Connecting dots in a Lagrangian way

https://snap.berkeley.edu/snap/snap.html#present:Username=d4s_over_dt4&ProjectName=connect%20the%20dots
d and mouse press to remove dot,drag to reposition dot,e to add dot
Challenge:Can someone make a "connect dots in a gregory way"?
Challenge #2:Try to do art with this.(remember,you can only have one dot in a vertical section/functions are not multivalued)

Also because of the way the "make lagrangian polynomial"(tries to construct function using macros,which are quite slow,and also makes gigantic blocks which are also slow)its quite slow.

《On a wavy day》


-41.42857142857143,22.857142857142858
12.857142857142858,-59.28571428571429
65.71428571428572,22.857142857142858
-92.85714285714286,92.85714285714286
-137.85714285714286,19.28571428571429
-177.14285714285717,-50
-207.14285714285717,29.28571428571429
-240.00000000000003,95
107.14285714285715,92.14285714285715
145.71428571428572,17.142857142857142
188.57142857142858,-62.85714285714286
《The End/Rouge Is Nigh》

-55,55
-4.285714285714286,-54.28571428571429
55.714285714285715,54.28571428571429
-115.71428571428572,-52.142857142857146
-165.71428571428572,57.85714285714286
-220,-62.142857142857146
-235.00000000000003,2.142857142857143
109.28571428571429,-55
167.14285714285717,55.714285714285715
232.14285714285717,-45.714285714285715