While there are a lot of resources available for different graphics API's, I have yet to find a good comprehensive tutorial or library for software rendering. Being interested, I would love to know if anyone has a reference at hand.
https://raytracing.github.io/books/RayTracingInOneWeekend.ht...
https://graphicscodex.courses.nvidia.com/app.html
https://www.gabrielgambetta.com/computer-graphics-from-scrat...
I can vouch for the first two as being good. I haven't actually looked at the third but I found I had a bookmark for it.