The above animation was created using my custom made 3D render, built using Java (because its all I knew at the time).
The idea behind this project was to build an entire 3D engine without the help of any math or 3D graphics libraries. I can't remember if this was out of desire to learn, or because I didn't know of the existance of these libraries. Perhaps an engine was a bit too optimistic given I'd never worked with any 3D graphics in my life at the time. At the very least, I learned a lot throughout this project.
I first became interested in this topic in highschool, so there was a lot to learn. By the end, I had self taught almost all the basics of linear algebra and projection.