基于粒子系统的雪景模拟

发布时间：2018-11-08 08:44

【摘要】：大自然中的诸多景象如云、雪、烟等不是简单的可以用数字化表示的,这些自然景物运动规律时刻都在变化,形状、颜色等属性也会随着运动规律的变化而变化。随着图形学的发展和游戏产业的需求日益提高,不仅对模拟显示画面的真实感有了更高的要求,作为虚拟现实的一部分,景物与环境间交互作用的研究也是很重要的,如何有效、实时地模拟自然景物是图形学研究的关键。雪景是人们广为熟知的一种自然景象,在影视特效、电视广告、电子游戏中有着不可或缺的地位,尤其是在雪灾的预防中,雪景的模拟有着积极的意义。雪景作为自然场景的一部分,得到了越来越多的学者的青睐和研究。现有模拟雪景的方法不是以牺牲实时性为代价就是以牺牲逼真性为代价,为了实现雪景模拟真实性与实时性的统一取得较为理想的结果,本文提出了基于粒子系统和物理模型的动态雪景模拟算法,在保证系统实时性的情况下实现更为逼真的雪景模拟。 (1)建立雪粒子系统模型。在粒子系统运行原理基础上,结合雪花本身特点完成雪粒子系统的分析和实现过程,包括雪粒子各属性的研究和相关属性更新方法等。采用纹理映射技术和公告板技术优化、完善雪粒子的绘制工作,实现了基于公告板的雪花绘制,并提出了重置死亡粒子的方法。 (2)设计了灵活的雪花物理运动模型。本文考虑了重力、浮力、向心力等对降雪的影响,在分析了外力影响下雪花飘落的运动规律后构造出其运动方程,并把向心力作为可供选项随机赋予粒子,随力场的改变实时地更新雪花的速度、位置数据,解决了粒子下落过程中运动轨迹单一的问题,体现出自然界中雪花降落来回摇曳、飘忽不定的运动特性。 (3)设计了雪花的碰撞检测模块。分析了雪花碰撞的两种情况并提出了每种情况下雪花碰撞后的速度和位置更新方法,通过位置和速度的改变表现出雪花与其他虚拟物体之间发生的碰撞关系。 (4)提出了将高度作为雪堆积的依据,通过场景中物体高度的变化量绘制雪的堆积,并用概率的方法衡量某处的堆积是否稳定。最后,对模拟系统的实时性优化方法做了讨论,并利用OpenGL提供的渲染功能完成了实时性保证下的真实感雪景的模拟。
[Abstract]:Many scenes in nature, such as clouds, snow, smoke and so on, can not be simply represented by digitization. These natural scenery moving laws are changing at all times, shape, color and other attributes will also change with the change of motion law. With the development of graphics and the increasing demand of the game industry, there is not only a higher demand for the realistic sense of the simulated display screen, but also an important research on the interaction between scene and environment as a part of virtual reality. How to simulate natural scene effectively and in real time is the key of graphic research. Snow scene is a kind of natural scene widely known to people. It plays an indispensable role in film and television special effects, TV advertisements and video games, especially in the prevention of snow disaster, the simulation of snow scene has a positive significance. As a part of natural scene, snowscape has been favored and studied by more and more scholars. The present methods of snow scene simulation are either at the expense of real time or at the expense of realism. In order to achieve the unity of simulation authenticity and real time of snow scene, the ideal results are obtained. A dynamic snow scene simulation algorithm based on particle system and physical model is proposed in this paper. (1) the model of snow particle system is established. On the basis of the operation principle of particle system, the analysis and implementation process of snow particle system is completed according to the characteristics of snowflake, including the research of snow particle properties and the updating methods of related attributes. The texture mapping technique and bulletin board technology are used to optimize the snow particle rendering. The snowflake rendering based on the bulletin board is realized and the method to reset the dead particle is proposed. (2) A flexible physical model of snowflake motion is designed. In this paper, the effects of gravity, buoyancy and centripetal force on snowfall are considered. After analyzing the motion law of snowflake falling under the influence of external force, the motion equation of snowflake falling is constructed, and the centripetal force is randomly assigned to the particle as the available option. With the change of force field, the velocity and position data of snowflakes are updated in real time, which solves the problem of single track in the falling process of particles, and reflects the moving characteristics of snowflakes falling back and forth in nature. (3) the collision detection module of snowflake is designed. Two cases of snowflake collision are analyzed and the updating method of velocity and position after snowflake collision in each case is proposed. The collision relationship between snowflake and other virtual objects is shown by changing the position and velocity. (4) the height is taken as the basis of snow accumulation, and the snow accumulation is plotted by the change of object height in scene, and the stability of snow accumulation is measured by the method of probability. Finally, the real-time optimization method of the simulation system is discussed, and the simulation of the realistic snow scene under the real-time guarantee is completed by using the rendering function provided by OpenGL.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TP391.9

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