Extrinsically smooth direction fields

Extrinsic - Zhiyang Huang (2016) ------------------------------------ This code implements the algorithm described in Huang Z, Ju T. Extrinsically smooth direction fields. Comput Graph(2016), http://dx.doi.org/10.1016/j.cag.2016.05.015i The basic function of this program is to compute extrinsically smooth direction fields “g” upon a curve, surface or volume while giving a references field “f”, such that “g” is orthogonal to “f”. In particular, the default setting of “f” for curve and surface are tangent field of the curve and normal field of the surface, respectively. The parameter-free initialization method based on least eigenvector problem and the Gauss–Seidel iterations, as described in the above paper, are implemented in this code and subjected to use. Currently the code is only tested on Mac OS X 10.10 or above, it should work at other platforms with minor modification.外禀平滑方向场——黄志阳（Zhiyang Huang，2016） ------------------------------------ 本代码实现了黄志阳（Zhiyang Huang）与朱涛（Tao Ju）于2016年发表在《计算机图形学（Comput Graph）》的论文《外禀平滑方向场（Extrinsically smooth direction fields）》中的算法，原文DOI链接：http://dx.doi.org/10.1016/j.cag.2016.05.015。 本程序的核心功能为：在给定参考场“f”的前提下，于曲线、曲面或体域上计算外禀平滑方向场“g”，且保证“g”与“f”正交。其中，针对曲线与曲面的默认参考场“f”分别为曲线的切向场与曲面的法向场。 本代码实现了上述论文中提及的、基于最小特征向量问题的无参数初始化方法，以及高斯-赛德尔（Gauss–Seidel）迭代算法，可直接投入使用。 目前本代码仅在Mac OS X 10.10及以上版本中完成测试，经少量修改后即可在其他平台上运行。