Reference:Discontinuous Patterns

Some patterns are discontinuous, meaning their slope is infinite. These patterns are not suitable for use as object norms, as objects with discontinuous norms may look odd. These patterns work best for textures and media. They are cells, checker, crackle, hexagon, object, square and triangular.

Note: The cell and crackle patterns are mixed cases, that is, they are discontinuous at their respective boundaries. However, there is no limit to the different number of values, in the range of 0 to 1, that they can generate.