Comment by kushalkolar

OK now try to do this in 3D with arbitrary projections and interactivity! And guess what, you'd create a rendering engine :)

My earlier reply has a link to how GPUs actually push pixels to the screen.

There are also some excellent blog posts on how line rendering is done:

https://almarklein.org/triangletricks.html

https://almarklein.org/line_rendering.html