| 摘要: |
| 阴影的生成在体现虚拟现实环境的真实感程度方面起着重要的作用,但现有生成阴影的算法普遍速度较慢,不能适应实时绘制的要求.该文提出了一种基于点光源的实时生成三维阴影的算法.该算法的基本思想是基于在一个复杂的虚拟环境中,某一时段内只有少数多边形相对于光源发生形状的改变，从而导致相应阴影计算的改变，而大多数多边形相对于光源是静态的.这样就有可能针对静态物体与动态物体分别作不同的处理,使尽可能少的多边形参与阴影计算.方法是，先用Tiling方法对静态场景进行预处理,确定相关阴影多边形集合,然后用SVBSP(shad |
| 关键词: BSP树,SVBSP树,tiling,阴影生成,虚拟现实,真实感图形. |
| DOI： |
| 分类号: |
| 基金项目:本文研究得到国家自然科学基金（No.69873044）、国家863高科技项目基金（No.863-306-ZD-10）和Research Grant of University of Macao(RG009/99-00S/WEH/FST）资助。 |
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| A Real-Time Algorithm of 3-D Shadow Generation for Point Light Sources |
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LIU Lie-ming,WU En-hua
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| Abstract: |
| Shadow generation plays an important role in realistic image synthesis, but with the old algorithms, generation of shadows is quite time-consuming and can't be used in a real-time interactive environment. The authors present a new method to produce the real-time shadows for the point light sources in this paper. The algorithm takes advantage of the fact that in many cases, only a small number of polygons in the complex virtual environment change their shape relative to the lights resulting in a corresponding change to the shadow calculation while most of the polygons remain static relative to the lights. So it is possible to process the static and dynamic objects separately and thus make the number of polygons to be calculated as less as possible. The main idea is to prepocess the static scene with “Tiling” method and decide the precise shadow-relative sets, and then use SVBSP method to calculate the dynamic shadows. All the algorithms in this paper are realized in C++, and run on the microcomputer platform of Intel Pentium Ⅱ 400. The experimental results are satisfactory. |
| Key words: BSP tree, shadow volume BSP tree, tiling, shadow generation, virtual reality, realistic graphics. |
