Bitmap first draws some points on the paper. The size of points is not important, but if you want to draw better, draw with the same size, equal spacing and even arrangement. Then two adjacent points are connected by arcs, which can be drawn horizontally or vertically. However, it should be noted that after drawing an arc between two points, two adjacent points in a row or column should also draw an arc accordingly. The bending directions of two arcs are opposite or opposite, and the bending directions of two adjacent arcs at the same point must also be opposite. When finished, each point is connected by a horizontal and vertical arc, and then the shadow of the line is added along the direction of the horizontal and vertical arc. Finally, smear all these shadows evenly, and you can get a painting with obvious 3D visual effect.