If the sun is directional, like a flashlight you hold relatively close to the flat disc, you can move it around in a circle say along the inside of the circumference of the disc, then this creates “night” for those portions of the disc outside of its range…
Oddly enough, this might work as a sort of projection to model the actual path of sunlight across a flat projection of a map of the earth.
The sun is more like a spotlight idk
If the sun is directional, like a flashlight you hold relatively close to the flat disc, you can move it around in a circle say along the inside of the circumference of the disc, then this creates “night” for those portions of the disc outside of its range…
Oddly enough, this might work as a sort of projection to model the actual path of sunlight across a flat projection of a map of the earth.