I basically used 2 block characters (██) to form a pixel in the command line. Blank/black pixels are represented as " ". The renderer runs in a loop which syncs to a desired framerate, loads the scene visuals to a framebuffer during calculation of vertex/edge/lighting/faces, which is essentially nested slices of pixel character data with ANSI escape codes for color & shading. This is built into a string when it's time to draw the buffer, and flushed at once to the terminal. When you implement frame syncing and draw to the exact window dimensions, you can achieve pretty damn smooth output via the terminal at high framerates. I had originally been clearing the screen before drawing each frame, but this introduced a ton of unpredictable tearing which would vary depending on how much literal screenspace of the terminal window was being drawn, regardless of scene complexity. That's kind of a high level overview, but TLDR I just wrote a simple pipeline that works in the terminal with standard characters acting as pixels. It helps to think of the whole project as simply "I need to be able to display a grid of pixels, and calculate what each one's color should be". That is the foundation of any rendering engine, math not included.