直接光是从光源出发，直接照射到物体表面，由于物体问的遮挡和光源照射范围等因素，直接光照变化非常剧烈，分布很不均匀。而间接光照是由直接光照射到物体表面后，经过多次反射、折射产生的，因此。每个方向都有来自环境的间接光照，而且在空间的分布比较均匀，没有剧烈的变化，属于光照中的低频成分。由直接光照和间接光照产生的物体表面的光照效果可以统一表示为-Just starting directly from the source, direct exposure to the surface, due to object occlusion and asked range of factors such as light exposure, direct sunlight is very dramatic changes in the distribution is very uneven. Indirect illumination by direct light shines on the surface, after multiple reflections, refraction generated, so. Each direction from the environment, indirect light, but also more evenly distributed in space, there is no drastic change in the low-frequency components are light. By direct illumination and indirect illumination light generated by the surface effects can be expressed as a unified