The implicit grid data structure from there is a personal favorite of mine. I used it in a game once and it performed incredibly well for our use case.

It's a bit too complicated to totally summarize here, but it uses a bit per object in the scene. Then bit-wise operations are used to perform quick set operations on objects.

This data structure got me generally interested in algorithms that use bits for set operations. I found the Roaring Bitmap github page has a lot of useful information and references wrt this topic: https://github.com/RoaringBitmap/RoaringBitmap

I spent a lot of time optimizing an octree for ray tracing. It is my favorite "spatial index" because it's the only one I know that can be dynamically updated and always results in the same structure for given object placement.

It's a stellar book. I work on a commercial realtime physics engine, the "orange book" is practically required reading here.

I often recommend this book, RTCD, as a "better intro to data structures and algorithms" (sometimes as "the best"). The advice often falls on deaf ears, unfortunately.

Seconding the RTCD recommendation. Handy code examples, and my favorite part is that the book is real-world-performance-conscious (hence the "real-time" in the title).