This is (or at least used to be) a right of passage in the graphics world.

I think many people go through the very popular https://raytracing.github.io/

There was a big influx of this when Sebastian Lague did his video series on building a ray tracer.

And if you've decided you want to take it a bit more seriously, move on to:

https://www.pbrt.org/

which is effectively the bible, and has been for years (I wrote mine and moved into the VFX industry when the Second edition was still out! - I feel old now)