raycasting

Raycasting builds an image by firing thin rays outward from the camera's position and measuring the distance to the first wall or object each ray hits. Think of waving a flashlight around in a dark room: things close to the light look big and bright, things far away look small and dim. Raycasting turns that same idea into a calculation. Stitch together the distance readings from every ray, and you get a picture that looks three-dimensional even though it's drawn on a flat screen.

This technique was popular in early 3D games, back before graphics cards had anywhere near the 3D processing power they have today. Instead of building a ton of actual 3D models, developers could fake a convincing 3D space just by doing ray calculations over a flat map. More recently, this decades-old method has been dug up again for experimental projects that render results with text or symbols instead of polished graphics.

The article explains that a walkable ASCII city was built using nothing but 'raycasting' — no game engine, no 3D models. Easy to mix up: raycasting isn't an AI technology, it's a graphics calculation method that's been around for decades.