The designer arranges and twists the lines horizontally and vertically to form a regular arrow in the upper and lower directions. It is like a neatly arranged building roof in the city. It is like a window opened by a skyscraper, which makes people feel good. Deep and shallow changes in color and color gradient form realize the light and dark surface of the three-dimensional object, so that the entire two-dimensional square continuous pattern is both regular and full of three-dimensional.