They are quadratic B-splines. These slides describe both (and more) in the same framework: https://www.cs.utexas.edu/users/fussell/courses/cs384g-spring2017/le

They are quadratic B-splines. These slides describe both (and more) in the same framework: https://www.cs.utexas.edu/users/fussell/courses/cs384g-spring2017/lectures/Lecture13-Subdivision_curves.pdf https://www.cs.utexas.edu/users/fussell/courses/cs384g-sprin...