Thanks for this cool plugin.
I tried this with my midi piano vst to increase a line from 0 to 100% size based on the volume.
I don't know if the way it responds is due to the differences in absolute volume versus the way humans perceive volume, but it seems that the very softest sounds I can produce on my piano result in a line length of 50% or more, and the very loudest are close to 100%. I can reach the 100% with my loudest transients (the initial attack), but can never reach less than 50% with my softest transients. If I hold the note, it will eventually diminish in size down to zero, but not with the initial attack.
It might be interesting to have an option to specify the amount of scale to be applied across the spectrum, such as the way some photo editing software and some midi software allow one to specify a response curve which map input values to output values...
Or maybe an option to respond to transients only... but that might be difficult when many notes are playing at once...