Use mathematical equations in your scripts!

https://en.wikipedia.org/wiki/Parametric_equation

Kahn academy explanation (if you don´t remember it from high school):

Here´s some curves and also spheres in carthesian and polar coordinates:

09 - Mathematics And Geometry - Polar-Carthesian

And, of course, the funny Crazy polar curve! (Try to create your own equations!):

Crazy_polar_curve

Also, check out some old works from previous students here: http://scripting.cadzone.cz/