What are the mechanisms and idioms of code re-use in OpenSCAD?

user_6415465 0
Viewed 3012

I designed few simple 3D parts with OpenSCAD and I would like to move on to more complex parts now. As in most other programming languages, that would naturally include starting to re-use code that others have written before. Such as functions for round/bevel edges, infill corners, beziers curves and some common parts like screws, bolts.

How does that work in OpenSCAD? Specifically: What are the language features, idioms and officially recommended good practices of how code reuse is achieved in OpenSCAD?

(You are welcome to include pointers to good examples. But the question is about the mechanisms and good practices for code reuse in OpenSCAD, not about specific code that can be reused.)

openscad
2 Answers

Reusable code in OpenSCAD is organized in "libraries", similar to the package or library system in many other languages.

As with all code reuse, there is the problem of library scope overlap, where two libraries solve the same issue. This cannot be truly solved. But as a best practice, I would choose the one most appropriate library for each design project, and then stick with whatever that library has to offer. For example, don't depend on both BOSL and NopSCADlib because you like BOSL for everything except its threading functions, which you like better in NopSCADlib. For a small project, I like to work with only Round Anything, which is small and compact.

To help you get started with choosing a library appropriate for your project, I include a list of examples below that I thing show good practices of reusable OpenSCAD code. I had a long look at OpenSCAD libraries recently and this is the result. Most of them come from the official OpenSCAD libraries page, which I found to recommend only a few but very good libraries.

My favourite libraries, roughly in my personal order of desirability:

  1. BOSL (source, docs) and BOSL2. (source, docs) "The Belfry OpenScad Library - A library of tools, shapes, and helpers to make OpenScad easier to use." Includes lots of modules and functions to make OpenSCAD code more readable. Overall, it's like MCAD in scope, but much better in execution. BOSL2 is a much extended second edition of BOSL, but as of 2020-11 the author says it is not yet ready for production use.

    BOSL includes a very good Bezier library. Includes a threading library.

  2. Round Anything. (source, API, visual overview) "Round-Anything is primarily a set of OpenSCAD utilities that help with rounding parts, but it also embodies a robust approach to developing OpenSCAD parts."

  3. NopSCADlib. (source, docs) A very large library. Use for any kind of machine design, as it contains nuts, bolts, washers, electronic components, belts etc.. "It contains lots of vitamins (the RepRap term for non-printed parts), some general purpose printed parts and some utilities. There are also Python scripts to generate Bills of Materials (BOMs), STL files for all the printed parts, DXF files for CNC routed parts in a project and a manual containing assembly instructions and exploded views by scraping markdown embedded in OpenSCAD comments, see scripts."

    Also contains a 3D sweep function and a thread generation module.

  4. BOLTS. (source, docs) "BOLTS is an Open Library of Technical Specifications." Contains all kinds of models for metal hardware standard parts (example).

  5. dotSCAD. (source) Seems to be one of the best general library for OpenSCAD, being both huge, good quality, and well maintained. Mostly focused on math art parts. For an overview of the designs made by the author of dotSCAD, using that library, see here. For background articles about the designs made with dotSCAD, see here.

  6. MCAD. (source, docs) This is so far the only library shipped with every installation of OpenSCAD, so would qualify as its standard library. No need to tell users of your designs to install anything when you only include MCAD.

    Note that currently (as of 2020-11), a large rework is being done to MCAD, with the effect that the dev branch has nearly twice the commits as the master branch. You'll find many goodies here, but of course users of your design would then have to install the dev branch first.

    The problem with MCAD, esp. the current master branch, is that I don't find it useful. It's so far a rather a non-integrated hotchpotch of contributions from many authors. But since it's the standard library, we should give it a chance. When I have something to generally useful, I'd try to contribute it here.

  7. Revolve2. (source, announcement) In terms of speed, this is hands-down the best thread generation library I could find. I did not yet test the threading features in BOSL and NopSCADlib, though.

  8. 3D sweep demos. (source) But note that this is rather demo code than a library; first try the sweep module in NopSCADlib.

  9. scad-utils. (source)

  10. Relativity. (source) A library to arrange objects relative to each other. Also includes a CSS-like styling language for objects. Seemingly no longer in active development, but still great to learn really advanced OpenSCAD techniques.

user_12700080
user_64154650
Related