基于GPU的风中树木物理动画

Physical animation of trees in wind based on GPU

采用非均匀梁作为树枝物理模型,分析了梁的弯曲效应,推导出挠度曲线表达式,并对其运用多项式最小二乘法拟合,将拟合后的简洁表达式预计算于纹理中,有效降低了实时计算量。为平衡CPU与GPU的负载,设计了分层次的树木结构模型,将力学分析计算转移到GPU上进行,同时避免了将树枝分段计算导致段间断裂现象及分段过大引起模拟效果过于粗糙的缺点。实验表明,该方法能完全实时、真实地模拟出风中树木动画的物理效果,解决了目前树木物理动画速度太慢不能实时模拟的不足。

This paper introduced a new real-time tree animation method that was both significantly faster and more physically plausible than previous methods. Taking physical model of branches as linearly tapered circular beam,analyzed its bending effect and derived the expression of its deflection curve. To enhance computational efficiency,performed a least square fit to the deflection curve equation and then pre-computed its value to 2D-texture which was accessed by GPU run-time. To balance the load on CPU and GPU,this paper designed a hierarchical tree structure model that transfered all the mechanical analysis and calculation to GPU,meanwhile,avoided to segment a branch to model its deformation behavior. Experiments show that the presented method can be completely real-time,realistically simulate the tree in wind,solving the problem of current method in literature that cannot simulate the physical real-time animation of tree in wind.