Consider adding a license to the repo

[john-h-k]

Currently this is unlicensed, meaning

no one may reproduce, distribute, or create derivative works from your work
It seems providing a license or an explicit unlicense would be beneficial to anyone wanting to use the code here

[MasterDrake]

Yeah, seems weird to write a renderer book, publish the code and not add a license
What we can do with the code?

[AntMaster7]

I'm also looking into finding license details.