let's assume there are only three angles and no curves
In Euclidean geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in the plane that contains the rays. Angles are also formed by the intersection of two planes. These are called dihedral angles. Two intersecting curves may also define an angle, which is the angle of the rays lying tangent to the respective curves at their point of intersection.
My first interaction with type design, also in that same representation methods typeface design class by Sandra Winter.
Kaspar is based on the concept of creating a typeface based on 0, 45 and 90° Angles and no curves.