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Comment by esens | Hacker News Reader

Neither is designed for a CAD engine. CAD uses generally NURBS and a scene graph based around constraints. Game engines are not constraint based but rather about independent behaviour agents interacting using triangle meshes. Quite different.

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Interesting! Is there any game engine or open source engine or library that would support those kinds of code styles?

I desperately want open source CAD to be a thing. I would suppose that Freecad is probably a very good starting point. I don't think the lack of good open source CAD is due to a lack of a decent codebase so much as the fact that good CAD software is a very large project and we have just not directed enough efforts towards it. I am speculating however and may be wrong.

Rather than "just" Open source CAD I would like to see Open Source CAD-like applications. Well, at least in my mind CAD is something kind of specific and carries a lot of design assumptions with it.

I feel there is a lot of cool stuff you can build in the space of building shapes using constraints. Like visual programming languages made to visualize mathematical relationships using geometry.

Interesting. In my case I am specifically talking about mechanical design CAD for engineering. We have a huge need for that in my opinion. Freecad might be the closest thing but I suspect it needs more investment.

However what you’re talking about sounds important as well.

> I don't think the lack of good open source CAD is due to a lack of a decent codebase

I think the problem is exactly that. A good constructive solid geometry (CSG) is a difficult thing to make and there are no open source alternatives to the ones powering the mainstream CAD packages.

Closest thing would be a level editor, which is very much a CSG-based CAD program with roots going back to the Quake 1 generation. It's just not geared towards typical production applications where real objects are being machined.

Did it have boolean operations like add, subtract, and cut?

Yes, along with the usual extrusion and (I believe) lofting along a desired path.

(I have not looked so this is a genuine question)

Is there an actual issue with the freecad codebase? It has always seemed relatively functional.

It's hard to avoid the segfaults. I've tried to use it many times for simple projects. Some workflows it's every 10min or so, and often you get into corrupted states where you can tell it's about to happen, but of course if you save you risk your files completely.

It's also slow, onshape in my browser beats it at roughly everything.

For NURBS modelling there is OpenNURBS [1], made by the guys who made Rhinoceros 3D, an excellent NURBS 3D modelling program. However, although Rhino is available on Windows and macOS, it is not available on Linux and the authors seem pretty against making a Linux version. OpenNURBS is only available on Windows.

[1] https://www.rhino3d.com/opennurbs/

I personally use MoI3d (http://moi3d.com/). It is basically Rhino but cheaper (albeit with less tools and features).

But as an Indie dev it gets the job done for me.

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