一种真实感雪场景模拟方法

探讨已有降雪和积雪模拟方法，针对粒子系统难以同时兼得真实性与实时性的问题，提出一种真实感较强的雪场景实时绘制算法。算法用矩形基本粒子进行纹理叠加映射来建模雪粒子，用温度调节控制雪粒子大小及雪密度大小，归一化生命周期并用于颜色混合。飘雪阶段，引入层次细节(LOD)技术，根据雪粒子真实受力特点模仿其运动过程，并将其受力全面综合考虑并简化，提高降雪模拟效果真实度，并降低计算复杂度。积雪阶段，获取场景模型暴露面及其高度场，以暴露面中点的高度及其点坐标为基础，得到雪粒子落地位置，进而模拟积雪高度变化效果；将整个地面作为地面雪粒子发射器，模拟积雪融化效果，提高真实性。

Method of simulating realistic snow scene

The particle system can hardly simulate the natural features effectively and real-time at the same time. Based on the analysis of traditional simulation methods, a real-time rendering algorithm was presented. The algorithm used rectangular elementary to simulate snow particles，added texture mapping based on superposition，normalized snow lifecycle for color blending，and regulated the size of snow particle and snow density according to the size of temperature. In the snow-falling stage, this algorithm introduced Level Of Detail (LOD) technology, imitated the movement effect according to the whereabouts of the snow particles moving force characteristics, took the force comprehensive consideration and simplified to reduce the computational complexity and improve the snow simulation authenticity.In the snow-accumulating stage, this method obtained the exposed surface of the scene model and its height field. And then based on a point coordinates and the point height in the field in a plane, it got the position of snow particles steadily to simulate the height change effect. This new method used the whole surface as ground-object emitter and superimposed the corresponding particle texture to improve authenticity.