Shader is one of the important component of mental ray. Let me tell about it a bit. A shader is a program code fragment that computes how light interacts with objects. This was the original concept of shader in early computer graphics time and nowadays the role of shader and its meaning are expanded. In one of the common scenario in computer graphics, objects are usually represented as polygons. First, the intensity of each vertex is computed, then inside the polygon is filled by an interpolation method. This becomes more complex as the computer graphics technology developed. There were two shader development directions. One is a hardware rendering that concentrates rendering speed and interactivity. The other is a software rendering that concentrates the image quality. Nowadays graphics hardware is called GPU (Graphics Processing Unit). The early stage GPU has fixed functionalities. Because fixed functionality can be achieved more performance in practice. The implementation was based