A path in Photoshop is a closed or open curve segment composed of Bezier curves. Bezier curve is a parametric curve based on "infinite approximation" constructed by PEB of Renault Automobile Company in France in 1962. On the basis of this curve, the curve and surface design system UNISURF has been completed and applied in 1972. Bessel's method combines infinite approximation of functions with set representation, which makes designers draw curves on a computer as handy as using traditional drawing tools. The lines generated when drawing are called paths. A path consists of one or more straight lines or curves. The starting and ending points of line segments are marked by anchor points, just like pins used to fix lines. You can change the shape of a path by editing its anchor point. You can control the curve by dragging a direction point similar to an anchor point at the end of the direction line. The path can be open or closed. For an open path, the starting anchor point of the path is called the endpoint. From the figure, we can see that a Bezier curve is defined by four points, where P0 and P3 define the starting point and ending point of the curve, also called nodes, and P 1 and P2 are the control points for adjusting curvature. The polygon consisting of four points P0, P 1, P2 and P3 is called the control polygon of Bezier curve. By adjusting the nodes P0 and P3, the user can adjust the starting point and end point of Bezier curve, and by adjusting the position of P 1P3, the curvature of the whole Bezier curve can be flexibly controlled to meet the actual needs. At first, beginners in graphics may need some practice to get used to it. Here is a little experience: in general, first adjust the curvature, then adjust the nodes and change the position of the curve to meet the needs. This order can reduce repeated operations. Usually only one Bezier curve is not enough to express a complex curve area. In PHOTOSHOP, in order to construct a complex curve, the method of Bezier curve group is often used, that is, the endpoints of a Bezier curve are connected with each other. A. Connection mode The whole curve consists of a linear Bezier curve (a linear segment connecting the starting point and the ending point). This Bessel curve composition is generally used to outline a polygonal area composed of straight lines. B. The stitching method consists of two quadratic or cubic B curves, and the continuity of A is achieved at the connection point, which is called zero-order geometric continuity. C. The splicing method consists of a whole curve group consisting of a linear Bezier curve and a quadratic or cubic Bezier curve. These two Bezier curves realize B continuity at the intersection, that is, first-order geometric continuity. D. The splicing method consists of two quadratic or cubic B-curves, the main normals when they are connected are on the same straight line, and the curvature at the intersection of the two Bezier curves is the same, that is, the second-order geometric continuity is achieved. Path usage: Photoshop path pen usage animation illustration:/thread-31372-1-1.html Path ultimate tutorial:/thread-7084-1-1.html.