Pomax (the author) here: for those wondering about what's different since last time this hit HN, this is a slowly-but-surely updating project that has been in the works since 2011. If you remember seeing it before: you're not wrong! But it will probably have been less content or less functionality than it is this time round =)

The latest improvement is that the codebase now supports localization which means that if you're a dual (triple, etc) speaker and you want to help bring this content to people who don't speak English, now you can! Chinese and Japanese localizations are already underway (although it's a volunteer effort, much like the Primer itself, so progress is again steady, but slow) and currently cover the first 10 or so sections.

For more details on the fine points of the build system and how much work it was to overhaul an "everything is assumed to be English, no l10n provisions have been made whatsoever" to "EASY to localize" (not just 'possible to', but 'easy'), hit up http://pomax.github.io/1489108158510/localization-is-hard where I've blogged about the uplift and the tech choices I made.

And on a less impressive note but certainly more useful for social sharing, the social share buttons now actually point to the section you're reading, so that future sections can be shared waaay easier. For the last six years, those things have just pointed to the base article URL and that is not very useful when you want to share the fact that you just read up on how to split a Bézier curve using matrix operations, or want to link to the B-Spline section all the way at the bottom of the Primer.