I would like to acknowledge Fernando Goes, who is currently a PhD student at Caltech-USA, for suggesting class design of the PPS class. I am also very grateful to my co-authors and collaborators, Luiz Velho (IMPA-RJ, Brazil), Luis Gustavo Nonato (ICMC-USP, Brazil), Dianna Xu (Bryn Mawr College, USA), Jean Gallier (UPenn, USA), and Dimas Martínez Morera (UFAL, Brazil) for working with me on the development of the theoretical foundations of the PPS and its application to surface modeling.