Fake Lighting, Clamped Values

Hey everyone.
Im trying to create a sort of fake lighting in which an area is either 100% lit or 0% lit. Basically, I dont want Lighting to be gradient in any way.

Im starting to reach some result using Vertexnormal in a dot product with a fake light vector but I dont understand it that well and im mostly going by trial and mistakes…

Anyone has an idea how to simulate this flattened lighting?