三角网格上高斯曲率和平均曲率
ref:https://www.cnblogs.com/eat-too-much/p/12595574.htmlhttps://computergraphics.stackexchange.com/questions/1718/what-is-the-simplest-way-to-compute-principal-curvature-for-a-mesh-triangle同学的CSDN博客 https://blog.csdn.net/qq_38517015/article/details/1
