Abstract: How to simulate fast and realistically tree swaying in wind is still a great challenge topic in computer graphics.This paper addresses deformation of tree swaying by presenting a new method which combines fractal with physical mechanics deformation.First this method models trees by fractal，and then gives a wind model by simulating wind field based on its power and characteristics of the hierarchical structure tree.Finally the deformation of tree swaying is further simulated based on the principle of physical mechanics.Many experiments with this new method illustrate that animations of tree swaying in wind can be fast and easily realized，and that various states of trees are naturally generated.

Key words: fractal, 3D L system, recursion algorithm, tree, swaying

摘要： 如何真实且快速地模拟树在风中的自然摇曳是计算机图形学中一个非常具有挑战性的问题。针对树在风中的摇曳变形，提出了一种将分形技术和物理力学变形技术相结合的方法。该方法首先利用分形技术建立了树木模型，然后根据风力级数的强弱模拟风场，并结合树的层次结构特点，给出了风力模型，在此基础上根据物理力学原理进一步模拟了树的摇曳变形。实验表明，用该算法模拟树在风中的摇曳，可以简便快速地得到效果较好的动画系列画面，生成的树木逼真且多姿多态。

关键词: 分形, 三维L系统, 递归算法, 树, 摇曳