Refactored Faster Rolodex Compatible Filament Swatches (OpenSCAD)

The filament swatch Rolodex by 3D Printy is a great idea! However, while printing a bunch of swatches, I found the file sometimes took minutes to render - which really slowed down my experimentation to find the right size and text for each swatch. So to learn some more SCAD and more deeply understand the model, I have done some significant code refactors on this file. This is a work in progress as I learn SCAD optimization techniques. There may be more performance gains in the future!

Initial load+preview(F5) times, on Windows 10 with OpenSCAD 2021.01 (YMMV), opened by double-clicking the .scad file: 

• Original - Total rendering time: 0:00:00.445
• Refactored - Total rendering time: 0:00:00.340

Text change preview times, by adding a trailing ‘e’ to line 1 text and previewing:

• Original - Total rendering time: 0:00:00.298
• Refactored - Total rendering time: 0:00:00.352

Full render(F6) times after a fresh reload:

• Original - Total rendering time: 0:02:13.948
• Refactor - Total rendering time: 0:01:44.742
• Refactor + reduced $fn - Total rendering time: 0:00:41.564

In this version, you will find:

• All the same variables as in the base file! Just use whatever settings you had before. See the original for more info about what each does.
  • Except: Text line positions are now lower case! Use ["left", "center"].
• The model renders flat, in printable orientation. Convenient for color-change slicing.

This file is licensed CC-Attribution, the same as the original file. Use it the same way you would have the original.

Refactor changelog:

• Render each object flat in the native X-Y plane, with origin at the bottom left. This removes a lot of width/2 calculations, and confusing Y and Z coordinates. Plus, it enables:
  • Final position is controlled by an outer translate call surrounding each object.
  • All dimensions while creating the shape are based on the [0,0,0] origin for convenience.
• Render all shapes and text that go all the way through a card or spacer in 2D, then extrude that 2D shape to 3D all at one time.
• Generalize fillet function to round corners, generates a 2D negative round instead of removing cubes and re-adding cylinders in 3D.
• Basic card shape and Rolodex hole generation code are shared between cards and spacers - so they will always be the same.
• De-duplicated code for ring and star holes - now there is only one location where these are created.
• Cleaned up the logic for combined flag uses quite a bit - when ring and star holes are applied, or when card and spacer are both rendered.
• Combined text generation by making Line_x_Position variables take the same values as the halign argument. Saved a bunch of code for relocating text, and each line is generated on exactly one line of code for easier modification.
• Total line count reduced from 501 to 326 - with all the same flags and features. Much nicer to read
• Pre-render combined card shape before differencing with subtractive shapes. This reduces some of the math complexity in that difference calculation.
• Added some tiny additional margins for subtractive shapes, so fast previews don't show ghost surfaces.
• Reduced explicit $fn used for extrusion to 32 - not a significant quality impact at Rolodex size. This has the biggest performance impact, but is not shipped by default - I printed with 100, and have not tested it yet. Control with the extrude_fn variable at the top.

TODOs / investigations:

• Where might the render() call give additional benefits?
• More render optimization possible? Need to learn more!

This was an interesting exercise in learning OpenSCAD! I hope someone can learn from seeing two different code approaches to the exact same model.