This paper describes an algorithm that generates lines of varying thickness without any special information about the lines. The thickness is derived from only curvature and lengths from both ends. Therefore the algorithm is applicable in a variety of line rendering situations, for example 3D rendering engine for high quality cel-animation-like effects, reuse of geometrical data designed by CAD for advertising purposes, and photo retouching processes with edge detection methods and so on. In addition, using the generated varying thickness, this paper also describes algorithms for shading and embossing line rendering.