| In the field of computer graphics technique with illusion of reality, fractalmethods are widely applied in simulating nature scenery. Compared with traditionalgeometrical method which simulating nature scenery by means of splicing, fractalmethods use recursion or iteration of rules to generate scenery image, which arefrequently applied in simulating nature scenery, such as mountains, clouds, terrains,et. Many nature sceneries include tree, so simulating of tree become one hotspot ofcomputer graphics technique with illusion of reality. In this paper, simulating3D treeby using fractal methods is principally studied.So far, many fractal methods which simulate3D tree have been presented. AndLS grammar, IFSand fractal recursion are common methods of these, whichsimply make use of fractal structure to realize3D tree. The resultant sculpts are verystiff, short of vitality, and difficult to be under control. In this paper, to overcome thedrawbacks, a3D random fractal tree model is proposed based on the fractalrecursion algorithm and randomicity. At the same time, some key technologies areproposed, such as, using the knowledge of3D revolving transform to calculate theposition of the end point of each branch, and designing one pseudo-randomizerwhich satisfies our requirement.In addition, an extended wind model is presented, which uses wind force, windorientation and the sustained time of wind to control the swings of the tree. Theextended model synthetically uses3D method and2D method to simplify theimplementation of the real scenery of flickering3D tree.Finally, these models are realized by virtue of3D graphical interfaces OpenGL inthe environment of Visual C++. |
