What does HackerNews think of s2geometry?

I've been looking for good examples for my next book, but everything I've read about has turned out to be not used, including everything in Michael Bader's book [1], except for S2Geometry [2], but I feel like I need to talk to someone who has more expertise in the benefits/drawbacks of using that in an actual product.

[1]: https://www.google.com/books/edition/Space_Filling_Curves/zm... [2]: https://github.com/google/s2geometry

> It was quite hard for me to find open-source implementations of linear quadtrees.

You probably know this, but the S2 library has one: https://github.com/google/s2geometry

For an example of safe geometric calculation in floating point, see Google's S2 library:

https://github.com/google/s2geometry

> store and index it by tiles

Options include the https://sqlite.org/rtree.html module, and building an application-specific mapping from geometric indexes to an integer keyspace (https://github.com/google/s2geometry or similar).

We're using SQLite archives of many GB successfully without issue. As long as the primary keyspace is well-designed (see also https://sqlite.org/withoutrowid.html), ranged queries are extremely fast.

> I'm never sure how to properly copy raw struct binary data from sql, directly in ram.

BLOB columns and an application-specific serialization/deserialization step work well. memcpy to a struct works if you are absolutely certain that you know what the layout will be. All of the standard perils apply - alignment, internal padding, platform-specific layout, endianness, etc.

We're using Protobuf with success. I imagine Flatbuffers would also work well. I'd put Protobuf/Flatbuf and their competitors on the front of the tool shelf.