This book is really excellent- for its scope, use of metaphors and connections to the real world and other areas of computing, and its interactive examples.
I wish I’d had access to this in high school while I was learning trigonometry & vector math.
It’s not very long. Consider reading it!
What’s the current status? Seems half finished, but I’m not sure if work is ongoing or stalled.
You can look at the commit history on github: https://github.com/patriciogonzalezvivo/thebookofshaders
For the past few years, the changes have been translations to other languages and minor corrections.