The smoothstep function is used all the time in shader creation so I made a video about exactly how this function works, and how to derive it yourself.
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For a more indepth derivation of this function, check out 'Interpolation for Dummies':
https://youtu.be/NO5JGFJJ_Kk
To see what you can do by drawing ONE line after you have folded space, check out this video on the Koch fractals: https://youtu.be/il_Qg9AqQkE