Now if I ever get around to writing that terminal emulator for fun, I'll be tempted to do it with this algorithm for the code's aesthetic appeal.
A Professional Equation Editor for Windows 10/11 for 60$ that uses Slug for rendering. Presumably he‘s using it to write his great FGED books.
(I get it. It's an awesome replacement for MathType. It uses OLE so that it embeds in Microsoft Word nicely. Still...)
Most primary, secondary, and pre-university school teachers without an institutional understanding of LaTeX, which admittedly has an extremely high (technical, not financial) barrier to entry compared to Microsoft Word + MathType. This is what my secondary school teachers used, for instance. They're given bog-standard laptops with Windows to work with.
Also exam setters and writers in places like Cambridge University Press and Assessment. If you took a GCSE, O-level, or A-level exam administered by them, it had pretty high quality typesetting for maths, physics diagrams, chemistry skeletal diagrams and reaction pathways... But almost none of it was done with LaTeX, and instead probably all add-ons to Microsoft Word or Adobe InDesign.
> It's an awesome replacement for MathType. It uses OLE so that it embeds in Microsoft Word nicely.
But that's the rub - OLE doesn't embed particularly nicely. I haven't used it in over a decade (maybe two?). It's sort of very softly deprecated.
The new equation editor in Word which isn't based on MathType, and doesn't use OLE, works much more smoothly than the old one, even if it doesn't support everything. ("New"? I just checked and it was introduced in 2007!) I think a typical user would have to be really desperate for extra functionality to abandon that level of integration, at which point you'd probably switch away from Word altogether.
a) The winding number of a point is the number of intersections of a scanline and a closed path.
b) The winding number around a point is the total angle subtended by the path at that point.
Slug uses approach a) and that comes with a lot of edge cases (see chart in the post) and numerical precision issues. The approach by loop & blinn uses b) and is thus simpler and more robust. Likewise the patent on that one expired too: https://news.ycombinator.com/item?id=47416736#47420450
Also just to clarify regarding this statement:
> Slug uses approach a) and that comes with a lot of edge cases (see chart in the post) and numerical precision issues
Slug does not have numerical precision issues. It's the breakdown into different cases that _solves_ those issues, whereas your statement makes it sound like slug has _both_ the case complexity and the precision issues.
The original paper did assume no overlap yes. But that is not how anybody would implement it. For a long time one would use the stencil buffer with different operations depending on the front-face / back-face (this is where the paths rotation around the sample comes in and what makes this an angle based approach).
> which requires a complicated triangulation step. It can produce some nasty geometry in more complex cases.
Again, not how anybody would implement this. You can just stream the quadratic bezier curves unprocessed into the vertex shader, literally the simplest thing conceivable.
> With Slug, you can use only 1 quad per glyph if you want.
Nowadays one would probably implement loop & blinn in a tiled compute shader too (instead of using stencil buffers) to reduce memory bandwidth and over draw. That way you also get one quad per glaph, but without any of the geometry special casing that Slug does.
> It's the breakdown into different cases that _solves_ those issues, whereas your statement makes it sound like slug has _both_ the case complexity and the precision issues.
Correct, might have worded that badly. Still remains a trade off in a) which b) does not have.
For those of you who aren't familiar with Eric's work, he's basically the Fabrice Bellard of computer graphics.
Also, Microsoft's Loop-Blinn patent for cubic curves will expire on March 25. These might change the landscape of text rendering...
vello will probably do great under very heavy loads but for your average UI or text document? i reckon something far simpler (like slug!) will end up being more efficient simply by avoiding all those shader launches
Harfbuzz is only one piece of the puzzle, it's not a text renderer, only a 'text shaper' (e.g. translating a sequence of UNICODE codepoints into a sequence of glyphs). The actual font handling and text rendering still needs to be done by some other code (e.g. the readme in Mikko Mononen's Skribidi project gives a good overview about what's needed besides the actual rendering engine: https://github.com/memononen/Skribidi/)
At the time they were going with, approximating the curves out of triangles. I don't know if they're still doing that though.
Damn dude didn't you pay like ... over $10k for that patent?
This is cool but I did not know software patents were still a thing in the US.
Also thank you to Eric Lengyel, I have had my eye on Slug for a while and wished it was open-source.
https://web.archive.org/web/20260317185928/https://terathon....
