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Comment by aclindsa | Hacker News Reader

One of the best things about openscad is the ability to immediately see the results of a code change in the 3D view (all I do is save the file with :w in neovim and openscad re-renders it). Being able to interact like this makes it much quicker and easier to iterate on a design.

I read through the ucad website and book for 10 minutes and haven't been able to figure out if there is an analogue to this for ucad?

There are several things that look neat about ucad's language, but I would need to recreate something like openscad's workflow to consider switching.

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That immediacy is mostly thanks to OpenCSG which is essentially a magic trick to quickly fake 3d rendering of booleans between 3d objects using stencil buffer of gpu. http://opencsg.org/

In other words it renders the cylinders cubes spheres etc and their unions differences etc, to a 2d screen without actually calculating the intersection of those meshes / solids in 3d space.

This is the special thing about OpenSCAD design is they figured out how to build an abstract syntax tree that could either be sent to OpenCSG, CGAL (old engine), Manifold (new engine), or even the bare bones 'ThrownTogether' renderer (ancient engine on machines with no gpu that just draws 'negatives' as green blobs iirc).

It should be theoretically possible for any CAD program to do this. its just a lot of work.

wow, this is really neat. I always noticed how, when panning around with ortho view, it didn't need to re-render

I didn’t know they’d added an alternative kernel. The CGAL one used arbitrary precision which massively slowed it down.

Also, fillets are made using the Minkowski operation, which is super slow.

They added it in the dev branch. There hasn't been a stable release since 2021 and there has been a lot of ongoing development in the meantime, many people use the development release since it's significantly faster.

> This is the special thing about OpenSCAD design is they figured out how to build an abstract syntax tree that could either be sent to OpenCSG, CGAL (old engine), Manifold (new engine), or even the bare bones 'ThrownTogether' renderer (ancient engine on machines with no gpu that just draws 'negatives' as green blobs iirc).

Mostly.

I've still had several instances when drawing curved solids that the OpenCSG renderer worked well with (visually) but when it came to render-time, there was something wrong. It is very hard to debug things, or at least I found it so, when it goes wrong like that.

A viewer/preview is in development.

they got a grant for that. i couldn't find an english version though, sorry.

https://www.prototypefund.de/projects/microcad-viewer

This implies that you can preview in VS Code: https://docs.microcad.xyz/tutorials/book/lego_brick/preparat...

I'm not sure if it's on par with what you want, though.

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