提到Computer Graphics，众所周知的是如OpenGL、Direct3D这样非常流行的光栅化渲染器。事实上，这些大部分应用于游戏制作的API主要为实时渲染（Real-time Rendering）而设置，而它们所采用的光栅化(Rasterization)的渲染方式，通过渲染大量的三角形（或者其他的几何图元种类(Primitive types)），是与本文介绍的光线跟踪相对的一种渲染方式。这种基于光栅化的渲染系统，往往只支持局部照明(Local Illumination)。局部照明在渲染几何图形的一个像素时，光照计算只能取得该像素的信息，而不能访问其他几何图形的信息。(Referring to Computer Graphics, it is well known that raster renderer such as OpenGL and Direct3D is very popular. In fact, most of these applications in game API mainly for real-time rendering (Real-time Rendering) and set up, and they used the grating (Rasterization) rendering, by rendering a large number of triangles (or other types of geometric primitives (Primitive, types)) is a relative and rendering method is introduced in this paper ray tracing. This rasterization based rendering system often supports only partial illumination (Local Illumination). When local illumination is used to render a pixel of the geometric figure, the light calculation can only obtain the information of the pixel, but can not access the information of other geometric figures.)