Scratchapixel is a really comprehensive resource. I referred to it frequently while working on a 2-day workshop on writing a raytracer. What I've always found

Scratchapixel is a really comprehensive resource. I referred to it frequently while working on a 2-day workshop on writing a raytracer. What I've always found missing are resources that cover both the foundational theory and the implementation details, in a way that connects the two ends. That's why, when developing that workshop, I created a resource that goes over the theory of raytracing--including the relevant math--and walks you through a series of practical projects. I put up the resource online: https://avik-das.github.io/build-your-own-raytracer https://avik-das.github.io/build-your-own-raytracer The page also links to two reference implementations in Java and Javascript, so learners can follow along.