Seems like this is a good place to ask.
I really like the technical side of gaming, aka game engines. I've worked with OpenGL before to make a small 2D game but it was quite basic. I basically want to develop a modern game engine in my spare time with modern techniques like PBR shaders, GI, perhaps even ray tracing. The main objective would be learning with hands on practice.
What's the best place for a deep dive? Perhaps a nice book recommendation? I'll be ok with getting my hands dirty in terms of math or programming principles.