I have such fond memories of building a terrain viewer like this (first in Pascal, then in C & Assembly) in the 1990's at the same time I was learning the requi

I have such fond memories of building a terrain viewer like this (first in Pascal, then in C & Assembly) in the 1990's at the same time I was learning the requisite trigonometry in high school. Back then, all kinds of low-level optimizations were necessary to make it work. Figuring out how to do it, and optimize it with no books or internet to reference is one of the most personally rewarding things I've ever done.