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Comment by nikitaga | Hacker News Reader

Subjectively – it's a much more sane environment for programmers than point-and-click UI. If you want parametric design (and you probably do want it unless you're building simple one-off designs), with GUI CAD tools you need to deal with complex constraint systems, and either expensive subscriptions or quirky GUI (or both).

With code, you just deal with... code, aka math. Parametricity comes essentially built-in, the way variables and functions are built-in to a programming language. Plus all the standard things we take for granted in coding – straightforward component and logic reuse, versioning, etc.

This domain is very complex, and really good code-cad tools don't exist (CadQuery is the most decent IMO, but it's far from perfect), so it's nice to see more attempts at solving this problem.

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> Parametricity comes essentially built-in, the way variables and functions are built-in to a programming language.

That is a common misconception, but in reality that's not how it shakes out. Realworld CAD software uses a geometric constraint solver because real world design problems have geometric constraints.

If you want to draw a rectangle with width X and height Y, sure you can handle that with variables.

What do you do if you want a triangle where one side is tangential with an arc, the other two sides have an angle Z between them and the intersection between that two sides is straight down from the center of the arc (that is they have the same x coordinate)? Is this description well-defined or do we need to give one more measure/constraint before it becomes so? Or maybe even over-defined and we can't possibly satisfy all these constraints?

This is the kind of question a geometric solver can answer, realtime as you are editing the sketch. You can try to cook up an ad-hoc solver every time you need one (with variables and functions) but then you are not in the business of designing stuff, but in the business of ad-hoc CAD development.

I agree that a geometric constraint solver is very valuable. Having one built-in is a goal for Fornjot. We're not nearly there, though!

Awesome! Are you guys thinking about using some already existing solution or perhaps developing your own?

No worries if you haven't thought that far forward, that's also fine. :)

No idea :)

I know I want it, and that's about the extent of the design work. There's loads of more basic capabilities to add, before it makes sense to tackle constraints.

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