The Flot FillBetween plugin works nicely with line charts. However I need to smooth out the lines and make them more curvy. I have seen the CurvedLined plugin and the Spline plugin but both do not work properly with the fillbetween plugin.
Is there any way to use a two curved line/Spline series and fill the area between them? Something like the image below. Also fills any enclosed area between the two series any time when one crosses the other.
I am unfamiliar with the FillBetween plug-in. I am going to focus on aswering the smoothing part. I had a similar problem where those smoothing options did not work for me either. I used an external plug-in to make the smoothing. It's name is smooth.js and it worked for me. Smooth.js recives the data array and returns a function. To get a "smoothed point", apply the function to any value between 0 and the length of the array. The idea is to obtain more points than the original dataset.
For example, to smooth an array of values named test:
I made a JSFiddle with this example. You can use this plug-in and pass the smoothed data to flot and then use the FillBetween.