For a class at my university I had to explain the Fourier Analysis to my classmates. So I wrote a simple tool in processing to showcase its uses and implications. Some changes in the curves are animated, since the class required a video at the end. Otherwise that's me, playing around with the mouse.

And yeah, the way I draw the curves is kinda iffy, so I don't get perfect sinus curves, but the math behind them is corrcect.