disconnect. I am talking about modeling kernel geometric definitions and data structures. Whether NX has or doesn't have the boolean terms (union, intersect ...etc) doesn't change the fact that parasolid is BRep. Just because parasolid supports boolean operations, doesn't mean it is CSG.

IMHO: Any shape defined by a CSG modeling kernel can be defined in a BRep modeling kernel. The reverse is not true, short of some kind of 'hack'. BOT(bag of triangles)? Hybrid with mesh modeling?

The topic has come up and been a point of discussion, especially developing something akin to the ACIS or Parasolid kernels, but open source. In many areas, BRL-CAD's capabilities far exceed what OpenCascade provides, particularly w.r.t. CAE features, and in others it is noticeably lacking (e.g. export to polygonal). Couple years of effort have been invested in developing a new C++ API for exactly this purpose (codename "MOOSE").

Current dev focus is on conversion, rendering, and GUI modernization.

I wonder why do you care about rendering? There are many good open source renderers out there, now. For instance can't you just export the geometry and render with Yafaray?

Open source software doesn't need to die, as long as there's someone to maintain it. This project looks pretty active with regular commits:

https://github.com/BRL-CAD/brlcad/commits/main

Well said!

Like many open source communities, pandemic had a pretty significant impact, but development and releases are quite active.

New release coming out in a few weeks introduces conversion support for 150 new geometry and terrain file formats. This summer, Physically-based Rendering support is coming to open source CAD for the first time ever. All the while, devs are working on GUI infrastructure, mentoring GSoC, doing academic research, interacting with academia, and doing what they can to help foster an open source CAx community.

Fully agreed, solved problems should be considered dead and invalid so it will have to be solved time and time again, keeping human wisdom ephemeral and constantly eroding /s

BRL-CAD has a very rich and ongoing development history that is not immediately obvious. [1,2] Heavily actively used by gov'ts as it has unique features like validated full shotline solid ray tracing -- granted, not a feature most know, understand, or care about but absolutely critical to others. Development is actively funded annually (just not your priorities).

In total, BRL-CAD today has more than 500 full-time staff-years of effort invested, more than pretty much all other open source CAD combined.

There's simply no PR team, and limited bandwidth to provide support to those that don't contribute in kind. CAD modelers coming out of school are only accustomed to multibillion dollar company products that dedicated highly experienced devs to specific user-facing features under dedicated funding lines.

With open source, skillsets vary wildly and coordination, collaboration, and maintenance are a challenge until a project achieves critical mass. It's something the BRL-CAD community is working hard on, but it's not something that will be quick. Contributors are welcome!

[1] https://www.army.mil/article/92288/brl_cad_the_worlds_oldest... [2] https://brlcad.org/BRL-CAD_Bibliography.pdf

Thanks for the info. I didn't want to rain on your parade but it just doesn't seem very active judging from the homepage. Also, if you want more community involvement you should probably provide binaries for platforms like Mac OS and Windows to attract more end users that may eventually lead to more developer engagement.