State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou, 310058, China. humin@cad.zju.edu.cn|State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou, 310058, China. humin@cad.zju.edu.cn|State Key Laboratory of CAD & CG, Zhejiang University, Hangzhou, 310058, China. humin@cad.zju.edu.cn